User Manual

55
C
MI
=1(MPa/
MHz
)
When the frequency is 1 MHz and the peak pressure is 1 MPa, the MI value is 1 MI can be
considered as a threshold for cavitation. When gas and soft tissue exist at the same time to set the
MI value to the low value.

TI （Thermal index）：
TI is determined by the total acoustic power and the tissue temperature rise of 1 degrees Celsius
required sound power ratio. In addition, the organizational structure of different temperature is
different, so the TI is divided into three categories: TIS (soft tissue thermal index (TIB), and TIC
(bone thermal index) skull thermal index).

TIS: soft tissue thermal index applications, such as the abdomen and the heart

TIB: the use of bone thermal index, such as the fetus (in late pregnancy), focused
on or close to the focus of the acoustic beam in the bone

TIC: Skull thermal index applications such as pediatric and adult skulls.
WFUMB (World Federation of ultrasound in medicine and Biology) statement: 5 minutes
irradiation temperature rise of 4 degrees may cause potential harm to the embryo and fetal tissue.
The smaller the MI/TI, the lower the biological effect。
9.4.2 MI/TI display instructions
TI and MI display on the screen of centre. The operator should monitor these index values in the
inspection process, and to ensure that in the premise of effective diagnostic information under the
irradiation time and the output value is maintained at the lowest possible level.
The TI and MI values are displayed at any operating conditions, and the step value is not more
than 0.2.
TI display items can be set in the prefab, open [the image preset parameter ]"B/THI" page, you
can see the acoustic output parameters preset, as shown below：
Here you can set the level of TI display items and power levels.
Display accuracy is 0.1.
Be careful： If the MI or TI display values are greater than 1, please follow the ALARA
principle carefully