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Point mode
provides higher-spatial resolution because it
rejects low energy gamma photons that have been scattered
while in transit from their source to the
probe’s
detector.
This allows the user to more precisely locate the source of
the gamma photons: only those photons that have been
minimally-scattered between their source and the pr
obe’s
detector are counted, so the influence of background and
scattered radiation is reduced. Point mode can be used
when searching for hotspots where there is predominate
background or scattered radiation (e.g. from the injection
site or from nearby organs that uptake radiotracer), and
when attempting to more accurately localize small
radioactive hotspots.
Seed mode preferentially
accepts photons from I-125, while
rejecting the majority of photons from nearby Tc-99m. This
can be useful for detecting I-125 seeds or other sources of I-
125 isotope.
CHANGING THE AUDIO SCALE TO MATCH THE INCOMING
COUNT RATE
A range of audio feedback is produced in proportion to the range of
detected count rates. An increase in pitch and beat frequency
indicates an increase in detected count rate. Two audio ranges are
used to cover the range of count rates detectable by the
TruNode®
system. When the Probe is initialized, it defaults to the low range,
producing audio feedback for count rates up to 2,000 counts per
second. When more than 2,000 counts per second are detected, the
very high pitched sound alerts the user that the high range may be
needed. High range detects photons up to 10,000 counts per
second.
NOTE: The selected range does not affect the digital count display
or the count rate-meter.
