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169 Cards in this Set

  • Front
  • Back
Who invented X-ray and when?
Wilhelm conrad Roentgen. November 8, 1895
What was Roentgen working with when he invented X-ray?
Crookes tube.
Roentgen noticed what while working with a crookes tube?
A glow from the barium platincoyanide.
What type of energy did the crookes tube emit?
Energy that was not light and that passed through opaque black paper and other things.
How complete was Roentgens knowledge of X-ray?
All characteristics that we know today he knew besides biological effects.
Who invented the fluoroscope?
Thomas edison.
What did George eastman invent?
Commercial method for coating emulsion on photographic plates, flim for photography and radiography.
What did Coolidge invent?
Hot cathode x-ray tube.
Who invented the x-ray grid?
Bucky.
Who said energy can be neither created nor destroyed?
Newton.
What are the parts of an atom and what are their charges and where are they found at?
Nucleus- protons (+), Neutrons (no charge), Outershell- electrons (-).
What are the shells of an atom labeled?
K-Q.
X-rays and light are both forms of what type of energy?
Electromagnetic energy.
What is ionizing radiation?
When there is enough energy to remove an electron from its orbit and make the atom an ion.
What size of wavelength of electromagentic energy will be able to create ionizing radiation?
1 nanometer or less.
What is the quantum theory?
The theory that explanes that the smallest unit of electro-magnetic energy is called a photon.
How can an x-ray photon be visulaized?
As 2 perpendicular sine waves traveling in a straight line always at the speed of light.
What is amplitude, wavelength, frequency, and velocity of a sine wave?
Amp- distance from crest to valley. Wavelength- distance from crest to crest. Frequency- the number of crests or valleys that pass a fixed point. Velocity- wavelength X frequency.
What is the velocity like for electro-magnetic radiation?
It has a fixed velocity same as the speed of light.
What type of sine wave has more energy?
Shorter wavelengths.
What type of x-ray will be able to penetrate deeper?
Shorter wavelengths.
How long will x-rays travel?
They diverge into space from source until absorbed.
X-rays cause what to floresce?
Certain crystals.
Can x-rays be refracted by a lense?
No.
What is the difference between primary and secondary radiation?
primary- unattenuated, except by air so its direction and location are predicatable and controllable. Secondary- interaction between the primary beam and matter so it will create scatter radiation that travels in all directions and the directions it will scatter is difficult to control.
What will have less energy primary or secondary radiation?
Secondary.
What is remnant radiation?
Radiation that remains after the primary beam has been attenuated by matter.
What will have a shorter wavelength visible light or x-rays?
X-rays.
What will produce a pattern of exposure on the film with x-rays?
Differential penetration results in a pattern in the remnant radiation that will produce a pattern.
What will cause electrical charges to flow through a circuit?
The difference in electrical potential between 2 locations in a circuit.
What is KVp?
Kilovolts peak. Voltage measured at the peak of the electrical cycle in an x-ray tube circuit.
What are the basic units of electricity?
Volts.
What is current?
Flow of electrical charges in the circuit.
What are the units of current?
amperes or amps which is the rate of flow.
what is mA?
Milliampers which is the measurement of flow used for x-ray.
What is the difference between the electrical supply in a house and an x-ray machine?
House- 120V, 30amps. X-ray- 120,000 V or 120KVp, .3 amps or 300mA.
Name the 4 requirments for the production of X-rays?
1. Vacuum. 2. source of electrons. 3. Target for the electrons. 4. High potential difference between the source and the target.
What will the vacuum of an x-ray machine be made of?
Glass envelope.
What is the electron source made of?
Tungsten.
How is the electron source (filament) heated?
Electrical current.
The filament is located at one end of the evacuated glass envelope and what is at the other end?
A target- slanted, smooth metal surface at which the electrons will be aimed.
What is the target made of?
Tungsten.
The two ends of the tube (filament and target) are connected how?
By a circuit to a high voltage electrical supply.
What are the 2 ends of the tube called and what is found at each end?
Anode- taget. Cathode- filament.
What type of charge will the anode and cathode have?
anode- positive. Cathode- negative.
X-rays are produced when?
When electrons strike the target.
What are the 2 types of target interactions that produce x-rays?
1. Brensstrahlung. 2. Characteristic radiation.
How are brensstrahlung rays and characteristic rays each produced?
Brensstrahlung- formed by sudden halting of electron stream as kinetic energy is converted to other forms. Characterisitic radiation- formed within target atoms as a result of interactino with the incoming electron stream.
Most X-ray is from which brensstrahlung or characteristic radiation?
Brensstrahlung.
What will make the photons from the primary beam travel in a useful direction?
Tube housing.
What is focusing cup effect?
Without the focusing cup, electron stream spreads beyond target area.
What will a negatively charged focusing cup do?
Repels electrons, focusing them on small target area known as the focal spot.
