Research and Development of Compact Proton Accelerator Dedicated for Practical Application to Cancer Therapy

放射线癌症治疗因其保留人体形状和功能、减轻患者负担的优点而近年来受到关注。特别是带电粒子癌症治疗，由于布拉格峰的存在，可以将剂量定位到肿瘤部位，因此其有效性得到了验证。为了实现带电粒子癌症治疗的广泛应用，开发了具有组合功能晶格的紧凑型癌症治疗专用质子同步加速器。与功能分离型相比，这种类型具有以下优点：电源的控制变得紧凑，成本可以大大降低，因为循环质子束的偏转和聚焦是用同一磁体进行的，不需要偶极和四极磁体电源之间的跟踪控制，水平和垂直方向的电子感应加速器振荡调谐是固定的，日常操作变得非常容易。但第二点导致制造后没有灵活性，第一阶段建立良好的设计是必然条件。从这些角度出发，我们于1996年得到了组合功能同步加速器晶格的最终设计。在此基础上，1997年制作了组合功能磁体的实际尺寸模型磁体。在此过程中，利用3维磁场计算的结果调整F和D扇区之间的边界位置以优化电子感应加速器调谐的工作点。模型磁体的磁场还使用3维霍尔探针并根据映射数据进行了测量。现场测量，估计了水平和垂直方向的电子感应加速器调谐。

Radiation Cancer therapy has recently be paid attention to because of its merits of preserving shape and function of human body and reducing the load to the patient. Charged-particle cancer-therapy, in particular, has been verified in its effectiveness due to the fact that dose localization to the tumor part is possible because of the presence of Bragg Peak.For the purpose of realizing wide spread use of the charged-particle cancer-therapy, a compact proton synchrotron dedicated for cancer therapy with a combined-function lattice has been developed. Compared with the separated-function type, this type has the following merits as.Control of the power supply becomes compact and its cost can be largely reduced, because deflection and focusing of the circulating proton beam are performed with the same magnet and tracking control between power supplies of dipole and quadrupole magnets becomes unnecessary,Betatron oscillation tunes in horizontal and vertical directions are fixed and daily operation becomes very easy.The second point, however, leads to no flexibility after fabrication and the establishment of a good design at the first stage is the inevitable condition. From these points of view, we obtained the final design of the combined-function synchrotron lattice in 1996. Based on this, a real size model magnet of the combined-function magnet was fabricated in 1997. In this procedure, the position of the boundary between F and D sectors was adjusted to optimize the working point of betatron tunes utilizing the results of 3 dimensional magnetic field calculation.Magnetic field of the model magnet was also measured with use of 3-dimensional Hall-probe and from the mapped data of field measurement, betatron tunes in horizontal and vertical directions were estimated.