Aim: Patients exhale I-131 after radioiodine therapy. In this study we quantify the amount of radioactivity and resulting thyroid doses found in people living in close contact to patients treated with I-131 after their release from a therapy ward.
Methods: For 31 relatives of 25 patients treated with I-131 the incorporation was monitored using the thyroid probe of a whole body counter. These values are used for a determination of thyroid doses.
Results: 11 of the 31 monitored persons had a thyroid activity of less than the minimal detectable activity of 13 Bq. The mean value of the remaining 20 people was 104 Bq in the thyroid resulting in a mean thyroid dose of 0.2 mSv (Maximum: 2 mSv).
Conclusion: The intake of I-131 for persons in close contact to patients after dismissal from a therapy ward is low. In no case an effective dose exceeding 1 mSv was observed.