@misc{oai:repo.qst.go.jp:00065689,
 author = {Fukahori, Mai and Matsufuji, Naruhiro and Himukai, Takeshi and Kanematsu, Nobuyuki and Mizuno, Hideyuki and Fukumura, Akifumi and Tsuji, Hiroshi and Kamada, Tadashi and 深堀 麻衣 and 松藤 成弘 and 日向 猛 and 兼松 伸幸 and 水野 秀之 and 福村 明史 and 辻 比呂志 and 鎌田 正},
 month = {Sep},
 note = {Purpose: The aim of this study was to estimate normal tissue complication probability (NTCP) parameters after carbon ion radiation therapy (C-ion RT) for prostate cancer on rectal and urethral late complications.
Methods: Rectal and urethral dose-volume histograms (DVHs) and clinical records of 166 prostate cancer patients were considered. These patients included were treated with dose ranging from 57.6 Gy (RBE) up to 72 Gy (RBE) including dose escalation trial at the National Institute of Radiological Sciences (NIRS). The Lyman-Kutcher-Burman (LKB) model with DVH as a function of equivalent uniform dose (EUD) was used as a NTCP model and the model parameters were fit to the patient data by using the maximum likelihood analysis. The end points for the analysis was Grade ≥1, Grade ≥2 and Grade ≥3 toxicity for both the rectum and the urethra.
Results: Of the 166 patients, the derived LKB model parameters were the volume effect parameter; n = 0.058, the parameter of the steepness of NTCP curve; m = 0.086, the tolerance dose associated with 50% chance of complication; TD50 = 59.3 Gy (RBE) for more than Grade 1 rectum bleeding, n = 0.0015, m = 0.10, TD50 = 72.4 Gy (RBE) for more than Grade 2 urethra complications. The quite low n values of the rectum and urethra suggest that these are serial-like organs and emphasize the importance of reducing the high dose regions of the irradiated these organs for C-ion RT. Furthermore, our analysis suggests that the dose response of the rectum is not related to the grade of late complications but the TD50 of the urethra is highly correlated to the degree of the urethra complications.
Conclusion: With the derived parameter values, it has become possible to provide rectal and urethral NTCP in C-ion RT., The 7th Korea-Japan Joint Meeting on Medical Physics},
 title = {Estimation of the rectal and urethral normal tissue complication probability parameters in carbon ion therapy for prostate cancer},
 year = {2014}
}