重离子束在医学治疗中的应用

重离子束治癌是重离子束在医疗领域中的一项典型的应用技术，文章从重离子束在物理学与生物学上的特点，描述了它对肿瘤治疗具有优越性，物理剂量深度分布在射程末端有一个能量沉积集中区，其深度和大小均可调节；在靶区的相对生物效率（RBE）高、氧增比（OER）低；射程歧离与横向散射小；利用正电子发射断层照相（PET）技术术可以实时在线监测；可以三维扫描进行适用形治疗，半致死损伤修复小；辐射敏感性不依赖细胞周期相，文章还介绍了这项技术的国内外进展，并对其未来进行了展望。

APPLICATION OF HEAVY ION BEAMS IN MEDICAL TREATMENT

Cancer therapy with heavy ion beams is a typical application of heavy ion beams in medical treatment. The advantages of heavy ion beams in tumor treatment is described in detail with regard to both physical and biological characteristics. Compared to photon radiation, therapeutic ion beams offer the advantages of a depth dose profile with a pronounced Bragg maximum, a well-defined range, little lateral scattering, an increased biological effectiveness and a decreased oxygen enhancement ratio towards the end of the particle range. Little repair of half-lethal damage is required and the radio-sensitivity is independent of cell cycle progression. A 3D scan device combining lateral deflection and energy variation of the ion beams to realize dose conformation and in situ PET monitoring can be used to improve and control the precision of the tumor irradiation. Current progress at home and abroad and future prospects are overviewed.