@article{oai:repo.qst.go.jp:00046222,
 author = {Mori, Shinichiro and Kanematsu, Nobuyuki and Asakura, Hiroshi and Gregory, Sharp and Kumagai, Motoki and Dobashi, Suguru and Nakajima, Mio and Yamamoto, Naoyoshi and Kandatsu, Susumu and Baba, Masayuki and 森 慎一郎 and 兼松 伸幸 and 浅倉 裕史 and 熊谷 始紀 and 土橋 卓 and 中嶋 美緒 and 山本 直敬 and 神立 進 and 馬場 雅行},
 issue = {2},
 journal = {International Journal of Radiation Oncology Biology Physics},
 month = {Jun},
 note = {PURPOSE: We compared four-dimensional (4D) layer-stacking and conventional carbon ion beam distribution in the treatment of lung cancer between ungated and gated respiratory strategies using 4DCT data sets.
\nMETHODS AND MATERIALS: Twenty lung patients underwent 4DCT imaging under free-breathing conditions. Using planning target volumes (PTVs) at respective respiratory phases, two types of compensating bolus were designed, a full single respiratory cycle for the ungated strategy and an approximately 30% duty cycle for the exhalation-gated strategy. Beams were delivered to the PTVs for the ungated and gated strategies, PTV(ungated) and PTV(gated), respectively, which were calculated by combining the respective PTV(Tn)s by layer-stacking and conventional irradiation. Carbon ion beam dose distribution was calculated as a function of respiratory phase by applying a compensating bolus to 4DCT. Accumulated dose distributions were calculated by applying deformable registration.
\nRESULTS: With the ungated strategy, accumulated dose distributions were satisfactorily provided to the PTV, with D95 values for layer-stacking and conventional irradiation of 94.0% and 96.2%, respectively. V20 for the lung and Dmax for the spinal cord were lower with layer-stacking than with conventional irradiation, whereas Dmax for the skin (14.1 GyE) was significantly lower (21.9 GyE). In addition, dose conformation to the GTV/PTV with layer-stacking irradiation was better with the gated than with the ungated strategy.
\nCONCLUSIONS: Gated layer-stacking irradiation allows the delivery of a carbon ion beam to a moving target without significant degradation of dose conformity or the development of hot spots},
 pages = {597--607},
 title = {Four-dimensional Lung Treatment Planning in Layer-stacking Carbon Ion Beam Treatment: Comparison of Layer-stacking and Conventional Ungated/Gated Irradiation},
 volume = {80},
 year = {2011}
}