Dose Calibrator Linearity Testing Using an Improved Attenuator System

Nuclear Regulatory Commission (NRC) guidelines state that dose calibrators must be tested for linearity upon installation and quarterly thereafter over a range of activities from 10 ~J,Ci (370 kBq) to the highest dose administered to the patient (300 mCi [11.1 GBq] ofiodine-131 for therapy at our institution). The simplest method of linearity testing utilizes commercial attenuator kits. These kits consist of different attenuator tubes plus a central tube that remains in the dose calibrator during the entire testing process. The disadvantage of these kits is that the test has to be performed twice, once with a high activity source and a second time with a lower activity source, to cover the full range of activities required by the NRC. We have designed two accessory tubes that can be used in conjunction with a commercial attenuator system, thereby covering the range of activity required by the NRC with a single source of technetium-99m. It takes less than 4 min to complete the entire measurement with this improved linearity test kit.