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1前言肿瘤一直严重威胁人类生命,为征服这一疾病人类进行了长期坚持不懈的努力。放射治疗肿瘤已经成为治疗肿瘤的最重要手段之一。目前放疗的主流仍然是以X射线、γ射线和电子束为代表的常规放射治疗。但是这些射线的物理剂量分布和生物效应都不是很理想:进入人体的剂量分布随深度而指数衰减,因此这些射线在杀死肿瘤细胞的同时,也使周围正常组织受到不同程度的损伤。虽然现在
1 Introduction Tumor has always been a serious threat to human life, to conquer the human disease has made a long-term and unremitting efforts. Radiation treatment of cancer has become one of the most important means of treatment of cancer. The current mainstream of radiotherapy is still the conventional radiotherapy represented by X-ray, γ-ray and electron beam. However, the physical dose distribution and biological effects of these rays are not ideal: the dose distribution into the human body declines exponentially with depth, so that these rays kill the tumor cells and damage the surrounding normal tissue to varying degrees. Though now