Last PRE test UPDATED ACTUAL QUESTIONS AND
CORRECT Answers
how is spatial resolution/ detail quantified? lp/mm test
what is spatial resolution? the ability to distinguish small adjacent details from each other
as a spatial frequency number becomes larger, the increase
ability to resolve smaller objects (increase/decrease)
spatial frequency is (directly/inversely) related to pixel directly related
size (because each pixel can only visualize 1 shade of gray)
what is needed to distinguish detail and make up a line at least 2 pixels
pair?
how many lp/mm can a human eye resolve? about 10 lp/mm
DR has spatial resolution capabilities of approximately 3.7 lp/mm
lp/mm
1 inch = mm 25.4mm
pixel size formula Pixel size = FOV/matrix size
, if you have a FOV of 17 inches and a matrix size of 1024, 0.42mm= pixel size
what is your pixel size? (17 inches= 431.8mm) [17x25.4]
(431.= 0.42) [FOV / Matrix]
pixel size is (directly/ inversely) related to the FOV on pixel size is DIRECTLY related to FOV on monitor, INVERSELY related to IR
the monitor and (directly/inversely) related to the IR matrix size
matrix size
voxel volume element; section of tissue represented by a pixel
when displayed on the monitor: high density= low brightness (black)
High density is (high/low) brightness and (black/white). low density= high brightness (gray/white)
Low density is (high/low) brightness and (black/white)
what is the highest bit depth? 2^16
(2 to the 16th power)
what are the biggest factors that affect SNR? -mAs
-SID
-OID
-[body habitus]
what does a high SNR mean? more photons are reaching the IR
would an abdomen have a wide or narrow window wide
width? (wide= decrease contrast)
would a hand have a wide or narrow window width? narrow (narrow= high contrast)
t/f: di# provides immediate feedback of the patients false
exposure and dose it only gives immediate feedback of exposure to the IR
what will give you an overexposed image? -high mAs, kVp, FOV, ei#
-low collimation, filtration, grid#, SID
decrease contrast is (long/short) scale long scale (gray)
CORRECT Answers
how is spatial resolution/ detail quantified? lp/mm test
what is spatial resolution? the ability to distinguish small adjacent details from each other
as a spatial frequency number becomes larger, the increase
ability to resolve smaller objects (increase/decrease)
spatial frequency is (directly/inversely) related to pixel directly related
size (because each pixel can only visualize 1 shade of gray)
what is needed to distinguish detail and make up a line at least 2 pixels
pair?
how many lp/mm can a human eye resolve? about 10 lp/mm
DR has spatial resolution capabilities of approximately 3.7 lp/mm
lp/mm
1 inch = mm 25.4mm
pixel size formula Pixel size = FOV/matrix size
, if you have a FOV of 17 inches and a matrix size of 1024, 0.42mm= pixel size
what is your pixel size? (17 inches= 431.8mm) [17x25.4]
(431.= 0.42) [FOV / Matrix]
pixel size is (directly/ inversely) related to the FOV on pixel size is DIRECTLY related to FOV on monitor, INVERSELY related to IR
the monitor and (directly/inversely) related to the IR matrix size
matrix size
voxel volume element; section of tissue represented by a pixel
when displayed on the monitor: high density= low brightness (black)
High density is (high/low) brightness and (black/white). low density= high brightness (gray/white)
Low density is (high/low) brightness and (black/white)
what is the highest bit depth? 2^16
(2 to the 16th power)
what are the biggest factors that affect SNR? -mAs
-SID
-OID
-[body habitus]
what does a high SNR mean? more photons are reaching the IR
would an abdomen have a wide or narrow window wide
width? (wide= decrease contrast)
would a hand have a wide or narrow window width? narrow (narrow= high contrast)
t/f: di# provides immediate feedback of the patients false
exposure and dose it only gives immediate feedback of exposure to the IR
what will give you an overexposed image? -high mAs, kVp, FOV, ei#
-low collimation, filtration, grid#, SID
decrease contrast is (long/short) scale long scale (gray)
