15
the UFU. Up to 6 of the most recent average count rates can be
displayed, and they can be removed by touching the stored
count rate on the display.
To change the audio scale to match the count range:
Hold the
‘
+
’
button for 2 seconds
–
at which time “
High
Range”
will be
announced, and the audio feedback will reflect the higher
range. Clicking the ‘
-
’ button will togg
le back to low Range.
6.
IN SURGERY
CHANGING MODES
Three photon energy-resolving modes are available --
‘Scan’ and
‘Point’
modes are used for detecting Tc-99m and
‘Seed’ mode
is
used for detecting I-125.
Scan mode
provides higher-sensitivity because it counts
more gamma photons that have been scattered while in
transit from their source to the probe
’s d
etector. This allows
the user to survey wider areas more quickly than Point mode.
The relatively higher number of gamma photons that are
detected produce more rapid count-rate feedback
information, and Scan mode accepts scattered gamma
photons with lower energy than Point mode, and thus could
have emanated from a wider region. Scan mode can be used
for surveying larger areas, more quickly, especially when
there is less background or scattered radiation (e.g. from the
injection site or from nearby organs that uptake radiotracer).
Scan mode can also be used to obtain more accurate ex-vivo
specimen count rates because of its wider angle of
acceptance for scattered gamma photons that may be
emanating from the specimen.
