Olympus EVIS EXERA II - Page 243

Appendix D: Acoustic Output Information in Accordance with the FDA Guidance: “Information for Manufacturers
237
ULTRASOUND GASTROVIDEOSCOPE GF-UCT180
d
eq
(Z
sp
) Equivalent beam diameter as a function of axial distance z, and equal
to [(4/π) (W
0
/I
TA
(z))]
0.5
, where I
TA
(z) is the temporal-average intensity
as a function of z (centimeters)
f
c
Center frequency (MHz). For MI, f
c
is the center frequency associated
with the transmit pattern giving rise to the global maximum reported
value of MI. For TI, for combined modes involving transmit patterns of
unequal center frequency, f
c
is defined as the overall ranges of center
frequencies of the respective transmit patterns
Dim. of A
aprt
Active aperture dimensions for azimuthal (x) and elevational (y)
planes (centimeters)
PD Pulse duration (microseconds) associated with the transmit pattern
giving rise to the reported value of MI
PRF Pulse repetition frequency associated with the transmit pattern giving
rise to the reported value of MI (Hz)
p
r
@PII
max
Peak rarefactional pressure at the point where the free-field,
spatial-peak pulse intensely integral is a maximum (megapascals)
d
eq
@PII
max
Equivalent beam diameter at the point where the free-field,
spatial-peak pulse intensity integral is a maximum (centimeters)
FL Focal length, or azimuthal (x) and elevational (y) lengths, if different
(centimeters)
I
PA.3
@MI
max
Derated pulse-average intensity at the point of global maximum
reported MI (watts per square centimeter)
I
SPTA.3
Derated spatial peak temporal average intensity (milliwatts per square
centimeter)
Derated I
SPTA
Derated spatial peak temporal average intensity (milliwatts per square
centimeter)
PII Pulse intensely integral