Flashcards in Ch 1-4 8 Deck (56):

0

## When one value increases, and so does the other value, the two values are said to be ___________.

### Directly Proportional

1

## The molecules vibrate in the same direction as the sound travels. I.e, sound waves.

### Longitudinal Wave

2

## The molecules vibrate at 90 degrees to the direction of energy travel. i.e. Water ripples

### Transverse Wave

3

##
concentration of force

units: lb/sq inch, Pascals Pa

### Pressure

4

##
concentration of mass or weight

units: kg/cubic cm

### Density

5

##
measure of particle motion

units: cm, feet, miles

### Distance

6

## The distance of one wave cycle.

### Wavelength

7

##
•The length of time it takes to complete one single cycle of sound or to one complete single wavelength.

Units: seconds, msec, hours – all units of time

=1/frequency

### Period

8

##
The # of wave cycles per second.

1 cycle per second = 1 hertz Hz

### Frequency

9

## The speed at which wave cycles travel.

### Propagation Speed

10

##
(Sin Angle of Incidence)/(Sin Angle of Refraction)= c1/c2

Where c1 & c2 are the speeds of sound in the two mediums

### Snell's Law

11

##
Z=P/V

Where P = excess pressure and

V=the particle velocity. OR

Z=P x c

Where c=speed of light

### Acoustic Impedance

12

##
The dominant factor in attenuation (80%).

-conversion of sound to heat

### Absorption

13

##
Occurs at a boundary between 2 different media with different impedances.

-the sound bounces back (toward transducer)

### Reflection

14

## z=P x V , measured in Rayls. (z=Density x Prop Speed)

### Impedance

15

## Smooth surface that causes sound to bounce back toward the transducer.

### Specular Reflector

16

## Scatter returning in the same general direction as the transducer.

### BackScatter

17

## Interface has irregularities one wavelength or smaller.

### Non-specular scattering.

18

## Sound scatters symmetrically in all directions. Not related to incidence angle. Increase frequency, and increase this.

### Rayleigh scattering.

19

## %R=Reflected Intesity/Incidence Intensity=((z2-z1)/(z2+z1))^2

### Intensity Reflection Coefficient

20

## 90 degrees. (Porn)

### Normal Incidence

21

## not 90 degrees

### Oblique Incidence

22

## a bending from a straight line or path or a change in direction of a wave travelling from one medium to another. Must have two things: an Oblique Incidence, and2 media with different propagation speeds. Related to the change in acoustic velocity. (If medium 2 is faster, then it will increase the transmit angle.

### Refraction

23

## Sin (angle of transmit)/ sin (angle of incidence)=prop speed 2/prop speed 1

### Snell's Law

24

## "bulk modulus." The extent to which a material cannot be compressed. To increase this will increase propagation speed.

### Stiffness

25

## aka Harmonics

### Non-linear Propagation

26

## Pulse, then listen for echo

### Puled Ultrasound

27

## Time from the start of one pulse to the end of the same pulse. THis can only be changed by changing the transducer.

### Pulse Duration

28

## % of the time that the system is transmitting a pulse and not "listening." Determined by the sound source.

### Duty Factor

29

## # of pulses that occur in a single second(Hz/sec). Determined by the sound source.

### Pulse Repetition Frequency (PRF)

30

##
Time from the start of a pulse to the start of the next pulse (includes "listening time").

Determined by the sound source. CAN be changed by the sonographer by changing the listening time.

= 1/PRF

### Pulse Repetition Period (PRP)

31

##
The distance a pullse occupies in space. # of cycles in a pulse x wavelength. Determined by the sound source and the medium. Cannot be changed by the sonographer.

Increase freq, Increase this

### Spatial Pulse Length

32

## Weakening of a sound wave as it travels through media. Decrease in amplitude and decrease in intensity. Increase frequency and increase this

### Attenuation

33

##
+3 Db doubles the sound

+10 dB ten times the sound

### Decibels

34

## # value that expresses how different materials attenuate the sound beam per unit length (dB/cm). The average attenuation coefficient in soft tissue is 1/2 the transducer frequency.

### Attenuation Coefficient

35

## The distance the sound beam travls when its intensity is reduced to 1/2 its original value.

### Half-Value Layer

36

## The fraction of the original intensity after attenuation.

### Intensity Ratio

37

## a peak aligns with a peak; increase in amplitude

### Constructive Interference

38

## a peak aligns with a trough; decrease in amplitude

### Destructive Interference

39

##
Distance to Boundary = (go-return time x speed)/2

d=ct/2

### Range Equation

40

## Every 13 microseconds of go-return time means the reflector is 1 cm deeper in the body

### 13 microsecond rule

41

## when wave peaks and troughs continue to line up.

### In-Phase Wave

42

## When troughs from one wave continually line up with the peaks from another wave.

### Out-of-Phase Wave

43

## The strength of the sound beam, maximum variation from the baseline (dB)

### Amplitude

44

##
The rate that work is performed, rate of energy transfer in the entire beam. Measured in watts.

P=I x CS

P is proportional to Amplitude squared

### Power

45

##
Concentration of energy in certain areas of the sound beam

I=P/CS (watts/cm^2)

### Intensity

46

## The highest intensity area or time of the sound beam

### Peak

47

## (Peak + low + medium)/3

### Average Intensity

48

## Greatest at the center and in focal zone of the sound beam

### Spatial Intensities

49

## Occurs with Time

### Temporal non-uniformity

50

## Is greatest at the center of the beam

### Spatial non-uniformity

51

## Related or proportional

### Related, Proportional, Directly Proportional

52

## As one value increases, the other value decreases.

### Inversely proportional.

53

## The effects that are made on the human body

### Biological Effects

54

## The thing that is creating the sound wave

### Source

55