SonoSite S-Cath - Acoustic Output Measurement; In Situ, Derated, and Water Value Intensities

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Acoustic output measurement
Sincetheinitialuseofdiagnosticultrasound,thepossiblehumanbiologicaleffects(bioeffects)
fromultrasoundexposurehavebeenstudiedbyvariousscientificandmedicalinstitutions.In
October1987,theAmericanInstituteofUltrasoundinMedicine(AIUM)ratified areportfrom
itsBioeffectsCommittee(BioeffectsConsiderationsfortheSafetyofDiagnosticUltrasound,
J
UltrasoundMed.,Sept.1988:Vol.7,No.9Supplement).Thereport,sometimesreferredtoas
theStoweReport,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ultrasound
systemhasbeenmeasuredandcalculatedin
accordancewith“A co us t i c OutputMeasurementStandardforDiagnosticUltrasound
Equipment”(NEMAUD2‐2004),and“StandardforReal‐TimeDisplayofThermaland
MechanicalAcousticOutputIndicesonDiagnosticUltrasoundEquipment”(NEMA
UDe3‐2004).
In Situ, derated, and water value intensities
Allintensityparametersaremeasuredinwater .Sincewaterdoesnotabsorb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,typeoftissue,and
thefrequencyoftheultrasoundpassing
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)
]
Table 6: Transducer Surface Temperature Rise
Test
External Use (°C)
Internal Use
(°C)
C11x C60x
HFL38x HFL50x
L25x L38x
L38xi
P10x P21x
ICTx
SLAx
TEEx
Still air
17.6 16.2 15.5 10.7 16.1 16.3 12.5 15.6 16.8 9.2 9.5 9.3
Simulated
Use
9.1 8.8 7.9 7.7 8.5 9.6 8.8 9.8 9.0 5.2 4.8 5.8