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104 Cards in this Set
- Front
- Back
True or false. With any fluoroscopic unit, moving the body part away from the tube and towards the image intensifier will decrease magnification.
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True
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What are the processes when altering the pixel values and returning them to their original value on a CT image?
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convolution and deconvolution
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The man that gets credit for inventing CT is:
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Hounsfield
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First generation CT scanners used ______ type detectors.
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Crystal
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What is it called in CT when the sectional data can be combined to produce slices in different directions or create 3-D images?
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Reformation
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The type of CT slice that is an AP projection of the body is:
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Coronal
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The type of CT slice that shows a lateral projection of the body is called:
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Sagittal
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In a cardiovascular imaging suite, when doing a sequence of several rapid exposures combined with fluoro, it is a good idea to consult the _________ in order to insure that yoru study will not cause heat damage to the tube.
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Percent duty cycle chart
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In order to check if a single exposure could damage a tube you should check the:
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Tube rating chart
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After finishing a sequence of rapid exposures in a cardiovascular imaging room, you should check the _________ before starting a second sequence to insure that your tube does not overheat.
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Tube housing cooling and anode cooling charts
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Conventional radiography generators generally operate at _______ mA and ________ kVp than vascular imaging generators.
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Lower mA, higher kV
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In order to better visualize a vein injected with a contrast agent, it is best to use ________ kV and _________ exposure time.
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Low kV, short exposure time
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True or false. It is necessary to pre-warm contrast agents before placing them in pressure injectors.
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True
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When doing biplane imaging, the intensifier that requires a crosshatched grid to filter the increased scatter is the intensifier receiving the _________ projection.
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AP
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What is the rotation of the axis of rotation of a spinning nucleus?
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Precession
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In a static magnetic field, all protons of a given isotope will rotate with exactly the same frequency. This frequency is known as:
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Larmor frequency
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Protons that are ____________ have excessive energy, which they emit as electromagnetic radiation in the RF range.
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Anti-parallel
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Why do hydrogen atoms react well to a magnetic field?
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They have a single proton nucleus.
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The ratio between a magnetic moment and the moment of inertia in a nucleus placed in a magnetic field is called it's:
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Gyromagnetic ratio
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Since the human body would not send off RF radiation in a stationary magnetic field, it is necessary to:
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Pulse the stationary field with the use of gradient coils.
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For the best MRI imaging of small areas like the TMJ, it is best to use what type of coils?
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Surface
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Irregularities in a magnetic field created by outside ferromagnetic materials are compensated by:
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Shim coils
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What is the Hounsfield unit for water?
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Zero
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What is the Hounsfield for bone?
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+1000
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What is the Hounsfield for air?
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-1000
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What are the two cryogens used in a superconductive magnet?
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Helium and nitrogen
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In MRI, the type of coils used for the X, Y, and Z axis are :
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Gradient coils
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Helical scanners were made possible by:
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Slip ring technology
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True or false. Added filtration is not a neccessary component to a typical CT scanner.
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False
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The relationship between voltage, current and resistance is called:
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Ohm's law
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V=
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I x R, ohms x amps, Resistance x Current
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an ohm is a unit of :
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Resistance
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an amp is a unit of:
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Current
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If the voltage is increased, then the amperage is decreased at the same ratio to maintain the same wattage. This is the :
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Transformer law
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____________ is the force or electrical pressure that produces the electron movement.
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Voltage
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The unit of power is the _______.
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Watt
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Watts =
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Amps squared x resistance and volts squared/resistance
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Transformers operate by means of __________ induction.
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Mutual
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Transformers can only work with _____ current.
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AC
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What type of transformer has a fixed number of coils with output taps? It is used to control the voltage to a step up or step down transformer.
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An autotransformer
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Autotransformers use ______ induction.
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Self
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___________ induction occurs when two coils are placed in proximity and a changing current is applied to the primary coil.
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Mutual
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___________ induction is a single coil of wire supplied with a changing current. The process by which the current is reversed (AC) induces a change in the current at another portion of the coils.
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Self
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____ motors require a commutator ring to operate.
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DC
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____ motors require slip rings to operate.If
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AC
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Induction motors operate on ____ current.
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AC
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If ___________ are oriented in the same direction, they will exhibit a uniformly strong magnetic field. This is a magnet.
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Dipoles
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___________ radiation only occurs when the incident electron interacts with an inner shell electron.
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Brehmsstruhlung
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The energy of Brehmmstruhlung radiation can range from:
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Zero to the max kVp level
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____________ interactions only occur above 70 kVp.
