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181 Cards in this Set
- Front
- Back
What type of interaction causes unwanted density known as fog?
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Compton interaction
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The ________ is the portion of the x-ray tube that contains the filament which is the source of electrons for x-ray production
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Cathode
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The positive side of the x-ray tube where x-rays and heat are produced is the?
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Anode
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What is the name of the exact area on the anode that is struck by the electron beam?
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Focal spot
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What is the name of the device in a rotating anode x-ray tube that turns the rotor?
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Stator
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Effective use of the anode heel effect would involve positioning which portion of the part under the cathode
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the tickest portion of the part under the cathode
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_______ is the boiling off of electrons from the filament when current is applied
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Thermionic emission
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_________ is the loss of some energy from the x-ray beam as it passes through the tissue being imaged
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attenuation
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When the x-ray photon travels completely through the part, the activity if called what?
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Trasmission
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________ results in the process of image formation, whereby the beam interacts with the anatomic tissue and a portion of the beam strikes the image receptor
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Differential absorption
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When the x-ray photon strikes an atom within the tissue being imaged and loses all of it's energy to an inner shell electron of that atom, the photon is said to have been _________ and undergone the _________
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Absorbed
Photoelectric effect |
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When the x-ray photon strikes an atom within the tissue being imaged, loses only part of it's energy to an outer shell electron of that atom and them continues with less energy and in a different direction than the original path, the photon is said to have been _______ and has undergone the __________
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scattered
Compton effect |
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The x-ray beam that leaves the patient in the direction of the image receptor is often referred to as?
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exit radiation
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Remnant radiation is composed of?
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transmitted radiation
scattered radiation |
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imaging of the movement of internal structures is known as?
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flouroscopy
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This is the measurement of the overall blackening on the radiographic image
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Density
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When you must repeat a radiograph because it is too dark, whats the minimum change in mAs needed?
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reduce the mAs by 50% or 1/2
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How will density be affected when the SID is decreased by half?
Image will be lighter Image will be darker |
Image will be darker
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Contrast allows for visualization of which of the image qualities ?
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Recorded detail
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the misrepresentation of the size of an image is defined as what?
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magnification
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The ______ grid error results when the central ray is not aligned to the middle of the focused grid
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off-center
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A tech uses increased OID to permit the scattered x-rays to diverge from the IR without interaction, which technique is being used?
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Air-gap technique
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The number of lead strips per inch in a grid is a measure of what?
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grid frequency
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The ______ grid error results when the central ray is not aligned to the middle of the focused grid
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off-center
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This type of grid offers more clean up, has very little positioning latitude, requires higher exposure increasing patient dose.
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Crossed Grids
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The purpose of a grid is to ___ by removing scatter from the image.
A. decrease contrast B.Increase contrast C. Provide a shorter scale of contrast |
D. b & c
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What element of the collimator is responsible for preventing off focus radiation
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upper shutters
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In a cassette, which layer of the intensifying screen is in contact with the film?
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Protective layer
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A grid is constructed with ________ strips and ________ interspace material
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radiopaque, radiolucent
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If a body part appears white on an image, it indicates that the x-ray was:
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absorbed by the dense body part
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The amount of patient dose increase required with a grid is explained by the:
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GCF or bucky factor
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When using a grid, with no change or compensation from a non-grid exposure _______ will result
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decreased density
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Which of the following influences the amount of scatter radiation striking the image receptor, but does not affect the production of scatter?
a.reduce the exposure field size b.reduce the tissue thickness c.increase the grid ratio d.ask a patient with a large abomen to lie prone instead of supine |
c.increase the grid ratio
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What grid error will show a loss of density at the periphery (outside edges) of the image?
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off-focused grid
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This type of scatter occurs with the removal of an outer shell electron by ionization
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Compton scatter
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As grid ratio increases, the likelihood of grid cutoff ________
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increases
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The best contrast (high, short scale) is achieved with the use of _________ ratio grids which clean up best and/or the ________ possible kvp to reduce the production of scatter.
highest, lowest lowest, highest |
highest, lowest
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What is the emission of light from a screen when stimulated by radiation?
