Radiation protection principles for radioiodine therapy

In Germany, approximately 30,000 treatments with radioiodine are performed yearly in patients with benign or malignant thyroid diseases. These are car ried out generally in specialized therapy wards which are equipped with rad iation protection facilities. Ambulant (fractionated) radioiodine treatment is not permitted in Germany. More recently, the situation has been that th e discharge of patients is permitted, when they have spent a stay of at lea st 48 hours in the ward without the dose rate exceeding 3.5 mu S nu/hour at 2 meters distance from them, corresponding to 1 mS nu/year (this correlate s to a residual activity in the body of the patient of 250 MBq). The radiat ion exposure of personnel in the therapy ward dire to both external and int ernal exposure lies within a range of a few mS nu per year. According to re cent studies the exposure to family members and close friends via external exposure, inhalation or incorporation does not exceed the effective dose of 1 mS nu/year, provided the patient has been treated at least for 48 h as a n in-patient. This value has been laid down in a recommendation by the Euro pean Union as the dose constraint for children; for adults younger than 60 years of age, 3 mS nu are recommended, for older persons 15 mS nu.