ACQ EXAM 5 QUESTIONS WITH
CORRECT ANSWERS
What are common digital errors? - Answer- Exposure field too large
Anatomy not centered
Multiple body parts in image
Improper AEC use
Grid errors
What 3 things can digital imaging not fix? - Answer- Underexposure or missing data,
poor positioning, and bad detector selection
What is exposure latitude? - Answer- Margin for exposure error, range of exposures that
can produce an acceptable image for a particular system
For ______ systems, a much wider margin for error is allowed especially in the direction
of overexposure - Answer- Digital
For film based systems, the exposure latitude is - Answer- -30% - +50%
For digital systems, the exposure latitude is - Answer- -50% - +400%
________is not generally apparent in DR and CR images - Answer- Overexposure
It takes at least ________ the normal exposure to saturate a digital image - Answer-
10x
Some systems begin to show mottle at only a ______ reduction in mAs - Answer- 35%
Even though repeated rates have been reduced from 5% to about 3%, a ______
increase in radiation delivered per exam has been demonstrated - Answer- 40-50%
If a CR plate has been fogged prior to using it for an exposure, it will result in - Answer-
An image with poor contrast
Pre-fogging of a CR plate covers - Answer- The entire plate
Prefogging a CR plate will usually cause - Answer- Histogram analysis and EI errors
, T/F: Scatter radiation that occurs during an exposure does usually not result in
histogram analysis or EI errors - Answer- T
Prefogging of a CR plate primarily affects the ______ portions of the image - Answer-
Lighter (leaves no blank white pixels)
__________ can clean up specific fog patterns within the latent image - Answer-
Frequency processing
_______ can target structures of a specific size to eliminate them from the image -
Answer- Frequency processing
When a CR or DR system is installed, the AEC is recalibrated based on the
__________ produced at the selected speed class - Answer- Exposure indicator
If image mottle is a problem during AEC procedures, the _____ should be increased
until sufficient signal is reaching the detector cells - Answer- kVp
Any time AEC is used, off centering of the anatomy can result in - Answer- Image mottle
If grids are not used, patient dose is - Answer- Reduced
Patient dose can be reduced as low as _________ if grids are not used or grid ratios
are reduced - Answer- 1/3 - 1/4
Grids are one method of reducing the - Answer- Amount of noise
Anatomy smaller than _______ should not be done with grids - Answer- 13 cm
AEC controls - Answer- exposure time only (mAs)
Even with AEC, the radiographer must set the - Answer- kVp, mA, detector cell, backup
time/mAs, density control if needed
What is minimum response time (MRT)? - Answer- The shortest time the AEC can
terminate an exposure, minimum time it takes for the electric circuit to detect and react
to radiation
What is the range of MRT? - Answer- 0.002 - 0.02 seconds
The back up mAs or time prevents excessive duration of the exposure to - Answer-
Avoid heat overload on the tube anode and prevent excessive patient exposure
Most modern units have back up times or mAs pre set by the manufacturer but many of
them are - Answer- Excessive (sometimes 20x the average) and inconsistent
CORRECT ANSWERS
What are common digital errors? - Answer- Exposure field too large
Anatomy not centered
Multiple body parts in image
Improper AEC use
Grid errors
What 3 things can digital imaging not fix? - Answer- Underexposure or missing data,
poor positioning, and bad detector selection
What is exposure latitude? - Answer- Margin for exposure error, range of exposures that
can produce an acceptable image for a particular system
For ______ systems, a much wider margin for error is allowed especially in the direction
of overexposure - Answer- Digital
For film based systems, the exposure latitude is - Answer- -30% - +50%
For digital systems, the exposure latitude is - Answer- -50% - +400%
________is not generally apparent in DR and CR images - Answer- Overexposure
It takes at least ________ the normal exposure to saturate a digital image - Answer-
10x
Some systems begin to show mottle at only a ______ reduction in mAs - Answer- 35%
Even though repeated rates have been reduced from 5% to about 3%, a ______
increase in radiation delivered per exam has been demonstrated - Answer- 40-50%
If a CR plate has been fogged prior to using it for an exposure, it will result in - Answer-
An image with poor contrast
Pre-fogging of a CR plate covers - Answer- The entire plate
Prefogging a CR plate will usually cause - Answer- Histogram analysis and EI errors
, T/F: Scatter radiation that occurs during an exposure does usually not result in
histogram analysis or EI errors - Answer- T
Prefogging of a CR plate primarily affects the ______ portions of the image - Answer-
Lighter (leaves no blank white pixels)
__________ can clean up specific fog patterns within the latent image - Answer-
Frequency processing
_______ can target structures of a specific size to eliminate them from the image -
Answer- Frequency processing
When a CR or DR system is installed, the AEC is recalibrated based on the
__________ produced at the selected speed class - Answer- Exposure indicator
If image mottle is a problem during AEC procedures, the _____ should be increased
until sufficient signal is reaching the detector cells - Answer- kVp
Any time AEC is used, off centering of the anatomy can result in - Answer- Image mottle
If grids are not used, patient dose is - Answer- Reduced
Patient dose can be reduced as low as _________ if grids are not used or grid ratios
are reduced - Answer- 1/3 - 1/4
Grids are one method of reducing the - Answer- Amount of noise
Anatomy smaller than _______ should not be done with grids - Answer- 13 cm
AEC controls - Answer- exposure time only (mAs)
Even with AEC, the radiographer must set the - Answer- kVp, mA, detector cell, backup
time/mAs, density control if needed
What is minimum response time (MRT)? - Answer- The shortest time the AEC can
terminate an exposure, minimum time it takes for the electric circuit to detect and react
to radiation
What is the range of MRT? - Answer- 0.002 - 0.02 seconds
The back up mAs or time prevents excessive duration of the exposure to - Answer-
Avoid heat overload on the tube anode and prevent excessive patient exposure
Most modern units have back up times or mAs pre set by the manufacturer but many of
them are - Answer- Excessive (sometimes 20x the average) and inconsistent
