Safety
HD11 XE Getting Started
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cations, dealing with delicate parts of the body which require lower limits for
acoustic output.
The decision as to the amount of acoustic output is, in the final analysis, up to the
system operator. This decision must be based on the following factors: type of
patient, type of exam, patient history, ease or difficulty of obtaining diagnostically
useful information, and the potential localized heating of the patient due to trans-
ducer surface temperatures. Prudent use of the system occurs when patient
exposure is limited to the lowest index reading for the shortest amount of time
necessary to achieve acceptable diagnostic results.
Although a high index reading does not mean that a bioeffect is actually occurring,
a high index reading should be taken seriously. Every effort should be made to
reduce the possible effects of a high index reading. Limiting exposure time is an
effective way to accomplish this goal.
There are several system controls that the operator can use to adjust the image
quality and limit the acoustic intensity. These controls are related to the tech-
niques that an operator might use to implement ALARA. These controls can be
divided into three categories: direct, indirect, and receiver controls.
Direct Controls
Application selection and the Power control directly affect acoustic intensity.
There are different ranges of allowable intensity or output based on your selec-
tion. Selecting the correct range of acoustic intensity for the application is one of
the first things that occurs in any exam. For example, peripheral vascular intensity
levels are not recommended for fetal exams. Some systems automatically select
the proper range for a particular application, while others require manual selec-
tion. Ultimately, the user has the responsibility for proper clinical use. The ultra-
sound system provides both automatic (default) settings and manual
(user-selectable) settings.
Power has direct impact on acoustic intensity. Once the application has been
established, the Power control can be used to increase or decrease the intensity
output. The Power control allows you to select intensity levels less than the
established maximum. Prudent use dictates that you select the lowest output
intensity that is consistent with good image quality.
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