Therapeutic external irradiation in women of reproductive age: risk estimation of hereditary effects.

Exposure of women of childbearing age to ionizing radiation may result in induction of genetic disorders in future generations. This study aims to estimate the risk of hereditary effects attributable to therapeutic external irradiation in women. An anthropomorphic phantom was used to simulate radiotherapy in female patients and ovarian dose was measured for irradiation of brain, breast and lung cancer, and for treatment of Hodgkin's disease. These malignancies are among the most common tumours presenting in women of reproductive age. Dose measurements were undertaken using thermoluminescent dosemeters and all exposures were made with 6 MV X-ray beams. The dose to ovaries was found to be 2-3 cGy, 8-11 cGy and 11-15 cGy depending on the distance from the primary irradiation field during radiotherapy of brain, breast and lung cancer, respectively. The corresponding ovarian dose resulting from treatment of supradiaphragmatic and infradiaphragmatic Hodgkin's disease was 18-25 cGy and 128-356 cGy, respectively. A small excess risk of genetic diseases of (1-15) x 10(-4) was estimated for radiotherapy above the diaphragm. Pelvic irradiation resulted in an increased risk of hereditary effects of (77-214) x 10(-4).