Kong Xianghui, Yan Kaijin, Wang Xinjie, Wei Shenglan, Ni Jie, Li Haiyang, Qin Songbing, Sun Liang
Department of Radiation Oncology, The First Affiliated Hospital of Soochow University, State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, People's Republic of China.
Radiotherapy Department, Binhai County People's Hospital Affiliated to Kangda College of Nanjing Medical University, Yancheng, Jiangsu, People's Republic of China.
Phys Med Biol. 2025 Aug 14;70(16). doi: 10.1088/1361-6560/adf8aa.
In examining the biological effects of proton radiation, DNA is the primary sensitive target. This study utilizes Monte Carlo simulations to efficiently calculate DNA damage yields at various proton depths to analyze the biological effects of protons and their variability on different scales.A new method, the 'Coefficient Method' is used to replace the complete chemical processes by adjusting parameters to obtain suitable values for simulating DNA damage yields at different spread-out Bragg peak (SOBP) depths of low-energy protons, and these parameters are then applied to high-energy proton simulations based on a mesh-type cell model. We computed two relative biological effectiveness (RBE) at two different scales:RBEmax(at 0 Gy per fraction) andRBEDSB(based on DNA damage yields).. The results confirm the feasibility of the 'Coefficient Method,' with deviations inYDSBs(the yields of double-strand breaks (DSBs)) andYDSBc(the yields of complex DSBs) ranging from 0.60%-3.79% and 1.45%-4.1%, respectively, and a clear advantage in simulation efficiency. For high-energy protons,YSSBs(the yields of single-strand breaks) decreases with depth, whileYDSBsandYDSBcincrease. What's more, the differences in RBE across different scales are substantial. At 1 cm depth for 70_SOBP MeV protons,RBEmaxis 1.53 vsRBEDSBof 1.45; at the beam end,RBEmaxreaches 10.45 vsRBEDSBof 2.36. Mesh thickness has negligible impact onRBEmax.It is confirmed that using the 'Coefficient Method' to obtain DNA damage yields at different depths for high-energy protons is reliable. TheRBEDSBvalues based on this method show significant differences compared to the traditionalRBEmaxvalues. This indicates the importance of investigating the biological effects of proton radiation at the DNA scale and further emphasizes the significance of exploring the relationship between proton radiation quality and the target of interest.
在研究质子辐射的生物学效应时，DNA是主要的敏感靶点。本研究利用蒙特卡罗模拟有效地计算不同质子深度下的DNA损伤产额，以分析质子的生物学效应及其在不同尺度上的变化。一种新的方法，即“系数法”，通过调整参数来替代完整的化学过程，以获得适合模拟低能质子不同扩展布拉格峰（SOBP）深度下DNA损伤产额的数值，然后基于网格型细胞模型将这些参数应用于高能质子模拟。我们在两个不同尺度上计算了两个相对生物效应（RBE）：RBE max（每分次剂量为0 Gy时）和RBE DSB（基于DNA损伤产额）。结果证实了“系数法”的可行性，双链断裂（DSB）产额（Y DSBs）和复杂DSB产额（Y DSBc）的偏差分别为0.60% - 3.79%和1.45% - 4.1%，且在模拟效率上具有明显优势。对于高能质子，单链断裂产额（Y SSBs）随深度降低，而Y DSBs和Y DSBc增加。此外，不同尺度上的RBE差异很大。对于70_SOBP MeV质子，在1 cm深度处，RBE max为1.53，而RBE DSB为1.45；在射束末端，RBE max达到10.45，而RBE DSB为2.36。网格厚度对RBE max的影响可忽略不计。证实了使用“系数法”获取高能质子不同深度下的DNA损伤产额是可靠的。基于该方法的RBE DSB值与传统的RBE max值相比显示出显著差异。这表明在DNA尺度上研究质子辐射生物学效应的重要性，并进一步强调了探索质子辐射质量与感兴趣靶点之间关系的意义。