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Luminescence
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rare earth phosphors are better phosphors then calcium tungstate due to their ?
a. absorption efficiency b.detective quantum efficiency c.conversion efficiency d. a & c |
d. a & c
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This type of film is intended to be used with one or two intensifying screens.
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film screen
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The resolution of screens is measured with what type of units:
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lp/mm
( line pairs per millimeter ) ( the higher the # the better we can see the image) |
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What is the primary controlling factor for density?
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mAs
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CR/DR can compensate for under/over exposure up to the point of what?
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Saturation or quatum mottle
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What results when you do not have enough x-rays (photons) reaching the image?
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Noise (gives you a grainy look)
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kVp has a ___________ relationship to penetrability.
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Direct
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______ and _______ absorb the most x-rays and show up white (bright) on an image.
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Bone, muscle
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Low density in the body has ______ density on an image.
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High
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According to the 15% rule, if you increase kVp by 15%, you must ______ the mAs.
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half (decrease by 50%)
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According to the 15% rule, if you decrease kVp by 15% you must ______ the mAs
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double
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Window level controls ______.
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Brightness
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Window width controls _______
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Contrast
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What is used to assess film screen contact
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Wire mesh test tool
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What is achieved when the color of light emitted by an intensifying screen matches the color of light a film responds to?
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Spectral matching
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Increase of _______ will reduce the noise of quantum mottle.
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mAs
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Whats the primary controlling factor for density
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mAs
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A wide window width has _______ contrast.
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Low
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A narrow window width has _______ contrast
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High
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The level of visibilty of small objects having similar densities or shades of grays is _____.
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Contrast Resolution
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The range of exposure intensities an IR can accurately detect is ____.
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Dynamic Range
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When you have all the data that you can window until you find what you need is called ________.
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Linear Response Function
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What are the advantages of fixed kVp charts?
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-Easy use
-More consistent -Greater assurance of penetration -Uniform contrast -less PT dose -Better for equipment |
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What are the disadvantages of a fixed kVp chart?
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-increased scatter
-lower contrast |
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What are some advantages of a variable kVp chart?
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-easy use
-small incremental changes |
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What are some disadvantages of variable kVp charts?
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-higher contrast
-adequate penetration might not be achieved -have to accurately measure the body part |
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What gives radiographers guidelines to select standard techniques during an exam?
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Exposure technique charts
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What is a measurement of the amount of light transmitted through the film?
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Optical density
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If you decrease the SID andy ou do NOT change the technique what will happen to the optical density?
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It will increase causing the image to be darker
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According to the ______ the intensity of the x-ray beam is proportional to the square of the distance from the source.
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Inverse Square Law
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The distinctness of structural lines recorded in the radiographic image is called ____.
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Sharpness of recorded detail
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The smallest detail that can be detected on an image is called ____. This is really good with DR.
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Spatial resolution
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kVp is considered the controlling factor for radiographic __________
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contrast
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A radiograph with few densities but but great differences among them is said to have ______ contrast
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High contrast (short scale contrast)
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A radiograph with a large number of densities but little differences among them is said to have ______ contrast
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low contrast ( long scale contrast)
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Photographic properties of the recorded image and determined by the extent to which the structural components of the anatomic area of interest can be seen. (Anything that has to do with density & contrast) is called _____.
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Visibility of recorded detail
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The longer the SID gives you ____ recorded detail and ____ magnification.
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Better, decreased
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What type of distortion will we use to our benefit in imaging?
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elongation
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Images in F/S are stored in the ____ layer.
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Emulsion
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Where are the images stored in CR?
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Photostimuble phosphor plate
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If the intensifying screen glows after the x-rays have stopped it is called ____.
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Phosphorescence/Screen lag
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What is grid oscillation?
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When the grid moves during exposure to blur the grid lines.
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What is total filtration made up of?
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Added filtration and inherant filtration
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When using backup time we use _____% more mAs then what we anticipate to prevent overexposure to the patient.
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150%
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What is a graphic representation of where the shades of gray will be on an image?
