摘要
质子治疗中为减小对肿瘤周围正常组织的损伤而对病人进行多角度照射时,通常采用旋转机架传输质子束流并且要求束流在旋转机架等中心处形成圆束斑。而同步加速器引出束流具有明显的不对称特点给等中心处圆束斑的实现带来困难。分别针对在旋转机架入口的真空窗处满足"圆束流法"、等中心处满足"圆束流法"和不采用"圆束流法"等三种方案进行了束流光学设计,并利用蒙特卡罗软件Geant4模拟分析不同方案下束流经过旋转机架、治疗头和人体在等中心处形成的束斑。结果表明,三种束流光学设计方案中束流在旋转不同角度情况下在等中心处的束斑均接近圆形,在采用"圆束流法"的两种方案中实际束流分布与圆束斑的差异相对较小。
Background： Rotating Gantry is widely used in proton therapy due to its small radiation damage toward the normal tissue around the tumor. Proton therapy gantry optics which plays an important role in rotating gantry is under design in Shanghai Advanced Proton Therapy Facility （APTRON）. Purpose： To generate a circular beam profile at iso-center while the gantry rotates with different angles. Methods： Different gantry optics matching techniques are used to calculate the beam optics. These methods include the round-beam method （RBM） or not in the front of vacuum window, and use RBM at iso-center. The simulations of beam profile at iso-center after the beam passing through nozzle and body tissue are carried out with Geant4 software. Results： The beam profile at iso-center can be taken as similar among three cases, and there is slight improvement using RBM. Conclusions： The designed proton therapy gantry optics is intensive to the rotation angle and is applicable for the real application.
出处
《核技术》
CAS
CSCD
北大核心
2013年第7期21-25,共5页
Nuclear Techniques
