@article{oai:repo.qst.go.jp:00045607,
 author = {Ishizaki, Azusa and Kanematsu, Nobuyuki and Kanai, Tatsuaki and Yonai, Shunsuke and Takei, Yuka and Kase, Yuuki and Komori, Masataka and et.al and 石崎 梓 and 兼松 伸幸 and 金井 達明 and 米内 俊祐 and 武井 由佳 and 加瀬 優紀 and 小森 雅孝},
 issue = {6},
 journal = {Medical Physics},
 month = {May},
 note = {Passive irradiation methods deliver an extra dose to normal tissues upstream of the target tumor, while in dynamic irradiation methods, interplay effects between dynamic beam delivery and target motion induced by breathing or respiration distort the dose distributions. To solve the problems of those two irradiation methods, the authors have developed a new method that laterally modulates the spread-out Bragg peak (SOBP) width. By reducing scanning in the depth direction, they expect to reduce the interplay effects. They have examined this new irradiation method experimentally. In this system, they used a cone-type filter that consisted of 400 cones in a grid of 20 cones by 20 cones. There were five kinds of cones with different SOBP widths arranged on the frame two dimensionally to realize lateral SOBP modulation. To reduce the number of steps of cones, they used a wheel-type filter to make minipeaks. The scanning intensity was modulated for each SOBP width with a pair of scanning magnets. In this experiment, a stepwise dose distribution and spherical dose distribution of 60 mm in diameter were formed. The nonflatness of the stepwise dose distribution was 5.7% and that of the spherical dose distribution was 3.8%. A 2 mm misalignment of the cone-type filter resulted in a nonflatness of more than 5%. Lateral SOBP modulation with a cone-type filter and a scanned carbon ion beam successfully formed conformal dose distribution with nonflatness of 3.8% for the spherical case. The cone-type filter had to be set to within 1 mm accuracy to maintain nonflatness within 5%. This method will be useful to treat targets moving during breathing and targets in proximity to important organs.},
 pages = {2222--2227},
 title = {Development of an irradiation method with lateral modulation of SOBP width using a cone-type filter for carbon ion beams},
 volume = {36},
 year = {2009}
}