CAPINTEC, INC. CRC
®
-25R
MEASUREMENT PROCEDURES
Note: In order to obtain a correct reading for a Vial or Syringe, the supplied liner and dipper
must be used to achieve the correct geometry. If the source is contained in a different
type of container, then contact Capintec, Inc. for further assistance.
General Activity Measurement Procedure
To measure the activity of a sample:
• Insert the sample into the Chamber.
• Specify the Nuclide or input a Calibration Number.
To print a record of the measurement (if a printer is attached to the system):
• Press ENTER.
To determine what the activity will be at a different time:
• Press TIME.
Optimizing Low Activity Measurements
The CRC
®
-25R Calibrator has a stated resolution of 0.01µCi, which means that it is capable
of detecting activities in the range of a few hundredths of a microcurie.
However, in order to perform meaningful measurements at such a low level, the following
conditions must be met:
• The calibrator must be in excellent (as new) working condition (without excessive low
end noise or fluctuations),
• The measurement must be made in a low background area, with constant ambient
background rate, and
• The measurement should be made over a 2 minute period, taking measurements
every 5-10 seconds and the final value averaged.
A low activity rod source for a long-lived isotope (0.05µCi) would be very useful as a QC
source to confirm measurement capabilities at low activities.
Specifying Nuclide
A nuclide may be specified via one of the Pre-Set Nuclide keys, one of the USER keys or via
the NUCL key.
Pre-Set Nuclide key:
Press one of the 8 pre-set nuclide keys
F18, Ga67, Tc99m, In111, I123, I131, Xe133, Tl201
10 - 2 MEASUREMENT PROCEDURES March 15
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