Author: Marwa Y. Abdel Tawwab, Amin E Amin, Abdullah M. ElSharif, Somaia Metwally Elsayed, Magdy M. Khalil 👨🔬
Affiliation: School of Applied Health Science, Badr University in Cairo (BUC), Cairo, Egypt, Medical Physics, Radiation Oncology Department, Faculty of Medicine, Ain Shams University, Medical Biophysics, Department of Physics, Faculty of Science, Helwan University 🌍
Purpose: Prostate cancer radiotherapy typically employs conventional fractionation schedules over approximately eight weeks. This study investigates the effect of variations in the α/β ratio on dose constraints, aiming to design iso-effective schedules that achieve equivalent biological effects while reducing treatment duration and enhancing the therapeutic ratio.
Methods: Low- and intermediate-risk prostate cancer patients treated at Ain Shams University Hospitals, Cairo, Egypt, underwent CT imaging using a Toshiba Aquilion scanner. Treatment planning was performed with the Eclipse treatment planning system (version 18, Varian Medical Systems). Published α/β ratio values (i.e.3-10) were used to evaluate their impact on dose constraints for organs at risk (OARs), including rectum, bladder, bowel, femoral heads and penile bulb. Dose constraints were calculated for various fractionation schemes (5–39 fractions) and analyzed to assess deviations induced by changes in the α/β ratio. These calculated dose constraint curves were compared with clinical data to assess alignment and identify opportunities for refinement.
Results: Changes in the α/β ratio significantly influenced dose constraints, enabling the design of iso-effective treatment schedules. The resulting deviation patterns demonstrated a consistent distribution around the calculated dose constraint curves, indicating the potential for reducing doses to OARs. These findings support the feasibility of optimizing fractionation schemes to improve the therapeutic ratio while minimizing risks to adjacent normal tissues.
Conclusion: Modifying the α/β ratio represents a promising strategy for enhancing prostate cancer radiotherapy schedules. Optimized fractionation schemes can reduce treatment time, improve the therapeutic ratio, and enhance patient comfort. Future research should focus on translating these findings into clinical practice by refining dose constraints and exploring their practical applications to maximize therapeutic outcomes.