Flashcards in Lesson 7 Deck (26)

Loading flashcards...

1

## What 3 things make up attenuation?

###
1. Absorption

2. Reflection

3. Scattering

2

## Attenuation

### Weakening of sound

3

## What is the result of weaker signals?

### Weaker echoes

4

## What structures produce weaker signals?

### Structures that are farther away

5

## Where is the near field?

### Closest are to the transducer

6

## Where is the mid field?

### Between the near field and the far field

7

## Where is the far field?

### Farthest area to the transducer

8

## What happens to sound as it goes through a medium?

###
It gets weaker

- has to go through and come back

9

## What do we use that can fix attenuation?

### TGC

10

## What does TGC stand for?

### Time gain compensation

11

## Whats another word for TGC?

### DGC

12

## What does DGC stand for?

### Depth gain compensation

13

## What does the TGC slope provide?

### Amplification of specific field echoes

14

## What does TGC do?

###
It amplifies the far field to promote uniform in tissues

- eg) liver

15

## What does it mean when your TGC is straight on the ultrasound machine?

### You are getting equal amounts of amplification

16

## What does it mean when your TGC is on a diagonal on the machine?

###
You get amplification in different spots

- leads to a more uniform image

17

## What is the formula for attenuation in soft tissues?

###
a = 1/2f x L

a = attenuation

f = frequency

L = length/distance/thickness

18

## How does attenuation occur in soft tissues?

###
0.5 there and 0.5 back = 1

- dB/cm x MHz

- compensates for both directions

19

## What 2 things does overall gain do?

###
1. Amplification of entire field of view

2. Amplification of all incoming echo voltages

20

## What is attenuation's unit?

###
Decible

- dB

21

## How much is 3db? (2)

###
1. 1/2x

2. 2x

22

## How much is 10dB? (2)

###
1. 1/10x

2. 10x

23

## Define decible

### The ratio between 2 intensities

24

## What is the formula for attenuation in normal tissue?

###
a = ac x L

a = attenuation

ac = attenuation coefficient

L = length/distance

25

## What is the formula for attenuation coefficient?

###
ac = 1/2f

ac = attenuation coefficient

f = frequency

26