Assessment of a carcinogenic risk for treatment of Graves' ophthalmopathy in dependence on age and irradiation geometry

In view of the probable carcinogenic risk due to the irradiation of Graves' ophthalmopathy in young patients the effective dose was assessed for two geometries, Adjusting the field to the conical outline of the orbit resulted in appreciable reduction in dose to uninvolved areas such as brain and bone marrow. In Leiden and in Essen the initial target dose was 20 Gy in 10 fractions of 2 Gy. Since 1996 the target dose in Essen was lowered to 10 fractions of 1.6 Gy with equal positive results. The combined effect of field optimization and 20% reduction in target dose has lowered the effective dose from 65 to 34 mSv, The attributable lifetime risk for fatal malignancies of 0.3% as a population average will be considerably reduced when the exposure occurs at older age. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.