Acoustic Output Tables - FujiFilm SonoSite Edge II User Manual

Fixed-path tissue models, in which soft tissue thickness is held constant, sometimes are used to estimate
In Situ acoustic exposures when the beam path is longer than 3 cm and consists largely of fluid. When this
model is used to estimate maximum exposure to the fetus during transabdominal scans, a value of 1 dB/
cm MHz may be used during all trimesters.
Existing tissue models that are based on linear propagation may underestimate acoustic exposures when
significant saturation due to non-linear distortion of beams in water is present during the output
measurement.
The maximum acoustic output levels of diagnostic ultrasound devices extend over a broad range of values:
A survey of 1990-equipment models yielded MI values between 0.1 and 1.0 at their highest output
settings. Maximum MI values of approximately 2.0 are known to occur for currently available equipment.
Maximum MI values are similar for real-time 2D and M Mode imaging.
Computed estimates of upper limits to temperature elevations during transabdominal scans were
obtained in a survey of 1988 and 1990 pulsed Doppler equipment. The vast majority of models yielded
upper limits less than 1° and 4°C (1.8° and 7.2°F) for exposures of first-trimester fetal tissue and
second-trimester fetal bone, respectively. The largest values obtained were approximately 1.5°C (2.7°F)
for first-trimester fetal tissue and 7°C (12.6°F) for second-trimester fetal bone. Estimated maximum
temperature elevations given here are for a "fixed path" tissue model and are for devices having I
values greater than 500 mW/cm
based on calculation procedures given in Sections 4.3.2.1-4.3.2.6 in "Bioeffects and Safety of Diagnostic
Ultrasound" (AIUM, 1993).

Acoustic output tables

The acoustic output tables, starting with
output for the system and transducer combinations with a TI or MI equal to or greater than one. These tables
are organized by transducer model and imaging mode. For a definition of terms used in the tables, refer to
"Terms used in the acoustic output tables"
Notes
Acoustic Output
2
. The temperature elevations for fetal bone and tissue were computed
Table
For acoustic output tables for the P11x transducer, refer to the P11x Transducer
User Guide, included with the P11x transducer.
For acoustic output tables for the TEExi transducer, refer to the TEExi Transducer
User Guide, included with the TEExi transducer.
Acoustic output information is the same for the standard and armored versions of
a transducer.
The P11x transducer is not licensed for use in Canada.
10-6, and ending with
on page 10-68.
Table 10-59, indicate the acoustic
SPTA
10-13