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291 Cards in this Set
- Front
- Back
- 3rd side (hint)
The radiograph illustrated in the figure below was made using a single-phase, full-wave-rectified unit with a timer and rectifiers that are known to be accurate and functioning correctly. What exposure time was used to produce this image?
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When a spinning top is used to test the timer efficiency of full-wave-rectified single-phase equipment, the result is a series of dots or dashes, with each dot representing a pulse of radiation. With full-wave-rectified current and a possible 120 dots (pulses) available per second, one should visualize 12 dots at 1/10 second, 6 dots at 0.05 second, 10 dots at 1/12 second, and 3 dots at 0.025 second. Because three-phase equipment is at almost constant potential, a synchronous spinning top must be used for timer testing, and the result is a solid arc (rather than dots). The number of degrees covered by the arc is measured and equated to a particular exposure time. (Selman, 9th ed., p. 106)
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What are the advantages of photospot camera imaging over cassette spot imaging during fluoroscopy?
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Lower patient dose
Less interruption of the fluoroscopic examination |
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When the radiographer selects kilovoltage on the control panel, which device is adjusted?
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Autotransformer
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Because the high-voltage transformer has a fixed ratio, there must be a means of changing the voltage sent to its primary coil; otherwise, there would be a fixed kVp. The autotransformer makes these changes possible. When kVp is selected on the control panel, the radiographer is actually adjusting the autotransformer and selecting the amount of voltage to send to the high-voltage transformer to be stepped up. The filament circuit supplies the proper current and voltage to the x-ray tube filament for proper thermionic emission. The rectifier circuit is responsible for changing AC to unidirectional current. (Selman, 9th ed., pp. 88–89)
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Which of the following causes pitting, or many small surface melts, of the anode's focal track?
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Repeated, frequent overloading
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To be used more efficiently by the x-ray tube, alternating current is changed to unidirectional current by the
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rectifiers.
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The advantage(s) of collimators over aperture diaphragms and flare cones include
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the variety of field sizes available.
more efficient beam restriction. |
There are three types of beam restrictors: aperture diaphragms, cones and cylinders, and collimators. The most practical and efficient type is the collimator. Its design makes available an infinite number of field size variations that are not available with the other types of beam restrictors. Because aperture diaphragms and flare cones have a fixed aperture size and shape, their beam restriction is not as efficient as that of the variable-size collimator. Aperture diaphragms, cones, and cylinders may be placed on a collimator track so that the illuminated crosshairs are visualized. Although the collimator assembly contributes approximately 1.0 mm Al equivalent to the added filtration of the x-ray tube (because of the plastic exit portal and silver-coated reflective mirror), its functions are unrelated to the cleanup of scattered radiation. This is because the patient is the principal scatterer, and grids function to clean up scattered radiation generated by the patient. (Bushong, 8th ed., pp. 241–243)
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When the radiographer selects kilovoltage on the control panel, which device is adjusted?
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Autotransformer
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Because the high-voltage transformer has a fixed ratio, there must be a means of changing the voltage sent to its primary coil; otherwise, there would be a fixed kVp. The autotransformer makes these changes possible. When kVp is selected on the control panel, the radiographer is actually adjusting the autotransformer and selecting the amount of voltage to send to the high-voltage transformer to be stepped up. The filament circuit supplies the proper current and voltage to the x-ray tube filament for proper thermionic emission. The rectifier circuit is responsible for changing AC to unidirectional current. (Selman, 9th ed., pp. 88–89)
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Which of the following causes pitting, or many small surface melts, of the anode's focal track?
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Repeated, frequent overloading
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To be used more efficiently by the x-ray tube, alternating current is changed to unidirectional current by the
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rectifiers.
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The advantage(s) of collimators over aperture diaphragms and flare cones include
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the variety of field sizes available.
more efficient beam restriction. |
There are three types of beam restrictors: aperture diaphragms, cones and cylinders, and collimators. The most practical and efficient type is the collimator. Its design makes available an infinite number of field size variations that are not available with the other types of beam restrictors. Because aperture diaphragms and flare cones have a fixed aperture size and shape, their beam restriction is not as efficient as that of the variable-size collimator. Aperture diaphragms, cones, and cylinders may be placed on a collimator track so that the illuminated crosshairs are visualized. Although the collimator assembly contributes approximately 1.0 mm Al equivalent to the added filtration of the x-ray tube (because of the plastic exit portal and silver-coated reflective mirror), its functions are unrelated to the cleanup of scattered radiation. This is because the patient is the principal scatterer, and grids function to clean up scattered radiation generated by the patient. (Bushong, 8th ed., pp. 241–243)
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One thousandth of an ampere would be referred to as what
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Milliampere
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How many centimeters are in an inch?
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2.54
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How many pounds are in a kilogram?
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2.2
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The flow of electrons is known as what?
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The flow of electrons is known as current. It is determined by the voltage and the resistance in the conductor.
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Focal spot blur is greatest
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toward the cathode end of the x-ray beam
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As the image intensifier's FOV is reduced, how is the resulting image affected?
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Magnification increases
Brightness decreases Quality increases |
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The brightness level of the fluoroscopic image is dependent on
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1.
milliamperage. 2. kilovoltage. 3. patient thickness |
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Which of the following devices is used to control voltage by varying resistance?
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Rheostat
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The line focus principle refers to the fact that
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the actual focal spot is larger than the effective focal spot.
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Off-focus, or extrafocal, radiation may be minimized by
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restricting the x-ray beam as close to its source as possible.
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Rare earth phosphors that may be used in intensifying screens include
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2.
gadolinium oxysulfide. 3. lanthanum oxybromide. |
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The image intensifier's input phosphor is generally composed of
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cesium iodide.
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Congruence of the x-ray beam with the light field is tested using
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radiopaque objects.
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A star pattern is used to measure
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focal spot resolution.
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Which of the following will occur as a result of a decrease in the anode target angle?
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Decreased effective focal spot size
Greater photon intensity toward the cathode side of the x-ray tube |
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Disadvantages of moving grids over stationary grids include which of the following?
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They can prohibit the use of very short exposure times.
They increase patient radiation dose. |
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The line focus principle expresses the relationship between
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actual and effective focal spot.
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What is it called when a current is induced in a secondary coil by simply changing the current in the primary coil?
A. Back EMF |
Mutual induction
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Mutual means sharing, induction means to bring about. Mutual induction shares the power in the primary coil to bring about a current in the secondary coil. This setup is called a transformer.
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What are the particles called that continuously circle the nucleus of an atom?
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Electrons
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An electron has a mass of 9.1 x 10 to the -31st kg and a negative charge of 1.6 x 10 to the -19th coulombs.
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What is the unit for radiation exposure in air?
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Roentgen
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The roentgen is defined as the number of x or gamma rays required to produce 2.58 x 10-4 coulombs of charge in 1 kilogram of air.
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As the wavelength of an x ray increases, what happens to its frequency?
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Decreases
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Wavelength and frequency are inversely proportional. As one increases the other decreases. Higher energies produce higher frequencies which produce shorter wavelengths.
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Which of the following describes an electron?
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Mass and negative charge
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An electron has a mass of 9.1 x 10 to the -31st kg and a negative charge of 1.6 x 10 to the -19th coulombs.
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Which of the following is equal in all electromagnetic radiations?
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Speed
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All electromagnetic radiation, which includes x rays, gamma rays, microwaves, visible light, radar, radio, etc. travel at the speed of light.
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Which of the following is a byproduct of photoelectric absorption?
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Photoelectron
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Other byproducts of photoelectric absorption would be an ionized atom and secondary characteristic radiation.
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In the normal diagnostic range, what is the wavelength range of the x rays?
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.1 to .5 angstroms
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25 keV will produce x rays with wavelengths of .5 angstroms, 125 keV will produce x rays with wavelengths of .1 angstroms.
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What characterizes the Compton effect?
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Recoil electron
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The Compton effect produces a recoil electron, scatter photon, ionized atom and secondary characteristic radiation.
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Which of the following is responsible for most of the scatter radiation in the diagnostic range?
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Compton effect
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Photoelectric absorption totally absorbs the photon, nothing is left to scatter. Bremsstrahlung radiation makes up the primary beam before it scatters.
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Which of the following has the greatest effect on radiographic contrast?
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Compton effect
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Scatter radiation fogs the radiographic image which lowers the radiographic contrast. Lowering kVp will reduce the probability the Compton effect will take place.
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How many electrons may occupy the M-shell of an atom?
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18
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The formula 2n squared is used to determine how many electrons will fit into an atom's shell. n = the number of the shell. M is the third shell (K,L,M,N,O,P). Therefore, 2 times 3 squared (9) equals 18.
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Which of the following interactions does NOT occur under 125 kVp?
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Pair production
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Pair production requires an x ray to have 1.02 MeV of energy to produce a positron and electron.
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How can voltage be induced into a conductor?
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1. Move a wire through a magnetic field
2. Move a magnetic field across a wire 3. Place a wire in a varying magnetic field |
An English physicist, Michael Faraday, discovered that electricity could by produced by any of the above methods.
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If the voltage is stepped-up, what happens to the current in the secondary side of the transformer?
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Decreases
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Since energy can neither be created nor destroyed, when the voltage is stepped-up, because of the transformer ratio, the current must decrease to maintain the same power on both sides.
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How many angstroms are in a meter?
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10,000,000,000
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1 angstrom equals 1 x 10 to the -10th meters, or there are 10 billion angstroms in a meter.
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Which of the following describes a proton?
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Mass and positive charge
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A proton has a mass of 1.67 x 10 to the -27th kg and a positive charge of 1.6 x 10 to the -19th coulombs.
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What determines the wavelength of an x ray?
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Kilovoltage
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Energy determines the wavelength of an x ray. A high energy produces a high frequency which results in a short wavelength. Kilovoltage controls the energy.
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Which of the following refers to the number of electrons in the outer shell of an electron?
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Valence number
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The number of outer shell electrons determines how the atom will bond with other atoms to form molecules.
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Materials that are difficult to magnetize and demagnetize are said to have a high _______.
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Retentivity
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Materials that are difficult to magnetize will retain their magnetization, hence the term retentivity (retention).
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What type of bond holds atoms together by sharing their outer electrons?
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Covalent
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Outer shell electrons are called valence electrons. When atoms form a bond by sharing their valence electrons they are known as covalent bonds
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In the normal diagnostic range, which of the following interactions will occur most often?
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Compton effect
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The normal diagnostic range of x rays is between 25 keV and 125 keV. Because of these high energies, few of the x rays are absorbed, most of them are scattered
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How are alternating current values usually expressed?
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RMS values
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RMS stands for root, mean, square. It is the method of determining the effective voltage that is obtained when an alternating current's voltage continuously changes.
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The mass number of an atom is equal to which of the following?
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The number of protons and neutrons
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The number of protons and neutrons in the nucleus of an atom determines that atom's mass number.
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If a neutral atom has an atomic number of 10, then how many electrons will it have?
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10
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For an atom to be neutral, it has to have the same number of positive charges (protons = atomic number) as negative charges (electrons).
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What is the energy called that attracts the electrons to the nucleus of an atom?
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Binding energy
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The attraction force of the positively charged protons in the nucleus binds (holds secure) the negatively charged electrons near the nucleus.
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What is the unit of electrical power?
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Watt
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The watt is defined as one ampere of current flowing through one volt of potential difference per second.
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What type of transformer has more turns of wire in the secondary side than in the primary side?
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Step-up
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Since there are more turns of wire in the secondary coil than the primary coil the voltage will be increased. That is why it is called a step-up transformer.
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The quality of an x-ray beam refers to what?
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Energy of x rays
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An x-ray beam is identified by its quantity and quality. Quality refers to the amount of energy (keV) the x rays have.
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What are charged atoms called?
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Ions
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When an atom has more electrons than protons it will have a negative charge. When it has less electrons than protons it will have a positive charge. These charged atoms are called ions.
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What is it called when a primary photon changes direction but not energy?
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Coherent (classical) scatter
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Coherent (classical) scatter occurs when low energy x rays (below 10 keV) interact with outer-shell electrons.
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Exposures made at 100 mA, 200 mA, and 300 mA produced mR reading of 40 mR, 76 mR, and 126 mR respectively. Does this pass the mA linearity test?
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Yes
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In this case the 100 mA station produced .4 mR/mAs, the 200 mA station was .38 mR/mAs, and the 300 mA station was .42 mR/mAs. All are within the required +/- 10% of each other.
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Which of the following subatomic particles is the largest?
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Neutron
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A neutron is made up of a positive proton and a negative electron. That is why it is largest, plus why it has a neutral charge.
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Which of the following will NOT reduce the intensity of an x-ray beam?
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Characteristic effect
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The characteristic effect is a means of producing an x-ray beam. The intensity of the beam will be reduced by the Compton effect, photoelectric absorption and pair production.
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Maximum induction will occur when a conductor cuts a magnetic field at what angle?
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90 degrees
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When a wire cuts through a magnetic field at a 90 degree angle the forces exerted on the electrons in the wire will be the greatest.
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What is the unit of electrical current?
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Ampere
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1 ampere is defined as 1 coulomb of charge passing a point in a conductor per second. 1 coulomb = 6.3 x 10 to the 18th electrons.
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What are materials called that are weakly attracted to a magnet?
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Paramagnetic
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Paramagnetic materials have an odd number of electrons in their atoms, but most of the electron's spins cancel each others' magnetic effects. Aluminum is paramagnetic.
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Which of the following electromagnetic waves has the shortest wavelength?
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X ray
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The higher the energy, the shorter the wavelength. From shortest to longest wavelength: x ray, ultraviolet, visible light, radar.
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Which of the following pertains to atoms that have their outer electron shell completely filled?
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Chemically inert
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Atoms with their outer shells filled are found in the eighth column on the periodic chart and are referred to as inert gases. They are inert because they do not readily combine with other atoms.
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A material that disallows the flow of electrons is known as what?
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Insulator
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An insulator is made of a material whose electrons are tightly bound to their nuclei, inhibiting them from creating a current.
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Which particle in the nucleus of an atom has no charge?
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Neutron
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The neutron has no charge because it is made up of a positive proton and a negative electron. The positive and negative charges cancel each other.
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Which of the following would be found in the nucleus of an atom?
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1. Proton
3. Neutron |
Protons and neutrons are in the nucleus. Electrons orbit around the nucleus.
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What is the unit of capacitance?
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Farad
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The farad is defined as the amount of charge per volt that can be stored on a metal plate. C = q/v, where C = capacitance in farads, q = charge and v = volts.
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What is the unit for resistance?
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Ohm
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The ohm represents the characteristics of a material that inhibits the flow of electrons. It is determined by the length, diameter and type of conductor.
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2 ohm, 4 ohm and 6 ohm resistors connected in series would result in a total resistance of how many ohms?
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12
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Resistors connected in series are simply added together to find the total resistance. Rt = R1 + R2 + R3 + R . . . .
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According to Ohm's law, what would the voltage be if the resistance is 2 ohm and the current is 4 ampere?
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8 volt
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Ohm's law states V = IR. Therefore, V = 4 x 2 or 8 volt.
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If an atom obtains an additional electron, what kind of charge will that ion have?
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Negative
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If an atom obtains an additional electron it will have more negative charges than positive charges. This charged atom is known as a negative ion.
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Parallel resistors of 3 ohm and 6 ohm would result in a total resistance of how many ohm?
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2
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The reciprocal of the resistors connected in parallel are added together to find the total resistance. 1/Rt = 1/R1 + 1/R2 + 1/R3 . . . . A rule to remember is that the total resistance of a parallel circuit is always going to be less than the least resistor. In this question, the total resistance must be less than 3 ohm.
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According to Ohm's law, what would the current be if the voltage is 12 volt and the resistance is 1.5 ohm?
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8 ampere
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Ohm's law states I = V/R. Therefore, I = 12/1.5 or 8 ampere.
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Which of the following is equal to one volt?
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1 Joule/Coulomb
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A volt is defined as the work done on a charged particle. Its formula is V = W/Q. The unit for work (W) is the joule and the unit for charge (Q) is the coulomb.
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The atomic number of an atom is equal to which of the following?
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Number of protons
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The number of protons in the nucleus of an atom determines that atom's atomic number.
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How do fractionation and protraction affect radiation dose-effects?
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1. They reduce the effect of radiation exposure.
2. They permit cellular repair. 3. They allow tissue recovery. |
Fractionation and protraction influence the effect of radiation on tissue. Larger quantities, of course, increase tissue effect. The energy (quality, penetration) of the radiation determines whether the effects will be superficial (erythema) or deep (organ dose). Certain tissues (such as blood-forming organs, the lens, and the gonads) are more radiosensitive than others (such as muscle and nerve). If the dose is delivered in portions (fractionation), and/or delivered over a length of time (protraction), the less the tissue effects. (Bushong, 8th ed., p. 496)
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The radiation dose to an individual is dependent on which of the following?
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1. Type of tissue interaction(s)
2. Quantity of radiation 3. Biologic differences |
Photoelectric interaction in tissue involves complete absorption of the incident photon, whereas Compton interactions involve only partial transfer of energy. The larger the quantity of radiation and the greater the number of photoelectric interactions, the greater the patient dose. Radiation dose to more radiosensitive tissues, such as gonadal tissue or blood-forming organs, is more harmful than the same dose to muscle tissue. (Bushong, p 197)
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Stochastic effects of radiation are those that
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2. may be described as "all-or-nothing" effects.
3. are late effects. |
Late effects of radiation can occur in cells that have survived a previous irradiation months or years earlier. These late effects, such as carcinogenesis and genetic effects, are "all-or-nothing" effects—either the organism develops cancer or it does not. Most late effects do not have a threshold dose; that is, any dose, however small, theoretically can induce an effect. Increasing that dose will increase the likelihood of the occurrence, but will not affect its severity; these effects are termed stochastic. Nonstochastic effects are those that will not occur below a particular threshold dose and that increase in severity as the dose increases. (Bushong, 8th ed., p. 532)
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A radiolucent contrast agent
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2. causes anatomy to appear dark on the radiograph.
3. is composed of elements with low atomic numbers. |
The term radiolucent refers to a material through which x-rays will pass easily. Contrast agents such as barium and iodine are radioopaque; an example of a radiolucent contrast agent is air. Radioopaque contrast agents appear white on the finished image because many x-ray photons are absorbed by the dense agent. Radiolucent contrast agents appear black on the finished image because x-ray photons pass easily through. (Shephard, pp 200–202)
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When an image intensifier's magnification mode is used
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resolution increases.
