@misc{oai:repo.qst.go.jp:00070728,
 author = {Kumagai, Motoki and Mori, Shinichiro and Okada, Tohru and Asakura, Hiroshi and Kandatsu, Susumu and Tsuji, Hiroshi and Kamada, Tadashi and 熊谷 始紀 and 森 慎一郎 and 岡田 徹 and 浅倉 裕史 and 神立 進 and 辻 比呂志 and 鎌田 正},
 month = {Nov},
 note = {Purpose/Objective(s): In the hypofractionated prostate therapy, it is important to control the intrafractional movement per fraction than conventional fractionated therapy. To quantify carbon ion dose variation due to intrafractional movement in prostate treatment. 
Materials/Methods: A total of 20 patients with prostate cancer were subject to the four-dimensional CT (4DCT) examination under free-breathing conditions, using a 256 multi-detector CT. Two planning target volumes (PTVs) were defined to avoid the high dose to the rectum. Two types of PTVs were defined by adding 3D uniform margin (= PTV1) to clinical target volume (= CTV) and cutting in the straight line from the top surface of the rectum from PTV1 (= PTV2). Compensating boli were designed for respective PTVs at peak-exhalation phase. Carbon ion dose distributions were calculated by applying the compensating boli to the 4DCT data sets for a single respiratory cycle. 
Results: Small dose variations due to intrafractional motion were observed around the edge of the PTV1. The dose volume histograms (DVHs) for the prostate and PTV2 were almost same at all respiratory phases. D95 values of prostate and PTV2 were 96.8% and 94.2% averaged for all patients. DVH for the rectum lower than the 50% of the prescribed dose was decreased compare with the planning dose due to the variation of thickness of the abdomen surface.
Conclusions: In this study, we quantified intrafractional dose variation for prostate cancer patients using 4DCT imaging. Respiratory motion can affect dose conformation to the target, and respiratory induced abdominal wall thickness change was identified as the factor affecting dose variations even though prostate motion is small. However, the dose variations due to intrafractional respiratory motion may not be considered in the prostate treatment., ASTRO’s 52nd Annual Meeting},
 title = {Quantification of Respiratory Induced Dose Variation in Heavy Charged Particle Prostate Therapy Using Four-Dimensional CT},
 year = {2010}
}