Physics Before Final

Front 1

Milliseconds
1 ms = microsec

Back 1

Msec 10^-3

1 millisec = 1000 microseconds

Front 2

Microsecond

Back 2

Microsec = 10^6
1 microsec = .001 millisec

Front 3

1 cm = mm

Back 3

1 cm = 10 mm

Front 4

1 mm = cm

Back 4

1 millimeter = 0.1 centimeter

Front 5

Average value and unit for soft tissue regarding ultrasound parameter for Frequency

Back 5

3.5 Mhz

Front 6

Average value and unit for soft tissue regarding ultrasound parameter for period

Back 6

0.3 microsecond

Front 7

Average value and unit for soft tissue regarding ultrasound parameter for wavelength

Back 7

0.4 mm

Front 8

Average value and unit for soft tissue regarding ultrasound parameter for impedance

Back 8

1,630,000 rayl

Front 9

Average value and unit for soft tissue regarding ultrasound parameter for period

Back 9

0.3 microsecond

Front 10

Average value and unit for soft tissue regarding ultrasound parameter for propagation velocity

Back 10

1.54 mm/microsecond

Front 11

Average value and unit for soft tissue regarding ultrasound parameter for cycle per pulse

Back 11

3 cycles/pulse

Front 12

Average value and unit for soft tissue regarding ultrasound parameter for pulse repetition period

Back 12

1 millisecond

Front 13

Average value and unit for soft tissue regarding ultrasound parameter for pulse duration

Back 13

1 microsecond

Front 14

Average value and unit for soft tissue regarding ultrasound parameter for cycle per pulse

Back 14

3 cycles/pulse

Front 15

Average value and unit for soft tissue regarding ultrasound parameter for pulse repetition frequency

Back 15

1 kHz

Front 16

Average value and unit for soft tissue regarding ultrasound parameter for duty factor

Back 16

0.001(no unit) for PW
CW = 1

Front 17

Average value and unit for soft tissue regarding ultrasound parameter for cycle per pulse

Back 17

3 cycles/pulse

Front 18

Average value and unit for soft tissue regarding ultrasound parameter for pulse repetition frequency

Back 18

1 kHz

Front 19

Average value and unit for soft tissue regarding ultrasound parameter for duty factor

Back 19

0.001(no unit) for PW
CW = 1

Front 20

Average value and unit for soft tissue regarding ultrasound parameter for spatial pulse length

Back 20

1 mm

Front 21

Duty factor for CW

Back 21

DF for CW = 1

Front 22

Duty factor for PW

Back 22

DF for PW = less than 1

Front 23

Interference for a wave

Back 23

Waves from different point play major role in shaping the resultant beam. Motion of media particles are a composite of the wave interaction

Front 24

Diffusion

Back 24

Geometric dispersal of energy due to divergence of sound beam as it travels.
The area increases therefore intensity decreases because it's spread over a greater area

Front 25

Absorption

Back 25

Converting mechanical energy into heat energy.
Created by friction of particle and random motion.

Front 26

2 important things about absorption

Back 26

1. Absorption is the dominant form of attenuation in soft tissue

2. Absorption increases exponentially with increasing frequency

Front 27

Refraction

Back 27

The redirection of the transmitted sound beam which may occur when the beam crosses an interface

Front 28

Refraction is also called

Back 28

Bending

Front 29

Refraction occurring depends on 2 things

Back 29

1. If the angle of incidence is other than perpendicular

2. If there is a change in propagation speeds at the boundary

Front 30

Reflection

Back 30

Beam is redirected back toward the sound source.
Will vary depending on the surface of the reflecting surface

Front 31

Scattering

Back 31

Occurs when the surface is rough or equal to or smaller than the beam width (or 1 wavelength)

Front 32

Specular reflection

Back 32

Are mirror like reflections which occur from structure which are large, smooth, and flat relative to the wavelength.
Highly angularly dependent.
Strongest form of reflection

Front 33

Normal incidence (in speculation reflection)

Back 33

90 degrees allow for maximum detection of the reflected angle

Reflection is also angle dependent

Front 34

Oblique incidence (in specular reflection)

Back 34

Reflection doesn't travel back to the tx

The angle of reflection equals the angle of incidence

Front 35

Attenuation formula

Back 35

Total attenuation (dB) - attention coefficient (dB/cm-MHz) x depth (cm) x frequency (MHz)

Front 36

Order low to high for attenuation (dB/cm-MHz)

Back 36

Low to high
Water < fat < soft tissue < bone < air

Front 37

Low to high for speed of sound (m/sec)

Back 37

Low to high
Air < fat < water < soft tissue < bone

Front 38

Low to high for speed of sound (m/sec)

Back 38

Low to high
Air < fat < water < soft tissue < bone

Front 39

Low to high for acoustic impedance (rayls)