3. patient dose increases. |
During fluoroscopic procedures, as FOV decreases, magnification of the output screen image increases and contrast and resolution improve. The focal point on an image intensifier's 6-inch field/mode, is further away from the output phosphor than the focal point on the normal mode; therefore, the output image is magnified. Because less minification takes place, the image is not as bright. Exposure factors are automatically increased to compensate for the loss in brightness that occurs with smaller FOVs used in magnification mode. (Fosbinder, p 285)
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Which of the following will result as tube current increases?
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An increase in x-ray photon quantity
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The four primary exposure factors are current (expressed in mA/milliamperes), exposure time, kilovolt peaks (kVp), and source to image receptor distance (SID). Tube current is described as the flow of electrons between cathode and anode. The greater the number of electrons, the greater the tube current, the greater the mA, and the greater the number (quantity) of x-ray photons produced. Photon quality (energy, penetration, wavelength) is regulated by kilovoltage. Tube current has no effect on photon quality. (Bushong, 8th ed, pp 162, 265)
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The operation of personal radiation monitoring can be based on stimulated luminescence. Which of the following personal radiation monitors
function(s) in that manner? |
1. OSL
2. TLD |
Occupationally exposed individuals are required to use devices to record and document the radiation they receive over a given period of time, traditionally 1 month. The most commonly used personal dosimeters are the OSL, the TLD, and the film badge. These devices are worn only for documentation of occupational exposure, not for any medical or dental x-rays received as a patient. TLDs are personnel radiation monitors that use lithium fluoride crystals. Once exposed to ionizing radiation and then heated, these crystals give off light proportional to the amount of radiation received. OSL dosimeters are personnel radiation monitors that use aluminum oxide crystals. These crystals, once exposed to ionizing radiation and then subjected to a laser, give off luminescence proportional to the amount of radiation received. The pocket dosimeter contains an ionization chamber (containing air), and the number of ions formed (of either sign) is equated to exposure dose. (Bushong, 8th ed., p. 594)
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The advantages of beam restriction include the following:
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1. less scattered radiation is produced.
2. less biologic material is irradiated. |
With greater beam restriction, less biologic material is irradiated, thereby reducing the possibility of harmful effects. If less tissue is irradiated, less scattered radiation is produced, resulting in improved IR contrast. The total filtration is not a function of beam restriction, but rather is a radiation protection guideline aimed at reducing patient skin dose. (Selman, 9th ed., p. 247)
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In the production of characteristic radiation at the tungsten target, the incident electron
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ejects an inner-shell tungsten electron.
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Characteristic radiation is one of two kinds of x-rays produced at the tungsten target of the x-ray tube. The incident, or incoming, high-speed electron ejects a K-shell tungsten electron. This leaves a hole in the K shell, and an L-shell electron drops down to fill the K vacancy. Because L electrons are at a higher energy level than K-shell electrons, the L-shell electron gives up the difference in binding energy in the form of a photon, a "characteristic x-ray" (characteristic of the K shell). (Selman, 9th ed., p. 115)
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Which of the following affect(s) both the quantity and quality of the primary beam?
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1. Half-value layer (HVL)
2. kVp |
Kilovoltage (kVp) and half-value layer (HVL) change both the quantity and quality of the primary beam. The principal qualitative factor of the primary beam is kVp, but an increase in kVp will also effect an increase in the number of photons produced at the target. HVL is defined as the amount of material necessary to decrease the intensity of the beam to one half of its original value, thereby effecting a change in both beam quality and quantity. The mAs value is adjusted to regulate the number of x-ray photons produced at the target. X-ray beam quality is unaffected by changes in mAs. (Bushong, 8th ed., p. 165)
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Types of secondary radiation barriers include
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1. the control booth.
2. lead aprons. 3. the x-ray tube housing. |
Secondary radiation includes leakage and scattered radiation. The control booth wall is a secondary barrier; therefore, the primary beam must never be directed toward it. The x-ray tube housing must reduce leakage radiation to less than 100 mR/hour at a distance of 1 m from the housing. Lead aprons, lead gloves, portable x-ray barriers, and so on are also designed to protect the user from exposure to scattered radiation and will not protect her or him from the primary beam. (Selman, 9th ed., p. 403)
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Which of the following statements regarding the human gonadal cells is (are) true?
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3.
Both male and female stem cells reproduce only during fetal life. |
The development of male and female reproductive stem cells has important radiation protection implications. Male stem cells reproduce continuously. However, the female stem cells develop only during fetal life; females are born with all the reproductive cells they will ever have. It is exceedingly important to shield children whenever possible, as they have their reproductive futures ahead of them. (Bushong, 8th ed., p. 522)
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Circuit devices that will conduct electrons in only one direction are
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resistors. 2. valve tubes. 3. solid-state diodes. 1. resistors. 2. valve tubes. 3. solid-state diodes. |
Rectifiers change AC into unidirectional current by allowing current to flow through them in only one direction. Valve tubes are vacuum rectifier tubes found in older equipment. Solid-state diodes are the types of rectifiers used in today's x-ray equipment. Rectification systems are found between the secondary coil of the high-voltage transformer and the x-ray tube. Resistors, such as rheostats or choke coils, are circuit devices used to vary voltage or current. (Selman, 9th ed., p. 101)
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Which of the following terms is correctly used to describe x-ray beam quality?
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HVL
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Kilovoltage (kV) and the HVL effect a change in both the quantity and the quality of the primary beam. The principal qualitative factor of the primary beam is kV, but an increase in kV will also increase the number of photons produced at the target. HVL, defined as the amount of material necessary to decrease the intensity of the beam to one half, therefore changes both beam quality and beam quantity. Milliamperage is directly proportional to x-ray intensity (quantity/dose rate) but is unrelated to the quality of the beam. (Bushong, 8th ed., p. 165)
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Diagnostic x-radiation may be correctly described as
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low energy, low LET.
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X-radiation used for diagnostic purposes is of relatively low energy. Kilovoltages of up to 150 are used, as compared with radiations having energies of up to several million volts. LET (linear energy transfer) refers to the rate at which energy is transferred from ionizing radiation to soft tissue. Particulate radiations, such as alpha particles, have mass and charge, and therefore lose energy rapidly as they penetrate only a few centimeters of air. X- and gamma radiations, having no mass or charge, are low-LET radiations. (Bushong, 8th ed., p. 495)
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If the exposure rate at 2.0 meters from a source of radiation is 18 mR/min, what will be the exposure rate at 5 meters from the source?
|
2.8 mR/min
|
The relationship between x-ray intensity and distance from the source is expressed in the inverse square law of radiation. The formula is
Substituting known values, Distance has a profound effect on dose received and therefore is one of the cardinal factors considered in radiation protection. As distance from the source increases, dose received decreases. (Bushong, 8th ed., pp. 68-70) |
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|
Moving the image intensifier closer to the patient during fluoroscopy
|
1.
decreases the source-image distance (SID). 2. decreases patient dose. 3. improves image quality. |
Moving the image intensifier closer to the patient during fluoroscopy reduces the distance between the x-ray tube (source) and the image intensifier (image receptor), that is, the SID. It follows that the distance between the part being imaged (object) and the image intensifier (image receptor), that is, the OID, is also reduced. The shorter OID produces less magnification and better image quality. As the SID is reduced, the intensity of the x-ray photons at the image intensifier's input phosphor increases, stimulating the automatic brightness control (ABC) to decrease the mA and thereby decreasing patient dose (see the figure below). (Fosbinder and Kelsey, pp. 265–267)
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The interaction between x-ray photons and tissue that is responsible for radiographic contrast but that also contributes significantly to patient dose is
|
the photoelectric effect
|
In the photoelectric effect, the incident (low-energy) photon is completely absorbed, and thus is responsible for producing contrast and contributing to patient dose. The photoelectric effect is the interaction between x-ray and tissue that predominates in the diagnostic range. In Compton scatter, only partial absorption occurs, and most energy emerges as scattered photons. In coherent scatter, no energy is absorbed by the part; it all emerges as scattered photons. Pair production occurs only at very high energy levels, at least 1.02 MeV. (Bushong, 8th ed., p. 176)
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A dose of 25 rad to the fetus during the fourth or fifth week of pregnancy is more likely to cause which of the following:
|
skeletal anomalies
|
During the first trimester, specifically the 2 to 8 weeks of pregnancy (during major organogenesis), if the radiation dose is at least 20 rad, fetal anomalies can be produced. Skeletal anomalies usually appear if irradiation occurs in the early part of this time period, and neurologic anomalies are formed in the latter part; mental retardation and childhood malignant diseases, such as cancers or leukemia, can also result from irradiation during the first trimester. Fetal irradiation during the second and third trimester is not likely to produce anomalies, but rather, with sufficient dose, some type of childhood malignant disease. Fetal irradiation during the first 2 weeks of gestation can result in spontaneous abortion.
It must be emphasized that the likelihood of producing fetal anomalies at doses below 20 rad is exceedingly small and that most general diagnostic examinations are likely to deliver fetal doses of less than 1 to 2 rad. (Bushong, p 546) |
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|
The dose of radiation that will cause a noticeable skin reaction is referred to as the
|
skin erythema dose (SED).
|
Erythema is the reddening of skin as a result of exposure to large quantities of ionizing radiation. It was one of the first somatic responses to irradiation demonstrated to the early radiology pioneers. The effects of radiation exposure to the skin follow a nonlinear, threshold dose-response relationship. An individual's response to skin irradiation depends on the dose received, the period of time over which it was received, the size of the area irradiated, and the individual's sensitivity. The dose that it takes to bring about a noticeable erythema is referred to as the SED. (Bushong, 8th ed., p. 521)
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If a patient received 2000 mrad during a 10-minute fluoroscopic examination, what was the dose rate?
|
0.2 rad/min
|
Two thousand mrad is equal to 2 rad. If 2 rad was delivered in 10 minutes, then the dose rate must be 0.2 rad/min:
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If a patient received 4500 mrad during a 6-min fluoroscopic examination, what was the dose rate?
|
0.75 rad/min
|
Since 4500 mrad is equal to 4.5 rad, if 4.5 rad were delivered in 6 minutes, then the dose rate must be 0.75 rad/min:
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Which of the following combinations would pose the most hazard to a particular anode?
|
0.6 mm focal spot, 75 kVp, 30 mAs
|
Radiographic rating charts enable the operator to determine the maximum safe mA, exposure time, and kVp for a particular exposure using a particular x-ray tube. An exposure that can be made safely with the large focal spot may not be safe for use with the small focal spot of the same x-ray tube. The total number of HU that an exposure generates also influences the amount of stress (in the form of heat) imparted to the anode. The product of mAs and kVp determines HU. Groups A and C produce 2250 HU; groups B and D produce 1275 HU. Groups B and D deliver less heat load, but group D delivers it to a larger area (actual focal spot) making this the least hazardous group of technical factors. The most hazardous group of technical factors is group
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What is the approximate ESE for the average upright PA chest radiograph, using 115 kVp and a grid?
|
20 mrad
|
Patients will occasionally question the radiographer regarding the amount of radiation they are receiving during their examination. Most of these patients are merely curious because they have heard a recent news report about x-rays, or have perhaps studied about x-rays in school recently. It is a good idea for radiographers to have some knowledge of average exposure doses for patients who desire this information. The curious patient can also be referred to the medical physicist for more detailed information. The average high kVp chest with grid delivers an ESE of about 20 mrad (0.020 rad). The same chest done without grid at 80 kVp would deliver an ESE of about 12 mrad (0.012 rad). The average AP supine lumbar spine radiograph delivers an ESE of about 350 mrad (0.35 rad). The average AP supine abdomen delivers about 300 mrad; the average AP cervical spine is about 80 mrad. (Dowd and Tilson, 2nd ed., p. 247)
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Inherent and added filtration in the x-ray tube functions to
|
reduce patient skin dose.
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The x-ray tube's glass envelope and oil coolant are considered inherent filtration. Thin sheets of aluminum are added to make a total of 2.5 mm Al equivalent filtration in equipment operated above 70 kVp. The function of aluminum filtration is to remove from the x-ray beam the soft (long-wavelength) x-ray photons that do not contribute to image formation but simply contribute to patient dose. These soft x-rays penetrate only a small thickness of tissue before being absorbed. (Selman, p 411)
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Which of the following would be most likely to cause the greatest skin dose (ESE)?
|
Short SID
|
The shorter the SID, the greater the skin dose (ESE). That is why there are specific SSD restrictions in fluoroscopy. X-ray beam quality has a significant effect on patient skin dose. The use of high kVp produces more high-energy penetrating photons, thereby decreasing skin dose. Filtration is used to remove the low-energy photons that contribute to skin dose from the primary beam. Although mA regulates the number of x-ray photons produced, it does not affect photon quality. (Bushong, 8th ed., pp. 300-303)
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Which of the following affect(s) both the quantity and quality of the primary beam?
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1 and 2 only
|
Kilovoltage (kVp) and half-value layer (HVL) change both the quantity and quality of the primary beam. The principal qualitative factor of the primary beam is kVp, but an increase in kVp will also effect an increase in the number of photons produced at the target. HVL is defined as the amount of material necessary to decrease the intensity of the beam to one half of its original value, thereby effecting a change in both beam quality and quantity. The mAs value is adjusted to regulate the number of x-ray photons produced at the target. X-ray beam quality is unaffected by changes in mAs. (Bushong, 8th ed., p. 165)
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Isotopes are atoms that have the same
|
atomic number but a different mass number
|
Isotopes are atoms of the same element (the same atomic number or number of protons) but a different mass number. They differ, therefore, in the number of neutrons. Atoms with the same mass number but different atomic number are isobars. Atoms with the same number of neutrons but different atomic number are isotones. Atoms with the same atomic number and mass number are isomers. (Bushong, 8th ed., p. 47)
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According to National Council on Radiation Protection and Measurements (NCRP) regulations, leakage radiation from the x-ray tube must not exceed
|
100 mR/h.
|
X-ray photons produced in the x-ray tube can radiate in directions other than the one desired. The tube housing is therefore constructed so that very little of this leakage radiation is permitted to escape. The regulation states that leakage radiation must not exceed 100 mR/hour at 1 m while the tube is operated at maximum potential. (Bushong, 8th ed., p. 130)
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Reducing the number of repeat images is an important way to decrease patient exposure and can be accomplished by
|
1.
good patient communication. 2. accurate positioning skills. 3. using AEC. |
The best way to ensure patient cooperation is through effective communication. A patient who understands what the examination entails, who knows what to expect, and what will be expected of him or her is better able to cooperate with the radiographer. This patient is more likely to be able to maintain the required position and suspend their respiration when required—thereby avoiding a repeated image. Radiographers who use their knowledge along with patience and critical thinking skills are more apt to obtain good images the first time around, thus avoiding repeat examinations. The use of AEC also helps avoid repeat radiographs; AEC will adjust the exposure—compensating for position, habitus, or pathology, and reducing the likelihood of repeat radiographs. (Dowd & Tilson, p 243)
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If an individual receives an exposure of 150 mR/h at a distance of 2 feet from a radiation source, what will be their dose after 30 minutes at a distance of 5 feet from the source?
|
12 mR
|
The relationship between x-ray intensity and distance from the source is expressed in the inverse square law of radiation. The formula is
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|
Aluminum filtration has its greatest effect on
|
long wavelength radiation.
|
X-ray photons emerging from the focal spot comprise a heterogeneous primary beam. There are many low-energy x-rays that, if not removed, would contribute significantly to patient skin dose. These low-energy photons are too weak to penetrate the patient and expose the image receptor; they simply penetrate a small thickness of tissue before being absorbed. Filters, usually made of aluminum, are used in radiography to reduce patient dose by removing this low energy radiation (i.e., decreased beam intensity), and resulting in an x-ray beam of higher average energy. Total filtration is composed of inherent filtration plus added filtration. (Bushong, 8th ed., p. 165)
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What is used to account for the differences in ionizing characteristics of various radiations, when determining their effect on biologic material?
|
Radiation weighting factors (Wr)
|
The Tissue Weighting Factor (Wt) represents the relative tissue radiosensitivity of irradiated material (eg, muscle vs intestinal epithelium vs bone, etc). The Radiation Weighting Factor (Wr) is a number assigned to different types of ionizing radiations in order to better determine their effect on tissue (eg, x-ray vs alpha particles). The Wr of different ionizing radiations is dependent on the LET of that particular radiation. The following formula is used to determine Effective Dose (E):
Effective Dose (E) = Radiation Weighting Factor (Wr) x Tissue Weighting Factor (Wt) x Absorbed Dose |
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|
The principal function of filtration in the x-ray tube is to reduce
|
patient skin dose.
|
X-rays produced in the x-ray tube make up a heterogeneous beam. There are many low-energy, or "soft," photons that do not contribute to the radiographic image because they never reach the IR. Instead, they stay in the patient, contributing to skin dose. It is these photons that are removed by (aluminum) filtration. (Bushong, 8th ed., p. 12)
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Gonadal shielding should be provided for male patients in which of the following examinations?
|
1.
