Ultrasound Physics - 14\pulsed Echo Instrumentation

Front 1

Which system component can transform electrical energy into acoustic energy during transmission and acoustic energy into electrical energy during reception?

Back 1

Transducer

Front 2

Which system component determines amplitude, pulse repitition period/frequency?

Back 2

Pulser

Front 3

Which system component determines the firing delay pattern for phased array systems?

Back 3

Beam Former

Front 4

Which system component transforms the electrical signals from the transducer into a form suitable for display?

Back 4

Receiver

Front 5

Which system component presents processed data?

Back 5

Display

Front 6

Which system component archives ultrasound studies?

Back 6

Storage

Front 7

Which system component maintains and organizes the proper timing and interaction of the system's components?

Back 7

Master Synchronizer

Front 8

Does the pulser function during transmission or reception?

Back 8

Transmission

Front 9

What control does a sonographer use to modify pulser voltage?

Back 9

Output Gain
(aka, acoustic power, pulser power, energy output, transmitter output, power)

Front 10

Increasing pulser voltage (gain) will have what effect on the image?

Back 10

Increases Brightness

Front 11

What is the relationship between pulser voltage and returning echo strength?

Back 11

Direct Relationship

Front 12

Attempts to standardize output gain has resulted in what two measurements appearing onscreen?

Back 12

Thermal Index (TI)
Mechanical Index (MI)

Front 13

Random and persistent disturbance that obsures or reduces the clarity of a signal is called what?

Back 13

Noise

Front 14

A comparison between the amount of meaningful information and contamination in an image, is called what?

Back 14

Signal-to-Noise Ratio

Front 15

To improve image quality, what type of signal-to-noise ratio is desired?

Back 15

High Signal-to-Noise Ratio (improves image quality)

Front 16

What is the relationship between output power/gain and signal-to-noise ratio?

Back 16

Direct Relationship

Front 17

What is the most common method of overcoming noise? Why?

Back 17

Increase output power/gain. That increases the signal-to-noise ration since noise is generally constant

Front 18

In addition to controlling the strength of the transmitted sound wave, the pulser also determines the time between one voltage spike and the next, called what?

Back 18

Pulse Repitition Period

(PRF is also determined, since PRP & PRF are reciprocals)

Front 19

Changing the PRP/PRF (controlled by the pulser), directly affects what?

Back 19

Depth of View

Front 20

Identify the depth of imaging:
- short listening time
- short PRP
- higher PRF

Back 20

Shallow Imaging

Front 21

Identify the depth of imaging:
- longer listening time
- long PRP
- lower PRF

Back 21

Deep Imaging

Front 22

During transmission, this part receives the single electrical spike from the pulser and distributes it to the active elements of a phased array transducer

Back 22

Beam Former

Front 23

During transmission, the beam former adjusts electrical spike voltages in all types of transducers to prevent what?

Back 23

Prevent Side/Gradient Lobes
(aka Apodization)

Front 24

During reception, the beam former also varies the number of crystals used in order to control what?

Back 24

Dynamic Aperture

Front 25

What are three advantages of digital beam formers?

Back 25

1) Software (easy updates)
2) Stable (no mechanical parts)
3) Versatile (can use transducers with a wide range of frequencies)

Front 26

This component protects the delicate receiver components from the high voltage signals created during pulse creation. It also directs low voltage signals from the transducer to the appropriate processing components within the system.

Back 26

Switch

Front 27

A single crystal, the beam former/pulser electronics, and the wire connecting them is called what?

Back 27

Channel

Front 28

What are the five operations that must be performed during reception?

Back 28

1. Amplification
2. Compensation
3. Compression
4. Demodulation
5. Reject

Front 29

The first function of the receiver is to take each signal returning from the transducer and make them equally larger. What is this called?

Back 29

Amplification

Front 30

Does amplification improve signal-to-noise ratio? why or why not?

Back 30

No, because both signal and noise are amplified equally

Front 31

Does amplification affect the amount of patient exposure to ultrasound energy?

Back 31

No, because only returning signals are amplified

Front 32

AMPLIFICATION: units?

Back 32

Decibels / dB
(the final signal leaving the receiver is compared to the initial signal strenth entering the receiver)

Front 33

What is a synonym for amplification?

Back 33

Receiver Gain

Front 34

The process of improving signal quality before it is amplified is called what?

Back 34

Pre-amplification

Front 35

Where does pre-amplification occur within the ultrasound system?

Back 35

As close to the crystals as possible, often within the transducer itself

Front 36

What is the role of pre-amplification in processing signals from the transducer during reception?

Back 36

Preventing electronic noise from contaminating the tiny (yet meaningful) electrical signals created by the transducer's crystals

Front 37

The second function of the receiver is to correct for attenuation by creating an image uniformly bright from top to bottom. Signals are thus treated differently based on reflector depth. What is this called?

Back 37

Compensation

Front 38

What are synonyms for compensation?

Back 38

TGC (Time Gain Compensation)
DGC (Depth Gain Compensation)

Front 39

COMPENSATION: units?

Back 39

Decibels / dB

Front 40

An echo with three masses at 2cm, 4cm, and 6cm depths will appear progressively darker. How does compensation address this issue?

Back 40

Compensation produces an image of uniform brightness from top to bottom

Front 41

On a TGC curve, what does the X axis and Y axis represent?

Back 41

X=TGC (amount of compensation)
Y=depth

Front 42

At superficial depths, reflections undergo a small, constant amount of compensation. What is this called?

Back 42

Near Gain

Front 43

The depth at which compensation begins is called what?

Back 43

Delay

Front 44

Compensation corrects attenuation effects over path lengh. What is this area called?

