User guide

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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, “Bioeffects and
Safety of Diagnostic Ultrasound,” dated January 28, 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:
Table 4: Transducer Surface Temperature Rise, External Use (°C)
Test
C11x C60x
D2
HFL38x HFL50x
L25x L38x
L38xi
P10x P21x
Still air 17.6 16.2 8.3 15.5 10.7 16.1 16.3 12.5 15.6 17.2
Simulated
Use
9.1 8.8 1.9 7.9 7.7 8.5 9.6
8.8
9.8 9.2
Table 5: Transducer Surface Temperature Rise, Internal Use (°C )
Test
ICTx
SLAx
TEEx
Still air 9.2 9.5 9.3
Simulated
Use
5.2 4.8 5.8