Selection of Key Socio-Economic Factors for Establishing Relese Criteria Patients after Radioioidine Therapy

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Purpose: To assess the association between socioeconomic factors and release criteria after iodine-131 radionuclide therapy in different countries. Material and methods: 15 countries and 104 socioeconomic characteristics were selected for the study. The association between characteristics and the residual activity level at which a patient may be released for different countries was established according to the value of Pearson product moment correlation coefficient (r>0.3). A linear regression model was constructed for the selected characteristics using Microsoft Excel analysis package. The model was used to calculate the acceptable activity level at which a patient may be released for Russia. Results: A fundamental difference between the model used for calculation of release criteria after radionuclide therapy with iodine-131 in Russia and the model recommended by the Nuclear Regulatory Commission was shown: the use of the effective half-life in the second one. Replacing the physical halflife by the effective half life allows increasing the discharge criteria of patients after therapy with Na131I by 30 %. A moderate correlation was found between the value of acceptable activity at patient discharge after radioactive iodine therapy and the following socioeconomic characteristics: scientific activity (r=0.32), quality of higher education (r=0.36), Global Health Security Index (r=0.34), length of roads (r=0.36), population growth rate (r=0.36), average housing area (r=0.38), and average salary per year (r=–0.33). A linear regression was constructed using the factors listed above. The following recommended value of activity and effective dose rate at patient discharge from hospital was obtained: 0.6 GBq and 30 µSv/hour. Conclusion: The study demonstrates that the release criteria for radioactive iodine therapy used in the Russian Federation (0.4 GBq and 20 µSv/h) do not correspond to the standard of living achieved in Russia, which is reflected by the socio-economic factors considered in the paper. The proposed arguments raise the task of revising the currently used model with a consequent increase in the discharge criteria. It was observed that the release criteria in the world are independent of some factors that are directly related to population exposure. The need to develop a unified objective algorithm for establishing release criteria, which takes into account different socio-economic status of states and can be applied for different radionuclides and radiopharmaceuticals, including innovative ones, has been identified.