Doc #: 60-00118 Rev. A
60
In the Lucid
™ M1 System only the Cranial Thermal Index (TIC) is greater than one. This
information is especially important in performing temporal monitoring exams where longer
duration exposure to ultrasound energy could occur. Following ALARA principle, the TIC is used
to guide the user to set the power setting to the minimum required to obtain the appropriate
monitoring information. For a transcranial exam, this may be accomplished by initially exploring
the patient’s temporal window to find the thinnest area available and perform the examination at
this location, following the ALARA principle.
The Lucid
™ M1 System displays the TIC value at all times. Although not required by the NEMA
UD 3-2004 standard, displaying the TIC at all times during an exam helps to assist in
implementing the ALARA principle. TIC values equal to or greater than one are displayed in red
and help to alert the informed user to proceed with more caution. Please note that from the AIUM
Statement on Mammalian Biological Effects of Heat (approved March 2015), “For exposure
durations of up to 50 hours, there have been no significant adverse biological effects observed
due to temperature increases less than or equal to 1.5
C above normal.”
Limitations of the indices
•
The indices are calculated estimates and not actual temperature rise and is dependent
upon a number of factors such as exposure time, blood flow through the area and
bone/tissue characteristics. As a result, the indices should be used as a relative indicator
of potential risk of tissue heating
•
The indices are calculations of the temperature rise in tissue due to absorption. There
could be an effect of temperature rise of the transducer lens itself. The user should be
aware of this.
•
The indices are average values. Localized non-linear absorption could occur.
•
The TIC is not intended for ophthalmic application. Caution should be taken during
ophthalmic application.
•
The TIC is modeled assuming temperature diffusion due to blood flow & fluid perfusion.
Some situations where low blood circulation is expected, the TI should be kept at a lower
value.
Untrained personnel should not use the Neural Analytics Lucid
™ M1 System. The user should
be familiar with the document “Medical Ultrasound Safety” from the American Institute of
Ultrasound in Medicine (AIUM). This document may be ordered from AIUM (www.aium.org).
Review the section on Operating Controls prior to using this equipment.