Femur 2. Abdomen 3. Pelvis |
Gonadal shielding should be used when the gonads lie within 5 cm of the collimated primary beam, when the patient has reasonable reproductive potential, and when clinical objectives permit. Because their reproductive organs lie outside the abdominal cavity, male patients are more easily and effectively shielded than are female patients, whose reproductive organs lie within the abdominal cavity. Therefore, radiographic examinations of the male abdomen and pelvic structures should include evidence of gonadal shielding. (Sherer, 5th ed., p. 177)
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Referring to the nomogram in Figure A, what is the approximate patient ESE from an AP projection of the abdomen made at 105 cm using 70 kVp, 300 mA, 0.2-second, and 2.5 mm Al total filtration?
|
288 mR
|
An approximate ESE can be determined using the illustrated nomogram. First, mark 2.5 mm Al on the x/horizontal axis. Next, mark where a line drawn up from that point intersects the 70-kVp line. Draw a line straight across to the y/vertical axis; this should approximately reach the 4.8 mR/mAs point. Because 60 mAs was used for the exposure, the approximate entrance skin dose is 288 mR (60 x 4.8). (Bushong, 8th ed., p. 587)
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Which of the following contributes most to patient dose?
|
The photoelectric effect
|
As radiation passes through tissue, different types of ionization processes can take place, depending on the photon energy and the type of material being irradiated. In the photoelectric effect, a relatively low-energy photon uses all its energy to eject an inner-shell electron from the target atom, leaving a vacancy in that shell. An electron from the shell beyond drops down to fill the vacancy and, in doing so, emits a characteristic ray. This type of interaction contributes most to patient dose, because all the x-ray photon energy is being transferred to tissue. In Compton scatter, a high-energy incident photon uses some of its energy to eject an outer-shell electron. In doing so, the incident photon is deflected with reduced energy, but usually retains most of its original energy and exits the body as an energetic scattered photon. In Compton scatter, the scattered radiation will either contribute to image fog or pose a radiation hazard to personnel, depending on its direction of exit. In classical scatter, a low-energy photon interacts with an atom but causes no ionization; the incident photon disappears in the atom, then immediately reappears and is released as a photon of identical energy but changed direction. Thompson scatter is another name for classical scatter. (Selman, pp 125-128)
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Which of the following will occur as a result of a decrease in the anode target angle?
|
Decreased effective focal spot size
3. Greater photon intensity toward the cathode side of the x-ray tube |
Target angle has a pronounced geometric effect on the effective, or projected, focal spot size. As the target angle decreases, the effective (projected) focal spot becomes smaller. This is advantageous because it will improve radiographic detail without creating a heat-loading crisis at the anode (as would occur if the actual focal spot size were reduced to produce a similar detail improvement). There are disadvantages, however. With a smaller target angle, the anode heel effect increases; photons are more noticeably absorbed by the "heel" of the anode, resulting in a smaller percentage of x-ray photons at the anode end of the x-ray beam and a concentration of x-ray photons at the cathode end of the radiograph. (Shephard, p 221)
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|
What is the annual TEDE limit for radiation workers?
|
5000 mrem
|
Whenever a radiation worker could receive 10% or more of the annual TEDE (total effective dose equivalent) limit, that person must be provided with a radiation monitor. The annual TEDE limit for radiation workers is 5 rem (5000 mrem), but it is the responsibility of the radiographer to practice the ALARA principle, that is, to keep radiation dose as low as reasonably achievable. (Sherer et al., 5th ed., p. 250)
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Which of the following is a measurement of dose to biologic tissue?
|
Rem (Sv)
|
Roentgen is the unit of exposure; it measures the quantity of ionization in air. Rad is an acronym for radiation absorbed dose; it measures the energy deposited in any material. Rem is an acronym for radiation equivalent man; it includes the RBE specific to the tissue irradiated, and therefore is a valid unit of measurement for the dose to biologic material. (Bushong, p 24)
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Which of the following materials is used in direct digital radiography to convert x-ray photons into an electrical charge?
|
Amorphous selenium
|
Amorphous selenium is very efficient at releasing electrons when struck by x rays in a direct digital radiography system.
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|
What conversion occurs in the image at the photocathode of an image intensifier tube?
|
Light is converted to electrons
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The photocathode converts the visible light that leaves the input phosphor into an electron image.
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|
Which of the following is photoconductive?
|
Target plate
|
The target plate is made of antimony trisulfide. When struck by photons (light) it becomes a conductor and allows the electron beam to pass through to the signal plate.
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|
Which of the following is NOT an advantage of automatic exposure control (AEC)?
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More latitude in patient positioning
|
The key to using automatic exposure control is accurate positioning. There is less margin for error (latitude) in positioning when using AEC.
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|
Exposed silver halide crystals are changed to black metallic silver by the
|
reducers.
|
As the film emulsion is exposed to light or x-rays, latent image formation takes place. The exposed silver halide crystals are reduced to black metallic silver in the developer solution. Automatic processor developer agents are hydroquinone and phenidone. The preservative—sodium sulfite—helps prevent oxidation. The activator provides the necessary alkalinity for the developer solution, and hardener is added to the developer in automatic processing to keep emulsion swelling to a minimum. (Fauber, p. 164)
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|
An increase in kilovoltage will serve to
|
produce a longer scale of contrast.
|
An increase in kilovoltage increases the overall average energy of the x-ray photons produced at the target, thus giving them greater penetrability. (This can increase the incidence of Compton interaction and therefore the production of scattered radiation.) Greater penetration of all tissues serves to lengthen the scale of contrast. However, excessive scattered radiation reaching the IR will cause a fog and carries no useful information. (Selman, 9th ed., pp. 127–128)
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|
In digital imaging, as the size of the image matrix increases:
|
2.
pixel size decreases 3. spatial resolution increases |
The FOV and matrix size are independent of one another, that is, either can be changed and the other will remain unaffected. However, pixel size is affected by changes in either the FOV or matrix size. For example, if the matrix size is increased, pixel size decreases. If FOV increases, pixel size increases. Pixel size is inversely related to resolution. As pixel size decreases, resolution increases. (Fosbinder & Kelsey, p 285).
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Although the stated focal spot size is measured directly under the actual focal spot, focal spot size really varies along the length of the x-ray beam. At which portion of the x-ray beam is the effective focal spot the largest?
|
At the cathode end
|
X-ray tube targets are constructed according to the line focus principle—the focal spot is angled (usually 12° to 17°) to the vertical (see the figure below). As the actual focal spot is projected downward, it is foreshortened; thus, the effective focal spot is always smaller than the actual focal spot. As it is projected toward the cathode end of the x-ray beam, the effective focal spot becomes larger and approaches the actual size. As it is projected toward the anode end, it gets smaller because of the anode "heel" effect. (Selman, 9th ed., p. 139)
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|
Disadvantage(s) of using low kV technical factors include
|
1.
insufficient penetration. 2. increased patient dose. 3. diminished latitude. |
As the kilovoltage is decreased, x-ray beam energy (ie, penetration) is also decreased. Consequently, a shorter scale of contrast is obtained and, at lower kilovoltage levels, there is less exposure latitude (less margin for error in exposure). As kilovoltage is reduced, the mAs must be increased accordingly to maintain adequate density. This increase in mAs results in greater patient dose. (Shephard, p. 204)
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|
|
The term latitude describes
|
1.
an emulsion's ability to record a range of densities. 2. the degree of error tolerated with given exposure factors. |
The term latitude may refer to either film emulsion latitude or exposure latitude. Exposure latitude refers to the margin of error inherent in a particular group of exposure factors. Selection of high-kVp and low-mAs factors will allow greater exposure latitude than low-kVp and high-mAs factors. Film emulsion latitude is chemically built into the film emulsion and refers to the emulsion's ability to record a long range of densities from black to white (long-scale contrast). (Bushong, 8th ed., p. 185)
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|
Radiographic recorded detail is directly related to
|
SID.
|
SID is directly related to recorded detail because as SID increases, so does recorded detail (because magnification is decreased). OID is inversely related to recorded detail because as OID increases, recorded detail decreases. As screen speed increases, recorded detail decreases, as a result of greater diffusion of light. Therefore, of the given choices, only SID is directly related to recorded detail. OID and screen speed are inversely related to recorded detail. (Shephard, pp. 221–224)
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|
|
Disadvantage(s) of using low kV technical factors include
|
1.
insufficient penetration. 2. increased patient dose. 3. diminished latitude |
As the kilovoltage is decreased, x-ray beam energy (ie, penetration) is also decreased. Consequently, a shorter scale of contrast is obtained and, at lower kilovoltage levels, there is less exposure latitude (less margin for error in exposure). As kilovoltage is reduced, the mAs must be increased accordingly to maintain adequate density. This increase in mAs results in greater patient dose. (Shephard, p. 204)
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|
An increase in kVp will have which of the following effects?
|
More scattered radiation will be produced.
The exposure rate will increase. |
An increase in kilovoltage (photon energy) will result in a greater number (ie, exposure rate) of scattered photons (Compton interaction). These scattered photons carry no useful information and contribute to radiation fog, thus decreasing radiographic contrast. (Selman, 9th ed., p. 117)
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|
|
Capacitor discharge mobile x-ray units
|
use a grid-controlled x-ray tube.
provide a direct current output. |
There are two main types of mobile x-ray units: capacitor discharge and battery-powered. The capacitor discharge units consist of a capacitor, or condenser, which is given a charge and then stores energy until the x-ray tube uses it to produce x-rays. The charge may not be stored for extended periods, however, because it tends to "leak" away; the capacitor must be charged just before the exposure is made. Its x-ray tube is grid-controlled, permitting very fast (short) exposure times. Capacitors discharge a direct current (as opposed to single- or three-phase pulsating current) in which the kilovoltage decreases by a value of approximately 1 kV/mAs. Thus, although the value at the onset of the exposure may be 20 mAs and 80 kVp, at the end of the exposure the kV value will be approximately 60. In addition, capacitor discharge units permit only limited mAs values, usually 30 to 50 mAs per charge. (Bushong, 8th ed., pp. 123–124)
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Important considerations for radiographic examinations of traumatic injuries to the upper extremity include
|
both joints must be included in long bone studies
3. two views, at 90° to each other, are required |
All traumatic injuries require the radiographer to be particularly alert and observant. Patient status must be continually observed and monitored. The radiographer must speak calmly to the patient, explaining the procedure even if the patient appears unconscious or unresponsive. In the case of an injured limb, both joints must be supported if any movement is required. Both joints must also be included when examining long bones. The injured limb need not be placed in exact AP and lateral positions, but any two views of the part at right angles to each other must be obtained. (Frank, Long, and Smith, vol. 2, 11th ed., pp. 32–33)
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|
|
Operative cholangiography may be performed to
|
visualize biliary stones or a neoplasm.
2. determine function of the hepatopancreatic ampulla. 3. examine the patency of the biliary tract. |
Operative cholangiography may be performed to visualize biliary stones or a neoplasm, determine the function of the hepatopancreatic ampulla, and examine the patency of the biliary tract. Any strictures or obstructions may be localized when contrast medium is introduced into the catheter and images are obtained. It is important that no air bubbles are introduced into the biliary tract because they can imitate radiolucent stones. The radiographer can coordinate the time of exposure with the anesthesiologist to obtain the radiographs during suspended respiration. (Ballinger & Frank, vol 2, pp 76-77)
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|
A small bottle containing a single dose of medication is termed
|
an ampule
|
Injectable medications are available in two different kinds of containers. An ampule is a small container that usually holds a single dose of medication. A vial is a larger container that holds several doses of the medication. The term bolus is used to describe an amount of fluid to be injected. A carafe is a narrow-mouthed container; it is not likely to be used for medical purposes. (Adler & Carlton, p 269)
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|
To demonstrate a profile view of the glenoid fossa, the patient is AP recumbent and obliqued 45°
|
toward the affected side.
|
In the AP projection of the shoulder, there is superimposition of the humeral head and glenoid fossa. With the patient obliqued 45° toward the affected side, the glenohumeral joint is open, and the glenoid fossa is seen in profile. The patient's arm is abducted somewhat and placed in internal rotation. (Frank, Long, and Smith, vol. 1, 11th ed., pp. 192–193)
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Which of the following techniques would provide a PA projection of the gastroduodenal surfaces of the barium-filled, high and transverse stomach?
|
Angle the central ray 35° to 45° cephalad.
|
In the PA position, portions of the barium-filled hypersthenic stomach superimpose upon themselves. Thus, patients with a hypersthenic body habitus usually present a high transverse stomach, with poorly defined curvatures. If the PA stomach is projected with a 35° to 45° cephalad central ray, the stomach "opens up." That is, the curvatures, the antral portion, and the duodenal bulb all appear as a sthenic habitus stomach would appear. A 35° to 40° RAO position is used to demonstrate many of these structures in the average, or sthenic, body habitus. A lateral position is used to demonstrate the anterior and posterior gastric surfaces and retrogastric space. (Bontrager and Lampignano, 6th ed., p. 480)
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|
According to the line focus principle, an anode with a small angle provides
|
improved recorded detail.
2. improved heat capacity. |
The line focus principle illustrates that as the target angle decreases, the effective focal spot decreases (providing improved recorded detail), but the actual area of electron interaction remains much larger (allowing for greater heat capacity). It must be remembered, however, that a steep (small) target angle increases the heel effect, and part coverage may be compromised. (Saia, p 427)
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|
|
During an upper gastrointestinal (GI) examination, the AP recumbent projection of a stomach of average shape will usually demonstrate
|
2.
barium-filled fundus. 3. double-contrast body and antral portions |
With the body in the AP recumbent position, barium flows easily into the fundus of the stomach, displacing the stomach somewhat superiorly. The fundus, then, is filled with barium, while the air that had been in the fundus is displaced into the gastric body, pylorus, and duodenum, illustrating them in double-contrast fashion. Air-contrast delineation of these structures allows us to see through the stomach to the retrogastric areas and structures. Anterior and posterior aspects of the stomach are visualized in the lateral position; medial and lateral aspects of the stomach are visualized in the AP projection. (Ballinger & Frank, vol
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|
Which of the following factors has the greatest effect on radiographic density?
|
kVp
|
Doubling the grid ratio from 6:1 to 12:1 will decrease the density 166%. Doubling the mAs will increase the density 100%. But only a 15% increase in kVp will increase the density 100%. Focal spots sizes do not affect density.
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|
|
How does a small increase in developer temperature affect radiographic contrast?
|
Produces higher contrast
|
Small increases in developer temperature turns the silver halide crystals blacker, creating a bigger difference between blacks and whites. A large increase in temperature would cause the developer to reduce unexposed silver halide crystals which would produce fog and lower contrast.
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|
|
What is the primary function of the mAs as it relates to radiographic quality?
|
Control density
|
mAs is considered the controlling factor for radiographic density. It has no affect on any of the other three radiographic qualities.
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|
|
Subject contrast will be the lowest with which of the following body types?
|
Hypersthenic
|
Subject contrast refers to the differences in tissue densities in the patient. Large patients (hypersthenic) have a higher fat content which creates smaller differences between tissues which produces a lower contrast radiograph.
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|
|
Which of the following directly influences radiographic contrast?
|
Grid ratio
|
Radiographic grids remove scatter radiation before it reaches the image receptor to cause fog. This decrease in fog provides a higher contrast radiograph
|
|
|
How would an image with just a few, wide density differences be described?
|
High contrast
|
High contrast means there is a big difference in density between adjacent areas. An image with a few, wide density differences would be considered high contrast.
|
|
|
How are mA and seconds related to each other when used to maintain density?
A. Directly proportional B. Inversely proportional C. Mutually exclusive D. No relationship exists |
Inversely proportional
|
Inversely proportional means that if one increases the other must decrease in order to maintain the same density.
|
|
|
A graphic representation of the relationship between density and exposure is called what?
1. D log E curve 2. H & D curve 3. Characteristic curve |
1. D log E curve
2. H & D curve 3. Characteristic curve |
Plotting density against the log of the exposure produces a curve that is characteristic of the factors used to produce the various densities. Hurter and Driffield (H & D) developed this curve.
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|
|
Contrast can be measured from an H & D curve by finding the slope of which of the following parts?
A. Toe B. Shoulder C. Threshold D. Straight line portion |
Straight line portion
|
You can find the slope (tangent) of the straight line portion by the "rise over the run", or the vertical rise over the horizontal distance. This provides a number that represents the contrast on the film. The higher the number, the higher the contrast. A number 1 represents a 45 degree slope.
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|
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Which of the following is defined as the ability of a film to record a wide range of densities?
A. Film speed B. Film contrast C. Film gamma D. Film latitude |
Film latitude
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Latitude refers to the range of exposures that will produce densities within the diagnostic range. It is defined as the "margin of error" a radiographer has to produce a diagnostic radiograph. A film's characteristics may be able to record a narrow range or a wide range of densities, hence the term, film latitude.
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Which of the following describes a short scale of contrast?
A. High contrast B. Low contrast C. High number of density differences D. Greater film latitude |
High contrast
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Scale of contrast refers to the number of different densities seen on a radiograph. The shortest scale would be black and white. This would be a great difference between densities or a high contrast.
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Density was the term used to describe the overall blackening of a conventional radiograph. What term is used in digital radiography to describe this radiographic quality?
A. Window width B. Exposure C. Contrast D. Brightness |
Brightness
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Brightness is used because digital images are viewed on a monitor.
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Why is direct exposure film NOT recommended for modern day radiography?
A. Too much contrast B. Not enough contrast C. Requires long exposure times D. Increases patient exposure |
Increases patient exposure
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Direct exposure film requires from 20 - 50 times more exposure than when using intensifying screens. The risks of high exposures outweighs the benefits of increased recorded detail.
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Which of the following accessories can be used to demonstrate a scale of contrast or test for contrast?
A. Densitometer B. Penetrometer C. Rate meter D. Wire mesh |
Penetrometer
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A penetrometer, also known as a step wedge, is used to produce a scale of contrast. This can be used to test kVp accuracy, mAs reciprocity and a number of other quality assurance tests.
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Changing the mA controls which of the following?
A. Penetrating power of the x-ray beam B. Quality of the x-ray beam C. Quantity of the x-ray beam D. Average photon energy of the x-ray beam |
Quantity of the x-ray beam
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mA stands for milliamperage, which measures the number of electrons that travel across the x-ray tube. The energy of these electrons is converted to x rays. The more mA the more x rays.
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Which of the following represents the useful range of radiographic densities?
A. .10 to 1.0 B. .20 to 2.0 C. .25 to 2.5 D. .35 to 3.5 |
.25 to 2.5
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If you measured the various densities on a radiograph they would fall within the range of .25 to 2.5. Below .25 would be too light to show information and above 2.5 would be the black areas outside the anatomical area.
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Low energy radiation will result in which of the following?
A. Short scale contrast B. Medium scale contrast C. Long scale contrast D. Low scale contrast |
Short scale contrast
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Low energy radiation will be absorbed by the tissues of the body and therefore produce a short scale of contrast. High energy radiation is scattered by the tissues and produces long scale contrast. Low scale contrast is not a proper term to describe radiographic contrast.
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The light emitted from a screen contributes to what percentage of the overall film density?
A. 25% B. 55% C. 85% D. 95% |
95%
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The x rays are absorbed by the intensifying screen and converted to light energy. It is the light energy that exposes the film. Only about 5% of the film's density is produced by x rays.
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Which of the following screen speeds would produce a radiograph with low contrast?
A. 50 B. 100 C. 200 D. 400 |
50
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A 50 speed screen (also may be referred to as a slow speed or an extremity screen) will record soft tissue better than high speed screens so the contrast scale will be longer (low contrast).
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Which of the following factors contribute(s) to the efficient performance of a grid?
1. Grid ratio 2. Number of lead strips per inch 3. Amount of scatter transmitted through the grid |
1.
