CAPINTEC, INC. CAPRAC
®
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6-12 WELL COUNTER INITIALIZATION April 2021
Note: A Wipe Full Spectrum Efficiency value must be entered in the setup at all times.
Full spectrum means the total number of counts detected in all of the MCA channels. This is
the nominal value for Full Spectrum Efficiency for Tc99m when measured in a 1.5” × 1.75”
drilled well detector.
The default value for Full Spectrum Efficiency can be changed as required. To change the
Full Spectrum Efficiency, two methods are suggested:
1. Set the Full Spectrum Efficiency to the efficiency of the isotope that is used most
frequently at your facility. For example, general nuclear medicine facilities use Tc99m
most often, while nuclear cardiology facilities most frequently use Tl201. This method
will provide an accurate value for most of the wipe tests measured.
2. Calculate the total spectrum efficiency for several isotopes most frequently used. Set
the Full Spectrum Efficiency to the lowest efficiency. This will provide a conservative
estimate for activity by overestimating the activity of most wipes.
To calculate Full Spectrum Efficiency, first measure the nuclide in General
Measurement mode. The total count rate will appear on the printout in units of cpm.
Next convert the current activity of the nuclide measured in General Measurement
into units of dpm. Remember that 1µCi = 2.22 x 10
6
dpm. Then calculate the Full
Spectrum Efficiency.
minuteper
tionsdisintegra
100minuteper counts
Efficiency %
×
=
To view or change this value, touch the EDIT WIPE FULL SPECTRUM EFFICIENCY button.
The Edit Wipe Full Spectrum Efficiency screen will appear showing the currently set
efficiency value.
If the current value is correct, touch the CANCEL button. Figure 6-10 Efficiencies Setup
Screen will re-appear.
If the current value is not correct, touch the Full Spectrum Efficiency: field box.
The numeric keypad will appear. Input the desired efficiency value by touching the
appropriate numbers on the keypad. Touch the ACCEPT button to accept the entered
number. Touch the CANCEL button to abort any changes.
Note: The minimum Efficiency value is 0.001. The maximum Efficiency value is 99.999.
The Edit Wipe Full Spectrum Efficiency screen will re-appear showing the currently set
efficiency value. Touch the ACCEPT button to accept the displayed value. Touch the
CANCEL button to abort any changes. Figure 6-10 Efficiencies Setup Screen will re-appear.
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