Radiation Risk Assessment to the Fetus for Patients with Three-Dimensional Conformal Radiation Therapy on the Breast Area

Abstract

Objective: The purpose is to study outcome of radiation risk assessment to the fetus if patients have an incidence of pregnancy during three-dimensional conformal radiation therapy on the breast area.

Methods: This is an analytic study; the lower abdomen and pelvic cavity doses were measured in 32 breast cancer patients who received three-dimensional conformal radiation therapy underwent linear accelerator (LINAC) with a total tumor prescribed dose of 5,000 cGy (200 cGy x 25 fractions). The glass dosimeter chips were used for these measurements. For each patient, 3 glass dosimeter chips were placed on the skin surface at the top of iliac crest, umbilicus, and 10 cm under umbilicus.

Results: Most of the patients received irradiation were over 60 years old, 28.1%; and under 45 years were rare, 12.5%. The mean dose of the lower abdomen and pelvic cavity was 19.7 ± 94.7 cGy, average 0.4% of the tumor prescribed dose. For second week of gestation, the fetus dose ranged from 0.8–8.0 cGy. For fourth and sixth week, the fetus doses ranged from 8.8–16.0 cGy and 16.8–19.7 cGy respectively.

Conclusion: Mostly three-dimensional conformal radiation therapy on the breast area, the total tumor prescribed dose is 5,000 cGy. The mean of the fetus dose is 0.4%, which the radiation risk depends on the gestation and the amount of radiation received.