GE LOGIQ 500 Advanced Reference Manual page 192

Bioeffects
Operator intervention (cont'd)
CAUTION
6–8
S
Develop and practice skills to localize anatomy and
optimize image quality rapidly, then freeze the image as
soon as the necessary diagnostic information is obtained. It
takes time for tissue temperatures to increase, so reducing
exposure time can significantly reduce the potential for
injury.
S
Avoid susceptible tissues, if possible, by changing probe
position, entrance angles or probe type. Higher frequency
probes will not penetrate as deep while linear probes have
lower near-field energy density. Avoid focusing on bone or
poorly perfused tissue. Do not allow the acoustic beam to
penetrate or focus on or near the eye.
Although choices like probe selection, mode of operation and
other control adjustments have a significant affect on output
levels, the ability to change these selections is often restricted
by the type of examination or clinical objectives. Therefore,
some examinations may require relatively high output levels to
achieve success.
The decision to raise acoustic output to potentially harmful
levels must include an assessment of the risk/benefit potential.
Such decisions are routine with imaging modalities
incorporating ionizing radiation such as Nuclear Medicine, X-ray
and CT. The principle of ALARA is widely used in these
modalities for minimizing the exposure risk and is now a
recommended practice with high-level diagnostic ultrasound.
During each ultrasound examination, the clinical user is
expected to weigh the medical benefit of the diagnostic
information obtained against the risk of harmful effects. Once
an optimal image is achieved the need for increasing acoustic
output or prolonging the exposure can not be justified. It is
important, therefore, for the user to be familiar with system
controls that affect image quality as well as acoustic output.
Complete descriptions of image optimization and acoustic
output controls are provided in the user instructions.
LOGIQ 500 Advanced Reference Manual
2276614–100 Rev. 0