Patient release criterion after iodine-131 radionuclide therapy. The Iatropolis clinic experience

Abstract

Introduction Patient release criteria after radionuclide therapy are based on dose constraints and the potential contamination and exposure to other people with the aim of minimizing doses to family, close friends and other people as low as reasonably achievable. These dose constraints, together with certain recommendations on the behavior of the discharged patient are given in the European Commission’s Directive 97 on Radiation Protection and in the IAEA SRS No 63. Purpose The aim of the present work is to establish a criterion for patient release after Iodine-131 radionuclide therapy to be followed in our clinic. Materials and methods 400 patients were hospitalized in our clinic and treated for Iodine-131 therapy during a twelve month period approximately. For all patients, the equivalent absorbed dose rate @ 1m, R(1m,t), was measured with a survey meter (Victoreen, 451P) at 1 h, 24 h, 48 h and 72 h post administration. The NCRP 155 formalism was used to evaluate the Iodine-131 effective half-life for the patient population under investigation and to calculate the R(1m,t) that should not be exceeded in order to meet the dose constraint of 3 mSv for general public. Results According to our measured data, the remaining activity within the patient can be fitted with a single exponential function with an effective half-life of 48 h. The mean R(1m,48 h) was measured 17 μSv/h (min = 2 μSv/h, max = 45 μSv/h). The above measured dose rate results in an equivalent dose less than 3 mSv for the general public and occupancy factor equal to 1. Conclusion R(1m,48 h) ⩽30 μ Sv/h was established as a release criterion for Iodine-131 patients in our clinic. This criterion meets the dose constraint of 3 mSv and is considered safe for the general public. Disclosure Authors do not have any relationship that may bias this presentation.