Philips epiq 7, User Manual

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Ultrasound in Medicine, Vol. 7, No. 9 Supplement, September 1988), sometimes referred to as
the Stowe Report, which 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 system has been measured and calculated in accordance with the
“Acoustic Output Measurement Standard for Diagnostic Ultrasound Equipment” (Revision 3,
AIUM, NEMA, 2004), the “Standard for Real-Time Display of Thermal and Mechanical Acoustic
Output Indices on Diagnostic Ultrasound Equipment” (Revision 2, AIUM, NEMA, 2004), and the
September 2008 FDA document "Information for Manufacturers Seeking Marketing Clearance
of Diagnostic Ultrasound Systems and Transducers."
In Situ, Derated, and Water Value Intensities
All intensity parameters are measured in water. Since water absorbs very little 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 and type of tissue
and the frequency of the ultrasound that passes through the tissue. The intensity value in the
tissue, In Situ, has been estimated by using the following formula:
In Situ = Water [e
-0.23alf
]
Where:
Variable Value
In Situ In Situ intensity value
Water Water value intensity
e 2.7183
a Attenuation factor
Tissue a(dB/cm-MHz)
Amniotic Fluid 0.006
Brain 0.53
Heart 0.66
Kidney 0.79
Liver 0.43
Muscle 0.55
l Skin line to measurement depth (cm)
f Center frequency of the transducer/system/mode combination (MHz)
Biological Safety Safety
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