PT - JOURNAL ARTICLE AU - ITABASHI, YUSUKE AU - KUBOTA, YOSHIKI AU - OKAMOTO, MASAHIKO AU - TSUDA, KAZUHISA AU - SHIBA, SHINTARO AU - HOSHINO, YOSHIHIKO AU - SUTO, TAKAYUKI AU - OHNO, TATSUYA AU - NAKANO, TAKASHI TI - Potential Pitfalls of Diaphragm Structural Matching in Carbon-ion Radiotherapy for Pancreatic Cancer AID - 10.21873/anticanres.13603 DP - 2019 Aug 01 TA - Anticancer Research PG - 4351--4356 VI - 39 IP - 8 4099 - http://ar.iiarjournals.org/content/39/8/4351.short 4100 - http://ar.iiarjournals.org/content/39/8/4351.full SO - Anticancer Res2019 Aug 01; 39 AB - Background/Aim: To evaluate the effectiveness of diaphragm matching (DM) for carbon-ion radiotherapy (CIRT) of pancreatic cancer patients and develop a simple method to estimate tumour position. Patients and Methods: Treatment planning CTs from 27 pancreatic cancer patients treated with CIRT in our facility were used in this study, and 32 other CT image datasets taken on different days were used for measuring tumour and diaphragm displacements. A correction method (SI-correction) was developed using the coefficient x of the regression line formula for the displacements between the diaphragm and tumour in the superior–inferior direction. The tumour positioning errors of bone matching (BM), DM, and SI-correction were measured. Results: Mean (±standard deviation) absolute errors of BM, DM, and SI-correction were 5.10±3.31, 7.48±4.04, and 4.13±2.51 mm, respectively. DM showed significant differences compared to the other correction methods. Conclusion: DM was subject to larger errors than BM. Our correction method improved positional errors.