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

Table 4: Transducer Surface Temperature Rise, External Use (°C)
Test C8x C11x
Still air 11.3
Simulated 5.5
Use
Table 5: Transducer Surface Temperature Rise, Internal Use (°C )
Test
Still air
Simulated
Use

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:
HFL
C60x D2
38x
17.6 16.2 8.3 15.5
9.1 8.8 1.9
ICTx SLAx TEEx
9.2 9.5 9.3
5.2 4.8 5.8
HFL
L25x
50x
10.7 16.1
7.9 7.7 8.5
L38x L38xi P10x
16.3 12.5 15.6
9.6 8.8 9.8
Chapter 6: Safety
P21x
16.8
9.0
121