What will most modern general purpose tubes focus tubes be like?
Dual focus.
What will a dual focus tube have?
2 filaments, 2 focus cups and 2 concentric focal spots.
With dual focus tubes how are filaments and focal spots selected?
with the mA setting or by a separate switch.
25-150 mA utilizes a _____ filament and a _____ focal spot.
small and small
200 mA and above utilize a ____ filament and a ______ focal spot.
large and large.
The anode is made of tungsten that is imbedded in what?
Molybdenum disc.
What will conduct heat away from the target?
Mass of copper.
What is the target face like?
Angulation it is beveled so that the target area is on a 10-20 degree slant.
What are the focal spots like on the target?
one large and one small.
What is the area called on the target where the electon stream is focused?
Actual focal spot.
Dual focus tubes have ___ focal spots.
two.
What is the vertical projection of the actual or "true" focal spot called?
Effective focal spot.
The size of the focal spot on target surfaces affects what?
Heat capacity.
What type of focal spot on the target surface is best for heat capacity?
Bigger is better.
What type of focal spot on the target surface is best for sharper images?
Smaller.
Desirable actual focal spot size= ?
Large, for greater tube heat capacity.
Desirable effective focal spot size= ?
Small, for greater image sharpness.
The size of effective focal spot determines what?
Image sharpness.
The relative size of the effective focal spot is determined by what?
The target angle.
The steeper the target angle the greater _____?_____.
Difference between the actual and effective focal spot size.
What is the usual anode angulation?
12-15 degrees.
Anode angulation determines what?
Maximum field size.
The steeper the anode angulation the ___?____.
difference between actual and effective focal spots.
A steeper target angle results in what?
a smaller effective focal spot with a given actual focal spot size.
What is the anode heel effect?
Variation in radiation intensity across the length of the radiation field- more rays absorbed at the heel (therefore less intense).
Anode heel effect is only significant when?
When using the whole beam.
Thinner parts of the body should be placed closer to what?
towards the anode end of the tube.
What will control the rate of flow of electrons across the tube?
mA.
The rate of flow of electrons across the tube means what?
number of electrons flowing from the filament to the target each second.
Number of available electrons is determined by what?
The filament heat.
What controls the rate of x-ray production?
mA.
Quantity of radiation produced is proportional to what?
mA.
Radiation exposure is proportional to what?
mA.
What controls the exposure time?
Timer in the x-ray circuit.
The timer in the x-ray circuit contols the duration of exposure, therefore it controls what?
Quantity of x-rays produced.
Quantity of radiation produced is directly proportional to what?
exposure time.
Radiation exposure is proportional to what?
Exposure time.
What is a measure of total quantity of elctricity involved in exposure?
mA x time (sec.)= mAs.
mAs is indicative of what?
total quantity of radiation produced by an exposure.
kVp is controlled by what?
Manipulation of power source.
Increased kVp results in what?
increased speed and power of electrons across tube.
Faster electrons have what?
More kinetic energy.
Resulting photons from faster moving electrons results in what?
Photons with more energy and will have shorter wavelengths.
kVp controls what part of x-rays?
Penetration.
over 99% of x-ray energy is converted into what?
heat.
What happens if the anode face melts, boils, cools to rough surface?
Unsharp images.
What happens if gas from hot components compromises vacuum?
Erratic exposure.
What happens if heavy exposure happens on a cold tube?
Cracks anode.
What happens if the tube breaks, compromises tube/housing oil seal?
Destroys the tube.
The tube needs how many seconds between x-rays to cool down?
10-30 seconds.
When should tube rating charts be used specifically?
With large exposures.
How can we estimate tube load?
divide desired exposure by maximum exposure.
Cooling charts are especially usefull when?
When evaluating a series of exposures with little time in between.
What is HU and how is it figured out?
Heat units. mA x Time x kVp x 1.45= HU.
What is the purpose of a rotating anode tube?
To distribute heat over a greater surface.
An anode angle of at leaste 12 degrees is needed to cover a ____ x_____ film at a distance of ___ inches.
14 x 7 @ 40 inches.
What is cathode facing?
Pastients head is at the anode end and if they raised their head and looked up they would be facing the cathode end of the x-ray tube.
What is rectification?
Process of causing alternating current to flow in one direction only.
What are the 4 types of rectification list in order of leaste effective to most?
Half-wave, Full-wave, three-phase, high frequency generation.
What is the legal requirements for collimators?
rectangular collimator with independent adjustment of each dimension if more than 1 film size is used, within 2% of SID, must collimate to area of clinical interest in no case may field be larger than film.
What is the purpose of filtration?
Removes the long wave length radiation from the primary beam which significantly lowers the patients dose and the long rays wont go through the body so they are not part of the image anyway. It removes about 1/4 of dose.
What are the units used to measure filtration?
mm. Al equiv.
What are the types of filtration?
