Ch. 15 Review Exam Flashcards
Image formation is the result of_____ absorption.
differential
Ionization is the process through which an atom ejects a/an _____?
electron
Tissues comprised of atoms with low atomic numbers present ____ opportunities for scatter or absorption to occur.
less
Image brightness can be manipulated by adjusting technical factors and ______.
window level
The measurement of how efficient an image receptor is in converting x-ray exposure it receives into a quality radiographic image.
DQE
Pick the factors that affect magnification.
- SID
- OID
- kVp
- mAs
SID and OID
T/F - When aligning the central ray to the image receptor, it is ideal for the CR to enter the IR as closely to parallel as possible.
false
This form of digital imaging uses a removable phosphor plate.
CR
_____ is the material used as an activator in CR PSP.
europium
Direct DR systems use ____ as a photoconductor
amorphous selenium
Indirect DR systems use ____ as a photoconductor.
amorphous silicon
The main controller of contrast in digital imaging systems is ____.
LUT
The main controller of contrast in film-screen imaging systems is ____.
kVp
Increasing collimation may require more ____ to maintain the same level of exposure.
mAs
These kinds of grids can be either long or short dimension.
linear
T/F - Focused grids can be used effectively at any SID.
false
When going from no grid to a 5:1 grid, you have to multiply your original mAs by ___.
2
When going from no grid to a 16:1 grid, you have to multiply your original mAs by ____.
6
When going from no grid to a 10:1 grid, you have to multiply your original mAs by ____.
5
____ is a hollow air-filled cell connected to a timer circuit via wire.
ionization chamber
When using AEC, increasing kVp will do what to exposure time?
decrease time
In general, backup time should be set to terminate when the exposure has reached ____% of the desired exposure.
200
Of the two forms of technique charts, this is the most ideal.
fixed kVp/variable mAs
Fiberglass casts require ____ radiation to penetrate than plaster casts do.
less
What range of mA is used in fluoroscopy?
0.5-5
What range of mA is used in conventional radiography?
50-1200
What is the length of time that a fluoro unit can be used before the timer temporarily shuts off the ability to radiate?
5 mins
The input phosphor of the image intensifier is typically made up of?
cesium iodide
T/F - In terms of the path of energy traveling through the image intensifier, the input phosphor is the first thing energy interacts with.
true
T/F - In terms of the path of energy traveling through the image intensifier, the output phosphor is the last thing energy interacts with.
true
T/F - In terms of the path of energy traveling through the image intensifier, the photocathode comes before the focusing lenses.
true
T/F - In terms of the path of energy traveling through the image intensifier, the focusing lenses come before the accelerating anode.
true
The focusing lenses are not proper lenses, but are actually charged plates. What is their charge?
negative
The accelerating anode is given a constant electric potential in order to direct electron flow at a consistent rate. What is the electric potential?
25 kV
The ratio of the number of light photons at the output phosphor to the number of x-ray photons at the input
flux gain
The number of output light photons / number of input x-ray photons.
flux gain
The expression of how much an image is made smaller, from the input phosphor to the output phosphor.
minification gain
The expression of luminance at the output phosphor divided by the input exposure rate
conversion factor
The function that maintains the overall appearance of the image by adjusting kVp and mA as needed.
ABC
T/F - When operating in magnification mode, voltage to the focusing lenses is decreased.
false
The most common camera tube is the ____ tube
vidicon
T/F - When acquiring cassette spot films, mA stays the same throughout the process.
false
______ reduces overall dose and noise by averaging multiple frames together.
frame averaging
_____ automatically adjust mA, kVp, filtration, and pulse width to maintain optimum exposure.
AERC
The subpixels of plasma monitors are filled with ____.
xenon and neon
Skin-to-source distance for a stationary fluoroscopic unit should be no less than __ cm.
38 cm
Skin-to-source distance for a mobile fluoroscopic unit should be no less than __ cm.
30 cm
T/F - The tube radiates continuously during pulsed fluoroscopy.
false
T/F - The tube radiates continuously during standard fluoroscopy.
true
T/F - In fluoroscopy, the tube is above the patient, and the intensifier is below the patient.
false
