title: Intercepting radiotherapy using a real-time tumor-tracking radiotherapy system for highly selected patients with hepatocellular carcinoma unresectable with other modalities.
abstract: OBJECTIVE
  To assess the clinical outcome of intercepting radiotherapy, in which radiotherapy is delivered only when a tumor in motion enters a target area, using a real-time tumor-tracking radiotherapy (RTRT) system for patients with hepatocellular carcinoma who were untreatable with other modalities because the tumors were adjacent to crucial organs or located too deep beneath the skin surface.
  
  
  METHODS
  Eighteen tumors, with a mean diameter of 36 mm, were studied in 15 patients. All tumors were treated on a hypofractionated schedule with a tight margin for setup and organ motion using a 2.0-mm fiducial marker in the liver and the RTRT system. The most commonly used dose of radiotherapy was 48 Gy in 8 fractions. Sixteen lesions were treated with a BED(10) of 60 Gy or more (median, 76.8 Gy).
  
  
  RESULTS
  With a mean follow-up period of 20 months (range, 3-57 months), the overall survival rate was 39% at 2 years after RTRT. The 2-year local control rate was 83% for initial RTRT but was 92% after allowance for reirradiation using RTRT, with a Grade 3 transient gastric ulcer in 1 patient and Grade 3 transient increases of aspartate amino transaminase in 2 patients.
  
  
  CONCLUSIONS
  Intercepting radiotherapy using RTRT provided effective focal high doses to liver tumors. Because the fiducial markers for RTRT need not be implanted into the tumor itself, RTRT can be applied to hepatocellular carcinoma in patients who are not candidates for other surgical or nonsurgical treatments.
authors.affiliation: Department of Radiology, Hokkaido University School of Medicine, Sapporo, Japan. thiroshi@radi.med.hokudai.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Taguchi
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sakuhara
authors.forename: Shuhei
authors.initials: S
authors.lastname: Hige
authors.forename: Kei
authors.initials: K
authors.lastname: Kitamura
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Osaka
authors.forename: Daisuke
authors.initials: D
authors.lastname: Abo
authors.forename: Daichi
authors.initials: D
authors.lastname: Uchida
authors.forename: Akihiro
authors.initials: A
authors.lastname: Sawada
authors.forename: Toshiya
authors.initials: T
authors.lastname: Kamiyama
authors.forename: Tadashi
authors.initials: T
authors.lastname: Shimizu
authors.forename: Hiroki
authors.initials: H
authors.lastname: Shirato
authors.forename: Kazuo
authors.initials: K
authors.lastname: Miyasaka
mesh_terms: D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D016461:Chemoembolization, Therapeutic; D003199:Computer Systems; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008099:Liver; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009068:Movement; D011859:Radiography; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012189:Retrospective Studies; D015996:Survival Rate