ECO Series VET Digital Color Doppler Ultrasound System
11
increases with MI values above this threshold.
TI> 0.7 the overall exposure time of an embryo or fetus should be restricted in accordance with Table 2-2
below as a reference:
TI
Maximum exposure time
(minutes)
0.7
60
1.0
30
1.5
15
2.0
4
2.5
1
Maximum recommended exposure times for an embryo or fetus
Non-diagnostic use of ultrasound equipment is not generally recommended. Examples of non-diagnostic uses
of ultrasound equipment include repeated scans for operator training, equipment demonstration using normal
subjects, and the production of souvenir pictures or videos of a fetus. For equipment of which the safety
indices are displayed over their full range of values, the TI should always be less than 0.5 and the MI should
always be less than 0.3. Avoid frequent repeated exposure of any subject. Scans in the first trimester of
pregnancy should not be carried out for the sole purpose of producing souvenir videos or photographs, nor
should their production involve increasing the exposure levels or extending the scan times beyond those
needed for clinical purposes.
Diagnostic ultrasound has the potential for both false positive and false negative results. Misdiagnosis is far
more dangerous than any effect that might result from the ultrasound exposure. Therefore, diagnostic
ultrasound system should be performed only by those with sufficient training and education.
2.6.2
Understanding the MI/TI Display
Track-3 follows the Output Display Standard for systems that include fetal Doppler applications. The acoustic
output will not be evaluated on an application-specific basis, but the global maximum de-rated Ispta must be ≤
720 mW/ cm
2
and either the global maximum MI must be ≤ 1.9 or the global maximum de-rated Isppa must be
≤ 190 W/cm
2
. An exception is for ophthalmic use, in which case the TI = max (TIS_as, TIC) is not to exceed
1.0; Ispta.3 ≤50mW/cm
2
, and MI ≤ 0.23. Track-3 gives the user the freedom to increase the output acoustic
power for a specific exam, and still limit output acoustic power within the global maximum de-rated Ispta ≤
720 mW/cm
2
under an Output Display Standard.
For any diagnostic ultrasonic systems, Track-3 provides an Output Indices Display Standard. The diagnostic
ultrasound systems and its operation manual contain the information regarding an ALARA (As Low As
Reasonably Achievable) education program for the clinical end-user and the acoustic output indices, MI and TI.
The MI describes the likelihood of cavitations, and the TI offers the predicted maximum temperature rise in
tissue as a result of the diagnostic examination. In general, a temperature increase of 2.5°C must be present
consistently at one spot for 2 hours to cause fetal abnormalities. Avoiding a local temperature rise above 1°C
should ensure that no thermally induced biologic effect occurs. When referring to the TI for potential thermal
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