User's Manual

Clarius Ultrasound Scanner - HD3 Scanners Safety Topics
revision 1 54
• Incorrect object location due to refraction, multi-path reflections, side lobes, grating lobes,
speed error, or range ambiguity.
• Incorrect object size due to poor resolution, refraction, or speed error.
• Incorrect object shape due to poor resolution, refraction, or speed error.
Acoustic Output & Measurement
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 Scanners.”
In Situ, Derated, & Water Value Intensities
All intensity parameters are measured in water. Because 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
e2.7183
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 scanner/system/mode combination (MHz)