P3V Veterinary Digital Ultrasonic Diagnostic Imaging System User Manual
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The temperature rise is determined by the acoustic intensity, exposed area and thermophysical
properties of the tissue.
In order to indicate the potential for temperature rise caused by thermal effects, the AIUM and
NEMA formulate thermal index (TI). It is defined as the ratio of the total acoustic power to the
acoustic power required to raise the tissue temperature by 1ºC.
According to different thermophysical properties of the tissue, TI is divided into three kinds: TIS,
TIB and TIC.
TIS (Soft Tissue Thermal Index): It provides an estimate of potential temperature rise in soft or
similar tissues.
TIB (Bone Thermal Index): It provides an estimate of potential temperature rise when the
ultrasound beam passes through soft tissue and a focal region is in the immediate vicinity of
bone.
TIC (Cranial Bone Thermal Index): It provides an estimate of potential temperature rise in the
cranial bones or superficial bones.
A2.3.3. Display of MI/TI
The MI value of this system is lower than 1.0 and it is not displayed. The TI values in the upper
right part of the screen. In PW mode, the TI value is displayed and the start point is 0.1. The
operator should monitor these values during examinations and keep the exposure time and output
level at the minimum amounts needed for effective diagnosis.
The display precision is 0.2.
Display accuracy of TI is ±50%.
A2.4: Acoustic Output
A2.4.1. Factors that Contribute to Uncertainty in the Output Display
A number of factors should be considered in display accuracy determination methods, such as:
Transducer variability
System variability
Measurement variability and accuracy
The number of operating conditions of which the system is capable and the number tested in
obtaining display accuracy results
Whether display accuracy will be determined by specific combinations of system, mode,
transducer assembly and transmit patterns, or all allowed combinations of them
Accuracy of system software MI and TI calculation algorithms.
Engineering approximations for real-time calculations
A2.4.2. Differences between Actual and Displayed MI/TI
Actually, many assumptions adopted in the process of measurement and calculations are
