# DMS-US Physics Chapters 1-3

## 127 terms

### Ultrasound System

The Electronic Device & Transducer

### System is changed by?

Selecting a different transducer

### What parameters of sound can't be adjusted w/o changing the system?

Frequency & Wavelength

### What 4 factors can be changed

PRP, Duty Factor, Listening Time, Amplitude

### What is a graph?

A diagram representing data and relationships between data

X-Axis

Y-Axis

### What is related?

Relationship between two items
i.e Transducer Frequency and Depth

Easily

### What is unrelated?

Absence of a relationship between two items.

### Why are Frequency and propagation speed unrelated?

Speed is controlled by the medium.
Frequency is controlled by crystal thickness.

### 2 factors that affect propagation speed

Density and Stiffness

High frequency

Low frequency

### Directly Related

When one item increases, the other also increases.

Directly Related

Directly Related

### Inversely Related

When one item increases, the other decreases

### Frequency and Wavelength

Inversely Related

### Frequency and Period

Inversely Related

### Reciprocal Relationship

Multiplying two items is equal to one
i.e 10 and 1/10 are reciprocals

T = 1/f

### Period and Frequency

Reciprocal Relationship

### Megahertz in Frequency compliments

Microseconds in Period

### Millimeters or Microseconds in Speed compliments

Megahertz in Frequency

### Frequency in Hertz compliments

Period in Seconds

MHz, mm, us

Hz, m, s

### If Period is in seconds

Frequency must be in cycles/sec or Hz

### If Wavelength is in mm and Propagation speed is in mm/us

Frequency will be in MHz

us

s

mm is distance
ml is volume

10mm

100cm

1,000,000s

Cycles/sec

1,000 KHz

.1us

10MHz

### 5 Characteristics of a Sound Wave

1.Mechanical Wave 2.Longitudinal Wave 3.Travels in a straight line 4.travels through a medium 5.Composed of Compression and Decompression

Creates movement

### Longitudinal Wave

Travels in a direction parallel to the direction of sound propagation.

### Sound Wave composition

Compression and Decompression

Rarefaction

### Compression

High pressure area in the medium

### Decompression

Low pressure area in the medium

### 2 Biological effects of Ultrasound

Mechanical and Thermal

### Acoustic Variables

Changes that propagating sound produces in the medium

### Sound Variables

Things that oscillate in a sound wave

### List the 4 Acoustic Variables

1.Pressure
2.Density
3.Temperature (Heat)
4.Distance (Motion)

### Pressure

The concentration of force
(force/area) Unit: lb/sq in or Pascal (Pa)

### Density

Concentration of mass
(Mass/Volume) Unit: Kg/cu.cm

### Temperature

Concentration of heat energy

### Distance

Measure of particle motion
Unit: cm or mm

### Acoustic Parameters

Factors used to describe the characteristic of a sound wave

### List the 7 Acoustic Parameters

1. Period
2. Frequency
3. Amplitude
4. Power
5. Intensity
6. Wavelength
7. Propagation Speed

### Transverse Waves

Particles move in a perpendicular direction of the sound propagation.

### Interference

Different waves lose their individual characteristics and combine to form a single wave

### Constructive Interference

Two in-phase waves combine to form a larger single wave.

### Destructive Interference

Two out-of-phase waves combine to form a smaller single wave.

### Parameter

Things that we use can use to classify sound

### Period

Time it takes to create one cycle or sound wave.
Units: s, ms, us

0.1 - 0.5us

Crystal. No

### Is Period determined by the medium?

No. By the Transducer

Directly Related

2-10MHz

### What does Frequency have an important effect on?

Depth and image quality (Resolution)

Less than 20Hz

20Hz-20,000Hz

### Ultrasound Range

Greater than 20,000Hz

2-13 MHz

### Therapeutic Range

0.5MHz-3MHz
With intensities 0.25W/sq.cm-2.5 W/sq.cm

### H.I.F.U

High Intensity Focused Ultrasound- destroys tumors using 0.5MHz-10MHz, with intensities as high as 1500w/sq.cm

f=1/T

### What is the relationship between Period and Frequency?

Reciprocal Inverse Relationship

### If the Period PF a wave is 1/8sec, what is the Frequency?

8 cycles/sec (c/s)

Frequency

Unchanged

### What 3 Parameters describe the strength of a sound wave?

Power, Intensity, Amplitude

### Amplitude (1)

Between the MAX value and the average or undisturbed value of an acoustic variable

### Amplitude (2)

Between the MIN value and the average or undisturbed value of an acoustic variable

Amplitude

### What units are used for Amplitude?

Pressure-Pascals (only if lbs/sq.in)
Density-g/cm3

### Amplitude Pressure Value Range

1-3 million Pascals

### How do you adjust Amplitude?

By changing the power

Sound Source

### Power

The rate of energy transfer
Units: Watts or Milliwatts (mw)

### Power Value Range

4-90 mw or .004-0.90 Watts

Sound Source

### Relationship between Amplitude and Power

Directly Proportional

### Power is Proportional to?

Amplitude squared

### If Amplitude is decreased to 1/2 of it's original value?

Power is decreased to 1/4 of it's original value

### Intensity

Concentration of energy in the sound beam
(Power/cm2)

0.01-300 W/sq.cm

The Sound Source

### Relationship between Power and Intensity

Directly Proportional

### If a wave's Power is doubled?

The Intensity is doubled (if the Area is not changed)

### Relationship between Intensity and Amplitude

Proportional to the wave's Amplitude squared

### Wavelength

The length of one complete cycle
Units: mm, m

0.15-0.8mm

### The only Parameter Determined by?

Sound Source and Medium

### Calculate the Wavelength for a 2MHz Transducer

1540m/s divided by 2,000,000s=.00077m

### Relationship between Wavelength and Frequency

Inversely Related

### If Frequency is Doubled?

Wavelength is halved

### Shorter Wavelength sound produces?

A higher quality image w/ greater details

### Propagation Speed

Distance Sound Wave travels through a Medium
Units: mm/us, km/s, m/s

### Propagation Speed Value Range

1.54mm/us or 1540m/s

The Medium

### Propagation Speed Formula

c(m/s) = f(Hz) x wavelength(m)

### Factors that effect Propagation Speed

Stiffness and Density

### Stiffness

Ability to resist pressure, and Directly Proportional to Speed

### Density

mass/volume, and Inversely Proportional to Speed

### 5 Propagation Speeds

Bone; 3,500m/s
Soft Tissue; 1,540m/s
Blood and Liver; 1,560m/s
Water; 1,480m/s
Air; 330m/s

### Can adult Lungs be scanned?

No. Only Fetal Lungs, because the are filled with blood

### What 3 Parameters describe the strength or magnitude of sound?

Power, Intensity, Amplitude

Wavelength

Speed

### What 2 Parameters are reciprocals?

Period and Frequency

1.54mm

### What 2 Parameters can be measured using the same parts of a sound wave?

Wavelength and Period

### What is the difference between Speed and Velocity?

Velocity has a vector

Solid

Gas

Liquid