TELEMED ClarUs User Guide, REV 4.0 2013.12.04
36
particularly in the case of infants and neonates and especially if they
are pre-term;
o
ultrasonically induced capillary hemorrhaging of the intestine where
intestinal peristalsis is inhibited or conditions promote intraluminal or
sub-mucosal gas collections;
o
ultrasonically induced capillary hemorrhaging in other soft tissues when
Gas Contrast Agents are used.
Use of Gas Contrast Agents during a diagnostic ultrasound examination is not
recommended within 24 hours before extracorporeal shock wave lithotripsy.
Exposure can be reduced by lowering the
Mechanical Index
using the output
controls. Reducing the
dwell time
is of use if threshold pressures are
exceeded.
Quality Assurance
It is recommended that equipment operators implement quality assurance
measures to maintain the capability of obtaining reliable diagnostic information at
acoustic exposures which are
As Low As Reasonably Achievable
.
Since the quality of diagnostic information depends, in part, on operator
training, it is also recommended that sonographers (ultrasound technologists) are
appropriately qualified and registered in regional organizations of ultrasound
professionals.
B. Conclusions
General
Although there are many exposure conditions for which the risk of injury during
a diagnostic ultrasound examination is negligible, this is not the case for every
possible exposure condition using currently available equipment. Therefore,
the persons responsible for the ultrasonic exposure must ensure that the
exposure is justified, i.e. that reliable diagnostic information can be achieved
and that the benefits significantly outweigh the risk involved
The conclusions listed below provide guidance as to the risks due to thermal
and mechanical effects resulting from ultrasound exposure. To be useful, all
the conclusions need to be taken into consideration.
Thermal Effects
At the time of writing, the information published on output levels during B-
mode imaging indicates that the risk of injury from
ultrasonic heating
is
negligible during this type of examination. At this time, there appears to be no
reason based on thermal grounds to limit such scanning for any clinical
indication, including ultrasound examination of normally pregnant women.
In all other operating modes, especially those used for Doppler blood flow
examinations, the risk of injury from
ultrasonic heating
depends on the
temperature elevation and the
dwell time
as indicated by the conclusions
given below.
