Chapter 14

Question 1

Transducer

Answer 1

During transmission it transforms electrical energy into acoustic energy. During reception, it converts the returning acoustic energy into electrical energy.

Question 2

Pulser and Beam Former

Answer 2

Creates and controls the electrical signals sent to the transducer to generate sound pulses.

Question 3

Receiver

Answer 3

transforms the electrical signals from the transducer into a form suitable for display

Question 4

Display

Answer 4

Presents processed data on a monitor (CRT or LCD)

Question 5

Storage

Answer 5

Archives the data images onto a network, system hard drive, or other media (flash drive, DVD, older media such a photopaper, transparent film, videotape)

Question 6

Master Synchronizer

Answer 6

Maintains and organizes the proper timing and interaction of the system’s components

Question 7

Signal

Answer 7

displayed reflections arising from true structures
Intended, meaningful, constructs image

Question 8

Noise

Answer 8

displayed low level reflections not arising from true structures
Unintended, unmeaningful, contaminate image

Question 9

The Pulser

Answer 9

creates and sends the electrical signal that excites the crystal(s) to create the sound beam, thus functions during transmission

Question 10

Beam Former

Answer 10

receives the electrical spike from the pulser and distributes it to the active elements in an array transducer
It coordinates the electronic slope, electronic curvature, apodization, and dynamic aperture

Question 11

The Receiver

Answer 11

prepares the information contained in these minuscule signals for eventual display

Question 12

Order of Receiver Operations are in alphabetical order

Answer 12

Amplification
Compensation
Compression
Demodulation
Reject

Question 13

Amplification

Answer 13

each electrical signal returning from the probe to the receiver is made larger
adjusted by sonographer
knob: receiver gain
units: decibels
typical values: 60-100 dB

Question 14

Preamplification

Answer 14

prevent noise from contaminating the tiny signals; maintaining the quality of the signal

Question 15

Compensation

Answer 15

creates an image that is uniformly bright from top to bottom
adjusted by sonographer
AKA: time gain compensation (TGC), depth gain compensation (DGC), swept gain (SWC)
units: dB

Question 16

Anatomy of a TGC Curve

Answer 16

X axis = TGC, Y axis = depth
Near gain: at superficial depths reflections undergo a small constant amount of compensation
Delay: depth at which variable compensation begins
Slope: area of variable compensation
Knee: depth at which maximal compensation has been reached
Far Gain: represents the maximum amount of compensation the receiver can provide

Question 17

Compression (Automatic)

Answer 17

the system adjusts the dynamic range of electrical signals into a range that a system device can process accurately

Question 18

Dynamic range

Answer 18

range of electrical signals that a device can process accurately

Question 19

Compression (Sonographer Adjusted)

Answer 19

The sonographer uses the compression knob to assign the echo data signals amongst more or fewer shades of gray
AKA compress, log compression, or dynamic range knob

Question 20

Demodulation

Answer 20

this fourth receiver function is a two part process that changes the electrical signal into a form more suitable for display
Rectification and Smoothing
automatic

Question 21

Rectification

Answer 21

converts all the negative voltages into positive voltages

Question 22

Smoothing(enveloping)

Answer 22

places a smooth line around the “bumps” in the voltage signal

Question 23

Reject

Answer 23

this fifth receiver function eliminates low amplitude signals suspected to be noise
AKA: reject, threshold, or suppression knob

Question 24

Dynamic Frequency Tuning

Answer 24

The receiver processes only the high frequency signals to create the superficial portion of the image because they provide superior axial resolution
Lower frequency signals are used to create the deeper portions of the image because they are all that remain (the higher frequencies have attenuated)

Question 25

Output power

Answer 25

Entire image is brighter because stronger pulse is sent into the body
Higher output power increases patient exposure
Improves signal to noise ratio

Question 26

Receiver Gain

Answer 26

Amplifies the returning signals affecting the entire brightness of the image
It does not alter the signal to noise ratio since both signal and noise are boosted
Nor does it impact patient exposure to US