Analysis of the caregiver effective dose during I-131 therapy of thyroid.

Aims: The main objective of the present research is to analyze the caregiver effective dose during I-131 therapy of thyroid in some different situations using MCNP4C Monte Carlo code.

Patients And Methods: Two separate whole body Medical Internal Radiation Dosimetry (MIRD) phantoms have been defined simultaneously in a single Monte Carlo N-Particle (MCNP) input file as the patient and the caregiver. Two different groups of irradiation situations have been assumed for the caregiver related to the patient, (1) both the patient and the caregiver are standing and (2) the patient is lying in the bed while the caregiver is standing beside the patient.

Results: The results show that the caregiver effective dose is highly dependent on the position of the caregiver related to the patient. When the patient is lying on the bed and the caregiver is standing beside the patient near the head of the patient, the effective dose of caregiver will be the maximum value.

Conclusions: Although the maximum effective dose (0.2 mSv) is smaller than the allowed value for caregivers (5 mSv for each treatment), the final results of this research indicate the importance of caregiver position in close contact with the patient.