biodex ATOMLAB 500, Operation And Service Manual, Page: 68 / 212

To Measure An Isotope:
1. Touch the appropriate <Isotope> key. This tells the detector what dial value to use in the
calculations.
2. Place the isotope in the detector. The activity level is immediately displayed.
Changing the Selected Isotope
The selected isotope can be changed at any time with the activity for the new isotope displayed
within one second. Touch <Select Isotope> to display the full alphabetical isotopes list (see
Figure 4.66).
Isotope Response Time
The Atomlab 500 normally settles within three seconds as long as the minimum threshold level
is exceeded. When the source is first lowered into the well, the activity value quickly jumps to
the final value. For a few seconds, the value may fluctuate, but the value will settle down to a
small variation. As soon as the source is removed from the detector Well, the activity display
will drop down to a near zero value.
NOTE: Both the Detector Well Liner and Sample Holder should be periodically checked for
contamination as described in Appendix J under Records and Maintenance, Dipper and Well
Liner. (The more the dose calibrator is in use, the greater the frequency of contamination
checks required.)
Determining Dial Value Adjustments
Figure 5.3.
The Dial Value Adjustment screen.
The dial value adjustment screen allows the user to easily determine a modified dial value for
an isotope when a sample of a known activity is available. This adjustment is ideal for Beta
isotope samples that come in different configurations from different pharmacies. The user can
determine the proper dial value for the specific syringe or vial that is being used. Note that the
wall thickness and material can greatly affect the activity for a Beta sample.
This screen is also helpful if modifying the F-18 dial setting for a NIST traceable Ge-68/F-18
source. It can also be used for determining the dial value of any other isotope.