homework review 2 Flashcards
According to ACR Mammography Accreditation standards, what is the minimum frequency for evaluating the compression thickness indicator by the technologist?
monthly
During ACR phantom scoring, what will result in a full point being awarded when viewing the fibers?
> = 8 mm long
During ACR phantom scoring, what will result in a full point being awarded when viewing the specks?
4-6 specks
During ACR phantom scoring, what will result in a full point being awarded when viewing the masses?
≤½ & >¾ border
Mammographers must perform phantom image evaluation at least
weekly
The MQSA does not require facilities to have
ACR accreditation
The average glandular dose delivered during a single craniocaudal view of an FDA-accepted phantom simulating a standard breast shall not exceed ____ mGy per exposure.
3
The mAs recorded during phantom image testing of mammographic equipment should not vary by more than ____ from the initial control value.
±15%
The maximum allowable dose per exposure for mammographic images is ____ rad.
0.3
The recommended maximum tolerance of kVp variance for mammographic x-ray generators is
5%
A visual inspection of a CT unit should be evaluated at least _____ for ACR accreditation programs.
monthly
For ACR CT accreditation, the Water CT Number and Standard Deviation (Noise) should be evaluated by the CT technologist
daily
For a slice thickness of 5 mm or less, the slice thickness should not vary by more than ____ mm.
0.5
Patient dose values for CT scans should remain within ____ of the manufacturer’s specifications.
±10%
Section thickness should not vary by more than ____ mm for sections greater than 5 mm.
±1.0
The CT number of water should not deviate by more than ____ CT numbers from 0.
3
The CTDIvol pass/fail criterion for an adult abdomen is ____ mGy.
30
The laser light field and radiation field should coincide to within ____ mm.
2.0
The minimum distance between two objects that allows them to be seen as separate and distinct would define what CT imaging parameter?
high contrast resolution
The uniformity of the CT number of water should not vary by more than ____ HU from the center of the phantom to the periphery
5
A change in the strength of the main magnetic field can be caused by
a. All are correct.
b. external ferromagnetic materials.
c. cryogen boiloff.
d. shim coil failure.
a. All are correct
An acquisition with a 200-mm field of view and 256 x and y encodes yields a pixel size of ____ mm2.
0.78
Luminance uniformity of soft-copy displays used in MRI systems should be within ____ of the maximum brightness measured in the center of the screen.
30%
Nonuniformity in the magnetic field can be caused by
a. All are correct.
b. the presence of ferromagnetic material within the bore of the magnet.
c. uniformity in the RF coil.
d. a homogenous main magnetic field.
b. the presence of ferromagnetic material within the bore of the magnet.
The ACR slice position deviation in MR scanners should not exceed ____ mm.
5
The ability of an MR scanner to resolve small objects is known as
high contrast resolution
The ability of the MR system to differentiate between adjacent tissues having minimal differences in signal intensities is known as
low contrast resolution
The amount of geometric distortion in the image is the
spatial linearity
What is the maximum luminance for soft-copy display devices as suggested by the ACR?
greater than 90 nit
What is the resonant frequency in a unit with a 1.0-T magnet and a gyromagnetic ratio of 42.57 MHz/T?
42.57 MHz
A chemical fog artifact
a. appears as streaks.
b. results in lower contrast.
c. results in lower optical density.
d. is an exposure artifact.
b. results in lower contrast.
Data for determining repeat rates should include at least ____ patients to obtain a statistical sample large enough for valid results.
250
If residual thiosulfate is not properly removed during washing, the radiograph will
turn brown
Patient motion during exposure results in _____ artifact.
a. a handling
b. no
c. a processing
d. an exposure
d. an exposure
Pi lines are so named because they
a. occur at regular intervals.
b. appear as a section of pie.
c. None are correct.
d. occur on the finished radiograph.
a. occur at regular intervals
Wet pressure sensitization would be classified as _____ artifact.
a. an exposure
b. no
c. a processing
d. a handling
c. a processing
Which of the following artifacts can occur in both CR and film/screen radiography?
a. Moiré pattern
b. Water spots
c. Static electricity
d. Wet-pressure sensitization
a. Moiré pattern
Which of the following can occur as a result of a double set of grid lines?
a. Grid misalignment
b. Film fog
c. Static artifacts
d. Moiré effect
d. Moiré effect
Which of the following will run in the same direction as that of film travel?
a. Guide shoe marks
b. All are correct
c. Pi lines
d. Hesitation lines
a. Guide shoe marks
_______ can appear as dark bands at the interfaces of structures that differ widely in brightness level such as barium examinations or metal prosthesis.
Halo artifacts
