Measurement of peripheral dose to pelvic region and associated risk for cancer development after breast intraoperative electron radiation therapy

摘要： This study aimed to measure received dose to the pelvic region of patients during breast intraoperative electron radiation therapy (IOERT). Furthermore, we compared the findings with those of external beam radiation therapy. Finally, secondary ovary and uterus cancer risks following breast IOERT were estimated. In the current study, the received dose to the pelvic surface of 18 female patients during breast IOERT boost were measured by thermoluminescent dosimeter (TLD-100) chips. All patients were treated with 12 Gy given in a single fraction. To estimate the dose to the ovary and uterus of the patients, conversion coefficients for depth from surface dose were obtained in a Rando phantom. Given the received dose to the pelvic region of the patients, secondary ovary and uterus cancer risks following breast IOERT were estimated. The received doses to ovary and uterus surface of the patients were 0.260±0.155 mGy to 31.460±6.020 mGy and 0.485±0.122 mGy to 22.387±15.476 mGy, respectively. Corresponding intra-pelvic (ovary and uterus) regional doses were 0.012±0.007 mGy to 1.479±0.283 mGy and 0.027±0.001 mGy to 1.164±0.805 mGy, respectively. Findings demonstrated that the ratio of the received dose by pelvic surface to regional dose during breast IOERT was much less than external beam energies were 135.722±117.331 × 10-6 and 69.958±28.072 × 10-6, and for uterus were 17.342±10.583 × 10-6 and 2.971±3.604 × 10-6, respectively. According to our finding, the use of breast IOERT in pregnant patients can be considered as a safe radiotherapeutic technique, because the received dose to the fetus was lower than 50 mGy. Furthermore, IOERT can efficiently reduce the unnecessary dose to the pelvis region and lowers the risk of a secondary ovary and uterus cancer following breast irradiation.