Ch. 1 Foundations of Sonography

Question 1

Change in the direction of propagation of a sound wave transmitted across an interface where the speed of sound varies

Answer 1

Refraction

Question 2

Angle at which a sound beam strikes the interface between two types of tissue

Answer 2

Angle of incidence

Question 3

Power per unit area

Answer 3

Intensity

Question 4

Special material in the transducer that has the ability to convert electric impulses into sound waves

Answer 4

Crystal

Question 5

Propagation of energy that moves back and forth or vibrates at a steady rate

Answer 5

Wave

Question 6

Any device that converts energy from one form to another

Answer 6

Transducer

Question 7

Number of cycles per second that a periodic event or function undergoes

Answer 7

Frequency

Question 8

Measure of material’s resistance to the propagation of sound; expressed as the product of acoustic velocity of the medium and density of the medium

Answer 8

Acoustic Impedance

Question 9

Generation of electric signals as the result of an incident sound beam on a material that has piezoelectric properties

Answer 9

Piezoelectric Effect

Question 10

Region over which the effective width of the sound beam is within some measure of its width at the focal distance

Answer 10

Focal Zone

Question 11

Reduction in amplitude and intensity of a sound wave as it propagates through a medium

Answer 11

Attenuation

Question 12

Passive force in opposition to another, active force; occurs when tissue exerts pressure against the flow

Answer 12

Resistance

Question 13

Surface forming the boundry between media having different properties

Answer 13

Interface

Question 14

Region of increased particle density

Answer 14

Compression

Question 15

Distance over which a wave repeats itself during one period of oscillation

Answer 15

Wavelength

Question 16

Refers to the minimum distance between two structures positioned along the axis of the beam where both structures can be visualized as separate objects

Answer 16

Axial Resolution

Question 17

Rate of energy flow over the entire beam of sound

Answer 17

Power

Question 18

Unit used to quantitatively express the ratio of two amplitudes or intensities

Answer 18

Decible (db)

Question 19

1,000,000 Hz

Answer 19

Megahertz (MHz)

Question 20

Ability of the transducer to distinguish between two structures adjacent to one another

Answer 20

Resolution

Question 21

TIme interval required for generating the transmitted pulse

Answer 21

Pulse duration

Question 22

Sequence of events occurring at regular intervals

Answer 22

Cycle

Question 23

Speed of ultrasound wave; determined by tissue density

Answer 23

Velocity

Question 24

Minimum distance between two objects at which they still can be displayed as separate objects

Answer 24

Lateral resolution

Question 25

Unit for frequency; equal to 1 cycle per second

Answer 25

Hertz (Hz)

Question 26

Field closest to the transducer during formation of the sound beam

Answer 26

Fresnel zone

Question 27

Angle of incidence at which the sound beams strike the interface

Answer 27

Angle of reflection

Question 28

1000 Hz

Answer 28

Kilohertz (KHz)

Question 29

Field farthest from the transducer during formation of the sound beam

Answer 29

Fraunhofer zone

Question 30

Thickness of the secretion in a patient that contributes to echo signals on any one image

Answer 30

Slice thickness

Question 31

Sound transmitted and received intermittently with one transducer

Answer 31

Pulse wave (PW) Doppler

Question 32

Ability to compensate for attenuation of the transmittal beam as the sound wave travels through tissue in the body

Answer 32

Time gain compensation (TGC)

Question 33

Change in frequency of a reflected wave; caused by motion between the reflector and the transducer's beam

Answer 33

Doppler shift

Question 34

One transducer continuously transmits sound, and one continuously receives sound; used in high- velocity flow patterns

Answer 34

Continuous wave (CW) Doppler

Question 35

Normal pattern of vessel flow; flow in the center of the vessel is faster that it is at the edges

Answer 35

Laminar

Question 36

Rate at which images are updated on the display; dependent on transducer frequency and depth selection

Answer 36

Frame rate

Question 37

Analysis of the entire frequency spectrum

Answer 37

Spectral analysis

Question 38

Technical artifact that occurs when the frequency change is so great that it exceeds the sampling view and pulse repetition frequency

Answer 38

Aliasing

Question 39

In pulse-echo instruments, it is the number of pulses launched per second by the transducer

Answer 39

Pulse repetition frequency (PRF)

Question 40

Ability of the system to accurately depict motion

Answer 40

Temporal resolution

Question 41

Ratio of the largest to smallest signals that an instrument of a component of an instrument can respond to without distortion

Answer 41

Dynamic range

Question 42

In pulse Doppler, the Doppler signal must be sampled at least twice for each cycle in the wave if Doppler frequencies are to be detected accurately

Answer 42

Nyquist sampling limit

Question 43

Strength of ultrasound wave measured in decibels

Answer 43

Amplitude

Question 44

Measure of strength of the ultrasound signal

Answer 44

Gain

Question 45

Echo fil-in of the spectral window that is proportional to the severity of stenosis

Answer 45

Spectral broadening

Question 46

Ultrasound instrumentation that allows the image to be displayed many time per second to achieve a "real time" image of anatomic structures and ther motion pattern

Answer 46

Real time

Question 47

B-mode scanning technique that permits the brightness of the B-mode dots to be displayed in various shades of gray to represent different echo amplitudes

Answer 47

Gray scale

Question 48

Amount of change in the returning frequency compared with the transmitting frequency when the sound wave hits a moving target such as blood in an artery

Answer 48

Frequency shift

Question 49

Sample site from which the signal is obtained with pulsed Doppler

Answer 49

Gate

Question 50

Angle that the reflector path makes with the ultrasound beam; the most accurate velocity is recorded when the beam is parallel to flow

Answer 50

Doppler Angle