• K. Mizushima, T. Furukawa, Y. Iwata, K. Noda, S. Sato, T. Shirai
  NIRS, Chiba-shi
• T. Fujisawa, H. Uchiyama
  AEC, Chiba

A 3D scanning method gated with patient's respiration has been developed for the HIMAC new treatment facility. In the scanning irradiation, the RF-KO slow-extraction method has been used, because of the quick response to beam on/off from the synchrotron. However, a small amount of beam remained just inside the separatrix is extracted just before turning on the transverse RF field, which brings the extra dose. We proposed to apply another transverse RF-frequency component matched with the betatron frequency of the particles in the vicinity of the stopband, in addition to the original transverse RF field for the RF-KO slow-extraction. Using the proposed method, the particles just inside the separatrix, which cause the extra dose, can be selectively extracted during the irradiation; as a result, the extra dose can also be reduced. The validity of this approach has been verified by the simulation and the measurement with the non-distractive 2D beam profile monitor. We will report the result of this approach.

• K. Noda, T. Furukawa, T. Inaniwa, Y. Iwata, T. Kanai, M. Kanazawa, S. Minohara, K. Mizushima, S. Mori, T.M. Murakami, N. Saotome, S. Sato, T. Shirai, E. Takada, Y. Takei
  NIRS, Chiba-shi
• T. Fujimoto, T. Miyoshi, Y. Sano
  AEC, Chiba

Based on more than ten years of experience of the carbon cancer therapy with HIMAC, we have proposed a new treatment facility for the further development of the therapy with HIMAC. This facility will consist of three treatment rooms: two rooms equipped with horizontal and vertical beam-delivery systems and one room with a rotating gantry. For the beam-delivery system of the new treatment facility, a 3D hybrid raster-scanning method with gated irradiation with patient’s respiration has been proposed. A R&D study has been carried out toward the practical use of the proposed method, although this method was verified by a simulation study. In the R&D study, we have improved the beam control of the size, the position and the time structure for the proposed scanning method with the irradiation gated with patient’s respiration. Further, owing to the intensity upgrade of the synchrotron, we can successfully extend the flattop duration, which can complete one fractional irradiation with one operation period and can increase the treatment efficiency of the gated irradiation. We will report the recent progress on HIMAC for carbon therapy.

• N. Saotome, T. Furukawa, T. Inaniwa, Y. Iwata, T. Kanai, A. Nagano, K. Noda, S. Sato, T. Shirai, E. Takeshita
  NIRS, Chiba-shi
• T. Kohno
  TIT, Yokohama

The screen monitor system is an important tool for beam diagnostic of the high-energy-beam transport line at the Heavy-Ion Medical Accelerator in Chiba (HIMAC). We have developed a very thin fluorescent film and high speed charge-coupled-device camera. Because the fluorescent film is very thin (ZnS:Ag 2mg/cm³), the beam is measured with semi-non-destructively. Consequently we can use more than two monitors at the same time and multiple locations. Moreover we employ a high-speed three-processer for image processing, the system can be applied for online monitoring and interlock system (100Hz). When the beam profile measured by this system is inevitably changed over the setting tolerance during therapeutic irradiation for the patient, the beam is immediately turned off. The design and measurement result by irradiation test are discussed.