Radiation safety problems during the patient traveling by public transport after radiopharmaceutical therapy with 131I

Radiopharmaceutical therapy with 131I has been one of the most common types of radiopharmaceutical therapy  for  many  years.  Radiation  safety  of  the  public  is  ensured  by  limiting  the  patient  contacts  until  the radiological parameters are reduced to the established criteria. To increase the availability of the radiopharmaceutical therapy with 131I, softer patient release criteria for 131I have been proposed. However, early patient release may increase exposure to the public, e.g. in transport. The aim of the work is to evaluate the radiation exposure  from  patients  with 131I -MIBG  and  Na131I on  the  public  in  transport  considering  the  generation  of biological waste. In this work, 131I excretion from the body of patients in transport was evaluated for different scenarios of patient travel to the place of residence. As a result, it was found that mitigation of patient release criteria leads to an increase in the effective dose to the public in transport and an increase in the 131I activity excreted with patient waste. The specific activity in the tanks of biotoilets in transport, generated after the pas -sage of a patient with injected 131I -labeled radiopharmaceuticals, exceeds the limit value of classifying liquid waste as radioactive. To optimize radiation protection of the public, it is advisable to apply a differentiated approach to release patients after therapy with 131I: to group non-resident patients into a separate category retaining for them the established release criterion (without mitigation) to minimize the radiation impact on the public.