Micro-dose calibrator
AssigneeThe United States of America, as represented by the Secretary, Department of Health and Human Services
InventorStephen S. Adler
Life of this patent
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Abstract
Methods and apparatus for calibrating radioactive sources are described. An array of scintillation detectors forms a receptacle within which a sample or sample container can be retained by a holder. The scintillation detectors are coupled via light transducers such as photomultiplier tubes (PMTs) to independent electronic counters. Coincidence processing of time-tagged events yields a correlated event rate. One or more corrections can be applied as needed, for background counts, deadtime, or random coincidences. Voltage tuning of PMTs yields improved reproducibility. Accuracy of 1% has been demonstrated over a range of 10 kBq-3 MBq.
Claims20
An apparatus for calibration of a radioactive micro-dose sample, the apparatus comprising:
- a receptacle containing a sample chamber and configured to retain the radioactive micro-dose sample;
- an array of at least three scintillation detectors disposed around the sample chamber;
- an array of light transducers, each light transducer optically coupled to a respective one of the scintillation detectors;
- and
- a plurality of electronic counters comprising an electronic counter for each respective scintillation detector;
- wherein each light transducer is electrically coupled to a respective one of the electronic counters for independently counting radioactive decay events of the micro-dose sample detected by the respective scintillation detector.
One or more computer-readable media storing instructions which, when executed by one or more hardware processors, cause the one or more hardware processors to perform operations comprising:
- synchronizing respective counting electronics for an array of at least three scintillation detectors;
- and
- time-tagging and counting digital packets of micro-dose decay events independently for each of the scintillation detectors.
A method for calibrating a radioactive micro-dose, comprising:
- providing a ring of scintillation detectors coupled by photodetectors to respective counting electronics;
- tuning high-voltage power supplies coupled to the photodetectors so that photopeaks of particles emitted by a radioactive calibration source appear at aligned energy channels at the respective counting electronics;
- positioning a sample container containing a radioactive micro-dose at a central location of the ring of scintillation detectors;
- synchronizing the counting electronics;
- time-tagging decay events detected at the scintillation detectors, independently for each scintillation detector;
- detecting coincidences among the time-tagged decay events from two or more of the scintillation detectors;
- aggregating time-tagged decay events from the scintillation detectors, with coincidences being singly counted, to obtain a correlated event rate;
- determining a micro-dose radioactivity level by applying at least a basic calibration factor to the correlated event rate;
- and
- reporting the determined micro-dose radioactivity level.
Dependencies are inferred from the claim text.