Grid ratio 2. Number of lead strips per inch 3. Amount of scatter transmitted through the grid |
Grid ratio is defined as the ratio of the height of the lead strips to the width of the interspace material; the higher the lead strips, the more scattered radiation they will trap and the greater the grid's efficiency. The greater the number of lead strips per inch, the thinner and less visible they will be on the finished radiograph. The function of a grid is to absorb scattered radiation in order to improve radiographic contrast. The selectivity of a grid is determined by the amount of primary radiation transmitted through the grid divided by the amount of scattered radiation transmitted through the grid. (Selman, pp 236–237)
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An increase in the kilovoltage applied to the x-ray tube increases the
1. x-ray wavelength. 2. exposure rate. 3. patient absorption. |
2.
exposure rate. As the kilovoltage is increased, a greater number of electrons are driven across to the anode with greater force. Therefore, as energy conversion takes place at the anode, more high-energy (short-wavelength) photons are produced. However, because they are higher energy photons, there will be less patient absorption. (Selman, pp 117–118) |
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A slit camera is used to measure
1. focal spot size. 2. intensifying-screen resolution. 3. SID resolution. |
1.
focal spot size. A quality control program requires the use of a number of devices to test the efficiency of various parts of the imaging system (see the figure below). A slit camera, as well as a star pattern or pinhole camera, is used to test focal spot size. A parallel line-type resolution test pattern is used to test the resolution capability of intensifying screens. (Bushong, p 462) |
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Important considerations for radiographic examinations of traumatic injuries to the upper extremity include
1. the joint closest to the injured site should be supported during movement of the limb 2. both joints must be included in long bone studies 3. two views, at 90° to each other, are required 1. the joint closest to the injured site should be supported during movement of the limb 2. both joints must be included in long bone studies 3. two views, at 90° to each other, are required |
2.
both joints must be included in long bone studies 3. two views, at 90° to each other, are required All traumatic injuries require the radiographer to be particularly alert and observant. Patient status must be continually observed and monitored. The radiographer must speak calmly to the patient, explaining the procedure even if the patient appears unconscious or unresponsive. In the case of an injured limb, both joints must be supported if any movement is required. Both joints must also be included when examining long bones. The injured limb need not be placed in exact AP and lateral positions, but any two views of the part at right angles to each other must be obtained. (Frank, Long, and Smith, vol. 2, 11th ed., pp. 32–33) |
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Which of the following is recommended to demonstrate small amounts of air within the peritoneal cavity?
A. Lateral decubitus, affected side up B. Lateral decubitus, affected side down C. AP Trendelenburg D. AP supine |
A.
Lateral decubitus, affected side up Air or fluid levels will be clearly delineated only if the central ray is directed parallel to them. Therefore, the erect or decubitus position should be used. Small amounts of fluid within the peritoneal cavity are best demonstrated in the lateral decubitus position, affected side down. Small amounts of air within the peritoneal cavity are best demonstrated in the lateral decubitus position, affected side up. (Ballinger & Frank, vol 2, pp 40-41) |
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Any images obtained using DXA bone densitometry
1. are used to evaluate accuracy of the ROI. 2. are used as evaluation for various bone/joint disorders. 3. reflect the similar attenuation properties of soft tissue and bone. |
1.
are used to evaluate accuracy of the ROI. DXA imaging is used to evaluate BMD (bone mass density). It is the most widely used method of bone densitometry—it is low dose, precise, and uncomplicated to use/perform. DXA uses two photon energies—one for soft tissue and one for bone. Since bone is more dense and attenuates x-ray photons more readily, their attenuation is calculated to represent the degree of bone density. Soft tissue attenuation information is not used to measure bone density. Any images obtained in DXA/bone densitometry are strictly to evaluate the accuracy of the ROI (region of interest); they are not used for further diagnostic purposes—additional diagnostic examinations are done for any required further evaluation. Bone densitometry, DXA, can be used to evaluate bone mineral content of the body, or part of it, to diagnosis osteoporosis or to evaluate the effectiveness of treatments for osteoporosis. (Frank, Long, and Smith, vol. 3, 11th ed., pp. 455–456) |
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Which of the following precaution(s) should be observed when radiographing a patient who has sustained a traumatic injury to the hip?
1. When a fracture is suspected, manipulation of the affected extremity should be performed by a physician. 2. The AP axiolateral projection should be avoided. 3. To evaluate the entire region, the pelvis is typically included in the initial examination. |
1.
When a fracture is suspected, manipulation of the affected extremity should be performed by a physician. |
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Which of the following precaution(s) should be observed when radiographing a patient who has sustained a traumatic injury to the hip?
1. When a fracture is suspected, manipulation of the affected extremity should be performed by a physician. 2. The AP axiolateral projection should be avoided. 3. To evaluate the entire region, the pelvis is typically included in the initial examination. |
Typically, traumatic injury to the hip requires a cross-table (axiolateral) lateral projection, as well as an AP projection of the entire pelvis. Both of these are performed using minimal manipulation of the affected extremity, reducing the possibility of further injury. A physician should perform any required manipulation of the traumatized hip. (Frank, Long, and Smith, vol. 1, 11th ed., pp. 355, 358)
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Which of the following articulates with the base of the fifth metatarsal?
A. First cuneiform B. Third cuneiform C. Navicular D. Cuboid |
D.
Cuboid The bones of the foot include the seven tarsal bones, five metatarsal bones, and 14 phalanges. The calcaneus (os calsis) serves as the attachment for the Achilles tendon and articulates anteriorly with the cuboid bone. Articulating anteriorly with the navicular are the three cuneiform bones: medial/first, intermediate/second, and lateral/third. The navicular articulates laterally with the cuboid. The bases of the fourth and fifth metatarsals articulate with the cuboid. The fifth (most lateral) metatarsal projects laterally and presents a large tuberosity at its base making it very susceptible to fracture. (Tortora, 11th ed, p 250) |
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The ileocecal valve is normally located in which of the following body regions?
A. Right iliac B. Left iliac C. Right lumbar D. Hypogastric |
A.
Right iliac The abdomen is divided into nine regions. The upper lateral regions are the left and right hypochondriac, with the epigastric separating them. The middle lateral regions are the left and right lumbar, with the umbilical region between them. The lower lateral regions are the left and right iliac, with the hypogastric region between them. The ileocecal valve, cecum, and appendix (if present) are located in the lower right abdomen—therefore, the right iliac region. (Frank, Long, and Smith, vol. 1, 11th ed., p. 62) |
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The plus-density artifact pictured in the figure below was probably produced
1. by careless handling. 2. after exposure. 3. before exposure. |
1.
by careless handling. 3. before exposure. The crescent-shaped kink, or crinkle, marks seen on the radiographic image are caused by acutely bending the x-ray film. The artifact will usually appear as a plus-density (dark) artifact if it is produced before exposure, and as a minus-density (light) artifact if it is produced after exposure. X-ray film emulsion is very sensitive to mishandling, particularly after exposure. (Shepard, p. 110) |
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Which of the following will separate the radial head, neck, and tuberosity from superimposition on the ulna?
A. AP B. Lateral C. Medial oblique D. Lateral oblique |
D.
Lateral oblique In the AP projection of the elbow, the proximal radius and ulna are partially superimposed. In the lateral position, the radial head is partially superimposed on the coronoid process, facing anteriorly. In the medial oblique position, there is even greater superimposition. The lateral oblique projection completely separates the proximal radius and ulna, projecting the radial head, neck, and tuberosity free of superimposition with the proximal ulna. (Frank, Long, and Smith, vol. 1, 11th ed., pp. 143–147) |
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In the production of Bremsstrahlung radiation, the incident electron
A. ejects an inner-shell tungsten electron. B. ejects an outer-shell tungsten electron. C. is deflected, with resulting energy loss. D. is deflected, with resulting energy increase. |
is deflected, with resulting energy loss.
Bremsstrahlung (or Brems) radiation is one of the two kinds of x-rays produced at the tungsten target of the x-ray tube. The incident high-speed electron, passing through a tungsten atom, is attracted by the positively charged nucleus and therefore is deflected from its course, with a resulting loss of energy. This energy loss is given up in the form of an x-ray photon. (Bushong, pp 151-152) |
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Better resolution is obtained with
A. high SNR. B. low SNR. C. windowing. D. smaller matrix. |
A.
high SNR. Spatial resolution increases as SNR (signal-to-noise ratio) increases. A high SNR (e.g., 1000:1) indicates that there is far more signal than noise. A lower SNR (e.g., 200:1) indicates a "noisy" image. Windowing is unrelated to resolution; it allows for contrast and density post-processing manipulation. Image matrix has a great deal to do with resolution. A larger image matrix (1800 x 1800) offers better resolution than a smaller image matrix (700 x 700). Smaller image matrices look "pixelly." (Seeram, p 112) |
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The violet light emited by the photostimulable phosphor (PSP) is transformed into the image seen on the CRT by the
A. PSP. B. scanner-reader. C. ADC. D. helium-neon laser. |
C.
ADC. The exposed CR cassette is placed into the CR scanner reader, where the PSP/imaging plate is automatically removed. The latent image appears as the PSP is scanned by a narrow high-intensity helium-neon laser to obtain the pixel data. As the plate is scanned in the CR reader, it releases a violet light—a process referred to as photo-stimulated luminescence. The luminescent light is converted to electrical energy representing the analog image. The electrical energy is sent to an analog-to-digital converter (ADC) where it is digitized and becomes the digital image that is eventually displayed (after a short delay) on a high-resolution monitor and/or printed out by a laser printer. The digitized images can also be manipulated in postprocessing, electronically transmitted, and stored/archived. (Carlton and Adler, 4th ed., pp. 357–358) |
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Which of the lines indicated in the figure below represents the dynamic range offered by CR/DR?
A. Line A is representative of CR/DR. B. Line B is representative of CR/DR. C. Neither line is representative of CR/DR. D. Both lines are representative of CR/DR. |
A.
Line A is representative of CR/DR. One of the biggest advantages of CR/DR is the latitude it offers. The characteristic curve of typical film emulsion has a "range of correct exposure," limited by the toe and shoulder of the curve. In CR/DR, there is a linear relationship between the exposure, given the PSP and its resulting luminescence, as it is scanned by the laser, as illustrated in the figure shown. This affords much greater exposure latitude; technical inaccuracies can be effectively eliminated. Overexposure of up to 500% and underexposure of up to 80% are reported as recoverable, thus eliminating most retakes. This surely affords increased efficiency; however this does not mean that images can be exposed arbitrarily. The professional radiographer has a responsibility to keep dose reduction to a minimum. The same exposure factors as screen–film systems, or less, are generally recommended for CR/DR. (Shephard, p. 332) |
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That ossified portion of a long bone where cartilage has been replaced by bone is known as the
A. diaphysis. B. epiphysis. C. metaphysis. D. apophysis. |
C.
metaphysis Long bones are composed of a shaft, or diaphysis, and two extremities, or epiphyses. In the growing bone, the cartilaginous epiphyseal plate is gradually replaced by bone. The ossified growth area of long bones is the metaphysis. Apophysis refers to vertebral joints formed by articulation of superjacent articular facets. (Bontrager and Lampignano, 6th ed., p. 9) |
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The medical term used to describe the expectoration of blood is
A. hematemesis. B. hemoptysis. C. hematuria. D. epistaxis. |
B.
hemoptysis. Expectoration (coughing or spitting up) of blood is called hemoptysis. Blood is originating from the mouth, larynx, or respiratory structure. Hematemesis refers to vomiting blood. If the blood is dark in color, it is probably gastric in origin; if it is bright red, it is most likely pharyngeal in origin. Hematuria is the condition of blood in the urine. Epistaxis is the medical term for nosebleed. (Bontrager, p 80) |
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Examples of synovial pivot articulations include the
1. atlantoaxial joint. 2. radioulnar joint. 3. temporomandibular joint. |
1.
atlantoaxial joint. 2. radioulnar joint. 3. temporomandibular joint. Synovial pivot joints are diarthrotic, that is, freely movable. Pivot joints permit rotation motion. Examples include the proximal radioulnar joint that permits supination and pronation of the hand. The atlantoaxial joint is the articulation between C1 and C2 and permits rotation of the head. The temporomandibular joint is diarthrotic, having both hinge and planar movements. (Tortora and Derrickson, 11th ed., p. 269) |
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Which of the following projections of the calcaneus is obtained with the leg extended, the plantar surface of the foot vertical and perpendicular to the IR, and the central ray directed 40° caudad?
A. Axial plantodorsal projection B. Axial dorsoplantar projection C. Lateral projection D. Weight-bearing lateral projection |
B.
Axial dorsoplantar projection An axial dorsoplantar projection of the calcaneus is described; the central ray enters the dorsal surface of the foot and exits the plantar surface. The plantodorsal projection is done supine and requires cephalad angulation. The central ray enters the plantar surface and exits the dorsal surface. (Ballinger & Frank, vol 1, p 263) |
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The patient is usually required to drink barium sulfate suspension in order to demonstrate which of the following structure(s)?
1. Cecum 2. Ilium 3. Stomach |
3. Stomach
Oral administration of barium sulfate is used to demonstrate the upper digestive system, esophagus, fundus, and body and pylorus of the stomach, and barium progression through the small bowel. The large bowel, including the cecum, is usually demonstrated via rectal administration of barium. The ilium refers to the bony pelvis, whereas the ileum refers to the small bowel—which would be demonstrated by oral administration of barium. (Jones et al, p 165) |
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Which of the following is a measurement of dose to biologic tissue?
A. Roentgen (C/kg) B. Rad (Gy) C. Rem (Sv) D. RBE |
C.
Rem (Sv) Roentgen is the unit of exposure; it measures the quantity of ionization in air. Rad is an acronym for radiation absorbed dose; it measures the energy deposited in any material. Rem is an acronym for radiation equivalent man; it includes the RBE specific to the tissue irradiated, and therefore is a valid unit of measurement for the dose to biologic material. (Bushong, p 24) |
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For exposure to 1 rad of each of the following ionizing radiations, which would result in the greatest dose to the individual?
A. External source of 1-MeV x-rays B. External source of diagnostic x-rays C. Internal source of alpha particles D. External source of beta particles |
C.
Internal source of alpha particles Electromagnetic radiations such as x-rays and gamma rays are considered low LET-radiations because they produce fewer ionizations than the highly ionizing particulate radiations such as alpha particles. Alpha particles are large and heavy (two protons and two neutrons), and although they possess a great deal of kinetic energy (approximately 5 MeV), their energy is rapidly lost through multiple ionizations (approximately 40,000 atoms/cm of air). As an external source, alpha particles are almost harmless, because they ionize the air very quickly and never reach the individual. As internal sources, however, they ionize tissues and are potentially the most harmful. It may be stated that the alpha particle has one of the highest LETs of all ionizing radiations. (Bushong, 8th ed., p. 496) |
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An animal host of an infectious organism that transmits the infection via a bite or sting is a
A. vector. B. fomite. C. host. D. reservoir. |
A.
vector. A vector is an animal host of an infectious organism that transmits the infection via a bite or sting, such as the mosquito (malaria) and the deer tick (Lyme disease). A fomite is an inanimate object that has been in contact with an infectious microorganism. A reservoir is a site where an infectious organism can remain alive and from which transmission can occur. Although an inanimate object can be a reservoir for infection, living objects (such as humans) can also be reservoirs. For infection to spread, there must be a host environment. Although an inanimate object may serve as a temporary host for microbes to grow, microbes flourish on and in the human host, where plenty of body fluids and tissue nourish and feed the microbes. (Adler & Carlton, p 201) |
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Which of the following radiation exposure responses exhibit a nonlinear threshold dose-response relationship?
1. Skin erythema 2. Hematologic depression 3. Lethality |
1.
Skin erythema 2. Hematologic depression 3. Lethality The genetic effects of radiation and some somatic effects, like leukemia, are plotted on a linear dose-response curve. The linear dose-response curve has no threshold; that is, there is no dose below which radiation is absolutely safe. The nonlinear/sigmoidal dose-response curve has a threshold and is thought to be generally correct for most somatic effects—such as skin erythema, hematologic depression, and radiation lethality (death). (Ballinger & Frank, vol 1, p 45) |
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To determine how quickly an x-ray tube will disperse its accumulated heat, the radiographer uses a(n)
A. technique chart. B. radiographic rating chart. C. anode cooling curve. D. spinning top test. |
C.
anode cooling curve. An anode cooling curve identifies how many HU the anode can accommodate and the length of time required for adequate cooling between exposures. A radiographic rating chart is used to determine if the selected mA, exposure time, and kVp are within safe tube limits. A technique chart is used to determine the correct exposure factors for a particular part of the body of a given thickness. A spinning top test is used to test for timer inaccuracy or rectifier failure. (Selman, p 147) |
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Which of the following barium-filled anatomic structures is best demonstrated in the left anterior oblique (LAO) position?
A. Hepatic flexure B. Splenic flexure C. Sigmoid colon D. Iliocecal valve |
B.
Splenic flexure In the prone oblique positions (RAO, LAO), the flexure disclosed is the one closer to the image receptor. Therefore, the LAO position will "open up" the splenic flexure; the RAO position will demonstrate the hepatic flexure. The AP oblique positions (RPO, LPO) demonstrate the side farther from the image receptor. (Frank, Long, and Smith, 11th ed., vol. 2, pp. 179–180) |
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Blood is returned to the left atrium, from the lungs, via the
A. aorta. B. superior vena cava. C. pulmonary veins. D. pulmonary artery. |
C.
pulmonary veins. Deoxygenated blood is collected by the superior and inferior vena cava and emptied into the right atrium. Pulmonary circulation conveys deoxygenated blood from the right ventricle, through the pulmonary semilunar valve, into the pulmonary artery (the only artery that carries deoxygenated blood), and into the lungs where the blood becomes oxygenated. The oxygenated blood from the lungs is carried via the four pulmonary veins (the only veins that carry oxygenated blood) and emptied into the left atrium. (Tortora, 11th ed, p 792) |
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Which type of error results in grid cutoff at the periphery of the radiographic image?
A. Off-focus B. Off-center C. Off-level D. Off-angle |
A.
Off-focus The lead strips in a focused grid are made to parallel the x-ray beam. Therefore, scattered radiation, which radiates in directions other than that of the primary beam, will be absorbed by the grid. When the x-ray beam does not parallel the lead strips, some type of grid cutoff occurs. If the x-ray beam is not centered to the grid, or if the x-ray tube and grid surface are not parallel (level), there will be a fairly uniform decrease in radiographic density across the entire image. However, if the grid is not used within its recommended SID (focus) range (ie, if the SID is too great or too little), there will be a decrease in density at the periphery of the image. (Carlton and Adler, 4th ed., pp. 263–266) |
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Which of the following is (are) valid evaluation criteria for a lateral projection of the forearm?
