Clarius Scanner HD3 Safety Topics
revision 9 53
• Approximate index for the application: TIS is used for imaging soft tissue, TIB for a
focus at or near bone, and TIC for imaging through bone near the surface (for
example, a cranial exam).
• Mitigating factors that might create artificially high or low TI readings: Location of
fluid or bone, or blood flow. For example, is there a highly attenuating tissue path
so that the actual potential for local zone heating is less than the TI displays?
• Scanned modes versus unscanned modes of operation that affect the TI: For
scanned modes (such as B-Mode), heating tends to be near the surface. For
unscanned modes (such as M-Mode or Doppler-type modes), the potential for
heating tends to be deeper in the focal zone.
• MI: This is continuously displayed over the range of 0.0 to 1.9, in increments of 0.1.
TI Display
The TI indicates any conditions that may lead to temperature increase on the surface of the
body, within the body tissue, or at the point of focus of the ultrasound beam on bone. TI
informs you of a potential rise in temperature of body tissue, by estimating temperature
increases in those body tissue with specific properties. The actual temperature increase is
influenced by factors such as tissue type, vascularity, and mode of operation. Use the TI as a
guide for implementing the ALARA principle.
You can choose to display one of the following types of TI indices:
• TIS: Indicates potential for heating within soft homogeneous tissue.
• TIB: Indicates potential for heating at or near the focus after the ultrasound beam has
passed through soft tissue or fluid. For example, at or near second- or third-trimester fetal
bone.
• TIC: Indicates potential for heating of bone at or near the surface. For example, cranial
bone.
MI Display
The higher the MI value, the greater the likelihood of mechanical bioeffects occurring. The
potential for mechanical bioeffects varies by peak rarefactional pressure and ultrasound
frequency. The MI accounts for these two factors. There is no specific MI value that indicates
the occurrence of a mechanical effect. Use the MI as a guide for implementing the ALARA
principle.
When interpreting the MI, remember that it is intended to estimate the potential for
mechanical bioeffects. The higher the index reading, the greater the potential. However,
neither MI = 1 nor any other level indicates that a bioeffect is actually occurring. We should not
be alarmed by the reading, but we should use it to implement the ALARA principle.
Display Accuracy
The MI and TI have a precision of 0.1 unit on the system.
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