Related Guidance Documents; Transducer Surface Temperature Rise - FujiFilm SonoSite M-Turbo User Manual

Measurement errors of the acoustic parameters when taking the reference data are the major
source of error that contributes to the display uncertainty. The measurement error is described
in "Acoustic measurement precision and uncertainty" on page 165.
The displayed MI and TI values are based on calculations that use a set of acoustic output
measurements that were made using a single reference ultrasound system with a single
reference transducer that is representative of the population of transducers of that type. The
reference system and transducer are chosen from a sample population of systems and
transducers taken from early production units, and they are selected based on having an
acoustic output that is representative of the nominal expected acoustic output for all
transducer/system combinations that might occur. Of course every transducer/system
combination has its own unique characteristic acoustic output, and will not match the nominal
output on which the display estimates are based. This variability between systems and
transducers introduces an error into displayed value. By doing acoustic output sampling
testing during production, the amount of error introduced by the variability is bounded. The
sampling testing ensures that the acoustic output of transducers and systems being
manufactured stays within a specified range of the nominal acoustic output.
Another source of error arises from the assumptions and approximations that are made when
deriving the estimates for the display indices. Chief among these assumptions is that the
acoustic output, and thus the derived display indices, are linearly correlated with the transmit
drive voltage of the transducer. Generally, this assumption is very good, but it is not exact, and
thus some error in the display can be attributed to the assumption of voltage linearity.

Related guidance documents

Information for Manufacturers Seeking Marketing Clearance of Diagnostic Ultrasound
Systems and Transducers, FDA, 1997.
Medical Ultrasound Safety, American Institute of Ultrasound in Medicine (AIUM), 1994. (A
copy is included with each system.)
Acoustic Output Measurement Standard for Diagnostic Ultrasound Equipment, NEMA
UD2‐2004.
Acoustic Output Measurement and Labeling Standard for Diagnostic Ultrasound Equipment,
American Institute of Ultrasound in Medicine, 1993.
Standard for Real‐Time Display of Thermal and Mechanical Acoustic Output Indices on
Diagnostic Ultrasound Equipment, NEMA UD3‐2004.
Guidance on the interpretation of TI and MI to be used to inform the operator, Annex HH, BS
EN 60601‐2‐37 reprinted at P05699.

Transducer surface temperature rise

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Table 4 and Table 5 list the measured surface temperature rise from ambient (23°C 3°C) of
transducers used on the ultrasound system. The temperatures were measured in accordance
with EN 60601‐2‐37 section 42 with controls and settings positioned to give maximum
temperatures.
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