1. The radius and the ulna should be superimposed distally. 2. The coronoid process and the radial head should be partially superimposed. 3. The humeral epicondyles should be superimposed. |
1.
The radius and the ulna should be superimposed distally. 2. The coronoid process and the radial head should be partially superimposed. 3. The humeral epicondyles should be superimposed. To accurately position a lateral forearm, the elbow must form a 90° angle with the humeral epicondyles superimposed. The radius and ulna are superimposed distally. Proximally, the coronoid process and radial head are partially superimposed. Failure of the elbow to form a 90° angle, or the hand to be lateral, results in a less-than-satisfactory lateral projection of the forearm. (Frank, Long, and Smith, 11th ed., vol. 1, p. 142) |
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To obtain an AP projection of the right ilium, the patient's
A. left side is elevated 40°. B. right side is elevated 40°. C. left side is elevated 15°. D. right side is elevated 15°. |
A.
left side is elevated 40°. When the pelvis is observed in the anatomic position, the ilia are seen to oblique forward, giving the pelvis a "basin-like" appearance. To view the right iliac bone, the radiographer must place it parallel to the IR by elevating the left side about 40° (RPO). The left iliac bone is radiographed in the 40° LPO oblique position. (Ballinger & Frank, vol 1, p 308) |
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Chemical fog may be attributed to
1. excessive developer temperature. 2. oxidized developer. 3. excessive replenishment. |
1.
excessive developer temperature. 2. oxidized developer. 3. excessive replenishment. If developer temperature is too high, some of the less-exposed or unexposed silver halide crystals may be reduced, thus creating chemical fog. If the developer solution has become oxidized from exposure to air, chemical fog also results. If developer replenishment is excessive, too much new solution is replacing the deteriorated developer, and chemical fog is again the result. (Carlton and Adler, 4th ed., p. 285; Selman, 9th ed., p. 197) |
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Early symptoms of acute radiation syndrome include
1. leukopenia. 2. nausea and vomiting. 3. Cataracts. |
1.
leukopenia. 2. nausea and vomiting. Occupationally exposed individuals generally receive small amounts of low-energy radiation over a long period of time. These individuals are therefore concerned with the potential long-term effects of radiation, such as carcinogenesis (including leukemia) and cataractogenesis. However, if a large amount of radiation is delivered to the whole body at one time, the short-term early somatic effects must be considered. If the whole body receives 600 rad at one time, acute radiation syndrome is likely to occur. Early signs of acute radiation syndrome include nausea, vomiting, diarrhea, fatigue, and leukopenia (decreased white blood cells count); these occur in the first (prodromal) stage of acute radiation syndrome. (Bushong, 8th ed., p. 524) |
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Materials that emit light when stimulated by x-ray photons are called
A. ions. B. electrodes. C. phosphors. D. crystals. |
C.
phosphors Materials that emit light when stimulated by x-ray photons are called phosphors. Phosphors are used in intensifying screens, where they function to absorb x-ray photon energy and convert it to visible light energy. Typically, for each x-ray photon absorbed, many light photons are emitted; intensifying screens serve to amplify the action of x-rays. (Carlton & Adler, p 330) |
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Chemical substances that are used to kill pathogenic bacteria are called
1. antiseptics. 2. germicides. 3. disinfectants. |
2.
germicides. 3. disinfectants. Some chemical agents used in health-care facilities function to kill pathogenic microorganisms, while others function to inhibit the growth/spread of pathogenic microorganisms. Germicides and disinfectants are used to kill pathogenic microorganisms, whereas antiseptics (like alcohol) are used to stop their growth/spread. Sterilization is another associated term; it refers to the killing of all microorganisms and their spores. (Ballinger & Frank, vol 1, p 15) |
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Which of the following combinations would pose the least hazard to a particular anode?
A. 1.2-mm focal spot, 92 kVp, 1.5 mAs B. 0.6-mm focal spot, 80 kVp, 3 mAs C. 1.2-mm focal spot, 70 kVp, 6 mAs D. 0.6-mm focal spot, 60 kVp, 12 mAs |
A.
1.2-mm focal spot, 92 kVp, 1.5 mAs Radiographic rating charts enable the operator to determine the maximum safe mA, exposure time, and kVp for a particular exposure using a particular x-ray tube. An exposure that can be made safely with the large focal spot may not be safe for use with the small focal spot of the same x-ray tube. The total number of HU that an exposure generates also influences the amount of stress (in the form of heat) imparted to the anode. The product of mAs and kVp determines HU. Group A produces 138 HU, group B produces 240 HU, group C produces 420 HU, and group D produces 720 HU. The least hazardous group of technical factors is, therefore, group A. Group D is also delivering its heat load to the small focal spot, making this the most hazardous group of technical factors. (Selman, pp 144–145) |
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A diabetic patient who has prepared for a fasting radiographic examination is susceptible to a hypoglycemic reaction. This is characterized by
1. shaking and nervousness. 2. cold, clammy skin. 3. cyanosis. |
1.
shaking and nervousness. 2. cold, clammy skin. Hypoglycemic reactions can be very severe and should be treated with an immediate dose of sugar (e.g., in juice). Early symptoms of an insulin reaction are shaking, nervousness, dizziness, cold and clammy skin, blurred vision, and slurred speech. Convulsions and coma may result if the patient is not treated. Cyanosis is the lack of oxygenated blood, which is a symptom of shock. (Torres et al, p 169) |
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Which of the following projections of the elbow should demonstrate the coronoid process free of superimposition and the olecranon process within the olecranon fossa?
A. AP B. Lateral C. Medial oblique D. Lateral oblique |
C.
Medial oblique On the AP projection of the elbow, the radial head and ulna are normally somewhat superimposed. The lateral oblique demonstrates the radial head free of ulnar superimposition. The lateral projection demonstrates the olecranon process in profile. The medial oblique demonstrates considerable overlap of the proximal radius and ulna, but should clearly demonstrate the coronoid process free of superimposition and the olecranon process within the olecranon fossa. (Saia, p 96) |
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Which of the following positions will move the fundus of the gallbladder seen in Figure A away from the superimposed transverse process?
A. RAO B. LAO C. LPO D. Left lateral decubitus |
B.
LAO The image displayed is an erect PA projection on a patient of hyposthenic body habitus. Note the low position of the gallbladder: It is a result of body habitus and position (viscera assume a lower position in the erect position). The gallbladder may be moved away from the spine by using the LAO position. The right lateral decubitus will also move the gallbladder away from the spine. (Bontrager and Lampignano, 6th ed., p. 528) |
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The Bucky slot cover is in place to protect the
1. patient. 2. fluoroscopist. 3. technologist. |
2. fluoroscopist.
3. technologist. All fluoroscopic equipment has protective devices and protocols to protect the patient and user. Fluoroscopic equipment must provide at least 12 inches (30 cm), and preferably 15 inches (38 cm), between the x-ray source (focal spot) and the x-ray tabletop (patient) according to NCRP Report No. 102. The tabletop intensity of the fluoroscopic beam must not exceed 10 R/min or 2.1 R/min/mA. With undertable fluoroscopic tubes, a Bucky-slot closer/cover having at least the equivalent of 0.25 mm Pb must be available to attenuate scattered radiation coming from the patient, which poses a radiation hazard to the fluoroscopist and radiographer. Fluoroscopic milliamperage must not exceed 5 mA. Because the image intensifier functions as a primary barrier, it must have a lead equivalent of at least 2.0 mm. A cumulative timing device must be available to signal the fluoroscopist when a maximum of 5 minutes of fluoroscopy time has elapsed. Because occupational exposure to scattered radiation is of considerable importance in fluoroscopy, a protective curtain/drape of at least 0.25 mm Pb equivalent must be placed between the patient and fluoroscopist. (Bushong, p. 570) |
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With the patient seated at the end of the x-ray table, elbow flexed 90°, CR directed 45° toward the shoulder to the elbow joint, which of the following structures will be demonstrated best?
A. Radial head B. Ulnar head C. Coronoid process D. Olecranon process |
A.
Radial head The axial trauma lateral (Coyle) is described. If routine elbow projections in extension are not possible because of limited part movement, this position can be used to demonstrate the coronoid process and/or radial head. With the elbow flexed 90° and the CR directed to the elbow joint at an angle of 45° medially (ie, toward the shoulder), the joint space between the radial head and capitulum should be revealed. With the elbow flexed 80° and the CR directed to the elbow joint at an angle of 45° laterally (ie, from the shoulder toward the elbow), the elongated coronoid process will be visualized. (Bontrager, p 160) |
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Radiation safety requirements for fluoroscopic equipment include the following:
1. SSD at least 38 cm on stationary (fixed) equipment. 2. SSD at least 30 cm on mobile equipment. 3. high level/boost mode must have continuous audible signal. |
1.
SSD at least 38 cm on stationary (fixed) equipment. 2. SSD at least 30 cm on mobile equipment. 3. high level/boost mode must have continuous audible signal. Fluoroscopy is potentially a high patient dose procedure. The principal reason is that the source of x-ray photons is much closer to the patient than in overhead radiography. There are recommendations that provide guidelines for minimum SSD (Source-Skin Distance), maximum tube output, collimation, timer, exposure switch specifications, and others. SSD must be at least 38 cm (15 inches) in stationary (fixed) fluoroscopic equipment, and at least 30 cm (12 inches) for mobile fluoroscopic equipment. The tabletop intensity of the fluoroscopic beam must be less than 10 R/min. A cumulative timing device must be available to signal the fluoroscopist (audibly, visibly, or both) when a maximum of 5 minutes of fluoroscopy time has elapsed. High-level mode requires continuous manual activation and audible signal. (Dowd and Tilson, p 175) |
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Which of the following groups of exposure factors will produce the longest scale of contrast?
A. 200 mA, 0.08 second, 95 kVp, 12:1 grid B. 500 mA, 0.03 second, 81 kVp, 8:1 grid C. 300 mA, 0.05 second, 95 kVp, 8:1 grid D. 600 mA, 1/40 second, 70 kVp, 6:1 grid |
C.
300 mA, 0.05 second, 95 kVp, 8:1 grid Of the given factors, kilovoltage and grid ratio will have a significant effect on radiographic contrast. mAs has no effect on contrast. Because a combination of increased kilovoltage and a low-ratio grid would allow the greatest amount of scattered radiation to reach the IR, thereby producing more gray tones, C is the best answer. D also uses a low-ratio grid, but the kilovoltage is too low to produce as many gray tones as C. (Shepard, pp 305–308) |
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In which of the following ways can higher radiographic contrast be obtained in abdominal radiography?
1. By using lower kilovoltage 2. By using a contrast medium 3. By limiting the field size |
1.
By using lower kilovoltage 2. By using a contrast medium 3. By limiting the field size Higher contrast is shorter scale contrast; it is present in an image that has few shades of gray between white and black. High radiographic contrast is, in part, a result of lower energy photons (lower kVp). High radiographic contrast also results when radiographing anatomic parts that have high subject contrast, such as the chest. The abdomen has low subject contrast, and therefore abdominal radiographs will tend to have very low contrast unless technical factors are selected to increase contrast. To produce high radiographic contrast in abdominal radiography, lower kVp should be used. To better demonstrate high contrast within a viscus, a contrast medium such as barium, iodine, or air can be used. Restricting the size of the field will also function to increase contrast because less scattered radiation will be generated. (Carlton & Adler, p 397) |
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Which of the positions illustrated in Figure A will best demonstrate the lumbar apophyseal joints closest to the IR?
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A. RPO
Four positions for the lumbar spine are illustrated. Number 1 is an RPO, and number 2 an LAO. The posterior oblique positions (LPO and RPO) demonstrate the apophyseal joints closer to the IR, while the anterior oblique positions (LAO and RAO) demonstrate the apophyseal joints further from the IR (Fig. B). Number 3 is the AP projection, which demonstrates the lumbar bodies and disk spaces and the transverse and spinous processes. Number 4 is the lateral position, which provides the best demonstration of the lumbar bodies, intervertebral disk spaces, spinous processes, pedicles, and intervertebral foramina. (Bontrager & Frank, vol 1, pp 431, 434-435) |
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Which type of dose–response relationship expresses radiation-induced leukemia?
A. Nonlinear, nonthreshold B. Nonlinear, threshold C. Linear, nonthreshold D. Linear, threshold |
C.
Linear, nonthreshold Radiation-induced malignancy, leukemia, and genetic effects are late effects (or stochastic effects) of radiation exposure. These can occur years after survival of an acute radiation dose, or after exposure to low levels of radiation over a long period of time. Radiation workers need to be especially aware of the late effects of radiation because their exposure to radiation is usually low-level over a long period of time. Occupational radiation protection guidelines are therefore based on late effects of radiation according to a linear, nonthreshold dose-response curve. (Bushong, 8th ed., p. 499) |
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All of the following positions are likely to be employed for both single-contrast and double-contrast examinations of the large bowel except
A. lateral rectum. B. AP axial rectosigmoid. C. right and left lateral decubitus abdomen. D. RAO and LAO abdomen. |
C.
right and left lateral decubitus abdomen. Radiographic examinations of the large bowel generally include the AP or PA axial position to "open" the S-shaped sigmoid colon, the lateral position especially for the rectum, and the LAO and RAO (or LPO and RPO) to "open" the colic flexures. The left and right decubitus positions are usually employed only in double-contrast barium enemas to better demonstrate double contrast of the medial and lateral walls of the ascending and descending colon. (Frank, Long, and Smith, vol. 2, 11th ed., p. 186) |
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Which of the following pathologic conditions require(s) a decrease in exposure factors?
1. Pneumothorax 2. Emphysema 3. Multiple myeloma |
1.
Pneumothorax 2. Emphysema 3. Multiple myeloma All three pathologic conditions involve processes that render tissues more easily penetrated by the x-ray beam. Pneumothorax is a collection of air or gas in the pleural cavity. Emphysema is a chronic pulmonary disease characterized by an increase in the size of the air-containing terminal bronchioles. These two conditions add air to the tissues, making them more easily penetrated. Multiple myeloma is a condition characterized by infiltration and destruction of bone and marrow. Each of these conditions requires that factors be decreased from the normal to avoid overexposure. (Carlton and Adler, 4th ed., pp. 251-252) |
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Which of the following combinations would pose the most hazard to a particular anode?
A. 0.6 mm focal spot, 75 kVp, 30 mAs B. 0.6 mm focal spot, 85 kVp, 15 mAs C. 1.2 mm focal spot, 75 kVp, 30 mAs D. 1.2 mm focal spot, 85 kVp, 15 mAs |
A.
0.6 mm focal spot, 75 kVp, 30 mAs Radiographic rating charts enable the operator to determine the maximum safe mA, exposure time, and kVp for a particular exposure using a particular x-ray tube. An exposure that can be made safely with the large focal spot may not be safe for use with the small focal spot of the same x-ray tube. The total number of HU that an exposure generates also influences the amount of stress (in the form of heat) imparted to the anode. The product of mAs and kVp determines HU. Groups A and C produce 2250 HU; groups B and D produce 1275 HU. Groups B and D deliver less heat load, but group D delivers it to a larger area (actual focal spot) making this the least hazardous group of technical factors. The most hazardous group of technical factors is group |
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Which of the following positions will most effectively move the gallbladder away from the vertebrae in the asthenic patient?
A. LAO B. RAO C. LPO D. Erect |
A.
LAO |
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Which of the following articulates with the base of the first metatarsal?
A. First cuneiform B. Third cuneiform C. Navicular D. Cuboid A. First cuneiform B. Third cuneiform C. Navicular D. Cuboid |
A.
First cuneiform The base of the first metatarsal articulates with the first (medial) cuneiform. The base of the second metatarsal articulates with the second (intermediate) cuneiform; the third base of the metatarsal articulates with the third (lateral) cuneiform. The bases of the fourth and fifth metatarsals articulate with the cuboid. The navicular articulates with the first and second cuneiforms anteriorly and the talus posteriorly. (Bontrager, p 198) |
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The ridge that marks the bifurcation of the trachea into the right and left primary bronchi is the
A. root. B. hilus. C. carina. D. epiglottis. |
C.
carina. The carina is an internal ridge located at the bifurcation of the trachea into right and left primary, or mainstem, bronchi. The epiglottis is a flap of elastic cartilage that functions to prevent fluids and solids from entering the respiratory tract during swallowing. The root of the lung attaches the lung, via dense connective tissue, to the mediastinum. The root of the left lung is at the level of T6, and the root of the right is at T5. The hilus (hilum) is the slitlike opening on the medial aspect of the lung through which arteries, veins, lymphatics, and so forth, enter and exit. (Bontrager, p 68) |
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Which of the following is (are) well demonstrated in the lateral position of the lumbar spine pictured in Figure A?
1. Intervertebral joints 2. Pedicles 3. Apophyseal joints |
1.
Intervertebral joints 2. Pedicles A lateral projection of the lumbar spine is illustrated. The intervertebral joints (disk spaces) are well demonstrated. Because the intervertebral foramina, which are formed by the pedicles, are 90° to the MSP, they are also well demonstrated in the lateral projection. The articular facets, forming the apophyseal joints, lie 30° to 50° to the MSP and therefore are visualized in the oblique position. (Frank, Long, and Smith, vol. 1, 11th ed., pp. 428–429) |
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Which of the following radiation situations is potentially the most harmful?
A. A large dose to a specific area all at once B. A small dose to the whole body over a period of time C. A large dose to the whole body all at one time D. A small dose to a specific area over a period of time |
C.
A large dose to the whole body all at one time The greatest effect—response from irradiation is brought about by a large dose of radiation to the whole body delivered all at one time. Whole-body radiation can depress many body functions. With a fractionated dose, the effects would be less severe because the body would have an opportunity to repair between doses. (Bushong, 8th ed., p. 464) |
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The dose–response curve that appears to be valid for genetic and some somatic effects is the
1. linear. 2. nonlinear. 3. nonthreshold. |
2.
nonlinear. 3. nonthreshold. The genetic effects of radiation and some somatic effects, like leukemia, are plotted on a linear dose-response curve. The linear dose–response curve has no threshold; that is, there is no dose below which radiation is absolutely safe. The nonlinear/sigmoidal dose–response curve has a threshold and is thought to be generally correct for most somatic effects. (Bushong, 8th ed., p. 498) |
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Stochastic effects of radiation include
A. blood changes. B. genetic alterations. C. cataractogenesis. D. reduced fertility. |
B.
genetic alterations. Stochastic effects of radiation are nonthreshold and randomly occurring. Examples of stochastic effects include carcinogenesis and genetic effects. The chance of occurrence of stochastic effects is directly related to the radiation dose; that is, as radiation dose increases, there is a greater likelihood of genetic alterations or development of cancer. Nonstochastic effects are predictable, threshold responses; that is, a certain quantity of radiation must be received before the effect will occur, and the greater the dose, the more severe the effect. (Bushong, 8th ed., p. 532) |
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In a lateral projection of the nasal bones, the central ray is directed
A. 1/2 inch posterior to the anterior nasal spine. B. 3/4 inch posterior to the glabella. C. 3/4 inch distal to the nasion. D. 1/2 inch anterior to the EAM. |
C.
