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Flashcards in Physics reverse Deck (70):
1

Amplitude Modulation

Distance between transducer and structure determines where an echo is seen along hte time axis

1 dimensional image

Not used anymore

A-Mode

2

device in which data are represented by variable, measurable, physical quantities. Length, width, voltage or pressure

Analog Scan Converter

3

2D presentation of echo producing interfaces.

A mode signal converted to dots which vary in brightness depending on echo strength

Brightness Modulation

B-Mode

4

formation of cavities in a body tissue or an organ resulting from the sudden formation and collapse of low pressure bubbles by means of mechanical forces

Cavitation

5

image processing device that uses a stable electronic circuit to store and manipulate ultrasonic images in memory. The device then reconstructs and displays these images simultaneously to create one image

Digital Scan Converter

6

change in observed frequency of a wave. Freq increases as source and observer get closer, decreases as they move apart

Doppler effect

7

series of shades from black to white the more shades the more realistically an image can be recorded and displayed

Gray Scale Imaging

8

series of B-Mode dots are displayed on moving time base graph to show moving structures

basis of echocariography prior to real time scanning

used in conjunction with real time imaging in adult, pediatric and fetal echo

M-Mode

9

Mechanical deformation occurs when an electrical field is applied to a crystal the crystal vibrates mechanically. When a crystal vibrates mechanically it creates an electrical field

Piezoelectric Effect

10

waves sent from many directions to the returns are used to build a volume image in 3 dimensions

3-D imaging

11

3-d imaging with the addition of real time

4-D Imaging

12

sound with freq above the limits of human hearing greater than 20kHz

Ultrasound

13

Waves that move in an up and down motoin

Transverse Waves

14

Waves that move in a line

Longitudinal Waves

15

area of wave that gets closer together

Compression

16

area of wave that spreads apart

Rarefaction

17

material through which a wave is transmitted

Medium

18

period

frequency

amplitude

power

intensity

wavelength

propagation

Accoustic parameters

19

time

Period of wave

20

1/time

frequency of wave

21

"Bigness" of wave

dofference between peak and avg value of the wave

amplitude of wave

22

force

rate of energy transfer or rate which work is preformed

power

23

concentration of strength of a wave

Intensity = watts/cm^2

intensity

24

distance from one peak to the next

wavelength

25

speed wave travels through medium (avg 1540 soft tissue)

propagation speed

26

measurement of frequency

Hertz

27

sound below the human hearing level

Infrasound

28

20-20kHz

Audible sound

29

2mHz-12mHz

DMS frequency

30

any damage to tissue

ALARA as low as reasonably achievable

Bio effects

31

30MHz-40MHz

asses vessel walls characterize plaque morphology

transducer contained in a sheath attached to catheter

no air means high preq usable

Intravascular Ultrasound

32

.5MHz-3MHz

beam intensity result in tissue temperature increases

4°C as deep as 5cm

increases blood flow

treats muscle spasms, tendonitis and bursitis

joint swelling

Therapeutic Ultrasound

33

used for selective destruction of tissue volumes

cancerous lesions  in liver, kidney, breast and prostate

focusing the beam allows energy concentration on affected area while sparing surround tissue

High Intensity Focused Ultrasound

HIFU

34

Worse in Gas

better in liquid

best in solids

Wave Propagation

35

sound traveling pressure variation

regions of compression and rarefraction

particles vibrate back and forth

parallel to the directoin of travel

 

Sound wave propagation

36

needs physical interaction

must have medium

longitudinal 

transverse

Mechanical Wave

37

travel in medium or vacuum

light, heat, X-rays, gamma rays TV rays

transer of energy through a varying electrical and magnetic field

Electromagnetic Waves

38

Pressure

Density

Temperature

particle motion

Acoustic variables

39

concentration of force

Pascals

varies cyclically as sound wave propagates

Pressure

40

p=mass/volume

compression increases

rarefraction decreases

non linear imaging Harmonic Imaging

units kg/m3

Density

41

any mechanical movement produces heat

sound wave vibrate the tissue and some wave energy is lost to heat with tissue

important in Bioeffects

Celcius

Kelvin

Fahrenheit

Temperature

42

particels of tissue being imparted with momentum and traveling into the locale of the nearest neighbors

osscillate back and forth about their original location allowing energy to propagate along the wave p[ath

particles DO NOT travel with the wave

 

Particel Motion

43

As Low As Resonably Achievable

short scan time

low power settings

short use of color and spectral

ALARA

44

decrease in wave amplitude due to mechanical wave interaction wiht mnedium

units dB

absorption

reflection

refraction

Attenuation

45

conversion of energy from wave to heat within medium

as Freq increases amount of energy lost increases

 

Absorption

46

sound wave changes direction and does not continue to travel forward

returns to source

foundtation for diagnostic ultrasound

Ultrasound based on processing these refelctions

Reflection

47

bending of wave

change in propagation velocity when angle of incidence is other than 0

Refraction

48

without echoes

cysts

fluid filled organs

Anechoic

49

low level reflected signals

Hypoechoic

50

highly echogenic tissues

moderate to high reflected signals

Hyperechoic

51

strongly echoic

usually with acoustic shadows

calcified echoes

52

mixed echogenicity

with or without shadowing

 

Complex

53

Device that converts energy from one form to another

 

Transducers

54

Crystal

matching layers

Damping material

Transducer case

electronic cable

Transducer components

55

diameter determines beam shape

like beam of flashlight

shape is region in the patient which sound travels

Crystal

56

provide an acoustic connection between crystals and skin

reduces amount of reflection from large acoustic mismatch

allows wave to travel into the body

gel

matching layers

57

decrease secondary reverberations of crystal with returning signals

reduces the ring time and results in an increase in depth resolution (axial)

Damping material

58

provides housing for all internal components

Trasducer Case

59

caontains bundle wires to cary electrical signals to and from the crytals

Electronic cable

60

uses series of B-mode images to biuld a 2 d image of tissue

transducer attached to articulated arm to provide system with position and orientation

no longer used due to numerous drawbacks

B-scan (Static scan)

 

61

provides cinematic view of the area being evaluated by displaying a rapid series of images sequentially

Real Time B-Mode

62

all modern systems use real time approach

signals integrated into a scan converter for 2d image display

Real time movie

 

Real Time Imaging

63

Hz

images per second

2 factors Sound speed in medium

depth of imaging

higher frame rate better temporal resolution and image quality

Frame Rate

64

ability to precisely position a moving structure

important in adult and fetal echo

high rate yields better movies but worse photographs

Temporal resolution

65

shallow depth incrases frame rate and resolution

deeper decreases frame rate and degrades resolution

depth and frame rate inversely related

operator controlled 

imaging depth

66

Single Focus

Multi Focus

Focus

67

only 1 sound pulse is transmitted down the scan line

high frame rate 

superior resolution

inferior lateral resolution

Single Focus

68

Adj number of focus Pulses

longer time 

decreases frame rate

inferior temporal resolution

superior lateral resolution

Multi Focus

69

ability to distinguish between structures that are side by side

lateral resolution

70

operator controlled

size increases number of pulses increases

 

sector size

field of view