Ch. 7 Range Equation

Question 1

The elapsed time from pulse creation to pulse reception is called the ____________________ or _______________________.

Answer 1

The elapsed time from pulse creation to pulse reception is called Go-return time or Time-of-Flight

Question 2

The time-of-flight is directly related to ________________________ a sound pulse travels.

Answer 2

The time-of-flight is directly related to how deep a sound pulse travels

Question 3

Ultrasound systems’ computers are programmed with the average speed of sound in soft tissue, to _______________________.

Answer 3

1.54 mm/us

Question 4

Range equation formula:

Answer 4

depth (mm) = 1.54 mm/us x go-return time (us) / 2

Question 5

PRP and Max imaging depth formula:

Answer 5

PRP (us)= imaging depth(cm) x 13 us/cm

Question 6

PRF and Max imaging depth formula:

Answer 6

PRF (Hz)= 77,000 cm/s / imaging depth(cm)

Question 7

The 13-microsecond rule always applies when sound travels through _______________________.

Answer 7

soft tissue

Question 8

For every 13-microseconds of go-return time, the object creating the reflection is ______________ deeper in the body.

Answer 8

For every 13-microseconds of go-return time, the object creating the reflection is 1cm deeper in the body.

Question 9

a pulse’s time-of-flight is 26 microseconds when a reflector is ______________ deep

Answer 9

a pulse’s time-of-flight is 26 microseconds when a reflector is 2cm deep

Question 10

a pulse’s time-of-flight is 39 microseconds when a reflector is _________________ deep

Answer 10

a pulse’s time-of-flight is 39 microseconds when a reflector is 3cm deep

Question 11

If a pulse’s time-of-flight is 52 microseconds, what is the total distance traveled?

Answer 11

The total distance from the reflector and back is 8cm because the reflector itself is only 4cm deep

Question 12

When the depth of view is shallow, PRP is ______.

Answer 12

short

Question 13

When the depth of view is deep, the PRP is _____.

Answer 13

long

Question 14

When the depth of view is set to 10cm, PRP is _____________ microseconds

Answer 14

When depth of view is set to 10cm, PRP is 130 microseconds (10 x 13)

Question 15

When the depth of view is set to 5cm, PRP is _________________ microseconds

Answer 15

When depth of view is set to 5cm, PRP is 65 microseconds (5 x 13)

Question 16

When the depth of view is shallow, PRF is _____________

Answer 16

When the depth of view is shallow, PRF is high

Question 17

When the depth of view is deep, PRF is ________________

Answer 17

When depth of view is deep, PRF is low

Question 18

A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The depth of the reflector is 10cm in soft tissue. What is the go-return time?
A. 13 microseconds
B. 1.3 microseconds
C. 65 microseconds
D. 130 microseconds

Answer 18

D. Time of flight equals depth multiplied by 13 microseconds

10cm x 13microseconds/cm = 130 microseconds

Question 19

A sounds wave is created by a transducer, reflects off an object, and returns to the transducer. The go-return time is 26 microseconds. What is the depth of the reflector?
A. 1cm
B. 2cm
C. 3cm
D. 4cm

Answer 19

B. The reflector depth is 2cm

2cm x 13microseconds/cm = 26 microseconds

Question 20

A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The go-return time is 26 microseconds. What is the total distance that the pulse traveled?
A. 1cm
B. 2cm
C. 3cm
D. 4cm

Answer 20

D. Total distance traveled is twice the depth of the reflector

Question 21

The maximum imaging depth (depth of view) during an ultrasound exam is 10cm. The sonographer adjusts the imaging depth to 20cm. What happens to the pulse repetition period?
A. it is unchanged
B. it is halved
C. it is doubled
D. it is 20 times longer

Answer 21

C. Pulse repetition period is directly related to imaging depth. When imaging depth doubles, pulse repetition period doubles.

Question 22

The maximum imaging depth during an ultrasound exam is 10 cm. The sonographer adjusts the imaging depth to 20 cm. What happens to the PRF?
A. it is unchanged
B. it is halved
C. it is doubled
D. it is 20 times longer

Answer 22

B. Pulse repetition frequency is inversely related to imaging depth. When imaging depth doubles, PRF is halved

Question 23

The imaging depth during an ultrasound exam is 10 cm. The sonographer adjusts the imaging depth to 5 cm. What happens to pulse repetition period?
A. it is unchanged
B. it is halved
C. it is doubled
D. it is 20 times longer

Answer 23

B. Pulse repetition period is directly related to imaging depth. When imaging depth is halved, PRP is halved

Question 24

How long does it take for sound to make a round trip to and from the skin’s surface to a reflector depth of 1cm in soft tissue?
A. 13 microseconds
B. 150 milliseconds
C. 15 microseconds
D. 2 seconds

Answer 24

A. In soft tissue, sound can travel to and return from a depth of 1cm (a total distance of 2cm) in 13 microseconds (13 millionths of a second)

Question 25

In soft tissue, sound travels to a reflector and back to the transducer in 39 microseconds. How deep is the reflector?
A. 2cm
B. 6cm
C. 3cm
D. cannot be determined

Answer 25

C. For each 13 microsecond, sound travels a round trip of 1 centimeter. Thus in 39 microseconds, sound travels to and returns from a depth of 3cm

Question 26

In soft tissue, sound travels to a reflector and back to the transducer in 39 microseconds. What is the total distance that the pulse traveled?
A. 2cm
B. 6cm
C. 3cm
D. cannot be determined

Answer 26

B. Since the pulse traveled round trip, the total distance is 6cm.

For each 13 microseconds, sound travels a round trip depth of 1cm. Thus, in 39 microseconds, sound travels to and returns from a depth of 3cm.

Question 27

One reflector is 5 times deeper than another. The time of flight of sound to the deeper structure is ______the time of flight of the shallower reflector.
A) One fifth as much as
B) Equal to
C) Less than
D) Five times more than

Answer 27

D. Time of flight and reflector depth are directly related. When a reflector is five times deeper than another, the pulse’s time of flight is five times greater.