Esaote MyLab, Operator'S Manual

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M y L a b – S A F E T Y A N D S T A N D A R D
2-8
Maximum Acoustic Output
This system does not use the historic FDA limits for Isppa and Imax, but rather
the recently adopted MI, which is now considered a better relative indicator of
non-thermal bioeffect mechanisms. The maximum MI is below 1.9 (see the
“Getting Started” manual for your model actual maximum); the FDA has
recognized this value as equivalent to preamendments Isppa limits. The maximum
output for Ispta is limited to the preamendments FDA limit for peripheral vascular
applications (720 mW/cm
2
).
Other application limits have been established as per this table:
Application Preamendments Ispta
Limits (mW/cm2)
MyLab Maximum
(mW/cm2)
OB/Fetal 94 430
Cardiac 430 720
Pediatric 94 430
Peripheral Vascular 430 720
Other 94 720
The maximum output for a given probe can be less than the system limit, since the
maximum depends on various elements (crystal efficiency, mode of operation, …).
Acoustic Output Controls
Control features may be divided into three categories:
1.
controls which directly affect the intensity ( direct controls)
2.
controls which indirectly affect the intensity ( indirect controls)
3.
controls, which do not affect the intensity, such as the gains and the
processing curves.
Controls Which Directly Affect the Intensity
This category includes two system controls:

the application selection, which establishes the appropriate range of
intensities (see maximum output section); the application also
establishes the indices to be displayed;

the POWER control, which allows an increase or decrease in the
output intensity within the range of the selected application. This
parameter will affect both the MI and the TI values.
Controls Which Indirectly Affect the Intensity
This category includes controls, which change several aspects of the transmitted
ultrasonic field rather than the intensity. Intensity is affected because of the field
variations. Each mode has its own pulse repetition frequency (PRF) and intensity
level; moreover, for each mode, a number of parameters will indirectly affect the
transmitted field.
M A X I M U M
O U T P U T

MI < 1.9

Ispta<720 mW/cm
2
D I R E C T
C O N T R O L S

the Application
 the POWER
I N D I R E C T
C O N T R O L S
 PRF
 Focal Point
 Frequency
 CFM Process
 Sample Volume