3/4 inch distal to the nasion. The patient is placed in a true lateral position, and the central ray is directed perpendicular to a point 3/4 in distal to the nasion. An 8 x 10 cassette divided in half may be used for this procedure. (Frank, Long, and Smith, vol. 2, 11th ed., p. 360) |
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What type of shock results from loss of blood?
A. Septic B. Neurogenic C. Cardiogenic D. Hypovolemic |
D.
Hypovolemic Shock caused by an abnormally low volume of blood in the body is termed hypovolemic shock. Neurogenic shock can be caused by some kind of trauma to the nervous system, that is, spinal cord injury or extreme psychological stress. Cardiogenic shock is related to the heart and caused by failure of the heart to pump adequate blood to the body's vital organs. Septic shock can result when the body is invaded by bacteria; there are signs of acute septicemia and hypotension. (Torres et al., 6th ed., p. 163) |
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If a radiographer continues a lumbar spine examination after the patient states that he or she does not want to finish the examination, that radiographer can be found guilty of
A. assault. B. battery. C. false imprisonment. D. defamation. |
C.
false imprisonment. False imprisonment may be considered if a patient is ignored after stating that he or she no longer wishes to continue with the procedure or if restraining devices are used improperly or used without a physician's order. Assault is the threat of touching or laying hands on someone. If a patient feels threatened by a practitioner, either because of the tone or pitch of the practitioner's voice or because the practitioner uses words that are threatening, the practitioner can be accused of assault. A radiographer who performs the wrong examination on a patient may be charged with battery. Battery refers to the unlawful laying of hands on a patient. The radiographer could also be charged with battery if a patient was moved about roughly or touched in a manner that is inappropriate or without the patient's consent. The accusation of defamation can be upheld when patient confidentiality is not respected, and as a result, the patient suffers embarrassment or mockery. (Adler and Carlton, 4th ed., p. 374) |
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Which of the following positions is required to demonstrate small amounts of air in the pleural cavity?
A. AP supine B. AP Trendelenburg C. Lateral decubitus, affected side down D. Lateral decubitus, affected side up |
D.
Lateral decubitus, affected side up Air or fluid levels will be clearly delineated only if the CR is directed parallel to them. Therefore, to demonstrate air or fluid levels, the erect or decubitus position should be used. Small amounts of fluid within the pleural space are best demonstrated in the lateral decubitus position, affected side down. Small amounts of air within the pleural space are best demonstrated in the lateral decubitus position, affected side up. (Bontrager and Lampignano, 6th ed., p. 101) |
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The esophagus commences at about the level of
A. C3. B. C6. C. T1. D. T11. |
B.
C6. The esophagus is a musculomembranous tube commencing at about the level of the cricoid cartilage, that is, C5–6. It is located posterior to the larynx and trachea and extends to about the level of T11, where it joins with the proximal stomach. (Bontrager and Lampignano, 6th ed., p. 447) |
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The moral principle that describes the radiographer's aspiration to do no harm or to allow no act that might cause harm to the patient is termed
A. beneficence. B. nonmaleficence. C. autonomy. D. veracity. |
B.
nonmaleficence. There are many medicolegal terms with which the radiographer should be familiar. Beneficence refers to decisions and actions made to bring about good, ie, to benefit the patient. Nonmaleficence refers to the prevention of harm to the patient. Autonomy refers to the right of every individual to act with personal self-reliance. Veracity refers to telling the truth. (Adler and Carlton, 3rd ed, p 308) |
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Which of the following involve(s) intentional misconduct?
1. Invasion of privacy 2. False imprisonment 3. Patient sustaining injury from a fall while left unattended |
1.
Invasion of privacy 2. False imprisonment Invasion of privacy—that is, public discussion of privileged and confidential information—is intentional misconduct. False imprisonment, such as unnecessarily restraining a patient, is also intentional misconduct. However, if a radiographer left a weak patient standing while leaving the room to check images or get supplies, and the patient fell and sustained an injury, that would be considered unintentional misconduct or negligence. (Gurley & Callaway, p 187) |
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What determines the amount of fluorescent light emitted from a fluorescent screen?
1. Thickness of the active layer 2. Type of phosphor used 3. kV range used for exposure |
1.
Thickness of the active layer 2. Type of phosphor used 3. kV range used for exposure The thicker the active layer of phosphors, the more fluorescent light is emitted from the screen. Different types of phosphors have different conversion efficiencies; rare earth phosphors emit more light during a given exposure than do calcium tungstate phosphors. As the kVp level is increased, so is the amount of fluoroscopic light emitted by intensifying screen phosphors. (Selman, pp 177–182) |
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Free air in the abdominal cavity is best demonstrated in which of the following?
1. Lateral recumbent abdomen 2. Erect AP abdomen 3. Left lateral decubitus abdomen |
2.
Erect AP abdomen 3. Left lateral decubitus abdomen When air-fluid levels are to be demonstrated, it is important to direct the central ray horizontally. If the central ray is angled or directed vertically, the air or fluid level will be distorted or entirely obliterated. Free air in the abdominal cavity is best visualized when the patient is left lateral decubitus or erect AP. The decubitus allows the air to accumulate around the homogeneous liver. (Ballinger & Frank, vol 2, p 41) |
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Which of the following positions will demonstrate the lumbosacral apophyseal articulation?
A. AP B. Lateral C. 30° RPO D. 45° LPO |
C.
30° RPO The articular facets (apophyseal joints) of the L5–S1 articulation form a 30° angle with the MSP; they are therefore well demonstrated in a 30° oblique position. The 45° oblique demonstrates the apophyseal joints of L1 through L4. (Frank, Long, and Smith, vol. |
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In the lateral projection of the scapula, the
1. vertebral and axillary borders are superimposed. 2. acromion and coracoid processes are superimposed. 3. patient may be examined in the erect position. |
1.
vertebral and axillary borders are superimposed. 3. patient may be examined in the erect position. A lateral projection of the scapula superimposes its medial and lateral borders (vertebral and axillary, respectively). The coracoid and acromion processes should be readily identified separately (not superimposed) in the lateral projection. The erect position is probably the most comfortable position for a patient with scapula pain. (Frank, Long, and Smith, vol. 1, 11th ed., p. 214) |
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Which of the following structures will usually contain air, in the PA position on a sthenic patient, during a double-contrast upper GI (UGI) examination?
A. Duodenal bulb B. Descending duodenum C. Pyloric vestibule D. Gastric fundus |
D.
Gastric fundus The stomach is normally angled with the fundus lying posteriorly and the body, pylorus, and duodenum inferior to the fundus and angling anteriorly. Therefore, when the patient ingests barium and lies AP recumbent, the heavy barium gravitates easily to the fundus and fills it. With the patient PA recumbent, barium gravitates inferiorly to the body, pylorus, and duodenum, displacing air into the fundus. (Frank, Long, and Smith, 11th ed., vol. 2, pp. 144-145) |
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If a radiograph exposed using an AEC is overexposed because an exposure shorter than the minimum response time was required, the radiographer generally should
A. decrease the mA. B. use the minus density. C. use the plus density. D. decrease the kVp. |
A.
decrease the mA. Because using the master control's minus-density adjustment involves decreasing the exposure time (and this is not possible), this adjustment will be ineffective. Decreasing the kVp will produce a change in radiographic contrast. Because too long an exposure time results in excessive density, the best way to compensate is to decrease the milliamperage. (Carlton and Adler, 4th ed., p. 541; Shephard, p. 286) |
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Which of the following statements is/are true regarding the position illustrated in RPO position Figure A?
1. The left (elevated) kidney is parallel to the IR. 2. The right (adjacent to the table) kidney is parallel to the IR. 3. The degree of obliquity should be about 45°. |
1.
The left (elevated) kidney is parallel to the IR. An RPO position is illustrated. The oblique IVU projections should be approximately 30°; this position significantly changes the position of the kidneys. When the abdomen is obliqued, the kidney of the "down" side is perpendicular to the IR; the kidney of the "up" side is parallel to the IR. (Frank, Long, and Smith, vol. 2, 11th ed., p. 220) |
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Which of the following cells is the least radiosensitive?
A. Myelocytes B. Myocytes C. Megakaryocytes D. Erythroblasts |
B.
Myocytes Bergonié and Tribondeau theorized in 1906 that all precursor cells are particularly radiosensitive (e.g., stem cells found in bone marrow). There are several types of stem cells in bone marrow, and the different types differ in degree of radiosensitivity. Of these, red blood cell precursors, or erythroblasts, are the most radiosensitive. White blood cell precursors, or myelocytes, follow. Platelet precursor cells, or megakaryocytes, are even less radiosensitive. Myocytes are mature muscle cells and are fairly radioresistant. (Bushong, p. 495) |
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An esophagogram might be requested for patients with which of the following esophageal disorders/symptoms?
1. Varices 2. Achalasia 3. Dysphasia |
1.
Varices 2. Achalasia Dilated twisted veins, or varices, of the esophagus are frequently associated with obstructive liver disease or cirrhosis of the liver. These esophageal veins enlarge and can rupture, causing serious hemorrhage. Achalasia is dilation of the esophagus as a result of the cardiac sphincter's failure to relax and allow food to pass into the stomach. Dysphasia is a speech impairment resulting from a brain lesion; it is unrelated to the esophagus. Dysphagia refers to difficulty swallowing and is the most common esophageal complaint. Hiatal hernia is another common esophageal problem; it is characterized by protrusion of a portion of the stomach through the cardiac sphincter. It is a common condition, and many individuals with the condition are asymptomatic. Each of these conditions of the esophagus may be evaluated with an esophagogram. Positions usually include the posteroanterior, right anterior oblique, and right lateral. (Bontrager and Lampignano, 6th ed., pp. 463–464) |
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Which of the following is (are) located on the posterior aspect of the femur?
1. Intercondyloid fossa 2. Intertrochanteric crest 3. Intertubercular groove |
1.
Intercondyloid fossa 2. Intertrochanteric crest The femur is the longest and strongest bone in the body. The femoral shaft is bowed slightly anteriorly and presents a long, narrow ridge posteriorly, called the linea aspera. The proximal femur consists of a head that is received by the pelvic acetabulum. The femoral neck, which joins the head and shaft, normally angles upward about 120° and forward (in anteversion) about 15°. The greater and lesser trochanters are large processes on the posterior proximal femur. The intertrochanteric crest runs obliquely between the trochanters; the intertrochanteric line parallels the intertrochanteric crest on the anterior femoral surface. The intercondyloid fossa, a deep notch, found on the distal posterior femur between the large femoral condyles, and the popliteal surface is a smooth surface just superior to the intercondyloid fossa. The intertubercular groove is found on the proximal humerus between the humeral tubercles. (Frank, Long, and Smith, vol. 1, 11th ed., pp. 234–235) |
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What is the purpose of the thin layer of lead that is often located behind the rear intensifying screen in a image receptor?
A. To prevent crossover B. To increase screen speed C. To diffuse light photons D. To prevent scattered radiation fog |
D.
To prevent scattered radiation fog The purpose of the thin layer of lead that is often located behind the rear intensifying screen in a cassette is to absorb x-rays that penetrate the screens, strike the rear of the cassette, and bounce back toward the film emulsion, resulting in scattered radiation fog. The thin layer of lead absorbs these x-ray photons and thus improves the radiographic image. (Shephard, pp. 41–42) |
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To produce a just perceptible increase in radiographic density, the radiographer must increase the
A. mAs by 30%. B. mAs by 15%. C. kVp by 15%. D. kVp by 30%. |
A.
mAs by 30%. If a radiograph lacks sufficient blackening, an increase in mAs is required. The mAs regulates the number of x-ray photons produced at the target. An increase or decrease in mAs of at least 30% is necessary to produce a perceptible effect. Increasing the kVp by 15% will have about the same effect as doubling the mAs. (Shephard, p. 173) |
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When comparing the male and female bony pelves, it is noted that the
1. male pelvis is deeper. 2. female pubic arch is greater than 90°. 3. female greater sciatic notch is wider. |
1.
male pelvis is deeper. 2. female pubic arch is greater than 90°. 3. female greater sciatic notch is wider. The male and female bony pelves have several differing characteristics. An overview of comparisons is listed below. Male pelvis Heavy and thick general structure Greater, or false, pelvis is deep Pelvis brim, or inlet, is small and heart-shaped Acetabulum is large and faces laterally Pubic angle is less than 90° Ilium is more vertical Female pelvis Light and thin general structure Greater, or false, pelvis is shallow Pelvis brim, or inlet, is large and oval Acetabulum is small and faces anteriorly Pubic angle is more than 90° Ilium is more horizontal |
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Which of the following structures is best demonstrated in Figure A?
. Sigmoid colon B. Splenic flexure C. Hepatic flexure D. Rectosigmoid |
C.
Hepatic flexure The radiograph illustrates an air-contrast barium enema examination. The intent of this examination is to coat the intestinal mucosa with barium, then fill the lumen with air. Typically, some structures will be imaged filled with barium, and others will be imaged as double-contrast (barium and air); how structures are filled depends to a large extent on the position employed. Radiographic examinations of the large bowel generally include the AP or PA axial position to "open" the S-shaped sigmoid colon, the lateral position especially for the rectum, and the LAO and RAO (or LPO and RPO) to "open" the colic flexures. Left and right decubitus positions are usually employed only in double-contrast barium enemas to better demonstrate double contrast of the medial and lateral walls of the ascending and descending colon. An LPO position is illustrated. The LPO and RAO positions demonstrate the hepatic flexure and adjacent ascending colon. The LAO and RPO positions demonstrate the splenic flexure and descending colon. (Frank, Long, and Smith, 11th ed., vol. 2, pp. 172–175) |
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Which of the following statements is (are) true regarding the PA axial projection of the cranium?
1. The central ray is directed caudally to the OML. 2. The petrous pyramids are projected into the lower third of the orbits. 3. The frontal sinuses are visualized. |
1.
The central ray is directed caudally to the OML. 2. The petrous pyramids are projected into the lower third of the orbits. 3. The frontal sinuses are visualized. The PA axial (Caldwell) projection of the cranium can be used to demonstrate the frontal and ethmoid bones and the frontal and ethmoidal sinuses. The central ray is angled caudally 15° to the OML. This projects the petrous pyramids into the lower one third of the orbits, thus permitting optimal visualization of the frontal and ethmoidal sinuses. If the paranasal sinuses are being investigated, the OML forms a 15° angle with the horizontal CR. Additionally, the vertical grid should be angled 15°, or the patient's neck extended and forehead moved away from the IR. This is done to avoid tube angulation which could distort any sinus air/fluid levels. (Bontrager and Lampignano, 6th ed., p. 439) |
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Which of the following combinations will present the greatest heat-loading capability?
A. 17° target angle, 1.2-mm actual focal spot B. 10° target angle, 1.2-mm actual focal spot C. 17° target angle, 0.6-mm actual focal spot D. 10° target angle, 0.6-mm actual focal spot |
B.
10° target angle, 1.2-mm actual focal spot The smaller the focal spot, the more limited the anode is with respect to the quantity of heat it can safely accept. As the target angle decreases, the actual focal spot can be increased while still maintaining a small effective focal spot. Therefore, group B offers the greatest heat-loading potential, with a steep target angle and a large actual focal spot. It must be remembered, however, that a steep target angle increases the heel effect, and film coverage may be compromised. (Selman, 9th ed., pp. 145–146) |
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A technique chart should include which of the following information?
1. Recommended SID 2. Grid ratio 3. Screen-film combination |
1.
Recommended SID 2. Grid ratio 3. Screen-film combination Technique charts are exposure factor guides that help technologists produce radiographs with consistent density and contrast. They suggest a group of exposure factors to be used at a particular SID with a particular grid ratio, screen-film combination, focal spot size, and central ray angulation. Technique charts do not take into account the nature of the part (disease, atrophy, etc). (Shephard, p. 298) |
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Components of digital imaging include
1. computer manipulation of the image. 2. formation of an electronic image on the radiation detector. 3. formation of an x-ray image directly on the image receptor. |
1.
computer manipulation of the image. 2. formation of an electronic image on the radiation detector. Traditional x-ray imaging involves formation of the x-ray image directly on the image receptor (film). In digital imaging, x-rays form an electronic image on a special radiation detector. This electronic image can be manipulated by a computer and stored in the computer memory or displayed as a matrix of intensities. This final digital image is often viewed on a computer monitor and looks just like a traditional x-ray image, but the computer often has the capability of postprocessing image enhancement. (Bushong, 8th ed., p. 402) |
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The carpal scaphoid may be demonstrated in the following projection(s) of the wrist:
1. PA oblique 2. PA with ulnar flexion/deviation 3. PA with forearm elevated 20° |
1.
PA oblique 2. PA with ulnar flexion/deviation 3. PA with forearm elevated 20° Lateral carpals, especially the scaphoid, are demonstrated in the PA oblique projection and the ulnar flexion/deviation maneuver. The scaphoid may also be demonstrated with the wrist PA and elevated 20°. The central ray is directed perpendicular to the carpal scaphoid. The medial carpals, especially the pisiform, are well demonstrated in the AP oblique projection and with the radial flexion/deviation maneuver. (Frank, Long, and Smith, vol. 1, 11th ed., p. 132-133) |
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With which of the following does the femoral head articulate?
1. Ilium 2. Ischium 3. Pubis |
1. Ilium
2. Ischium 3. Pubis The pelvic girdle consists of two innominate bones, one on each side of the sacrum. Each innominate bone consists of three fused bones: the ilium, ischium, and pubis. Parts of these three bones contribute to the formation of the acetabulum—the socket articulation for the femoral head. (Tortora, 11th ed, pp 242, 243) |
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Use your mouse to drag the following tissues into order (A–D) from lowest weighting factor (Wt) to highest weighting factor.