Back 39

Low to high
Air < fat < water < soft tissue < bone

Front 40

Soft tissue in attenuation

Back 40

1 dB/cm-Mhz

Range- .5-.9 dB/cm-Mhz

Front 41

Soft tissue in attenuation

Back 41

1 dB/cm-Mhz

Range- .5-.9 dB/cm-Mhz

Front 42

Soft tissue in acoustic impedance

Back 42

1.63 x 10^6 rayls

1.63 x M rayls

Front 43

Soft tissue in speed of sound

Back 43

1540 m/sec or 1.540 mm/microsec

Front 44

Specular reflectors

Back 44

Soft tissue-lung
Soft tissue bone
Diaphragm
Pericardium
Bladder wall
Vessels
Muscles
Baby head

Front 45

Specular reflectors

Back 45

Soft tissue-lung
Soft tissue bone
Diaphragm
Pericardium
Bladder wall
Vessels
Muscles
Baby head

Front 46

Scatterers

Back 46

Fat-liver
Soft tissue-fat
Soft tissue-muscle
Castor oil soft tissue
Liver cells
Myocardium

Front 47

Snell's law

Back 47

The amount of bending or deflection is related to the velocity change
CI/ct - incident velocity/transmitted velocity = incident angle/transmitted angle

V1 > V2 = fast to slow
Angle 1 > angle 2
Fast to slow= angle reduced
If V1 < V2 then slow to fast
Angle 1 < angle 2 Slow to fast = angle enlarged

Front 48

Pulse cycle

Back 48

Non repeated event

Front 49

Things that effect velocity of a sound wave with respect to location and time are-

Back 49

Pressure
Particle density
Temperature
Particle motion (distance)

Front 50

Huygen's principle

Back 50

All points on a wave can be considered a small seperate individual point source for the production of 3d spherical waves.
Different shape to 3d wavefront.
Get wavelets and planar (lines)

Front 51

Acoustic impedance

Back 51

Z value or rayls
Low to high
Measurement of resistance of a medium to sound passing through it
Determines how easy mechanic waves can be formed in or travel through a medium
It affects the strength and the amplitude of the reflected echoes
Used to calculate the % of sound reflected at an interface

Front 52

Duty factor

Back 52

A ratio that represents the fraction of time the tx actively transmits sound.
Used in calculated values to bio effects
Unit less
% of time the system is transmitting (putting energy or doing work on the body)

Front 53

Pulse duration

Back 53

In microseconds
The time for which the pulse lasts
Pd= T x Nc

Front 54

Pulse repetition frequency

Back 54

# of pulses per second a measure over time
Measure in kHz
Determined by source

Front 55

Pulse repetition period

Back 55

Time from beginning of one pulse to beginning of next pulse. Made up PD and PLT.
Determined by sound source and not medium

Front 56

Attenuation is dependent on

Back 56

Depth of penetration

Front 57

Subdivisions of attenuation

Back 57

Interference
Diffusion
Absorption
Reflection
Refraction

Front 58

Subdivisions of attenuation

Back 58

Interference
Diffusion
Absorption
Reflection
Refraction

Front 59

Attenuation is

Back 59

A non-linear process

Front 60

Attenuation unit

Back 60

dB

Front 61

Attenuation unit

Back 61

dB

Front 62

Attenuation is dependent on

Back 62

Depth of penetration
Frequency of beam
Attenuation coefficient

Front 63

Intensity

Back 63

The distribution of power over area

Front 64

Rayl

Back 64

Measures acoustic impedance
Kg/m^2/s

Front 65

Rayleigh

Back 65

Scattering occurs when the reflecting structures are very small in comparison to the wavelength.
Highly frequency dependent.
As frequency increases, the wavelength decreases making the rbc look larger thereby increasing amount of scattering

Front 66

Infrasound
Audible
Ultrasound

Back 66

I- less than 20hz
A- 20-20,000 hx
U - more than 20,000hz

Front 67

Period and frequency

Back 67

Inversely proportional

Front 68

Period and frequency

Back 68

Inversely proportional

Front 69

Frequency

Back 69

# of oscillations per second
In hertz

Hertz is 1/sec

Front 70

If amplitude is ____ power is _____

Back 70

A doubled, p quadruple

Front 71

Power

Back 71

Measure of how much work or energy is expended per time

In watts

Front 72

Phase

Back 72

Used to compare two waves. The part of the cycle that a wave of signal waveform happens to be in at that point considered. A method of timing events within a single cycle. Terms used are circles and pi radians

Front 73

Wavefront

Back 73

The beam is a result of combining wavelets emanating from the small sources

Front 74

Decibel

Back 74

Measures sound intensity
Ratio or comparison
Used for non-linear relationships
Ultrasound intensities change by -3dB it corresponds to reducing the intensity by half or 50% (hvl)