Deck 12: Ultrasound Equipment Quality Assurance

Question 1

A measure of the minimum spacing along the beam axis that still allows two reflectors to be identified is called the

A) lateral resolution.
B) axial resolution.
C) axial depth of visualization.
D) axial distance measurement accuracy.

Answer 1

B
Axial resolution is a measure of how close two reflectors can be to one another along the axis of an ultrasound beam and still be resolved as separate reflectors.

Question 2

Maximum depth of visualization tests are performed using _____ receiver gain and _____ transmit power.

A) minimum; maximum
B) maximum; minimum
C) maximum; maximum
D) minimum; minimum

Answer 2

C
The output power control is positioned for maximum output, and the receiver gain is adjusted for the highest values without excessive noise on the display.

Question 3

The maximum depth of visualization can indicate changes in

A) vertical distance measurement accuracy.
B) axial and lateral resolution.
C) slice thickness.
D) sensitivity.

Answer 3

D
A commonly used technique for detecting variations in maximum sensitivity is the measure of the maximum depth of visualization for signals from scattered echoes in the tissue-mimicking phantom.

Question 4

Maximum depth of visualization is often limited by

A) noise at high gain.
B) poor axial resolution.
C) too low a power setting.
D) too low a transducer frequency.

Question 5

On the viewing monitor of a scanner, a sonographer counts 16 shades of gray in the gray-bar pattern. The hard-copy B-mode image displays only the 13 brightest gray bars. This should be interpreted as

A) normal performance.
B) too low a receiver gain.
C) inadequate photography and processing that need correction.
D) poor contrast and brightness settings on the viewing monitor.

Question 6

Suppose that the maximum depth of visualization using a 3.5-MHz transducer is 14.2 cm. On the previous two tests, 3 months and 6 months earlier, it was 14.4 and 14.1 cm, respectively. These variations should be interpreted as

A) just barely tolerable performance.
B) normal variations inherent in the machine.
C) excessive variations, indicating that the machine requires immediate service.
D) normal variations inherent in the measurement process.

Question 7

A scan is done of a uniform section in a phantom, and a vertical shadow emanates from a position on the image corresponding to the transducer surface. This is likely caused by

A) poor TGC control.
B) poor lateral gain.
C) inadequate gray-scale photography.
D) loss of signal from one or more transducer elements.

Question 8

A measurement comparing the actual separation between two reflectors placed at different positions along the beam axis with the separation indicated on the calipers is a test of

A) axial resolution.
B) ultrasound wavelength.
C) vertical distance measurement accuracy.
D) horizontal distance measurement accuracy.

Question 9

For the measurement described in question 7, the digital caliper cursors should be placed at the

A) top of the higher reflector and at the bottom of the other.
B) top of each reflector.
C) left side of one and at the right side of the other.
D) bottom of the higher reflector and at the top of the other.

Question 10

For which of the following tests would it be acceptable for the results to vary with the transducer frequency?

A) Maximum depth of visualization
B) Axial distance measurement accuracy
C) Lateral distance measurement accuracy
D) Scan uniformity