Back 44

Slope

Front 45

The depth at which max compensation is used

Back 45

Knee

Front 46

The maximum amount of compensation that the receiver can provide is called what?

Back 46

Far Gain

Front 47

You are using a 4 MHz transducer and are given a new one to use. The new TGC slope is to the lower left of the old one. Is the new transducer frequency higher or lower than the old one?

Back 47

The new transducer is less than 4 MHz since it is imaging deeper (y=depth)

Front 48

You are using a 4 MHz transducer and are given a new one to use. The new TGC slope is to the upper right of the old one. Is the new transducer frequency higher or lower than the old one?

Back 48

The new transducer is more than 4 MHz since it is imaging shallower (y=depth)

Front 49

The third function of the reciever is to keep grayscale content within the range of detection of the human eye & electrical signal levels within the accuracy range of the system's electronics. Signals are thus treated differently based on strength. This is called what?

Back 49

Compression

Front 50

What are synonyms of compression?

Back 50

Log Compression
Dynamic Range

Front 51

COMPRESSION: units?

Back 51

Decibels, dB

Front 52

Why is log compression clinically important?

Back 52

Most meaningful backscattered signals from biologic tisues are very weak and we must be able to see differences in these weak reflections

Front 53

The fourth function of the receiver is a two-part process that changes the electrical signals within the receiver into a form for suitable for CRT display

Back 53

Demodulation

Front 54

Converting all the negative voltages into positive voltages is called what?

Back 54

Rectification

Front 55

Does demodulation have a visible effect on the image?

Back 55

No, it simply modifies the signal so it can be fully displayed on a monitor

Front 56

This, part of demodulation, eliminates the small bumps in the voltage signal

Back 56

Smoothing
Enveloping

Front 57

The fifth function of the receiver allows us to choose whether or not to display low-level (weak signal) grayscale information; strong signals remain unchanged

Back 57

Reject

Front 58

What are synonyms for reject?

Back 58

Threshold
Suppression

Front 59

What type of reflections does reject affect?

Back 59

Low-level signals, regardless of location
Bright signals are not affected

Front 60

Which receiver function is NOT adjustable by the sonographer?

Back 60

Demodulation

Front 61

As a result of damping, sound pulses used for imaging contain a wide range of frequencies. This is called what?

Back 61

Wide Bandwidth

Front 62

Using the high frequency portion of the pulse to create the shallow images, and the low frequency portion to create the deep images, is called what?

Back 62

Dynamic Frequency Tuning

Front 63

What is the difference between output gain and receiver gain?

Back 63

Output Gain - improves signal-to-noise ratio, possibility of more bioeffects
Receiver Gain - does not (both are amplified equally), no risk of additional bioeffects

Front 64

What does ALARA stand for?

Back 64

As Low As Reasonably Achievable

Front 65

What does ALARA principle mean?

Back 65

Choose settings that will maximize image quality while minimizing patient ultrasound exposure

Front 66

In harmony with the ALARA principle, what is the first thing to do if the image is too dark?

Back 66

Try increasing receiver gain

Front 67

In harmony with the ALARA principle, what is the first thing to do if the image is too bright?

Back 67

Try decreasing output gain

Front 68

Which gain (output or receiver) does the following:
- changes brightness of entire image
- alters signal-to-noise ratio
- alters patient exposure
- has bioeffect concerns

Back 68

Output Power/Gain

Front 69

Which gain (output or receiver) does the following:
- changes brightness of entire image
- does not affect signal-to-noise ratio
- does not change patient exposure
- no bioeffect concerns

Back 69

Receiver Gain

Front 70

Which of the following is best when only deep reflectors are displayed, not shallow ones?
A. adjust compensation
B. use higher frequency transducer
C. decrease output power
D. adjust the reject level

Back 70

A

Front 71

Which of the following is best when the image is saturated (too bright everywhere)?
A. decrease the amplification or gain
B. use a higher frequency transducer
C. decrease the output power
D. adjust the reject level

Back 71

C

Front 72

Which of the following is best when the image displays only bright reflectors but no weak reflectors throughout the image?
A. increase overall gain
B. use higher frequency transducer
C. increase the output power
D. adjust the reject level

Back 72

D

Front 73

Which of the following is best when the image displays only shallow reflectors but no deep reflectors?
A. adjust compensation
B. use a higher frequency transducer
C. increase the power output
D. adjust the reject level

Back 73

A

Front 74

All of the following are components of an ultrasound system except:
A. transducer
B. pulser
C. alternator
D. synchronizer
E. display
F. receiver

Back 74

C

Front 75

This type of pulser generates a constant electrical signal in the form of a sine wave:
A. pused wave, array
B. continuous wave
C. pulsed wave, single crystal

Back 75

B

Front 76

This type of pulser generates a single electrical spike, which ultimately creates a single sound pulse:
A. pulsed wave, phased array
B. continuous wave
C. pulsed wave, single crystal

Back 76

C

Front 77

This type of pulser generates numerous electrical spikes, which ultimately create a single sound pulse:
A. pulsed wave, phased array
B. continuous wave
C. pulsed wave, single crystal

Back 77

A

Front 78

The acoustic power of a sound beam emitted from a transducer is determined by the ___ of the pulser's crystal:
A. PRF
B. frequency
C. voltage
D rectification

Back 78

C

Front 79

All of the following are functions of the receiver except:
A. demodulation
B. amplification
C. suppression
D. attenuation

Back 79

D

Front 80

Place these functions in the order in which the system performs them:
A. reject
B. demodulation
C. amplification
D. compression
E. compensation

Back 80

C, E, D, B, A
(hint: alphabetical order)

Front 81

T/F: Amplification processes all reflected signals in a similar manner

Back 81

T

Front 82

T/F: Compensation processes all reflected signals in a similar manner

Back 82

F