biodex ATOMLAB 500, Руководство по эксплуатации и обслуживанию, Страница: 98 / 212

Linearity Testing
Figure 6.42. The Linearity Testing Screen
The linearity test is used on a dose calibrator to determine the variation in the displayed activity
values from the true values, over a linear range of proportional source activities.
This test is usually performed using a vial or syringe of Tc-99m whose activity is at least as
large as the maximum activity normally assayed in a prepared radiopharmaceutical kit, in a
unit dosage syringe, or in a nuclear pharmaceutical therapy, whichever is largest.
Linearity means the proportionality of the measurement results to the activity measured, as
determined over the intended range of use for the dose calibrator.
NOTE: Other Isotopes such as F-18 can be used to perform linearity testing.
There are several acceptable methods for performing linearity testing. The differences in
these methods are all acceptable for determining the normalized value.
1. Decay correct the test sample from the first reading and compare each reading to the
decay corrected reading.
2.
For Tc-99m, select 30 hours as the normalized reading and decay correct this reading
to calculate the expected activities at the times the readings were taken. Compare
the readings to the calculated activities. The user can change from 30 hours to
another time point and perform a normalized calculation from that time point. The
Atomlab 500 automated linearity test uses 30 hours as the default method.
3. The average decay method described decay corrects each reading, averages
these calculated activities, and divides the average by the time corrected reading
to determine a correction factor. If the correction factor is between certain values,
the calibrator is linear.
Linearity Testing Options Include:
•
Manual Decay Test
•
Semi-Automated Decay Test
•
Automated Decay Test
•
Lineator Initial Test
•
Lineator Test
•
Calicheck Initial Test
•
Calicheck Test