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Characteristic
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___________ interactions only occur when the incident electron interacts with an inner shell electron.
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Characteristic
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How may millimeters are in a meter?
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1000
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How many centimeters are in a meter?
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100
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How many meters are in a kilometer?
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1000
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__________ is the complete or partial loss of x-ray energy within the patient.
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Attenuation
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What are the four factors that impact attenuation:
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xray energy, tissue thickness, tissue density, atomic #
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Which generation CT scanner was the first with a fan shaped beam?
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2nd
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Which generation CT scanner had 30 detectors?
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3rd
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Which generation CT scanner was created due to a contract awarded by the U.S. Institute of Health?
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4th
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Which generation CT scanner was created for cardiac units?
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5th
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Which generation CT scanner was helical/spiral?
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6th
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Which generation of CT scanner was MSCT?
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7th
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______________ is the distance between scan sections.
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Section interval
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CT operates at _____ kVp and _____ mAs.
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120 kVp and up to 1000 mAs
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What is the relationship between Gauss and Tesla?
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1 Tesla = 10,000 Gauss
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In Nuc Med, as SID increases detail ____________.
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Decreases
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________ coils are placed within the coils of the stationary magnet to compensate for irregularities.
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Shim
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________________ are RF coils. They may serve as both the transmitter and receiver of signal.
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Body and surface
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_____________ coils can be operated to emit pulse sequence for spatial localization of anatomical section.
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Gradient
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The process of layering cryogens is ____________.
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Ramping
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Superconductive magnets use liquid cryogens. ___________ is used in the inner deward and _________ in the outer.
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Helium, nitrogen
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What is the formula for computing heat units?
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HU = kVp x mAs x Rectification constant x # of exposures
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What is the rectification constant for single phase?
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1
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What is the rectification constant for 3 phase 6 pulse?
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1.35
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What is the rectification constant for 3 phase 12 pulse?
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1.4
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During what interaction does the incident photon loses some or all of its energy when it impacts with an inner k shell electron and removes it from orbit. The filling of this vacancy produces a characteristic x-ray of low energy.
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Photoelectric effect
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Characteristic interactions occur at the:
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Tube
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Photoelectric effect occurs at the:
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Patient
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Name the interaction. When an incident photon collides with an outer shell electron, the original photon continues in a different direction minus the energy that it took to remove the electron from its orbit.
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Compton's
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What is the atomic # for molybdenum?
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42
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What is the atomic # for lead?
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82
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What is the atomic # for tungsten?
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74
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True or false. As kVp increases, the efficiency of photon production also increases.
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True
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The type of radiation that is produced by an incident electron interacting with the nuclei of a target atom is:
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Brehmmstruhlung
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True or false. Attenuation is absorption or scatter.
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True
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The type of x-ray interaction that never varies in energy levels but depends on the atomic # of the anode is:
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Characteristic
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When viewing an x-ray spectrum for any exposure, most of the x-rays will have a peak energy level of:
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about 1/3 of the kVp setting on the control panel
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What happens to the peak overall average energy of the beam when filtration is added to the beam?
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Increases because the weaker x-rays are removed
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What happens to image detail when SID is increased?
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Detail increases
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Moving the image intensifier towards the body part (increasing the SOD) will have what type of effect on magnification and detail?
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Magnification decreases and image detail increases
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What effect does using an air gap technique have on image detail?
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Decreases
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_________ is the lack of detail caused by focal spot size.
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Penumbra
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True or false. Magnification is a distortion of an image in at least two different directions.
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True
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What factor impacts beam quality?
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kVp
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What is the reason we don't use small focal spots on all exams is?
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It increases exposure time on larger patients
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The term used to indicate the conversion of AC current into DC current before the current is applied to an x-ray tube is:
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Rectification
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_________ is the force or electrical pressure that produces electron movement and current flow.
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Voltage
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The unit of electriccal power is the ______.
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Watt
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True or false. An autotransformer can operate on both AC or DC current.
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False, only AC
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What type of motor is used to drive the anode in an x-ray tube?
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Alternating current induction motor
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True or false. Rectification of alternating current to pulsating direct current is done using diodes or semiconductors.
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True
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The type of rectifier used a long time ago that was similar to an x-ray tube except that it operated at lower energy levels was called a _________.
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Valve tube
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How many diodes are used with a half wave rectified circuit?
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1
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A device that utilizes several coils of wire with current passing through them in order to create a magnetic field that can be turned on and off in order to repel or attract a magnet is known as:
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solenoid
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