Kanematsu Nobuyuki, Matsufuji Naruhiro, Inaniwa Taku
Medical Physics Section, National Institute of Radiological Sciences Hospital, QST; 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan.
Department of Accelerator and Medical Physics, National Institute of Radiological Sciences, QST; 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan.
Radiol Phys Technol. 2018 Jun;11(2):242-247. doi: 10.1007/s12194-018-0444-7. Epub 2018 Feb 22.
A treatment of carbon-ion radiotherapy (CIRT) is generally evaluated using the dose weighted by relative biological effectiveness (RBE) while ignoring the radiation quality varying in the patient. In this study, we have developed a method of estimating linear energy transfer (LET) from the RBE in an archived treatment plan to represent the radiation quality of the treatment. The LET in a beam database was associated with the RBE by two fitting functions per energy, one for the spread-out Bragg peak (SOBP) and the other for shallower depths, to be differentiated by RBE per energy per modulation. The estimated LET was generally consistent with the original calculation within a few keV/μm, except for the overkill region near the distal end of SOBP. The knowledge of experimental radiobiology can thereby be associated with CIRT treatments through LET, which will potentially contribute to deeper understanding of clinical radiobiology and further optimization of CIRT.
碳离子放射治疗（CIRT）的治疗效果通常使用相对生物效应（RBE）加权剂量来评估，而忽略了患者体内辐射质量的变化。在本研究中，我们开发了一种从存档治疗计划中的RBE估算线性能量传递（LET）的方法，以表征治疗的辐射质量。通过每个能量的两个拟合函数，将射束数据库中的LET与RBE相关联，一个用于扩展布拉格峰（SOBP），另一个用于较浅深度，通过每个能量每个调制的RBE进行区分。除了SOBP远端附近的过杀区域外，估计的LET与原始计算结果在几keV/μm范围内基本一致。由此，实验放射生物学知识可通过LET与CIRT治疗相关联，这可能有助于更深入地理解临床放射生物学，并进一步优化CIRT。
