A6T/A6/A5 Portable Ultrasonic Diagnostic System
4701-0040-01A
B-1
Appendix B Principle for Using Acoustic Power
ALARA
Please observe ALARA (As Low As Reasonably Achievable) principle when
using ultrasound. So far there is no confirmed evidence to prove that
ultrasound has obvious harm to humans, but the users shall be cautious
when using ultrasound. Provided that sufficient diagnostic information is
acquired, try to shorten the time to examine the patient with the probe on one
body position. The ultrasound power and acoustic intensity are relevant to
scanning time. The user shall observe ALARA principle to select an
appropriate ultrasound power for the exam based on his exam needs.
Ultrasound Effects
Ultrasound effect shall include heating and cavitation.
Heating effect: Ultrasound in nature is mechanical wave. During its
propagation in human body, the human tissues are oscillated, heat is
generated, and human tissue temperature rises. Be vigilant to damage due to
the heating effect, and always follow ALARA principle.
Cavitation: Cavitation can occur when sound passes through an area that
contains small bubbles. With ultrasound impact on these small bubbles,
temperature and pressure around the space of the bubbles will increase, or
even oscillate and explode, which may result in physical or chemical effects
on the surrounding tissues.
Relevant Parameters
The main parameters related to acoustic power are: transmit frequency,
transmit focus number, transmit voltage, transmit angle, element pitch, etc.
These parameters vary subject to exam modes. Follow ALARA principle to
select the appropriate power for scanning.
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