Chapter 12 - System Safety and Maintenance Acoustic Output Indices
Terason t3000 / Echo Ultrasound System User Guide 271
Acoustic Output Index Displays
This section describes the acoustic output display in various modes.
Only certain transducers used with the Terason Ultrasound System are intended for
transcranial examinations (Neo-natal Cephalic uses). If the transducer used does not
support transcranial exams, the index display does not include TIC.
Index Display in 2D
In 2D only, with the Freeze control off, a value for MI (the Mechanical Index) displays.
When the maximum value of a relevant acoustic for a particular transducer is less than 1.0,
the 2D image display always shows the label for the Mechanical Index in standard video,
with no current MI value displayed.
Since 2D operation under such conditions is considered without significant risk from non-
linear acoustic effects, the Terason Ultrasound System can be used in 2D with all available
transducers, for all intended applications, without concern for monitoring and minimizing
a displayed MI value. However, in keeping with ALARA, the system should generally be
operated in the shallowest depth control setting that yields the desired image quality (to
minimize the MI value).
Index Display for Modes Other Than 2D
When any mode other than 2D is active, the MI display is replaced by a display showing
the thermal indices relevant to the transducer in use. The indices are TIS (soft tissue), TIB
(bone), and TIC (cranial). When control settings for the active transducer do not allow
TIS, TIB, or TIC to exceed 1.0, the indices are shown without any value. In those cases,
the Thermal Index display is as follows:
Any mode, other than 2D-
only
Include either Adult Cephalic or
Neonatal Cephalic
TIS, TIB, TIC
Warning: For neonatal head imaging, Terason recommends that you
exercise special care during neonatal cephalic scanning to avoid
possible damage to the posterior region of the eye.
The ultrasound energy emitted by the transducer easily
penetrates the fontanels of the infant.
MI:
TIB:
TIS:
TIC:
Acoustic Output Indices for Modes and Transducers
Mode Type Currently
Active
Allowed Transducer
Applications
Relevant
Indices
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