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Histogram
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This provides a method of altering the image to change the display of the digital image. Matches the contrast & brightness to the mathmatical formula that is programmed for that body part.
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Look up table
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The computer language in medicine is called ____.
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DICOM (Digital imaging and communication in medicine)
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Patient information language is called ____.
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HL7 (health level 7)
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You do not want to use the minimum response time for what type of patients?
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pediatrics, geriatrics, or uncooperative patients
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Pneumonia is a(n) _____ type of pathology to a chest image.
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additive
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Emphysema is a(n) ____ type of pathology a chest image.
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destructive
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Ascites is a(n) _____ type of pathology to the abdomen image.
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additive
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Air is a(n)____ type of pathology to the abdomen image.
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destructive
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What does APR stand for?
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anatomically programmed radiography
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When using film-screen, what happens when outside detectors are selected for an AP thoracic spine?
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The spine will have insufficient density
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Changing the kilovoltage peak by ______ will have the same effect on radiographic density as doubling the mAs, or reducing the mAs by 50%
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15%
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What happens if an AEC is activated for the table bucky but the upright bucky is being used?
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back-up time is reached resulting in high exposure to the patient and IR
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What describes the shortest exposure time required for the AEC device to operate
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minimum response time
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AEC devices work by measuring radiation that is transmitted through the ______
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patient
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When using AEC with film screen examinations how can the radiographer adjust the density?
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Using the density control
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simplest type of beam restricting device constructed of a flat piece of lead that has a hole in it.
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aperature diaphragm
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This is the high end of overexposure.
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saturation
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KVP is which of the following
a. energy b. quality c. penetrability d. all of the above |
d. all of the above
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This occurs when a projectile electron completely avoids the orbital electrons of the tungsten atom and travels very close to it's nucleus
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Bremmsstrahlung interactions
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The product of both flux gain and minification gain
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Brightness gain
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This is comprised of a filament and a focusing cup
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Cathode
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This describes that similar anatomic parts can use similar exposure techniques to achieve diagnostic radiographs
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comparative anatomy
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This refers to the area on the anode target that is exposed to electrons from the tube current.
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Actual focal spot size
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This refers to the focal spot size as measured directly under the anode target
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effective focal spot size
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This describes how the x-ray beam has greater intensity on the cathode side of the tube, with the intensity diminishing toward the anode side.
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anode heel affect
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Which x-ray tube component serves as a source of electrons for x-ray production
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filament
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Electrons interact with the ____ to produce x-ray and heat
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target
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the cloud of electrons that forms before x-ray production is referred to as
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space charge
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The intensity of the x-ray beam is great on the :
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cathode side
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According to the line focus principle, as the target angle decreases, what happens to the effective focal spot size?
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it decreases
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Which type of target interaction is responsible for the majority of the x-rays in the diagnostic beam
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bremmsstrahlung
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The ability of an x-ray photon to remove an atoms electron is a characteristic known as
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ionization
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The x-ray interaction responsible for absorption is
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photoelectric
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The x-ray interaction responsible for scattering is
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compton
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Electrons flow from _______ to ______
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cathode to anode
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tube current is measured in ______
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milliamperes
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As electrons strike the anode target about ______ % of their kinetic energy is converted to heat, whereas only _____ % of their energy is converted to x-rays.
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99 % is heat , 1 % is x-rays
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brightness gain is created on the ______ phosphor
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output
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If you are given 200 mA and an exposure time of 1/40 calculate the mAs.
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1/40 = 0.025
200 x 0.025 = 5 Answer 5 mAs |
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Given mA= 400 and mAs= 80 calculate the exposure time.
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80 / 400 = .2
Answer .2 seconds |
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Whats the density maintenance formula?
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mAs1 D1^2
--------- = ------- mAs2 D2^2 |
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Whats the inverse square law formula
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I 1 D2^2
-------- = ---------- I 2 D1^2 |
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A _____ change in mAs or a ____ change in kVp is necessary for a visible difference in density on a radiograph.
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A 30 % change in mAs or a 15% change in kVp is necessary for a visible difference in density on a radiograph.
