instruments

Question 1

a returning echo is what kind of wave?

Answer 1

mechanical wave

• at the transducer, it is converted to an electrical wave

Question 2

power ratio =??

Answer 2

gain (dB)

Question 3

gain=?

Answer 3

output power/ input power

Question 4

input electrical power is 20 W;
output electrical power is 200 W

What is the power ratio?

Answer 4

10x

Question 5

what is amplification the opposite of?

Answer 5

attenuation

Question 6

If you can calculate voltage ratio, you can find out power ratio. What is the ratio?

Answer 6

(VOLTAGE ratio)2 = (POWER ratio)

Question 7

Amplifiers allow for? (2)

Answer 7

• amplification (gain)

- compensation (TGC/LGC)

Question 8

TGC= ?

Answer 8

time gain compensation

aka depth gain compensation

Question 9

TGC ‘slope’ = ?

Answer 9

1 dB/cm∙MHz

Question 10

aplification max?

Answer 10

100 dB

Question 11

Lateral gain compensation is used for?

Answer 11

For adjacent structures that have different attenuation

Question 12

Drawback to amplification?

Answer 12

• amplifies noise

Question 13

Summer function?

Answer 13

• Signals added together as a ‘scan line’
• Also involved in reception apodization
• reducing the returning voltages on the peripheral of the transducer

Question 14

If gain is 30 dB and output power is reduced by one half, the new gain is __________ dB.

Answer 14

27

Question 15

reception channel of beam former function?

Answer 15

amplifies and combines the echo voltages from individual elements and sends them to signal processor

Question 16

signal processor functions (3)

Answer 16

• filtering
• detection
• compression

Question 17

pulsed wave ultrasound produces a ________ of transmitted frequencies?

Answer 17

bandwidth

Question 18

rage of frequencies contained in a pulse?

Answer 18

bandwidth

Question 19

signal processor- filtering?

Answer 19

• passes range of frequencies

- rejects those above and below the bandwidth

Question 20

filtering is done with?

Answer 20

bandpass filters

Question 21

filtering is done with?

Answer 21

bandpass filters

Question 22

modification of the sinusoidal waveform as it propagates through the tissue is known as?

Answer 22

harmonics

Question 23

filters in signal processor perform what function?

Answer 23

harmonics function

Question 24

at the signal processor what is filtered out?

Answer 24

fundamental frequency

• happens when we press THI

Question 25

benifits of harmonics?

Answer 25

- side lobes/grating lobes are eliminated - reduction of anterior reverberation - generated further into tissue- less chance for reverb - better detail resolution (lateral and elevational)

Question 26

anterior reverberation aka?

Answer 26

main bang

Question 27

what is anterior reverb?

Answer 27

- reflections between transducer face and skin - can cause multiple horizontal lines of echoes to appear in near field - can happen at ribs

Question 28

benifits of harmonics?

Question 29

filtering drawbacks?

Answer 29

- decreased penetration | - worse axial resolution

Question 30

filtering drawbacks?

Answer 30

- decreased penetration | - worse axial resolution

Question 31

detection (demodulation)?

Answer 31

radio frequency form - video form/amplitude form

Question 32

2 steps to detection/demodulation?

Answer 32

1. rectification | 2. smoothing

Question 33

what is rectification?

Answer 33

- turns negative voltages into postive voltages

Question 34

what is smoothing?

Answer 34

- wraps an envelope around the signal to make it less bumpy

Question 35

power ratio of largest to smallest amplitude that system can handle is known as?

Answer 35

dynamic range

Question 36

what performs dynamic range function?

Answer 36

compression

Question 37

Power ratio = ?

Answer 37

voltage ratio ^2

Question 38

what is compresstion?

Answer 38

the process of decreasing the differences bwteen the smallest and largest echo amplitudes to a usable range

Question 39

Weaker signals are amplified ____ than the stronger ones

Answer 39

more

Question 40

compression reduces?

Answer 40

dynamic range with selective amplification

Question 41

compression affects?

Answer 41

- affects contrast | - aperator controlled (DR button)

Question 42

decreased DR=?

Answer 42

granier

Question 43

increased DR=

Answer 43

smoother image