Axial Resolution

Question 1

Axial resolution describes the accuracy related to visualizing two structures that are ____ to a sound beam’s main axis.

a. parallel
b. perpendicular
c. oblique
d. normal

Answer 1

a. parallel

Question 2

You are purchasing a diagnostic ultrasound system. System X has axial resolution of 0.7 mm whereas System D’s is 0.4 mm. Based on this information, which system will produce the better quality picture?

a. System X
b. System D
c. they have the same quality
d. cannot be determined

Answer 2

b. System D

Question 3

The axial resolution of an imaging system is reported to be 0.85 mm at the beam’s focus. What is the closest estimate of the system’s radial resolution at a location that is 5 cm deeper than the focus?

a. less than 0.85 mm
b. equal to 0.85 mm
c. greater than 0.85 mm

Answer 3

b. equal to 0.85 mm

Question 4

Two systems are undergoing evolution. System A has 1,000,000 pixels, each with 4 bits. System B has 750,000 pixels, each with 12 bits. Which system has the best longitudinal resolution?

a. System A
b. System B
c. both are the same
d. cannot be determined

Answer 4

d. cannot be determined

Question 5

True or False?

The lower the numerical value of the longitudinal resolution, the worse the picture.

Answer 5

False

Question 6

True or False?

One way that a sonographer can alter the axial resolution achieved during an exam is to adjust the maximum imaging depth.

Answer 6

False

Question 7

True or False?

With a specific ultrasound system and transducer, the system’s axial resolution is invariant, and the sonographer can do nothing to improve.

Answer 7

True

Question 8

True or False?

The shorter the pulse duration, the better the picture.

Answer 8

True

Question 9

An ultrasonic pulse has a pulse repetition period of 1.2 msec, a spatial pulse length of 2.0 mm, and a wavelength of 0.4 mm. What is the axial resolution of the system?

a. 2.0 mm
b. 1.0 mm
c. 0.4 mm
d. 1.8 mm

Answer 9

b. 1.0 mm

Question 10

True or False?

The more there are in a pulse, the greater the detail that will be visualized in the ultrasound scan.

Answer 10

False

Question 11

Two ultrasound systems produce acoustic pulses. A pulse from System 1 has a wavelength of 0.5 mm, 4 cycles per pulse, and a pulse repetition period of 1.2 msec. The pulses from System 2 have a wavelength of 1.0 mm, 2 cycles per pulse, and a pulse repetition period of 1.8 msec. Which ultrasound system will have a lower numerical value of axial resolution?

a. System 1
b. System 2
c. both are the same
d. cannot be determined

Answer 11

c. both are the same

Question 12

Which transducer has the best axial resolution?

a. 2 cycles/pulse, 4 MHz
b. 4 cycles/pulse, 4 MHz
c. 4 cycles/pulse, 2 MHz
d. 2 cycles/pulse, 2 MHz

Answer 12

a. 2 cycles/pulses, 4 MHz

Question 13

Which transducer has the worst axial resolution?

a. 2 cycles/pulse, 4 MHz
b. 4 cycles/pulse, 4 MHz
c. 4 cycles/pulse, 2 MHz
d. 2 cycles/pulse, 2 MHz

Answer 13

c. 4 cycles/pulse, 2 MHz

Question 14

Two ultrasound systems produce pulses. One pulse is 0.4 usec in duration and the other is 0.2 usec long. Which pulse is most likely to provide the best radial resolution?

a. 0.4 usec system
b. 0.2 usec system
c. they are the same
d. cannot be determined

Answer 14

b. 0.2 usec system

Question 15

A sonographer is performing a study on a patient and desires superior depth resolution. Which of the following changes would create such a system?

a. higher frequency
b. shorter wavelength
c. fewer cycles per pulse
d. less ringing
e. all of the above

Answer 15

e. all of the above

Question 16

True or False?

The higher the frequency of the cycles within a pulse, the lower the numerical value of the axial resolution.

Answer 16

True

Question 17

True or False?

The shorter the pulse length, the better the picture.

Answer 17

True