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The density on a radiograph will be equal for any combination of mA and time, as long as the final product of mAs stays the same according to:
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the Reciprocity Law
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To maintain a certain density, if you increase the kVp by 15% you must divide the original mAs by ____
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2
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How would you decrease 80 kVp by 15%
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80 x 0.85 = 68 kvp
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How would you increase 80 kVp by 15%
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80 x 1.15 = 92 kVp
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To maintain a certain density when decreasing kVp by 15% multiply the original mAs by ______
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2
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The function of contrast is to make _______ visible
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recorded detail
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You get high contrast by using ______ kvp
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low
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high contrast = _____ scale
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short
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high contrast / short scale is primarily used for ______ body parts
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extremities (bones)
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If you are doing a chest and using 110 kvp, and than you want to see the ribs how would you adjust the kVp?
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Use less kvp so it doesn't penetrate the ribs and you get white on your image = photoelectric effect (absorption)
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Which type of tissue is going to easily absorb x-rays and why?
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muscle, because it's dense
(molecules are packed tightly together) |
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Low density in the body = ____ density on the image receptor
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high density
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Is kVp for CR/DR controlling contrast?
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NOOO.. the computer controls the contrast ( or allows us to control it)
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Whats is the purpose of kVp when dealing with CR/DR since the computer controls contrast?
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penetrability
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kVp is a secondary contributing factor to _______
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quantity
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Visible change for kvp is _____ %
Visible change for mAs is ______ % |
5 % for kvp
30% for mAs |
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Wider width = ______ greys
Narrow width = ______ greys |
wider width = less greys
narrow width = more greys |
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more greys =more latitude which makes for more ________ ________
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dynamic range
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preferred technique is ___ kvp and ____ mAs
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preferred technique is high kvp, low mAs
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If going from a 72 inch distance to a 40 inch distance what happens to density
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it increases
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Contrast resolution is a selling point for which of the following
Film screen DR CR CR & DR |
DR & CR
( with CR & DR spatial resolution is not good) |
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smallest thing that can be seen is:
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spatial resolution
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Sharpness of detail is what type of property
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geometric property
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A long SID gives the best ________
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recorded detail
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long SID cuts down on what?
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magnification
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Is a short or long OID preferable
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Short
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short OID improves _______ which improves _______
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short OID improves magnification which improves recorded detail
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What type of focal spot size is best for the best sharpness and recorded detail
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Small focal spot size
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What two terms go along with shape distortion
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elongation and foreshortening
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Which type of shape distortion can be used to your advantage
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elongation
( calcaneus projection) |
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________ is critical in order to avoid shape distortion
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alignment
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in order to reduce the amount of heat being used what size focal spot should a tech use?
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A larger focal spot
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Why does the anode spin?
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the dissipate the heat
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Electrons are + or -
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negative
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Whats within the focusing cup that produces electrons
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filament
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Whats the filament made out of?
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tungsten ( high atomic #, can handle a lot of heat )
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Whats the charge on the focusing cup?
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negative
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Electrons travel at:
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the speed of light
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increasing time of exposure allows the electrons to:
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flow from cathode to anode a longer period of time.
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Why does a tube have housing ?
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to protect from leakage and electrical shock
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When were x-rays discovered?
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November 8 1895
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Where is the image on film
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emulsion layer
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Where is the image in CR
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photostimuable phosphur plate
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where is the image with DR
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on the computer screen
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Whats the intensifying screen made of?
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rare phosphor
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What is it called when a intensifying screen continues to give off light when it shouldn't (it keeps glowing)
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phosphorescence (bad)
(after) |
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screens are considered radiation protection devices because?
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they allow you to use less radiation
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what is a small discrete bundle of energy
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quantum or photon
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the faster the screen system the more ______ emitted.
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light
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_______ permits x-rays to penetrate, _______ does not allow x-rays to penetrate
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radiolucent permits x-ray penetration
radiopaque does not allow x-ray penetration |
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When x-rays spread out it's called?
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divergence
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filtration decreases patient dose because it removes the _________
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lower energy x-rays
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outer shell electron is:
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compton
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inner shell electron is:
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photoelectric
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thinning out the beam is:
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attenuation
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