User's Manual
Table Of Contents
- S Series Ultrasound System User Guide
- Contents
- Introduction
- Chapter 1: Getting Started
- Chapter 2: System Setup
- Chapter 3: Imaging
- Chapter 4: Measurements
- Chapter 5: Troubleshooting and Maintenance
- Chapter 6: Safety
- Ergonomic safety
- Electrical safety classification
- Electrical safety
- Equipment safety
- Battery safety
- Clinical safety
- Electromagnetic compatibility
- ALARA principle
- Acoustic artifacts
- Guidelines for reducing MI and TI
- Output display
- Transducer surface temperature rise
- Acoustic output measurement
- Acoustic output tables
- Labeling symbols
- Chapter 7: Specifications
- Glossary
- Index
Chapter 6: Safety 69
Safety
Acoustic output measurement
Sincetheinitialuseofdiagnosticultrasound,thepossiblehumanbiologicaleffects(bioeffects)
fromultrasoundexposurehavebeenstudiedbyvariousscientificandmedicalinstitutions.In
October1987,theAmericanInstituteofUltrasoundinMedicine(AIUM)ratifiedareport
preparedbyitsBioeffectsCommittee(BioeffectsConsiderationsfortheSafetyofDiagnostic
Ultrasound,JUltrasoundMed.,Sept.1988:Vol.7,No.9Supplement),sometimesreferredtoas
theStoweReport,whichreviewedavailabledataonpossibleeffectsofultrasoundexposure.
Anotherreport“BioeffectsandSafetyofDiagnosticUltrasound,”datedJanuary28,1993
providesmorecurrentinformation.
Theacousticoutputforthisultrasoundsystem
hasbeenmeasuredandcalculatedin
accordancewiththe“A c o us t i c OutputMeasurementStandardforDiagnosticUltrasound
Equipment”(NEMAUD2‐2004),andthe“StandardforReal‐TimeDisplayofThermaland
MechanicalAcousticOutputIndicesonDiagnosticUltrasoundEquipment”(NEMA
UDe3‐2004).
In Situ, derated, and water value intensities
Allintensityparametersaremeasuredinwater.Sincewaterdoesnotabsorbacousticenergy,
thesewatermeasurementsrepresentaworstcasevalue.Biologicaltissuedoesabsorbacoustic
energy.Thetruevalueoftheintensityatanypointdependsonthe amount,typeoftissue,and
thefrequencyoftheultrasoundpassing
throughthetissue.Theintensityvalueinthetissue,
In Situ,hasbeenestimatedbyusingthefollowingformula:
In Situ=Water[e
‐(0.23alf)
]
where:
In Situ=In Situintensityvalue
Water=Waterintensityvalue
e=2.7183
a=attenuationfactor(dB/cm MHz)
Attenuationfactor(a)forvarioustissuetypesaregivenbelow:
brain=0.53
heart=0.66
kidney=0.79
liver=0.43
muscle=0.55
l=skinlinetomeasurementdepthincm
f=center
frequencyofthetransducer/system/modecombinationinMHz