J - 2 Operator’s Manual
J Acoustic Power Data and Surface Temperature Data
TIB
as,ns
Bone Thermal Index at-surface, non-scanning
TIB
bs,sc
Bone Thermal Index below surface, scanning
TIB
bs,ns
Bone Thermal Index below surface, non-scanning
TIC Cranial-bone Thermal Index
p
r,α
(z) Attenuated peak-rarefactional acoustic pressure, value of the peak-
rarefactional acoustic pressure after attenuation, at a specified distance
from the external transducer aperture in MPa.
P Output power, the time-average power in mW, radiated by an ultrasonic
transducer into an approximately free field under specified conditions
in a specified medium, preferably water.
P
1×1
Bounded-square output power, the time-average acoustic output power
in mW, emitted from any one-centimetre square region of the active
area of the transducer. The one-centimetre square region having 1cm
dimensions in the x- and y-directions.
z
s
Depth for TIS below surface for non-scanning modes in centimeter, is
the distance along the beam axis from the external transducer aperture
to the plane at which the lower value of the attenuated output power and
the product of the attenuated spatial-peak temporal-average intensity
and 1cm
2
is maximized over the distance range equal to, or greater
than, the break-point depth, z
bp
z
b
Depth for bone thermal index for non-scanning modes in centimeter, is
the distance along the beam axis from the external transducer aperture
to the plane where the product of attenuated output power and
attenuated spatial-peak temporal-average intensity is a maximum over
the distance range equal to, or greater than, the break-point depth, zbp.
z
bp
Break-point depth in centimeter, is the closest distance to the solid
surface of the transducer or the enclosure of any stand-off path, is given
by (centimeters)
A
aprt
The -12dB output beam area, which can be calculated as the area of
active aperture.
z
MI
Depth for mechanical index, is the depth on the beam axis from the
external transducer aperture to the plane of maximum attenuated pulse-
intensity integral (pii
α
)
z
pii,α
Depth for peak attenuated pulse-intensity integral, is the depth on the
beam axis from the external transducer aperture to the plane of
maximum attenuated pulse-intensity integral (pii
α
)
f
awf
Acoustic working frequency in MHz, is the arithmetic mean of the most
widely separated frequencies f
1
and f
2
at which the amplitude of the
acoustic pressure spectrum is 3dB below the peak amplitude
prr Pulse repetition rate in Hz, is the reciprocal of the time interval between
two successive acoustic pulses.
srr Scan repetition rate in Hz, is the reciprocal of the scan repetition period
which is the time interval between indentical points on two successive
frames.
n
pps
Number of pulses per ultrasonic scan line, is the number of acoustic
pulses traveling along a particular ultrasonic scan line
Symbol Description
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