User's Manual

Table Of Contents
Chapter 6: Safety 71
Safety
•Computedestimatesofupperlimitstotemperatureelevationsduringtransabdominalscans
wereobtainedinasurveyof1988and 1990pulsedDopplerequipment. Thevastmajorityof
modelsyieldedupperlimitslessthanand4°C(1.8°and7.2°F)forexposuresof
firsttrimesterfetaltissueandsecondtrimesterfetalbone,
respectively.Thelargestvalues
obtainedwereapproximately1.5°C(2.7°F)forfirsttrimesterfetaltissueand7°C(12.6°F)for
secondtrimesterfetalbone.Estimatedmaximumtemperatureelevationsgivenherearefor
a“fixedpath”tissuemodelandarefordeviceshavingI
SPTA
valuesgreaterthan500 mW/
cm
2
.Thetemperatureelevationsforfetalboneandtissuewerecomputedbasedon
calculationproceduresgiveninSections4.3.2.14.3.2.6in“BioeffectsandSafetyofDiagnostic
Ultrasound”(AIUM,1993).
Acoustic output tables
Table 8throughTable 13indicatetheacousticoutputforthe systemandtransducer
combinationswithathermalindexormechanicalindexequaltoorgreaterthanone.These
tablesareorganizedby transducermodelandimagingmode.Foradefinitionoftermsusedin
thetables,see“Termsusedintheacoustic
outputtables”onpage 78.