title: Relative clinical effectiveness of carbon ion radiotherapy: theoretical modelling for H&N tumours.
abstract: Comparison of the efficiency of photon and carbon ion radiotherapy (RT) administered with the same number of fractions might be of limited clinical interest, since a wide range of fractionation patterns are used clinically today. Due to advanced photon treatment techniques, hypofractionation is becoming increasingly accepted for prostate and lung tumours, whereas patients with head and neck tumours still benefit from hyperfractionated treatments. In general, the number of fractions is considerably lower in carbon ion RT. A clinically relevant comparison would be between fractionation schedules that are optimal within each treatment modality category. In this in silico study, the relative clinical effectiveness (RCE) of carbon ions was investigated for human salivary gland tumours, assuming various radiation sensitivities related to their oxygenation. The results indicate that, for hypoxic tumours in the absence of reoxygenation, the RCE (defined as the ratio of D(50) for photons to carbon ions) ranges from 3.5 to 5.7, corresponding to carbon ion treatments given in 36 and 3 fractions, respectively, and 30 fractions for photons. Assuming that interfraction local oxygenation changes take place, results for RCE are lower than that for an oxic tumour if only a few fractions of carbon ions are used. If the carbon ion treatment is given in more than 12 fractions, the RCE is larger for the hypoxic than for the well-oxygenated tumour. In conclusion, this study showed that in silico modelling enables the study of a wide range of factors in the clinical considerations and could be an important step towards individualisation of RT treatments.
authors: Medical Radiation Physics, Department of Physics, Stockholm University, Stockholm, Sweden.
authors: Laura
authors: L
authors: Antonovic
authors: Department of Radiation Physics and Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
authors: Alexandru
authors: A
authors: Dasu
authors: Next Generation Medical Physics Research Program and International Open Laboratories, National Institute of Radiological Sciences, Chiba 263-8555, Japan.
authors: Yoshiya
authors: Y
authors: Furusawa
authors: Medical Radiation Physics, Department of Physics, Stockholm University, Stockholm, Sweden Medical Radiation Physics, Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden Iuliana.Livia.Dasu@ki.se.
authors: Iuliana
authors: I
authors: Toma-Dasu
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002244:Carbon; D015687:Cell Hypoxia / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D003198:Computer Simulation; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D063193:Heavy Ion Radiotherapy / Q000379:methods*; D006801:Humans; D008954:Models, Biological; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012062:Relative Biological Effectiveness; D012468:Salivary Gland Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D016896:Treatment Outcome
chemical_list: D002244:Carbon
keywords: RBE; RCE; RCR; TCP; carbon ion; fractionation; hypoxia