Sorrell Chapter 2

Question 1

Frequency range of human hearing

Answer 1

20,000 Hz to 20Hz

Question 2

Frequency range of cardiac ultrasound probes.

Answer 2

1 to 12 MHz

Question 3

The velocity of sound transmission in soft tissue

Answer 3

1.54 km/s or 1,540M/s

Question 4

Gain

Answer 4

The degree of amplification of the returning sound signal

Question 5

Intensity

Answer 5

Distribution of power within an area, analogous to loudness

Question 6

Attenuation

Answer 6

The net loss of ultrasound energy during propagation

Question 7

Absorption

Answer 7

The transfer of ultrasound energy to the tissue during the propagation

Question 8

Acoustic impedance

Answer 8

Product of tissue density and the velocity of sound.

Question 9

Formula for estimating attenuation

Answer 9

0.5dB/cm/MHz

Question 10

Dead time

Answer 10

the time in between pulses that the echograph is not emitting ultrasound

Question 11

Duty factor

Answer 11

a unitless number between 0 and 1 representing the fraction of time that the transducer is emitting ultrasound

Question 12

Far filed

Answer 12

the diverging conical portion of the beam beyond the near field

Question 13

frequency

Answer 13

number of cycles per second, measured in Hz

Question 14

Half layer value

Answer 14

the distance a ultrasound beam penetrates into a medium before its intensity has attenuated to half the original value

Question 15

near field

Answer 15

the proximal cylindrical shaped portion of the ultrasound beam before divergence begins to occur

Question 16

period

Answer 16

the time required to complete one cycle, usual expressed in microseconds

Question 17

Power

Answer 17

rate of transfer over time of acoustic energy from the propagating wave to the medium, measured in watts

Question 18

pulse

Answer 18

burst or packet of emitted ultrasound of finite duration containing a fixed number of cycles traveling together

Question 19

pulse length

Answer 19

the physical length or distance that a pulse occupies in spaced, usually expressed in mm.

Question 20

pulse repetition

Answer 20

the rate at which pulses are emitted from the transducer, usually measured over a period of 1 second.

Question 21

wavelength

Answer 21

distance measurement of one cycle of ultrasound wave

Question 22

Specular reflectors

Answer 22

large targets like pericardium, endocardium, and valves

Question 23

scattered reflectors

Answer 23

created by small targets, only small portion of ultrasound is reflected back such as myocardium (Rayleigh scatterer.)

Question 24

In M mode the pulse repetition rate is ____ compared to 2D

Answer 24

lower. More pulses/s needed to create 90 degree sector of 2D. Temporal resolution much better for M-Mode.

Question 25

In 2D echo, two sweeps of the ultrasound constitute …

Answer 25

1 frame