(A) Skin (B) Breast (C) Lung (D) Bone marrow |
(D) Bone marrow
(A) Skin (B) Breast (C) Lung The tissue weighting factor (Wt) represents the relative tissue radiosensitivity of irradiated material (e.g., muscle versus intestinal epithelium versus bone, etc.). The tissue weighting factor of the gonads is 0.20. The tissue weighting factor of bone marrow, colon, lung, and stomach is 0.12. The bladder, breast, esophagus, liver, and thyroid have a tissue weighting factor of 0.05. The skin and surface of bone weighting factor is 0.01. The radiation weighting factor (Wr) is a number assigned to different types of ionizing radiations in order to better determine their effect on tissue (e.g., x-rays versus alpha particles). The Wr of different ionizing radiations depends on the LET of that particular radiation. The radiation weighting factor of x and gamma radiation, as well as electrons, is 1. The radiation weighting factor of protons is 2 and of alpha particles is 20. The radiation weighting factor of neutrons can be anywhere between 5 and 20 depending on their energy. The following formula is used to determine effective dose (E): |
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Use your mouse to drag the following bony parts into order (A–D) from most proximal to most distal
(A) Fovea capitis (B) Intertrochanteric crest (C) Linea aspera (D) Popliteal surface |
(D) Popliteal surface
(B) Intertrochanteric crest (A) Fovea capitis (C) Linea aspera The femur is the longest and strongest bone in the body. The femoral shaft is bowed slightly anteriorly. The proximal end of the femur consists of a head, which is received by the acetabulum of the pelvis. The femoral head has a small notch, the fovea capitis femoris, for ligament attachment. The femoral neck, which joins the head and shaft, angles upward approximately 120 degrees and forward (in anteversion) approximately 15 degrees. The greater (lateral) and lesser (medial) trochanters are large processes on the posterior proximal femur. The greater trochanter is a prominent positioning landmark that lies in the same transverse plane as the public symphysis and coccyx. The intertrochanteric crest runs obliquely between the trochanters; the intertrochanteric line runs anteriorly parallel to the crest. The femoral shaft presents a long, narrow ridge posteriorly called the linea aspera. Its distal anterior portion presents the patellar surface—a triangular depression over which the patella glides during flexion. The distal posterior surface presents the popliteal surface—a depression that houses the popliteal artery. The medial and lateral femoral condyles are very prominent posterior structures, and between them is the deep intercondyloid fossa. Just above the condyles are the medial and lateral femoral epicondyles. (Bontrager and Lampignano, 6th ed., pp. 217, 262) |
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The interaction between x-ray photons and matter pictured in Figure A is associated with
1. high-energy x-ray photons. 2. ionization. 3. characteristic radiation. |
2.
ionization. 3. characteristic radiation. Diagnostic x-ray photons interact with tissue in a number of ways, but most frequently they are involved in the photoelectric effect or in the production of Compton scatter. The photoelectric effect is pictured in Figure B; it occurs when a relatively low-energy x-ray photon uses all its energy to eject an inner-shell electron. That electron is ejected (photoelectron), leaving a "hole" in the K shell and producing a positive ion. An L-shell electron then drops down to fill the K vacancy, and in doing so emits a characteristic ray whose energy is equal to the difference between the binding energies of the K and L shells. The photoelectric effect occurs with high-atomic-number absorbers such as bone and positive contrast media, and is responsible for the production of contrast. Therefore, its occurrence is helpful for the production of the radiographic image, but it contributes significantly to the dose received by the patient (because it involves complete absorption of the incident photon). Scattered radiation, which produces a radiation hazard to the radiographer (as in fluoroscopy), is a product of the Compton scatter interaction occurring with higher-energy x-ray photons. (Selman, 9th ed., pp. 125-126) |
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What is used to account for the differences in ionizing characteristics of various radiations, when determining their effect on biologic material?
1. Radiation weighting factors (Wr) 2. Tissue weighting factors (Wt) 3. Absorbed dose |
1.
Radiation weighting factors (Wr) The Tissue Weighting Factor (Wt) represents the relative tissue radiosensitivity of irradiated material (eg, muscle vs intestinal epithelium vs bone, etc). The Radiation Weighting Factor (Wr) is a number assigned to different types of ionizing radiations in order to better determine their effect on tissue (eg, x-ray vs alpha particles). The Wr of different ionizing radiations is dependent on the LET of that particular radiation. The following formula is used to determine Effective Dose (E): Effective Dose (E) = Radiation Weighting Factor (Wr) x Tissue Weighting Factor (Wt) x Absorbed Dose |
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The ARRT Rules of Ethics are
1. aspirational. 2. mandatory. 3. minimally acceptable standards. |
2. mandatory.
3. minimally acceptable standards. The ARRT Standards of Ethics is a three-part document. Following the Preamble, it consists of the Code of Ethics, the Rules of Ethics, and Administrative Procedures. The Code of Ethics serves as a guide thta imaging professionals use to direct their conduct and growth—it addresses humanistic behavior, delivery of care without bias, good judgment, minimizing exposure to ionizing radiation, assuming responsibility, not attempting to diagnose or interpret, etc. The Code of Ethics is aspirational. The Rules of Ethics are minimally acceptable mandatory and enforceable standards required of all imaging professionals to ensure quality patient care. Violation of the Code of Ethics renders the individual subject to sanction. The Rules of Ethics cover issues such as fraud/deceit regarding individual ARRT certification; subversion/attempt to the subvert the certification examination process; conviction of a crime; failure to report charges concerning the individual's permit, license, or certification; engaging in unethical conduct; etc. There are 20 Rules of Ethics with which the imaging professional should be familiar. (Adler and Carlton, 4th ed., p. 350) |
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What is used to account for the differences in tissue sensitivity to ionizing radiation when determining effective dose (E)?
1. Tissue weighting factors (Wt) 2. Radiation weighting factors (Wr) 3. Absorbed dose |
1. Tissue weighting factors (Wt)
The tissue weighting factor (Wt) represents the relative tissue radiosensitivity of irradiated material (e.g., muscle versus intestinal epithelium versus bone, etc.). The tissue weighting factor of the gonads is 0.20. The tissue weighting factor of bone marrow, colon, lung, and stomach is 0.12. The bladder, breast, esophagus, liver, and thyroid have a tissue weighting factor of 0.05. The skin and surface of bone weighting factor is 0.01. The radiation weighting factor (Wr) is a number assigned to different types of ionizing radiations in order to better determine their effect on tissue (e.g., x-rays versus alpha particles). The Wr of different ionizing radiations depends on the LET of that particular radiation. The radiation weighting factor of x and gamma radiation, as well as electrons, is 1. The radiation weighting factor of protons is 2 and of alpha particles is 20. The radiation weighting factor of neutrons can be anywhere between 5 and 20 depending on their energy. The following formula is used to determine effective dose (E): E = Wr x Wt x absorbed dose |
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To demonstrate the first two cervical vertebrae in the AP projection, the patient is positioned so that
A. the glabellomeatal line is vertical. B. the acanthiomeatal line is vertical. C. a line between the mentum and the mastoid tip is vertical. D. a line between the maxillary occlusal plane and the mastoid tip is vertical. |
a line between the maxillary occlusal plane and the mastoid tip is vertical.
To clearly demonstrate the atlas and axis without superimposition of the teeth or the base of the skull, a line between the maxillary occlusal plane (edge of upper teeth) and mastoid tip must be vertical. If the head is flexed too much, the teeth will be superimposed. If the head is extended too much, the cranial base will be superimposed on the area of interest. A line between the mentum and the mastoid tip is used to demonstrate the odontoid process only through the foramen magnum (Fuchs method). (Frank, Long, and Smith, vol. 1, 11th ed., p. 393) |
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Techniques that function to reduce the spread of microbes are termed
A. surgical asepsis. B. medical asepsis. C. sterilization. D. disinfection. |
medical asepsis.
Medical asepsis refers to practices that reduce the spread of microbes, and therefore the chance of spreading disease or infection. Washing your hands is an example of medical asepsis. It reduces the spread of infection, but it does not eliminate all microorganisms. Disinfection involves the use of chemicals to either inactivate or inhibit the growth of microbes. The complete killing of all microorganisms is termed sterilization. Surgical asepsis refers to the technique used when performing procedures to prevent contamination. (Adler & Carlton, p 211) |
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The scapular Y projection of the shoulder demonstrates
1. an oblique projection of the shoulder. 2. anterior or posterior dislocation. 3. a lateral projection of the shoulder. |
1.
an oblique projection of the shoulder. 2. anterior or posterior dislocation. The scapular Y projection requires that the coronal plane be about 60° to the IR, thus resulting in an oblique projection of the shoulder. The vertebral and axillary borders of the scapula are superimposed on the humeral shaft, and the resulting relationship between the glenoid fossa and humeral head will demonstrate anterior or posterior dislocation. Lateral or medial dislocation is evaluated on the AP projection. (Ballinger & Frank, vol 1, p 179) |
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Which of the following is (are) classified as rare earth phosphors?
1. Lanthanum oxybromide 2. Gadolinium oxysulfide 3. Cesium iodide |
1.
Lanthanum oxybromide 2. Gadolinium oxysulfide Rare earth phosphors have a greater conversion efficiency than do other phosphors. Lanthanum oxybromide is a blue-emitting rare earth phosphor, and gadolinium oxysulfide is a green-emitting rare earth phosphor. Cesium iodide is the phosphor used on the input screen of image intensifiers; it is not a rare earth phosphor. (Shephard, p. 68) |
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Which of the following contribute(s) to inherent filtration?
1. X-ray tube glass envelope 2. X-ray tube port window 3. Aluminum between the tube housing and the collimator |
1.
X-ray tube glass envelope 2. X-ray tube port window Inherent filtration is that which is "built into" the construction of the x-ray tube. Before exiting the x-ray tube, x-ray photons must pass through the tube's glass envelope and port window; the photons are filtered somewhat as they do so. This inherent filtration is usually the equivalent of 0.5 mm Al. Aluminum filtration placed between the x-ray tube housing and the collimator is added to contribute to the total necessary requirement of 2.5 mm Al equivalent. The collimator itself is considered part of the added filtration (1.0 mm Al equivalent) because of the silver surface of the mirror within. It is important to remember that as aluminum filtration is added to the x-ray tube, the HVL increases. (Selman, 9th ed., p. 132) |
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In the lateral projection of the foot, the
1. plantar surface should be perpendicular to the IR. 2. metatarsals are superimposed. 3. talofibular joint should be visualized. |
1.
plantar surface should be perpendicular to the IR. 2. metatarsals are superimposed. When the foot is positioned for a lateral projection, the plantar surface should be perpendicular to the IR, so as to superimpose the metatarsals. This may be accomplished with the patient lying on either the affected or the unaffected side (usually the affected), that is, mediolateral or lateromedial. The talofibular articulation is best demonstrated in the medial oblique projection of the ankle. (Frank, Long, and Smith, vol. 1, 11th ed., p. 264) |
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In digital imaging, as the size of the image matrix increases:
1. FOV increases 2. pixel size decreases 3. spatial resolution increases |
2.
pixel size decreases 3. spatial resolution increases The FOV and matrix size are independent of one another, that is, either can be changed and the other will remain unaffected. However, pixel size is affected by changes in either the FOV or matrix size. For example, if the matrix size is increased, pixel size decreases. If FOV increases, pixel size increases. Pixel size is inversely related to resolution. As pixel size decreases, resolution increases. (Fosbinder & Kelsey, p 285). |
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Which of the following projections of the calcaneus is obtained with the leg extended, the plantar surface of the foot vertical and perpendicular to the IR, and the central ray directed 40° caudad?
A. Axial plantodorsal projection B. Axial dorsoplantar projection C. Lateral projection D. Weight-bearing lateral projection |
Axial dorsoplantar projection
An axial dorsoplantar projection of the calcaneus is described; the central ray enters the dorsal surface of the foot and exits the plantar surface. The plantodorsal projection is done supine and requires cephalad angulation. The central ray enters the plantar surface and exits the dorsal surface. (Ballinger & Frank, vol 1, p 263) |
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All of the following statements regarding the inferosuperior axial (nontrauma, Lawrence method) projection of the shoulder are true, except
A. the coracoid process and lesser tubercle are seen in profile. B. the arm is abducted about 90° from the body. C. the arm should be in internal rotation. D. the CR is directed medially 25° to 30° through the axilla. |
the arm should be in internal rotation.
The inferosuperior axial (nontrauma, Lawrence method) projection of the shoulder demonstrates the glenohumeral joint and adjacent structures. The patient is supine with arm abducted 90°, and in external rotation. The (horizontal) CR is directed medially 25° to 30° through the axilla. The coracoid process and lesser tubercle are seen in profile. (Bontrager, p 179) |
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If the patient's zygomatic arch has been traumatically depressed or the patient has flat cheekbones, the arch may be demonstrated by modifying the SMV projection and rotating the patient's head
A. 15° toward the side being examined. B. 15° away from the side being examined. C. 30° toward the side being examined. D. 30° away from the side being examined. |
15° toward the side being examined.
When one cheekbone is depressed, a tangential projection is required to "open up" the zygomatic arch and draw it away from the overlying cranial bones. This is accomplished by placing the patient in the SMV position, rotating the head 15° toward the affected side, and centering to the zygomatic arch. A 30° rotation places the mandibular shadow over the zygomatic arch. (Frank, Long, and Smith, vol. 2, 11th ed., pp. 364–365) |
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When using the smaller field in a dual-field image intensifier,
1. a smaller patient area is viewed. 2. the image is magnified. 3. the image is less bright. |
1.
a smaller patient area is viewed. 2. the image is magnified. 3. the image is less bright. When a dual-field image intensifier is switched to the smaller field, the electrostatic focusing lenses are given a greater charge to focus the electron image more tightly. The focal point, then, moves further from the output phosphor (the diameter of the electron image is therefore smaller as it reaches the output phosphor), and the brightness gain is somewhat diminished. Hence, the patient area viewed is somewhat smaller and is magnified. However, the minification gain has been reduced and the image is somewhat less bright. (Bushong, 8th ed., p. 363) |
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Moving the image intensifier closer to the patient during fluoroscopy
1. decreases the source-image distance (SID). 2. decreases patient dose. 3. improves image quality. |
1.
decreases the source-image distance (SID). 2. decreases patient dose. 3. improves image quality. Moving the image intensifier closer to the patient during fluoroscopy reduces the distance between the x-ray tube (source) and the image intensifier (image receptor), that is, the SID. It follows that the distance between the part being imaged (object) and the image intensifier (image receptor), that is, the OID, is also reduced. The shorter OID produces less magnification and better image quality. As the SID is reduced, the intensity of the x-ray photons at the image intensifier's input phosphor increases, stimulating the automatic brightness control (ABC) to decrease the mA and thereby decreasing patient dose (see the figure below). (Fosbinder and Kelsey, pp. 265–267) |
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In the AP projection of an asthenic patient whose knee measures less than 19 cm from ASIS to tabletop, the central ray should be directed
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5° caudad
In the AP projection of the knee, the position of the joint space is significantly affected by the patient's overall body habitus and the distance between the ASIS and the tabletop. When the patient is of sthenic habitus with a distance of 19 to 24 cm between ASIS and tabletop, the central ray is directed perpendicularly. When the patient is of asthenic habitus with a distance of less than 19 cm between ASIS and tabletop, the central ray is directed 5° caudad. With a patient with a hypersthenic habitus and an ASIS-to-table measurement greater than 24 cm, the central ray is directed 5° cephalad. (Frank, Long, and Smith, 11th ed., vol. 1, p. 302) |
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Types of moving grid mechanisms include
1. oscillating. 2. reciprocating. 3. synchronous. |
1.
oscillating. 2. reciprocating. Grids are devices constructed of alternating strips of lead foil and radiolucent interspacing material. They are placed between the patient and the IR, and they function to remove scattered radiation from the remnant beam before it forms the latent image. Stationary grids will efficiently remove scattered radiation from the remnant beam; however, their lead strips will be imaged on the radiograph. If the grid is made to move (usually in a direction perpendicular to the lead strips) during the exposure, the lead strips will be effectively blurred. The motion of a moving grid, or Potter-Bucky diaphragm, may be reciprocating (equal strokes back and forth), oscillating (almost circular direction), or catapult (rapid forward motion and slow return). Synchronous refers to a type of x-ray timer. (Bushong, p 256) |
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The advantages of digital subtraction angiography over film angiography include
1. greater sensitivity to contrast medium. 2. immediately available images. 3. increased resolution. |
1.
greater sensitivity to contrast medium. 2. immediately available images. Superimposition of bony details frequently makes angiographic demonstration of blood vessels less than optimal. The method used to remove these superimposed bony details is called subtraction. Digital subtraction angiography (DSA) accomplishes this through a computer. The advantages of DSA over film angiography include greater sensitivity to contrast medium, immediate availability of images, and lower total cost. Although DSA applications are increasing, film angiography may be preferred in cases in which resolution is critical. (Frank, Long, and Smith, vol. 3, 11th ed., p. 28) |
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The image intensifier's input phosphor is generally composed of
A. cesium iodide. B. zinc cadmium sulfide. C. gadolinium oxysulfide. D. calcium tungstate. |
cesium iodide.
The image intensifier's input phosphor receives the remnant beam from the patient and converts it to a fluorescent light image. To maintain resolution, the input phosphor is made of cesium iodide crystals. Cesium iodide is much more efficient in this conversion process than was the phosphor previously used, zinc cadmium sulfide. Calcium tungstate was the phosphor used in cassette intensifying screens for many years prior to the development of rare earth phosphors such as gadolinium oxysulfide. (Bushong, 8th ed., p. 360) |
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The x-ray imaging system that uses a flat panel detector built into the x-ray table is
A. film/screen system. B. computed radiography. C. direct digital radiography. D. fluoroscopy. |
direct digital radiography.
Medical imaging is experiencing rapid technological growth, and x-ray images can be obtained in a number of ways. Traditional x-ray imaging, still available in many facilities, records the image using film sandwiched between intensifying screens within a cassette. Some imaging facilities are using computed radiography (CR). CR uses a cassette-like device to enclose an image plate (IP). When the IP is exposed, it stores the image; a scanner-reader then converts the IP image to a digital image displayed on a computer monitor. Direct digital radiography (DR) eliminates the cassette and IP. The x-ray image is captured by a flat panel detector in the x-ray table and converts it to a digital image displayed immediately on a computer monitor. Fluoroscopy is a "live action" or "real-time" examination where the dynamics (motion) of parts can be evaluated; "still" images can be made during the fluoroscopic exam. (Ballinger and Frank, 10th ed, vol 1, p 3) |
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To be used more efficiently by the x-ray tube, alternating current is changed to unidirectional current by the
A. filament transformer. B. autotransformer. C. high-voltage transformer. D. rectifiers. |
rectifiers.
