For some isotopes which require a high Calibration Value,
you may observe fluctuations of ±0.5 µCi or more. Keep in
mind that the Calibration Value for an Isotope is related to
gain of the electrometer, or by what factor the electrometer
has to amplify the signal from the detector. The Calibration
for Tc-99m is 33.6, and a reading of 10 µCi for Tc-99m is
equivalent to 10-12 Amps measured by the electrometer.
High Calibration Values impact gains so that the electrome-
ter amplifies inherent noise to a greater degree. Thus,
greater fluctuations are observed in the Activity Display.
For instance, the Calibration Value for Co-60 is 5.0. The fluctua-
tion due to noise probably would not be noticeable (±0.01 µCi).
The fluctuation due to noise for Tc-99m (33.6) is approximately
±0.05 µCi. For an isotope requiring a Calibration Value of 500
(for P-32 it is 632) the fluctuation will be ±0.5 µCi or more.
The Atomlab Dose Calibrator begins averaging display data
the moment you press the Mo-99 key (Calibration Value
=180). This means that at first the fluctuations will seem rela-
tively high before gradually decreasing. This is why the
Atomlab Dose Calibrator provides the 30-second countdown.
In addition, the relatively high Calibration Value means the
fluctuation due to inherent noise will be slightly higher than
for the other common isotopes. Again, these fluctuations are
to be expected and do not require any action on your part.
UNEXPECTED READINGS
If for some reason you suspect that the reading on the
Activity Display is inaccurate, ensure that the Calibration
Value for the proper Isotope Selection key is correct.
DETERMINING THE CURRENT SOFTWARE VERSION
To verify the current Atomlab 100 Display Unit firmware level:
1) Press SETUP.
2) Press TEST. The Display Unit software level
will appear on the ETD (#1) window.
ATOMLAB Dose Calibrator Operation Manual Appendix A
Biodex Medical Systems A-3 Release 2.0
Display Fluctua -
tions For High
Calibration
Values
Mo-99
Fluctuations
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