Intro Quiz 1 Physics Flashcards Preview

DMSO > Intro Quiz 1 Physics > Flashcards

Flashcards in Intro Quiz 1 Physics Deck (140)
Loading flashcards...
31

Intravascular Ultrasound

30MHz-40MHz

asses vessel walls characterize plaque morphology

transducer contained in a sheath attached to catheter

no air means high preq usable

32

Therapeutic Ultrasound

.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

33

High Intensity Focused Ultrasound

HIFU

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

34

Wave Propagation

Worse in Gas

better in liquid

best in solids

35

Sound wave propagation

sound traveling pressure variation

regions of compression and rarefraction

particles vibrate back and forth

parallel to the directoin of travel

 

36

Mechanical Wave

needs physical interaction

must have medium

longitudinal 

transverse

37

Electromagnetic Waves

travel in medium or vacuum

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

transer of energy through a varying electrical and magnetic field

38

Acoustic variables

Pressure

Density

Temperature

particle motion

39

Pressure

concentration of force

Pascals

varies cyclically as sound wave propagates

40

Density

p=mass/volume

compression increases

rarefraction decreases

non linear imaging Harmonic Imaging

units kg/m3

41

Temperature

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

42

Particel Motion

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

 

43

ALARA

As Low As Resonably Achievable

short scan time

low power settings

short use of color and spectral

44

Attenuation

decrease in wave amplitude due to mechanical wave interaction wiht mnedium

units dB

absorption

reflection

refraction

45

Absorption

conversion of energy from wave to heat within medium

as Freq increases amount of energy lost increases

 

46

Reflection

sound wave changes direction and does not continue to travel forward

returns to source

foundtation for diagnostic ultrasound

Ultrasound based on processing these refelctions

47

Refraction

bending of wave

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

48

Anechoic

without echoes

cysts

fluid filled organs

49

Hypoechoic

low level reflected signals

50

Hyperechoic

highly echogenic tissues

moderate to high reflected signals

51

calcified echoes

strongly echoic

usually with acoustic shadows

52

Complex

mixed echogenicity

with or without shadowing

 

53

Transducers

Device that converts energy from one form to another

 

54

Transducer components

Crystal

matching layers

Damping material

Transducer case

electronic cable

55

Crystal

diameter determines beam shape

like beam of flashlight

shape is region in the patient which sound travels

56

matching layers

provide an acoustic connection between crystals and skin

reduces amount of reflection from large acoustic mismatch

allows wave to travel into the body

gel

57

Damping material

decrease secondary reverberations of crystal with returning signals

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

58

Trasducer Case

provides housing for all internal components

59

Electronic cable

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

60

B-scan (Static scan)

 

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