Ch. 9 Test Flashcards
Image brightness can be adjusted by adjusting:
window level and exposure factors
____ can occur when an image receptor is over exposed.
saturation
These are numeric values that indicate the amount of radiation an image receptor receives.
EI and S numbers
The exhibited difference in brightness levels within an image.
contrast
Digital imaging uses a _____ dynamic range
wide
The absorption characteristics of the tissues being imaged.
subject contrast
T/F - Effective atomic number has no impact on subject contrast.
false
T/F - An abdomen has greater subject contrast than a chest.
false
T/F - The quality of a radiographic beam effects the way it may be attenuated.
true
An image of high contrast is mostly _____
black and white
An image of low contrast has ____
lots of shades of gray
Pixel size =
FOV/matrix size
The term used to evaluate the accuracy of anatomical structural lines.
spatial resolution
T/F - Pixel size is the primary factor that affects spatial resolution.
true
T/F - Spatial frequency has no impact on spatial resolution.
false
T/F - Larger objects have larger spatial frequency.
false
The measurement of how efficiently an image receptor is in converting x-ray exposure it receives into a quality radiographic image.
DQE
The measure of an imaging systems ability to display the contrast of anatomic objects varying in size.
MTF
The misrepresentation of the anatomic part in imaging, resulting in an image that represents the anatomy with altered shape or size.
distortion
T/F - Increasing OID reduces magnification.
false
T/F - Increasing SID reduces magnification.
true
T/F - Increased SID with reduced OID is ideal.
true
T/F - Decreased SID with increased OID is ideal.
false
T/F - It is possible to completely eliminate OID.
false
T/F - The radiographer should use as much SID as possible at all times.
false
T/F - Elongation means that the imaged part appears shorter than it is.
false
T/F - Foreshortening means that the imaged part appears shorter than it is.
true
T/F - When aligning the part to the IR, the part should always be perpendicular to the IR.
false
T/F - When aligning the CR to the IR, the CR should be as close to parallel to the IR as possible.
false
In general, the ___ should strike the ___ and the anatomic part perpendicularly, and the ___ should be as close to parallel with the IR as possible, to avoid shape
CR, IR, anatomic part
A method of describing the strength of radiation exposure compared with the amount of noise present in a digital image.
SNR
A method of describing contrast resolution compared with the amount of noise present in the image.
CNR
Any unwanted brightness level in a radiographic image.
artifact
T/F - Digital algorithms can correct any and all exposure errors made.
false
T/F - Short dynamic range allows us to use less radiation to produce a diagnostic image.
false
