Introduction to Ultrasound Physics

Question 1

Infrasound

Answer 1

Below 20Hz

Question 2

Audible Range

Answer 2

20Hz - 20,000Hz

Question 3

Ultrasound

Answer 3

Over 20,000Hz

Question 4

Medical Applications of Ultrasound (7)

Answer 4

1. M-mode
2. Two-Dimensional (2D)
3. Doppler (Conventional & Color Flow)
4. Stress/Dobutamine Echocardiography
5. Transesophageal (TEE) (Intraoperative)
6. Intracoronary Ultrasound
7. 3-D

Question 5

Wave

Answer 5

Is a propagating (traveling) variation in quantities – wave variables.

Question 6

Ultrasound Waves

Answer 6

Are mechanical vibrations which induce alternate refractions & compressions of any physical medium through which they pass

Question 7

Sound Waves

Answer 7

A mechanical, longitudinal wave that travels in a straight line

Question 8

Acoustic Variables (4)

Answer 8

1. Pressure – concentration of force (lb/square inch)
2. Density- concentration of mass or weight (kg/cubic cm)
3. Temperature- concentration of heat energy (degrees)
4. Particle motion (distance – cm)

Question 9

Particle Motion

Answer 9

-Particle is a small portion of the medium through which sound travels
-Particles oscillate back & forth as a sound wave travels
-At any point in the medium→pressure, density and temperature increase & decrease in repetitive cycles as the wave travels

Question 10

Rarefactions

Answer 10

Regions of low pressure & density

Question 11

Compressions

Answer 11

Regions of high pressure & density

Question 12

Parameters of Sound Waves (7)

Answer 12

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

Question 13

Speed of Sound through Soft Tissue (4)

Answer 13

1,540 m/s
1.54 mm/µs
1.54 km/s
1 mile/second

Question 14

Period

Answer 14

The time it takes for one cycle to occur

Question 15

Period Units

Answer 15

Microseconds, one-millionth of a second

Question 16

Frequency

Answer 16

The number of cycles per second

Question 17

Frequency Units

Answer 17

Hertz (Hz), Kilohertz (kHz), Megahertz (MHz)

Question 18

Amplitude

Answer 18

Size of the sound wave ;the difference between the maximum or minimum value and the average value of an acoustic variable

Question 19

Amplitude Units

Answer 19

Appropriate for the acoustic variable e.g Pascals (Pa) for pressure amplitude.