Inherent- part of the glass tube, alluminum plates placed over tube, collimator parts.
What is the amount of inherent filtration?
0.5 mm Al equiv.
What is total filtration like?
It is inherent filtration + added filtration(permanently installed).
Since chiropractic X-ray machines will use more than 70 kVp what is the total filtration requirements?
2.5 mm Al equiv.
What are 4 things that can change the image quality?
1. milliamperage. 2. Exposure time. 3. Milliampere-seconds. 4. kVp.
Increased mA does what to the image quality?
Results in darker radiograph.
How will exposure time change image quality?
Increased time = darker image.
What is the primary controller of radiographic contrast and radiographic density?
Radiographic contrast- kVp. Radiographic density- mAs
What is radiographic density?
how dark the image is.
What will a high kVP and a low kVp do to the image?
High- low contrast image. Low- high contrast image.
What is SID?
Source image distance and this is the distance between the tube target and imaging receptor.
What is the Inverse square law?
Intensity1/ intensity2= distance2/ distance1
Suppose you have an intensity of 1 at 40 inches SID what would the relative intensity be at 80 inches SID?
It would be 0.25.
Suppose a satisfactory exposure was made using 10 mAs at 40inches SID how much mAs will provide a similar exposure at 72inches SID?
it would be 32.4
Radiographic density refers to what?
Overall blackness or darkness of the film.
Density affects the ________ of the _______.
visibility of the detail.
density is the result of what?
exposure.
Radiographic density is primarily controlled by what?
mAS, but also influenced by kVP, SID and others.
What is contrast?
the difference in radiographic density between adjacent portions of the image.
Contrast is primarily controled by what?
Kilovoltage.
Contrast affects the ___ of the _____.
visibility of the detail.
What are the 2 main things that affect contrast?
kVp and tissue density.
Where would low and high contrast be wanted?
Low- abdomen. High- chest.
What is short scale vs. long scale?
They both refer to contrast; short scale- will give a low contrast and low kVP should be used, long scale- high contrast is wanted and a high kVp should be used.
What is fog?
General unwanted exposure to the film and may be caused by scatter radiation, processing and film storage.
What will fog do to contrast?
Decreases it.
What is distortion?
difference between actual object and the radiographic image.
What are 2 types of distortion?
Size- from enlargment. Shape- from unequal magnification.
What 2 things affect size distortion and how?
Increased Object image distance OID = increased magnification. Increased SID = decreased magnification.
How can the least amount of shape distortion happen?
Plane of the subject should be parallel to the plane of the image receptor, and the central ray should be perpendicular to both.
Recorded detail is aka?
Resolution, sharpness, or definition.
What part of an image is recorded detail most noticable?
The edges.
What is penumbra?
The opposite of detail or no detail.
What will decrease the penumbra?
A decreased focal spot size.
What are the only 3 factors that affect recorded detail?
Focal spot size FSS, Source-image distance SID, Object-image distance OID.
What can be done to FSS, OID, and SID to increase the detail?
FSS- decrease, OID- decrease, SID- increase.
What is PACS?
Picture archiving and communication system.
What is the main role of cassettes?
Provides suitable mounting for intensifying screens.
What will a pair of intesnsifying screens be used for?
This doubles the film exposure and the X-ray can be given at half the radiation.
What is the advantage of a single intensifying screen?
For higher detail.
What is the intensifying screen like?
Flat surface coated with fluorescent cyrstals called phosphors that give off light when exposed to x-rays and this is called fluorescence.
What % of the x-ray image is formed by the screen light?
99%.
What is screen speed?
The efficiency of a screen in converting x-rays to light.
What will greater efficiency of a screen speed mean?
less exposure necessary.
What is the industry standard of screen speed?
it is 100.
What is the difference between 100 and 200 screen speed?
200 would be twice as fast as a 100 speed and require only 1/2 the exposure but have lower detail.
The higher the screen speed the _____ the exposure, and the _____ the detail.
lower, lower.
Why will higher screen speeds lower the exposure and lower the detail?
The faster the screen speed the larger the crystals and they produce more film exposure and the large crystals provide less detail.
What are the screen phosophors made of?
Rare earth phosphorus like gadolinium, lanthanum, ytrium.
How much more effective are screen phosophors vs old technology?
4 times.
What is spectral emission?
refers to the color of light emitted by phosphor and is usually green, or yellow-green, blue or blue-violet.
What is the formula used to adjust exposure for variation in screen speeds?
speed1/ speed2 X mAs1 = mAs2
suppose 10mAs is a good exposure for an ankle on an extremity cassette with a relative speed of 100. Because the patient cannot hold still, you decide to use a rapid cassette with a relative speed of 400. What should the new mAs be?
2.5 mAs.
What should never be done with a cassette?
Never leave a cassette lying open.
What type of digital x-ray uses cassets and what type will not?
Computed radiography CR- will use cassets. Digital radiography DR- will not.