Krämer M, Weyrather W K, Scholz M
GSI/Biophysics, Planckstrasse 1, D-64291 Darmstadt.
Technol Cancer Res Treat. 2003 Oct;2(5):427-36. doi: 10.1177/153303460300200507.
The increased biological effectiveness of heavy charged particle beams like e.g., carbon ions in the tumor volume in comparison to the lower effectiveness in the surrounding healthy tissue represents one of the major rationales for their application in tumor therapy. This increased effectiveness also characterizes the advantage of heavier ions compared to proton beams. The increased effectiveness has to be taken into account in treatment planning in order to estimate the corresponding photon equivalent doses in normal and tumor tissues, thus allowing a link e.g., to normal tissue dose limits in conventional photon therapy. Due to the complex dependencies of RBE on parameters like dose, beam energy, LET, atomic number and cell or tissue type, the relevant RBEs cannot be solely determined from experimental data. Therefore, within the framework of the pilot project of tumor therapy with carbon ions performed at GSI Darmstadt, treatment planning is based on a biophysical model, which has been extensively tested. The paper first summarizes the essential systematic dependencies of RBE on different parameters like e.g., dose, LET, atomic number and cell type. The basic principle of the biophysical model is then introduced, and special emphasis is given to the application of the model to in vivo and clinical endpoints. Model predictions are compared to experimental data in vitro and in vivo. Finally, the implementation of the biophysical model in the treatment planning procedure is presented. The biological verification of the whole treatment planning procedure is explained and examples of patient treatment plans are given.
与在周围健康组织中较低的有效性相比，重带电粒子束（例如碳离子）在肿瘤体积中的生物有效性增加，这是其在肿瘤治疗中应用的主要理论依据之一。这种有效性的增加也体现了重离子相对于质子束的优势。在治疗计划中必须考虑这种有效性的增加，以便估计正常组织和肿瘤组织中相应的光子等效剂量，从而例如能够与传统光子治疗中的正常组织剂量限值建立联系。由于相对生物学效应（RBE）对剂量、束能量、传能线密度（LET）、原子序数以及细胞或组织类型等参数存在复杂的依赖性，相关的RBE不能仅从实验数据中确定。因此，在德国达姆施塔特重离子研究中心（GSI）进行的碳离子肿瘤治疗试点项目框架内，治疗计划基于一个经过广泛测试的生物物理模型。本文首先总结了RBE对不同参数（如剂量、LET、原子序数和细胞类型）的基本系统依赖性。然后介绍了生物物理模型的基本原理，并特别强调了该模型在体内和临床终点的应用。将模型预测结果与体外和体内实验数据进行了比较。最后，介绍了生物物理模型在治疗计划程序中的实施情况。解释了整个治疗计划程序的生物学验证，并给出了患者治疗计划的示例。
