Acoustic Output Measurement; In Situ, Derated, And Water Value Intensities - FujiFilm SonoSite Edge II User Manual

Acoustic output measurement

Since the initial use of diagnostic ultrasound, the possible human biological effects (bioeffects) from
ultrasound exposure have been studied by various scientific and medical institutions. In October 1987, the
American Institute of Ultrasound in Medicine (AIUM) ratified a report from its Bioeffects Committee
(Bioeffects Considerations for the Safety of Diagnostic Ultrasound, J Ultrasound Med., Sept. 1988: Vol. 7, No.
9 Supplement). The report, sometimes referred to as the Stowe Report, reviewed available data on possible
effects of ultrasound exposure. Another report,
1993, provides more current information.
The acoustic output for this ultrasound system has been measured and calculated in accordance with
"Acoustic Output Measurement Standard for Diagnostic Ultrasound Equipment" (NEMA UD2-2004), and
"Standard for Real-Time Display of Thermal and Mechanical Acoustic Output Indices on Diagnostic
Ultrasound Equipment" (NEMA UDe3-2004).

In Situ, derated, and water value intensities

All intensity parameters are measured in water. Since water does not absorb acoustic energy, these water
measurements represent a worst case value. Biological tissue does absorb acoustic energy. The true value
of the intensity at any point depends on the amount, type of tissue, and the frequency of the ultrasound
passing through the tissue. The intensity value in the tissue, In Situ, has been estimated by using the
following formula:
-(0.23alf)
In Situ= Water [e
where:
In Situ = In Situ intensity value
Water = Water intensity value
e = 2.7183
a = attenuation factor (dB/cm MHz)
Acoustic Output
Bioeffects and Safety of Diagnostic Ultrasound
]
, dated January 28,
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