Treatment of benign diseases with megavoltage X-ray beams: is there a risk for gonadal damage?

AIMS: To measure the testicular and ovarian doses and to assess the risk for gonadal damage to patients treated with megavoltage X-ray beams for benign diseases.

MATERIALS AND

METHODS

Radiation therapy of benign diseases was simulated on an anthropomorphic phantom with a 6MV photon beam. The gonadal dose was calculated during the irradiation of heterotopic ossification, liver and vertebra haemangiomas, bone cysts, Graves' ophthalmopathy and gynaecomastia. Dose measurements were carried out using thermoluminescent dosimeters. For the radiotherapy of heterotopic ossification, the effect of using lead blocks to spare lymphatic drainage on the gonadal dose was determined.

RESULTS

The ovarian and testicular total doses were found to be 2.00-680 and 2.0-39.0 mGy, respectively, depending on the gonadal location in respect to the treatment volume. The introduction of blocks into the primary beam resulted in an increase in gonadal dose up to a factor of 1.7. The radiation-induced risk of hereditary disorders in future generations was (1.0-40.8) x 10(-4) and (1.0-23.4) x 10(-4) for women and men, respectively.

CONCLUSIONS

Radiation therapy of benign diseases always resulted in gonadal doses below 1 Gy and therefore there was no risk for permanent gonadal failure. The excess risk of radiation-induced hereditary disorders in offspring was low in comparison with the natural frequency of these effects. However, there was a considerable excess in risk after irradiation in the hip bone.