Kremkau Chapter 4 Key Terms

Question 1

compression

Answer 1

reduction in difference between small and large amplitudes. region of high density and pressure in a compressional wave.

Question 2

scan line

Answer 2

a line produced on a display that represents ultrasonic echoes returning from the body. a sonographic image is composed f many scan lines

Question 3

shear wave

Answer 3

transverse wave

Question 4

stress

Answer 4

a force per unit area applied to a material that compresses or stretches it

Question 5

postprocessing

Answer 5

image processing done after storage in the memory

Question 6

contrast resolution

Answer 6

ability of a gray scale display to distinguish between echoes of slightly different intensities.

Question 7

picture archiving and communications systems

Answer 7

the system provides means for electronically communicating images and associated information to work stations and devices external to the sonographic instrument, the examining room, and even the building in which the scanning is done. PACS

Question 8

bandpass filter

Answer 8

passes a range of frequencies (its bandwidth) and rejects those above and below the acceptance bandwidth.

Question 9

channel

Answer 9

a single 1 or 2 way path for transmitting electric signals, in distinction to other parallel paths; an independent transmission delay line and transducer element path

Question 10

analog to digital converter

Answer 10

a device that converts voltage amplitude to a number. ADC

Question 11

temporal resolution

Answer 11

ability to distinguish closely spaced events in time; improves with increased frame rate

Question 12

real time display

Answer 12

a display that, with a sufficient frame rate, appears to image moving structures or a changing scan plane continuously

Question 13

compensation

Answer 13

equalization of received echo amplitude differences caused by different attenuations for different reflector depths. aka TGC DGC

Question 14

persistence

Answer 14

averaging sequential planes together.

Question 15

detection

Answer 15

conversion of voltage pulses from radio frequency to video form.

Question 16

a mode

Answer 16

mode of operation in which the display presents echo amplitude versus depth

Question 17

elastography

Answer 17

imaging tissue stiffness by tracking movement under mechanical stress

Question 18

cine loop

Answer 18

sequential display of all the frames stored in memory at a controllable frame rate.

Question 19

refresh rate

Answer 19

the number of times each second that information is sent from the image memory to the display. the number of times per second that a computer monitor redraws the information found in the memory

Question 20

young’s modulus

Answer 20

a measure of the hardness of a material. it is the ratio of the applied stress to the resulting strain in a material subjected to the stress.

Question 21

amplifier

Answer 21

a device that accomplishes amplification

Question 22

analog

Answer 22

related to a procedure or system in which data are represented by proportional, continuously variable, physical quantities

Question 23

scanning

Answer 23

the sweeping of a sound beam through the anatomy to produce an image.

Question 24

signal

Answer 24

information bearing voltages in an electric circuit

Question 25

TGC

Answer 25

equalization of echo amplitude differences caused by different attenuations for different reflector depths.

Question 26

frame rate

Answer 26

number of frames of echo information stored each second

Question 27

signal processor

Answer 27

an electronic device that manipulates electric signals in preparation for appropriate presentation of information contained in them

Question 28

digital

Answer 28

related to a procedure or system in which data are represented by numeric digits

Question 29

freeze frame

Answer 29

constant display of one of the frames in memory

Question 30

frame

Answer 30

a single image produced by one complete scan of the sound beam

Question 31

lateral gain control

Answer 31

gain controls that enable different gain values to be applied laterally across an image to compensate for differing attenuation values in different anatomic regions

Question 32

bit

Answer 32

binary digit; one or zero

Question 33

gain

Answer 33

ratio (dB) of amplifier output to input electric power

Question 34

real time

Answer 34

imaging with a rapid frame sequence display

Question 35

dynamic range

Answer 35

ration (dB) of largest to smallest power that a system can handle; ratio of the largest to smallest intensity of echoes encountered

Question 36

panoramic imaging

Answer 36

the extension of the field of view beyond the normal limits of a transducer scan plane

Question 37

b mode

Answer 37

mode of operation in which the display presents a spot of appropriate brightness for each echo received by the transducer

Question 38

gray scale

Answer 38

range of brightness between white and black

Question 39

pixel

Answer 39

picture element; the unit into which imaging information is divided for storage and display in a digital instrument

Question 40

digital to analog converter

Answer 40

a device that converts a number to a proportional voltage amplitude. DAC

Question 41

strain

Answer 41

the increase or decrease of the length of a segment of a material, subjected to a stress, divided by its original length

Question 42

image memory

Answer 42

the part of the image processor where echo information is stored in image format

Question 43

preprocessing

Answer 43

signal and image processing accomplished before storage in the memory

Question 44

b scan

Answer 44

a b mode image that represents an anatomic cross section through the scanning plane.

Question 45

coded excitation

Answer 45

a sophisticated form of transmission in which the driving voltage pulses have intrapulse variations in amplitude, frequency, and or phase.

Question 46

bistable

Answer 46

having two possible states.

Question 47

display

Answer 47

a device that presents a visual image derived from voltages received from an image processor

Question 48

image processor

Answer 48

an electronic device that manipulates and prepares images for visual presentation

Question 49

depth gain compensation

Answer 49

same as compensation. aka DGC

Question 50

volume imaging

Answer 50

3D imaging

Question 51

flat panel display

Answer 51

a backlighted rectangular matrix of thousands of liquid crystal display elements.

Question 52

spatial compounding

Answer 52

averaging of frames that view the anatomy from different angles

Question 53

m mode

Answer 53

a b mode presentation of changing reflector position( motion) versus time

Question 54

demodulation

Answer 54

detection

Question 55

radio frequency

Answer 55

voltages representing echoes in cyclic form

Question 56

amplification

Answer 56

the process by which small voltages are increased to larger ones