
Chapter 2 Introduction
2-7
Tips!
Principles of Operation of the Diagnostic Ultrasound System
Medical ultrasound images are created when the computer's digital memory converts the high-
frequency wave signals that are transmitted and received by the probe.
As ultrasound waves propagate through the human body, they generate reflected signals
whenever they encounter a change in density. For example, reflected signals are generated when
signals pass from fatty tissues to muscle tissues. Reflected signals return to the probe where they
are converted into electronic signals. The reflected signals are amplified and processed by analog
and digital circuits that have filters for various frequencies and response time options. Then they
are again converted into high-frequency electronic signals, and saved as a series of digital image
signals. The monitor displays the image signals stored on the storage device in real time.
The entire process of transmitting, receiving, and processing signals is controlled by the computer.
Adjusting Brightness
Use the left/right arrow keys on the keyboard. However, brightness cannot be adjusted in Text Mode.
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