Potential third-party radiation exposure from outpatients treated with 131I for hyperthyroidism

Area of Science:

• Nuclear Medicine
• Radiological Protection
• Endocrinology

Background:

• Radioiodine (131I) therapy is a common treatment for hyperthyroidism.
• Radiation protection guidelines necessitate dose constraints for individuals in contact with treated patients.
• Effective dose estimation is crucial for providing accurate radiation safety advice.

Purpose of the Study:

• To evaluate the efficacy of pretreatment dosimetry in predicting effective doses to travelers, co-workers, and sleeping partners of hyperthyroid patients treated with radioiodine.
• To determine if these predictions ensure compliance with European Commission effective dose constraints.
• To assess the risk of radioactive contamination from patients undergoing radioiodine therapy.

Main Methods:

• Thirty-three hyperthyroid patients received radioiodine therapy.
• Effective doses were estimated by integrating measured dose rates post-administration.
• Correlations between maximum thyroid uptake activity (AUmax) and effective dose were analyzed.
• Contamination potential was assessed via perspiration and saliva samples.

Main Results:

• Mean effective doses were 0.11 mSv (travelers), 0.24 mSv (co-workers), and 1.8 mSv (sleeping partners).
• Strong correlations were observed between AUmax and effective doses to all groups (r=0.88-0.93, p<0.01).
• Contamination risk was minimal, with low 131I activity levels detected in samples.

Conclusions:

• Pretreatment dosimetry reliably predicts effective doses from radioiodine therapy.
• Radiation protection advice based on dosimetry ensures compliance with dose constraints.
• Radioiodine-treated patients present a low risk of radioactive contamination to others.