Rectifiers (solid-state or the older valve tubes) permit the flow of current in only one direction. They serve to change AC, which is needed in the low-voltage side of the x-ray circuit, to unidirectional current. Unidirectional current is necessary for the efficient operation of the x-ray tube. The rectification system is located between the secondary coil of the high-voltage transformer and the x-ray tube. The filament transformer functions to adjust the voltage and current going to heat the x-ray tube filament. The autotransformer varies the amount of voltage being sent to the primary coil of the high-voltage transformer so that the appropriate kVp can be obtained. The high-voltage transformer "steps up" the voltage to the required kilovoltage and steps down the amperage to milliamperage. (Carlton & Adler, p 78) |
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All the following can be associated with the elbow joint except
A. the capitulum. B. the trochlea. C. the tubercles. D. the epicondyles. |
the tubercles.
The distal humerus articulates with the radius and ulna to form the elbow joint. The lateral aspect of the distal humerus presents a raised, smooth, rounded surface, the capitulum, that articulates with the superior surface of the radial head. The trochlea is on the medial aspect of the distal humerus and articulates with the semilunar/trochlear notch of the ulna. Just proximal to the capitulum and trochlea are the lateral and medial epicondyles; the medial is more prominent and palpable. Lateral epicondylitis ("tennis elbow") is a painful condition caused by prolonged rotary motion of the forearm. The tubercles are prominences located at the proximal humerus and are anatomically remote from the elbow joint. (Tortora and Grabowski, 11th ed., pp. 237–238) |
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What is the most superior structure of the scapula?
A. Apex B. Acromion process C. Coracoid process D. Superior angle |
Acromion process
It is easy to determine the highest point of the scapula when it is viewed laterally. The coracoid process projects anteriorly and is quite superior. However, the acromion process, which is an anterior extension of the scapular spine, projects considerably more superior than the coracoid. (Frank, Long, and Smith, 11th ed., vol. 1, p. 168) |
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Ingestion of barium sulfate is contraindicated in which of the following situations?
1. Suspected perforation of a hollow viscus 2. Suspected large-bowel obstruction 3. Presurgical patients |
1.
Suspected perforation of a hollow viscus 2. Suspected large-bowel obstruction 3. Presurgical patients Barium sulfate suspension is the usual contrast medium of choice for investigation of the alimentary tract. There are, however, a few exceptions. Whenever there is the possibility of escape of contrast medium into the peritoneal cavity, barium sulfate is contraindicated and a water-soluble iodinated medium is recommended, as it is easily aspirated before surgery. Rupture of a hollow viscus (eg, perforated ulcer) and patients who are scheduled for surgery are two examples. Patients with suspected large-bowel obstruction should also ingest only water-soluble iodinated media. (Frank, Long, and Smith, vol. 2, 11th ed., p. 306) |
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Which of the following groups of exposure factors will deliver the least amount of exposure to the patient?
A. 400 mA, 0.25 second, 100 kVp B. 600 mA, 0.33 second, 90 kVp C. 800 mA, 0.5 second, 80 kVp D. 800 mA, 1.0 second, 70 kVp |
400 mA, 0.25 second, 100 kVp
mAs regulates the quantity of radiation delivered to the patient, and kVp regulates the quality (penetration) of the radiation delivered to the patient. Therefore, higher energy (more penetrating) radiation (which is more likely to exit the patient), accompanied by lower mAs, is the safest combination for the patient. (Thompson et al, p. 275) |
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The medical term for nosebleed is
A. vertigo. B. epistaxis. C. urticaria. D. aura. |
epistaxis.
The medical term for nosebleed is epistaxis. Vertigo refers to a feeling of "whirling" or a sensation that the room is spinning. Some possible causes of vertigo include inner ear infection and acoustic neuroma. Urticaria is a vascular reaction resulting in dilated capillaries and edema and causing the patient to break out in hives. An aura may be classified as either a feeling or a sensory response (such as flashing lights, tasting metal, smelling coffee) that precedes an episode such as a seizure or a migraine headache. (Adler & Carlton, p 247) |
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Which of the positions illustrated in Figure A will best demonstrate the lumbar apophyseal joints closest to the IR?
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Four positions for the lumbar spine are illustrated. Number 1 is an RPO, and number 2 an LAO. The posterior oblique positions (LPO and RPO) demonstrate the apophyseal joints closer to the IR, while the anterior oblique positions (LAO and RAO) demonstrate the apophyseal joints further from the IR (Fig. B). Number 3 is the AP projection, which demonstrates the lumbar bodies and disk spaces and the transverse and spinous processes. Number 4 is the lateral position, which provides the best demonstration of the lumbar bodies, intervertebral disk spaces, spinous processes, pedicles, and intervertebral foramina. (Bontrager & Frank, vol 1, pp 431, 434-435)
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Which of the following ionizing radiations is described as having an RBE of 1.0?
A. 10 MeV protons B. 5 MeV alpha particles C. Diagnostic x-rays D. Fast neutrons |
Diagnostic x-rays
LET increases with the ionizing potential of the radiation, for example, alpha particles are more ionizing than x-radiation, therefore they have a higher LET. As ionizations and LET increase, there is greater possibility of an effect on living tissue; therefore, the RBE increases. The RBE (sometimes called QF—Quality Factor) of diagnostic x-rays is 1; the RBE of fast neutrons is 10; the RBE of 5 MeV alpha particles is 20, and the RBE of 10 MeV protons is 5.0. (Bushong, 8th ed., p. 496) |
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According to the NCRP, the annual occupational whole-body dose equivalent limit is
A. 1 mSv. B. 50 mSv. C. 150 mSv. D. 500 mSv. |
50 mSv
According to the NCRP, the annual occupational whole-body dose equivalent limit is 50 mSv (5 rem or 5000 mrem). The annual occupational whole-body dose equivalent limit for students under the age of 18 years is 1 mSv (100 mrem or 0.1 rem). The annual occupational dose equivalent limit for the lens of the eye, a particularly radiosensitive organ, is 150 mSv (15 rem or 15,000 mrem). The annual occupational dose equivalent limit for the skin and extremities is 500 mSv (50 rem or 50,000 mrem). The total gestational dose equivalent limit for embryo/fetus of a pregnant radiographer is 5 mSv (500 mrem or 0.5 rem). (Bushong, 9th ed., p. 619) |
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How is SID related to exposure rate and radiographic density?
A. As SID increases, exposure rate increases and radiographic density increases. B. As SID increases, exposure rate increases and radiographic density decreases. C. As SID increases, exposure rate decreases and radiographic density increases. D. As SID increases, exposure rate decreases and radiographic density decreases. |
As SID increases, exposure rate decreases and radiographic density decreases.
According to the inverse square law of radiation, the intensity or exposure rate of radiation is inversely proportional to the square of the distance from its source. Thus, as distance from the source of radiation increases, exposure rate decreases. Because exposure rate and radiographic density are directly proportional, if the exposure rate of a beam directed to an IR is decreased, the resultant radiographic density would be decreased proportionally. (Selman, p 117) |
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How does the use of rare earth intensifying screens contribute to lowering the patient dose?
1. It permits the use of lower mAs. 2. It permits the use of lower kVp. 3. It eliminates the need for patient shielding. |
It permits the use of lower mAs.
The faster the intensifying screens used, the less the required mAs. Decreasing the intensity (mAs, quantity) of photons significantly contributes to reducing total patient dose. Decreasing the kilovoltage would increase patient dose because the primary beam would be made up of less penetrating photons, and so the mAs would have to be increased. The importance of patient shielding is never diminished. (Bushong, 8th ed., p. 222) |
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The cycle of infection includes the following components:
1. Reservoir of infection 2. Pathogenic organism 3. Means of transmission |
1.
Reservoir of infection 2. Pathogenic organism 3. Means of transmission The cycle of infection includes four components: a susceptible host, a reservoir of infection, a pathogenic organism, and a means of transmission. Pathogenic organisms are microscopic and include bacteria, fungi, and viruses. The reservoir of infection is the environment in which the microorganism thrives; this can be the human body. A susceptible host may have reduced resistance to infection. The means of transmission is either direct (touch) or indirect (vector, fomite, airborne). (Torres et al, 6th ed., p. 53) |
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Of the four stages of infection, which is the stage during which the infection is most communicable?
A. Latent period B. Incubation period C. Disease phase D. Convalescent phase |
Disease phase
Of the four stages of infection, the stage during which the infection is most communicable is the disease phase. In the initial phase, the latent period, the infection is introduced and lies dormant. As soon as the microbes begin to shed, the infection becomes communicable. The microbes reproduce (during the incubation period), and during the actual disease period signs and symptoms of the infection may begin. The infection is most active and communicable at this point. As the patient fights off the infection, and the symptoms regress, the convalescent (recovery) phase occurs. (Torres et al, p 56) |
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Referring to the anode cooling chart shown below, if the anode is saturated with 300,000 heat units (HU), how long will the anode need to cool before another 160,000 heat units can be safely applied?
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Each x-ray exposure made by the radiographer produces hundreds or thousands of heat units at the target. If the examination requires several consecutive exposures, the potential for extreme heat load is increased. Just as each x-ray tube has its own radiographic rating chart, each tube also has its own anode cooling curve to describe its unique heating and cooling characteristics. An x-ray tube generally cools most rapidly during the first 2 minutes of nonuse. First, note that the tube is saturated with heat at 300,000 HU. In order for another 160,000 HU to be safely applied, the x-ray tube must first release 160,000 HU, which means that it has to cool down at least to 140,000 HU. Find the 140,000 point on the vertical axis and follow across to where it intersects with the cooling curve. It intersects at about the 4-minute point. (Selman, 9th ed., p. 147)
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Tangential axial projections of the patella can be obtained in which of the following positions?
1. supine flexion 45° (Merchant) 2. prone flexion 90° (Settegast) 3. prone flexion 55° (Hughston) |
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supine flexion 45° (Merchant) 2. prone flexion 90° (Settegast) 3. prone flexion 55° (Hughston) The tangential axial projections of the patella are also often referred to as "sunrise" or "skyline" views. The supine flexion 45° (Merchant) position requires a special apparatus, and the patellae can be examined bilaterally. This position also requires patient comfort without muscle tension—muscle tension can cause a subluxed patella to be pulled into the intercondyler sulcus, giving the appearance of a normal patella. The two prone positions differ according to the degree of flexion employed. The 90° flexion (Settegast) position must not be employed with suspected patellar fracture. (Bontrager, pp 240, 241) |
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To demonstrate the first two cervical vertebrae in the AP projection, the patient is positioned so that
A. the glabellomeatal line is vertical. B. the acanthiomeatal line is vertical. C. a line between the mentum and the mastoid tip is vertical. D. a line between the maxillary occlusal plane and the mastoid tip is vertical. |
a line between the maxillary occlusal plane and the mastoid tip is vertical.
To clearly demonstrate the atlas and axis without superimposition of the teeth or the base of the skull, a line between the maxillary occlusal plane (edge of upper teeth) and mastoid tip must be vertical. If the head is flexed too much, the teeth will be superimposed. If the head is extended too much, the cranial base will be superimposed on the area of interest. A line between the mentum and the mastoid tip is used to demonstrate the odontoid process only through the foramen magnum (Fuchs method). (Frank, Long, and Smith, vol. 1, 11th ed., p. 393) |
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With which of the following does the trapezium articulate?
A. Fifth metacarpal B. First metacarpal C. Distal radius D. Distal ulna |
First metacarpal
The first metacarpal, on the lateral side of the hand, articulates with the most lateral carpal of the distal carpal row, the greater multangular/trapezium. This articulation forms a rather unique and very versatile saddle joint, named for the shape of its articulating surfaces. (Bontrager and Lampignano, 6th ed., p. 136) |
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Immature cells are referred to as
1. undifferentiated cells. 2. stem cells. 3. genetic cells. |
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undifferentiated cells. 2. stem cells. Cells are frequently identified by their stage of development. Immature cells may be referred to as undifferentiated or stem cells. Immature cells are much more radiosensitive than mature cells. (Bushong, 8th ed., pp. 591, 592) |
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Which of the following projections of the elbow should demonstrate the coronoid process free of superimposition and the olecranon process within the olecranon fossa?
A. AP B. Lateral C. Medial oblique D. Lateral oblique |
Medial oblique
On the AP projection of the elbow, the radial head and ulna are normally somewhat superimposed. The lateral oblique demonstrates the radial head free of ulnar superimposition. The lateral projection demonstrates the olecranon process in profile. The medial oblique demonstrates considerable overlap of the proximal radius and ulna, but should clearly demonstrate the coronoid process free of superimposition and the olecranon process within the olecranon fossa. (Saia, p 96) |
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What is the annual TEDE limit for radiation workers?
A. 5000 rem B. 500 rem C. 5000 mrem D. 50 mrem |
5000 mrem
Whenever a radiation worker could receive 10% or more of the annual TEDE (total effective dose equivalent) limit, that person must be provided with a radiation monitor. The annual TEDE limit for radiation workers is 5 rem (5000 mrem), but it is the responsibility of the radiographer to practice the ALARA principle, that is, to keep radiation dose as low as reasonably achievable. (Sherer et al., 5th ed., p. 250) |
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What is the approximate ESE for the average upright PA chest radiograph, using 115 kVp and a grid?
A. 20 rad B. 20 mrad C. 200 rad D. 200 mrad |
20 mrad
Patients will occasionally question the radiographer regarding the amount of radiation they are receiving during their examination. Most of these patients are merely curious because they have heard a recent news report about x-rays, or have perhaps studied about x-rays in school recently. It is a good idea for radiographers to have some knowledge of average exposure doses for patients who desire this information. The curious patient can also be referred to the medical physicist for more detailed information. The average high kVp chest with grid delivers an ESE of about 20 mrad (0.020 rad). The same chest done without grid at 80 kVp would deliver an ESE of about 12 mrad (0.012 rad). The average AP supine lumbar spine radiograph delivers an ESE of about 350 mrad (0.35 rad). The average AP supine abdomen delivers about 300 mrad; the average AP cervical spine is about 80 mrad. (Dowd and Tilson, 2nd ed., p. 247) |
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Diseases whose mode of transmission is through the air include
1. tuberculosis. 2. mumps. 3. rubeola. |
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tuberculosis. 2. mumps. 3. rubeola. Diseases that are transmitted through the air include pulmonary TB, rubeola (measles), mumps, and influenza. Airborne precautions require the patient to wear a mask to avoid the spread of acid-fast bacilli (in the bronchial secretions of TB patients) or other pathogens during coughing. If the patient is unable or unwilling to wear a mask, the radiographer must wear one. The radiographer should wear gloves, but a gown is required only if flagrant contamination is likely. Patients infected with diseases calling for airborne precautions require a private, specially ventilated (negative-pressure) room. A private room is also indicated for all patients on droplet precautions, that is, with diseases that are transmitted via large droplets expelled from the patient while speaking, sneezing, or coughing. The pathogenic droplets can infect others when they come in contact with the mouth or nasal mucosa or conjunctiva. Rubella ("German measles"), mumps, and influenza are among the diseases spread by droplet contact; a private room is required for the patient, and health-care practitioners must use gown and gloves. (Adler and Carlton, 4th ed., pp. 232–233) |
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The functions of the automatic processor's recirculation system include
1. keeping the solution in contact with the film emulsion. 2. maintaining uniform temperatures. 3. mixing and agitating solutions. |
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keeping the solution in contact with the film emulsion. 2. maintaining uniform temperatures. 3. mixing and agitating solutions. The processor's pumping mechanisms transport the solution through heating devices to maintain the proper temperature. The solution is then returned under pressure for recirculation. The added pressure functions to agitate the solution and keep it in close contact with the film emulsion. (Bushong, p 212) |
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Examples of COPD include
1. bronchitis. 2. pulmonary emphysema. 3. bronchiectasis. |
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bronchitis. 2. pulmonary emphysema. 3. bronchiectasis. COPD is the abbreviation for chronic obstructive pulmonary disease; it refers to a group of disorders, including bronchitis, emphysema, asthma, and bronchiectasis. COPD is irreversible and decreases the ability of the lungs to perform their ventilation functions. There is often less than half the normal expected maximal breathing capacity. (Taber, 20th ed., p. 416) |
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Which of the following technical changes would best serve to remedy the effect of widely different tissue densities?
A. Use of high-speed screens B. Use of a high-ratio grid C. High kVp exposure factors D. High mAs exposure factors |
High kVp exposure factors
When tissue densities within a part vary greatly (eg, chest x-ray), the radiographic result can be unacceptably high contrast. To "even out" these densities and produce a more appropriate scale of grays, exposure factors using high kVp should be employed. Radiographic contrast generally increases with an increase in screen speed. The higher the grid ratio, the higher the contrast. Exposure factors using high mAs generally result in excessive image density, frequently obliterating much of the gray scale. (Bushong, 8th ed., p. 273; Shephard, p. 200) |
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Which of the following are demonstrated in the oblique position of the cervical spine?
1. Intervertebral foramina 2. Apophyseal joints 3. Intervertebral joints |
Intervertebral foramina
Intervertebral joints are well visualized in the lateral projection of all the vertebral groups. Cervical articular facets (forming apophyseal joints) are 90° to the midsagittal plane and are therefore well demonstrated in the lateral projection. The cervical intervertebral foramina lie 45° to the midsagittal plane (and 15° to 20° to a transverse plane) and are therefore demonstrated in the oblique position. (Bontrager and Lampignano, 6th ed., p. 292) |
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According to the NCRP, the annual occupational whole-body dose equivalent limit is
A. 1 mSv. B. 50 mSv. C. 150 mSv. D. 500 mSv. |
50 mSv.
According to the NCRP, the annual occupational whole-body dose equivalent limit is 50 mSv (5 rem or 5000 mrem). The annual occupational whole-body dose equivalent limit for students under the age of 18 years is 1 mSv (100 mrem or 0.1 rem). The annual occupational dose equivalent limit for the lens of the eye, a particularly radiosensitive organ, is 150 mSv (15 rem or 15,000 mrem). The annual occupational dose equivalent limit for the skin and extremities is 500 mSv (50 rem or 50,000 mrem). The total gestational dose equivalent limit for embryo/fetus of a pregnant radiographer is 5 mSv (500 mrem or 0.5 rem). (Bushong, 9th ed., p. 619) |
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