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

肿瘤放射治疗因其能保持人体形态和功能，减轻患者负担等优点，近年来受到广泛关注。为了实现带电粒子治癌的广泛应用，研制了一台具有复合功能的紧凑型质子同步加速器。与分离功能型相比，这种类型具有以下优点：电源的控制变得紧凑，并且其成本可以大大降低，因为循环质子束的偏转和聚焦是用同一个磁体进行的，并且在双极磁体和四极磁体的电源之间的跟踪控制变得不必要，水平和垂直方向的Betatron振荡曲调是固定的，日常操作变得非常容易。然而，第二点，导致制造后没有灵活性，在第一阶段建立良好的设计是必然的条件。从这些观点出发，我们在1996年获得了组合功能同步加速器晶格的最终设计。在此基础上，于1997年制造了组合功能磁体的真实的尺寸模型磁体。利用三维磁场计算结果，调整F、D扇区边界位置，优化电子感应加速器调谐工作点，并利用三维霍尔探头测量模型磁体的磁场，根据磁场测量的映射数据，估算电子感应加速器在水平和垂直方向上的调谐。

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.