Acoustic Output 15-3
15.4.2 MI/TI Display
TI and MI values are displayed in the upper part of the screen in real-time. The operator should monitor
these index values during examinations and ensure that exposure time and output values are
maintained at the minimum amounts needed for effective diagnosis.
If there is a value of MI or TI exceeds 1.0, you must be careful to practice the ALARA
principle.
The display precision is 0.1.
Real-time Display accuracy: MI ≤28.5%, TI≤38.7%
15.5 Acoustic Power Setting
Acoustic power adjustment
Rotate the [A.power] knob to adjust the acoustic power percentage, and its value is displayed on
the corresponding item, as well as at the top of the screen. The greater the acoustic power
percentage, the greater the current acoustic output. When the image is frozen, the system stops
transmitting acoustic power.
Default setting of acoustic power
Selection of diagnostic applications is the most important factor for controlling ultrasound output.
The permissible level of intensity of ultrasound differs depending on the region of interest. For fetal
examinations, in particular, much care must be exercised.
In this system, imaging setups can be created using the ultrasound output set by you. Once you
perform preset settings, default setting values of the system may be changed and invalid. It
is the user’s responsibility for any change to the default settings.
Adjusting range
Initial power: 0.1% to 100%*
Definition of 100%: The maximum acoustic power of a probe determined by the increase in probe
surface temperature in the selected mode and the acoustic power restrictions specified by the FDA.
Default settings of acoustic power value refer to the best image quality of the probe. The larger the
acoustic power value, the better the image quality.
In the Resona I9 series product, to obtain optimum images for applications under the requirements
of safety and ALARA principle, we set acoustic power default values in factory to be maximum
93.3% in all exam modes for a better image quality. The user can make adjustments according to
the imaging effect in practical use.
This system automatically returns to the settings whenever changes are made to the
values (when you turn on the power, switch between probes, tap [End], or select OK or
Cancel in the Setup menu). In the factory default settings, the Acoustic Output is limited
below 100%. Following the ALARA restriction, you are allowed to increase the acoustic
power under FDA 510(k) Guidance-Track3 limits and to set it in the image preset screen.
The acoustic output of the system has been measured and calculated in accordance with
IEC60601-2-37: 2015, FDA 510(K) GUIDANCE, IEC 62359: 2017, Ultrasonics-Field
characterization-Test methods for the deter mination of thermal and mechanical indices related to
medical diagnostic ultrasonic fields.
15.6 Acoustic Power Control
The qualified operator may use the system controls to limit the ultrasound output and to adjust the
quality of the images. There are three categories of system controls relative to output. They are,
Controls that have direct effect on the output
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