title: Fiducial marker matching versus vertebral body matching: Dosimetric impact of patient positioning in carbon ion radiotherapy for primary hepatic cancer.
abstract: OBJECTIVE
  The aim of this study was to compare the dose-volume parameters of fiducial marker matching (MM) with vertebral body matching (VM) in patient positioning for carbon ion radiotherapy for primary hepatic cancer.
  
  
  METHODS
  Twenty patients with primary hepatic cancer were retrospectively studied to assess changes in reproducibility of tumor position and dose distribution on two CT scans. One was for treatment planning and another was for dose confirmation, acquired the day before the first treatment day. The coverage of the clinical target volume (CTV) (D98) and normal liver volume excluding the CTV which received 20Gy relative biological effectiveness (RBE) (V20) were used as evaluation parameters. Additionally, the correlation of tumor movement and D98was calculated in VM and MM. The prescription dose was 60.0Gy (RBE) delivered in four fractions (15Gy/fx).
  
  
  RESULTS
  The median (range) D98for VM and MM was 57.9 (20.8-59.9) and 59.9 (57.2-60.3) Gy (RBE), respectively. The median (range) V20for VM and MM was 17.9 (4.8-44.4) and 16.2 (4.7-44.9) Gy (RBE), respectively. The D98for MM was significantly larger than that for VM (p=0.001), although V20showed no significant difference (p>0.05). Twelve patients were clinically acceptable (D98>57Gy (RBE)) with VM, while all patients were clinically acceptable with MM. Marker movement correlated with a decrease of D98for VM (R=-0.814).
  
  
  CONCLUSIONS
  Compared with VM, MM was clinically acceptable in all patients. This suggests that MM is more robust than VM.
authors.affiliation: Department of Radiology, Gunma University Hospital, 3-39-15 Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Abe
authors.affiliation: Gunma University Heavy Ion Medical Center, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan. Electronic address: y_kubota@gunma-u.ac.jp.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Kubota
authors.affiliation: Department of Radiation Oncology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Shibuya
authors.affiliation: Department of Radiation Oncology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Koyama
authors.affiliation: Department of Radiation Oncology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Abe
authors.affiliation: Gunma University Heavy Ion Medical Center, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ohno
authors.affiliation: Gunma University Heavy Ion Medical Center, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan; Department of Radiation Oncology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakano
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D057918:Fiducial Markers; D063193:Heavy Ion Radiotherapy / Q000592:standards*; D006801:Humans; D008113:Liver Neoplasms / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D056888:Patient Positioning / Q000379:methods*; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012189:Retrospective Studies; D013131:Spine
keywords: Carbon ion radiotherapy; Fiducial marker matching; Hepatic cancer; Vertebral body matching