Fda-Limits For Acoustic Output And Bioeffects - GE VOLUSON 730Pro Basic User Manual

2.13.4

FDA-Limits for Acoustic Output and Bioeffects

The American Food and Drug Administration (FDA) has laid down maximum values in situ *
(recalculated) for different clinical applications, which are valid independent of the operation mode
(2D, M-Mode, Doppler). These values are not defined on the basis of the ultrasound bioeffects, but are
based on the output power of instruments, that were manufactured prior to the modification of FDA-
Regulations 1976. The enclosed acoustic output tables contain the recalculated limits as laid down by
FDA and the values mentioned in the AIUM-report.
•
Contains the recalculated limits as laid down by FDA and the values mentioned in the AIUM-
report.
•
No limits were laid down by the FDA for measurements in water.
2.13.5 Summary
1. Presently limits for the output power are laid down neither by the FDA, nor by AIUM-report of the
Bioeffects Committee. Thermal models in development in 1991 include the output power.
2. The AIUM-report contains no specific conclusions regarding an I SPPA within the FDA limits.
3. The I SPTA is a relevant parameter regarding bioeffects. The FDA limits and the values
recommended by the AIUM concerning bioeffects are compatible. In some of the thermal model in
development in 1991 there is an I SPTA factor.
4. The AIUM report does not contain any specific conclusions regarding an I MAX within the FDA
limits. Presently (1991) the FDA considers to renounce to the I MAX as a parameter of the output
power to be reported.
5. Presently the FDA considers a cavitation parameter the mechanical index MI which is based on Pr.
The limit for MI is 1.9.
6. The FDA considers I SATA as a relevant parameter regarding bioeffects. The FDA limits for the
I SATA are not based on bioeffects; they are rather based on the output power before the regulation
modification 1976.
7. No limits for the measurement in water were laid down.
8. In some cases the tissue can be exposed to sound and intensity values that are higher than those
given (recalculated) for in situ. In these cases the reported values in situ do not represent the worst
case of exposure. But this case occurs only if the tissue has an attenuation coefficient below 0.3
dB/cm/MHz, e.g. with a long way through liquids and a short way through tissue.
In such cases an output power of less than 100% is recommended; therefore the power should be
reduced by the examiner in order to reduce sound intensity impinging on the tissue.
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Voluson 730Pro - Basic User Manual
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