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The idea of MI/TI has been introduced recently to increase the diagnostic capability,
promoting relaxation of these acoustic power limits (TRACK3).
Application
All regions
(except eyes)
With this trend, control of the level of acoustic power has been transferred from
manufacturers to users.
CAUTION:
(5) ALARA (As Low As Reasonably Achievable)
It is required to practice ALARA when using ultrasound energy. Practicing ALARA
ensures that the total energy level is controlled below a low enough level at which
bioeffects are not generated while diagnostic information is being accumulated.
The total energy is controlled by output intensity and total radiation time. The
output intensity necessary for examinations differs depending on the patient and
the clinical case.
CAUTION:
Maximum limit for MI/TI display (TRACK3)
Ispta.3
2
(mW/cm
720
The FDA allows ultrasound equipment to output acoustic
power level TRACK3, which is higher than TRACK1,
provided that MI/TI values are displayed on the system.
This means that users have a higher degree of
responsibility for safety than manufacturers. Against this
background, users are required to understand the
ultrasound bioeffects and their causes.
It is strictly required that acoustic output be set based on
the ALARA (As Low As Reasonably Achievable) principle.
However, not all examinations can be performed with an
extremely low level of acoustic energy. Controlling the
acoustic level at an extremely low level leads to low-quality
images or insufficient Doppler signals, adversely affecting
the reliability of the diagnosis. However, increasing the
acoustic power more than necessary does not always
contribute to an increase in quality of information required
for diagnosis, rather increasing the risk of generating
bioeffects.
Users must take responsibility for the safety of patients
and utilize ultrasound deliberately. Deliberate use of
ultrasound means that output power of ultrasound must be
selected based on ALARA.
No. 2B771-004EN*M
24-10
Isppa.3
2
)
(W/cm
)
or
<190
MI
<1.9
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