Impact of Three Dimensional-Conformal Radiation Therapy (۳D-CRT) Fractionation Technique on Radiobiological Effects and Risk of Secondary Cancers: A Case Study of Post-Mastectomy Breast Cancer

Introduction: The study aimed to analyze and determine impact of the ۳D-CRT fractionation on risk of secondary cancer. Material and Methods: This study used a patient-specific anthropomorphic phantom, and radiation was performed using the Three Dimensional-Conformal Radiation Therapy Field in Field (۳D-CRT FinF) technique with conventional, hypofractionation, and hyperfractionation with a dose of ۲۰۰ cGy, ۲۶۰ cGy, and ۱۶۰ cGy in ۲۵, ۱۶, and ۳۰ fractions respectively. It focused on the contralateral breast, contralateral lung, and ipsilateral lung as Organs at Risk (OAR). In addition, the Dose Volume Histogram (DVH) value, normal tissue complication probability (NTCP), and risk of secondary cancer were evaluated.Results: The results showed that the average dose value (Dmean) for ipsilateral lung with hypofractionation was smaller than conventional and hyperfractionation of ۱۵۱۹.۸, ۱۸۲۶.۷, and ۱۷۵۳.۶ cGy, respectively. Furthermore, hypofractionation also reduced radiobiological effects by ۵۰% in the ipsilateral lung with an NTCP value of ۰.۰۱% compared to conventional and hyperfractionation with a value of ۰.۰۲%. Hypofractionation reduces the risk of secondary cancer in the contralateral breast, contralateral lung, and ipsilateral lung by ۱۶.۳۸, ۱۷, and ۲۲.۳۱% compared to conventional fractionation and ۱۲.۷۵, ۱۳.۵۴, and ۲۱.۳۴% compared to hyperfractionation, respectively. Conclusion: The dose profiles in OAR was smaller in treatment planning with hypofractionation. EBT۳ film verification results showed that the ipsilateral lung received more doses than planned, with an insignificant difference (p>۰.۰۵). In radiobiology, the ipsilateral lung has the highest probability of complications in treatment planning with conventional fractionation and hyperfractionation.

کلیدواژه ها:

Radiation Dose Fractionation Radiotherapy Radiation ، Induced Cancer Radiobiology