Spi Interaction Of Sound And Media

Front 1

Attenuation

Back 1

The decrease in intensity, power and amplitude of a sound wave as it travels. This is unrelated to speed.

dB, decibels♥️(must be negative, since the attenuation causes intensity to decrease)

Hint 1

dB can only be added or subtracted

Front 2

Total attenuation increases with

Back 2

Higher frequency

Or

Longer path length

Front 3

Soft tissue/blood interaction

Back 3

Lower frequency results in less attenuation and further penetration of low frequency sound♥️

Attenuation is unrelated to propagation♥️

Front 4

Components of attenuation

Back 4

Absorption (primary, sound converted into heat)

Scattering

Reflection

Front 5

Attenuation in air

Back 5

Much, much more attenuation than in soft tissue. Gel is used to remove air from the path of ultrasound♥️

Front 6

Attenuation in lung & bone

Back 6

More then soft tissue, bone absorbs and reflects. Lung scatters♥️

Front 7

Attenuation in water

Back 7

Much, much less than soft tissue♥️

Front 8

Reflection

Back 8

Occurs when propagating sound Energy strikes a boundary between two media and some returns to the transducer♥️

Front 9

Reflection

Back 9

Occurs when propagating sound Energy strikes a boundary between two media and some returns to the transducer♥️

Front 10

Specular reflection

Back 10

Reflections from a smooth reflector(mirror) are specular and return in one direction♥️

Also occur when the Wavelength is much smaller than the irregularities in the boundary ♥️

Front 11

Diffuse reflection or backscatter

Back 11

When a boundary is rough, reflected sound is disorganized and random

Front 12

Diffuse reflection or backscatter

Back 12

When a boundary is rough, reflected sound is disorganized and random

Front 13

Scattering

Back 13

If the boundary between two media has irregularities (with a size similar to what bit smaller than the pulses Wavelength), then the wave may be chaotically redirected and all directions.

Front 14

Rayleigh Scattering ♥️

Back 14

A reflector is much smaller than the wavelength of sound.

Is related to frequency(4) ♥️

Hint 14

The red blood cell is Rayleigh scattering♥️

Front 15

Attenuation and imaging depth♥️

Back 15

Attenuation ultimately limits the maximum that from which meaningful reflections are obtained

Front 16

Attenuation coefficient

Back 16

The amount of attenuation per centimeter. A way to report attenuation without dealing with distance

dB/cm♥️ decibels per centimeter

Related to frequency

Hint 16

In soft tissue, attenuation coefficient (dB/cm) is approximately one half of the frequency(MHz)

A mathematical expression that means half of the transducer frequency: 0.5dB/cm/MHz

Front 17

Impedance

Back 17

A number associated with a medium.

It's calculated not measured♥️

Rayls (z)

Front 18

Example of impedance♥️

Back 18

Two media, A & B, have the same propagation speed. Medium A's density is 10% higher than medium B's. Therefore, medium A's impedance is 10% higher than medium B's.

Front 19

Incidence

Back 19

Normal

Oblique

Front 20

Incidence

Back 20

Normal

Oblique

Front 21

Normal incidence

Back 21

5 names

Normal

Perpendicular

Orthogonal

Right angle

Ninety degrees

Hint 21

PORNN

Front 22

Oblique incidence

Back 22

Anything other than 90

♥️not right angel

Acute less than 90

Obtuse more than 90