Pass Ultrasound Physics Exam

Transcription

1 Pass Ultrasound Physics Exam Match the Answers By Mansoor Khan MBBS, RDMS, RDCS 1

2 Copyright 2014 Blue Cube Venture, LLC All rights reserved. The Pass Ultrasound Physics Exam Match the Answers is protected by copyright. No part of this study guide review may be reproduced in any form without written permission from the copyright owner. Introduction Practice Match the answers and prepare for ARDMS Sonography Principles and Instrumentation (SPI) exam. Get the results you deserve. This book is devoted to the ARDMS SPI exam and the material is based on the ARDMS physics exam outline. It explains the concepts in very simple and easy to understand way. If you are preparing to take ARDMS Ultrasound Physics Exam and looking for an ultrasound book which can help you, the Pass Ultrasound Physics Exam Math the Answers is for you. You can increase your chances to pass ARDMS Ultrasound Physics and Instrumentation exam by practicing and memorizing these match the answers. It is simple, effective, and fast so that you can succeed on your ARDMS test with a minimum amount of time spent preparing for it. Thank you for giving me the opportunity to help you. I will be improving this Match the Answers book and adding more material in future. I am in this field for more than ten years and my goal is to provide help to students and sonographers to become successful in their field. Mansoor Khan MBBS, RDMS, RDCS 2

3 Table of Contents Pulse Echo Instrumentation... 4 Amplification... 7 Compensation... 9 Compression Demodulation Doppler Instrumentation Hemodynamics Artifacts Bioeffects Intensity Propagation of Ultrasound Pulse Ultrasound Principles Resolution Sound Beam Ultrasound Transducers Types of Ultrasound Transducers

4 Pulse Echo Instrumentation output is also called acoustic power, transmit power, transmit gain, power gain, acoustic gain, output intensity, transmit voltage, output voltage power power controls the amplitude of the voltage that excites the PZT crystals output higher voltage causes amplitude mechanical oscillation of the PZT crystal higher higher voltage produces higher amplitude waves sound increasing output power can cause and tissue damage bioeffects pulsar produces signals which excite the PZT crystals in the transducer and produce continuous and pulsed sound waves electrical pulsar is also known as the transmit former beam pulsar also regulates the of the electrical signals produced by changing the acoustic output power amplitude the pulsar functions during the phase transmission increasing pulsar voltage will increase on the image brightness 4

5 there is a direct relationship between pulsar voltage and the returning echo strength beam former is a part of the transmitter that functions with array transducers during and reception transmission beam former creates the appropriate phase and pulse sequencing to create the transmit beam delays beam former also creates the appropriate phase delays and pulse to create the receive beam sequencing random and persistent disturbance that reduces the clarity of a signal is called noise a comparison between the amount of meaningful information and contamination in an image is called to noise ratio signal to improve image quality signal to noise ratio is desired high there is a direct relationship between output and signal to noise ratio power amplitude level below which no signals are visible because of the presence of noise is called floor noise amplitude of the signal divided by the amplitude of the noise is called to noise ratio signal 5

6 signal to noise ratio is related to the of the signal quality higher signal to noise ratio means signal quality better a strong signal does not guarantee a signal to noise ratio good a weak signal does not guarantee a signal to noise ratio bad increasing the receiver gain does not the signal to noise ratio improve when the overall gain is increased, the signal and noise are amplified by the amount same random signals caused by electric amplification of small returning echoes is called noise electronic random of electrons within the electronics creates electronic noise excitation electronic noise looks like white speckle with high receiver gain in spectrum Doppler electronic noise looks like random color pixels where there is no flow in Doppler color clutter happens when returning echoes obliterate weaker signals larger 6

7 clutter is classified as noise but the signal from clutter and other noise sources are distinctly different in electrical interference, the transducer receives energy from other devices or electromagnetic waves such as radio transmission electrical the electrical interference can be carried through the air or from the supplying the system power electrical interference looks like a bright flashlight down the middle of an or a barber pole flashing image the electrical interference appear on Doppler as bright white horizontal or zigzag lines in the spectrum called Doppler tones spectrum Amplification each active is connected to an amplifier and processing chain element amplifier and processing chain are collectively known as the receive channel 256 to 512 active receive channels are present in systems ultrasound benefit of more receive channels in ultrasound systems is greater flexibility processing 7