Document Type : Original Paper
Department of Physics, Institut Teknologi Sepuluh Nopember, Kampus ITS Sukolilo &ndash; Surabaya 60111, East Java, Indonesia
Department of Physics, Institut Teknologi Sepuluh Nopember (ITS)
Department of Physics, Faculty of Science, Institut Teknologi Sepuluh Nopember, Surabaya, Indonesia
Department of Radiation Oncology, MRCCC Siloam Hospitals
Purpose: The study aimed to analyze and determine fractionation on radiobiological effects and the risk of post-mastectomy left breast secondary cancer.
Materials and Methods: This study used a patient-specific anthropomorphic phantom, and radiation was performed using the Three Dimensional-Conformal Radiation Therapy Field in Field (3D-CRT FinF) technique with conventional, hypofractionation, and hyperfractionation with a dose of 200 cGy, 260 cGy, and 160 cGy in 25, 16, and 30 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 1519.8, 1826.7, and 1753.6 cGy, respectively. Furthermore, hypofractionation also reduced radiobiological effects by 50% in the ipsilateral lung with an NTCP value of 0.01% compared to conventional and hyperfractionation with a value of 0.02%. It decreased the risk of secondary cancer for the contralateral breast, contralateral lung, and ipsilateral lung by 16.38, 17, and 22.31% against conventional fractions and reduced 12.75, 13.54, and 21.34% risk of hyperfractionation, respectively.
Conclusion: The dose distribution in OAR was smaller in treatment planning with hypofractionation. EBT3 film verification results showed that the ipsilateral lung received more doses than planned, with an insignificant difference (p>0.05). In radiobiology, the ipsilateral lung has the highest probability of complications in treatment planning with conventional fractionation and hyperfractionation.