PadScan HD 2
Caresono Technology Co., Ltd
34
Appendix C: Definitions and Symbols
MI
the Mechanical Index
TISscan
the Soft Tissue Thermal Index in an auto-scanning mode
TISnon-scan
the Soft Tissue Thermal Index in a non-auto-scanning mode.
TIB
the Bone Thermal Index.
TIC
the Cranial Thermal Index.
Aaprt
the area of the active aperture (square centimeters).
pr.3
the derated peak rarefractional pressure associated with the transmit pattern
giving rise to the value reported under MI (megapascals)
Wo
For TIB and TIC: time average acoustic power at the source, in milliwatts. (Also
see the definitions for W
01
and W
01x1
that follow.) For TIS scan, W
o =
W
o1 +
W
o1x1
For TIS non–scan, W
o =
W
o1x1
W
o1:
For scanning modes and/or scanning components of combinational
modes: time average acoustic power at the source, per cm, in milliwatts. This is
the acoustic power emitted from the central 1–cm length, in the scan direction, of
the aperture corresponding to the scanned pulses.
W
o1x1:
For non–scanning modes and/or non–scanning components of
combinational modes: time average acoustic power at the source, per cm
2
, in
milliwatts. This is the acoustic power emitted from the central 1 cm
2
of the active
non–scanned aperture through which the highest acoustic power is being
transmitted.
W
.3
(z
1
)
the derated ultrasonic power at axial distance z
1
(milliwatts
I
TA.3
(z
1
)
the derated spatial-peak, temporal-average intensity at axial distance z
1
(milliwatts per square centimeter).
z
1
the axial distance corresponding to the location of max[min(W
.3
(z), I
TA.3
(z) x
1cm
²
)], where z = z
bp
(centimeters).
z
bp
1.69
√Aaprt
(centimeters).
z
sp
For MI, the axial distance at which p
r.3
is measured for TIB, the axial distance at
which TIB is a maximum (i.e., z
sp
= z
B.3
)
(centimeters).
deq(z)
the equivalent beam diameter as a function of axial distance z, and is equal
to
[(4/ )(W
o
/I
TA
(z))]
0.5
where I
TA
(z) is the temporal-average intensity as a
function of z (centimeters).
fc
is the center frequency (MHz). For MI, fc is the center frequency associated with
the transmit pattern giving rise to the maximum reported value of MI. For TI, for
combined modes involving transmit patterns of unequal center frequency, fc is
defined as the overall range of center frequencies of the respective transmit
patterns.
Dim. of Aaprt
the active aperture dimensions for the azimuthal and elevational planes
(centimeters).
PD
the pulse duration (microseconds) associated with the transmit pattern giving rise
to the reported value of MI.
