Radionuclide impurity fraction algorithm and methods of implementation
AssigneeMirion Technologies Inc.
InventorsHenrik Ingvar Persson, Kara Elizabeth Phillips
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Abstract
This disclosure provides novel processes and methods of use for determining compliance with a maximum regulatory limit of an impurity radionuclide as compared to a primary radionuclide. The disclosed principles propose that a better and more defendable way is to calculate the activity and uncertainty of the impurity and primary radionuclide, and calculate the probability density of the ratio of the two normal probability density functions. From the probability density of the ratio, one can define an upper limit that the ratio can have with a certain confidence, and this number can be compared to the regulatory limit of the ratio of the activities in order to determine compliance with that regulatory limit.
Claims16
A method of determining an upper limit with a specified confidence of the ratio of measurements of the activities and their uncertainties of two radionuclides in a sample, the method comprising:
- measuring activity of a primary radionuclide and activity of an impurity radionuclide;
- calculating an uncertainty of the measured activity of the primary radionuclide and an uncertainty of the measured activity of the impurity radionuclide;
- determining a probability density of activity of the primary and impurity radionuclides based on the measured activity and calculated uncertainty of each of the primary and impurity radionuclides;
- establishing a probability density of the activity ratio of the impurity radionuclide to the primary radionuclide based on the determined probability density of the primary and impurity radionuclide, respectively;
- determining a normalization factor (N) to offset when the determined ratio probability density of the activity ratio of the impurity and primary radionuclides is non-zero for negative values;
- calculating an upper limit to a specified confidence of the activity ratio of the impurity and primary radionuclides given the measured activities and uncertainties and a-priori knowledge that the activity ratio cannot be negative;
- and
- indicating that the activity ratio of an impurity radionuclide to the primary radionuclide is below a predetermined limit if the calculated upper limit is equal to or below the predetermined limit.
Dependencies are inferred from the claim text.