Using TLD in determining the absorbed dose in the area outside the irradiation region after mastectomy

Abstract

Introduction: The most common cancer in women worldwide is breast cancer and radiotherapy is the best treatment choice after mastectomy.1,2 In the radiation therapy after mastectomy, depending on the type of tumor, the area of the breast removed goes under radiotherapy. Methods: TLD (Thermoluminescence Dosimetry) chips were used in this project. Typically, each patient under an irradiation of 200 cGy during 25 sessions received a total of 5000 cGy. Radiation therapies were performed in such a way that the patient was subjected to 10 MV photovoltaic radiations in a 10×10 Cm2 area in the mastectomy region. Meanwhile, according to the depth of the tumor inside the chest, the radiation of gamma rays of cobalt 60 was used in surrounding regions. The absorption dose coefficients were the same in the TLD obtained from the photovoltaic radiation 10MV and the gamma beam of cobalt 60. Results: Then the absorbed dose as calculated by hospital dosimeters standard was compared with the absorbed dose measured by TLD. The areas determined as zero absorption doses by Hospital dosimeters standard were calculated as non-zero absorbed dose by TLD. There were also areas where the doses calculated by TLD were different from the hospital dosimeters standard. Conclusion: To reduce the possibility of side effects of additional radiation, it is suggested that in the final absorption, which is determined for the patient during radiotherapy, doses be calculated for the area outside the treated area, too.