title: Reducing the probability of radiation-induced hepatic toxicity by changing the treatment modality from helical tomotherapy to fixed-beam intensity-modulated radiotherapy.
abstract: OBJECTIVE
  To estimate and compare the risk of radiation-induced hepatic toxicity (RIHT) in helical tomotherapy and fixed-beam intensity-modulated radiotherapy (IMRT) for the treatment of hepatocellular carcinoma (HCC).
  
  
  METHODS
  Twenty patients with unresectable HCC treated with tomotherapy were selected. We performed tomotherapy re-planning to reduce the non-target normal liver volume receiving a dose of more than 15 Gy (NTNL-V15Gy), and we created a fixed-beam IMRT plan (FB-P). We compared the dosimetric results as well as the estimated probability of RIHT among the tomotherapy initial plan (T-IP), the tomotherapy re-plan (T-RP), and the FB-P.
  
  
  RESULTS
  Comparing the T-RP and FB-P, the homogeneity index was 0.11 better with the T-RP. However, the mean NTNL-V15Gy was 6.3% lower with the FB-P. These differences result in a decline in the probability of RIHT from 0.216 in the T-RP to 0.115 in the FB-P. In patients whose NTNL-V15Gy was higher than 43.2% with the T-RP, the probability of RIHT markedly reduced from 0.533 to 0.274.
  
  
  CONCLUSIONS
  By changing the treatment modality from tomotherapy to fixed-beam IMRT, we could reduce the liver dose and the probability of RIHT without scarifying the target coverage, especially in patients whose liver dose is high.
authors.affiliation: Department of Radiation Oncology, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju, Korea.
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Song
authors.affiliation: Department of Radiation Oncology, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Seok Hyun
authors.initials: SH
authors.lastname: Son
authors.affiliation: Department of Radiation Oncology, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Chul Seung
authors.initials: CS
authors.lastname: Kay
authors.affiliation: Department of Radiation Oncology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Hong Seok
authors.initials: HS
authors.lastname: Jang
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008099:Liver / Q000528:radiation effects*; D008113:Liver Neoplasms / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D011336:Probability; D011832:Radiation Injuries / Q000209:etiology / Q000517:prevention & control*; D011874:Radiometry; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects* / Q000379:methods; D015203:Reproducibility of Results
keywords: fixed-beam intensity-modulated radiotherapy; helical tomotherapy; hepatocellular carcinoma; radiation-induced hepatic toxicity