title: Dose prescription in carbon ion radiotherapy: How to compare two different RBE-weighted dose calculation systems.
abstract: In carbon ion radiotherapy (CIRT), the use of different relative biological effectiveness (RBE) models in the RBE-weighted dose (DRBE) calculation can lead to deviations in the physical dose (Dphy) delivered to the patient. Our aim is to reduce target Dphy deviations by converting prescription dose values.
  
  
  
  Planning data of patients treated at the National Institute of Radiological Sciences (NIRS) were collected, with prescribed doses per fraction ranging from 3.6Gy (RBE) to 4.6Gy (RBE), according to the Japanese semi-empirical model. The Dphy was Monte Carlo (MC) re-calculated simulating the NIRS beamline. The local effect model (LEM)_I was then applied to estimate DRBE. Target median DRBE ratios between MC+LEM_I and NIRS plans determined correction factors for the conversion of prescription doses. Plans were re-optimized in a LEM_I-based commercial system, prescribing the NIRS uncorrected and corrected DRBE.
  
  
  
  The MC+LEM_I target median DRBE was respectively 15% and 5% higher than the NIRS reference, for the lowest and highest dose levels. Uncorrected DRBE prescription resulted in significantly lower target Dphy in re-optimized plans, with respect to NIRS plans.
  
  
  
  Prescription dose conversion factors could minimize target physical dose variations due to the use of different radiobiological models in the calculation of CIRT RBE-weighted dose.
authors.affiliation: CNAO Foundation, Pavia, Italy. Electronic address: molinelli@cnao.it.
authors.forename: Silvia
authors.initials: S
authors.lastname: Molinelli
authors.affiliation: CNAO Foundation, Pavia, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Magro
authors.affiliation: CNAO Foundation, Pavia, Italy; Heidelberg Ion Beam Therapy Center, Heidelberg, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Mairani
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Naruhiro
authors.initials: N
authors.lastname: Matsufuji
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kanematsu
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Inaniwa
authors.affiliation: CNAO Foundation, Pavia, Italy.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Mirandola
authors.affiliation: CNAO Foundation, Pavia, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Russo
authors.affiliation: CNAO Foundation, Pavia, Italy.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Mastella
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Azusa
authors.initials: A
authors.lastname: Hasegawa
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsuji
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Yamada
authors.affiliation: CNAO Foundation, Pavia, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Vischioni
authors.affiliation: CNAO Foundation, Pavia, Italy.
authors.forename: Viviana
authors.initials: V
authors.lastname: Vitolo
authors.affiliation: European Organization for Nuclear Research CERN, Geneva, Switzerland.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Ferrari
authors.affiliation: CNAO Foundation, Pavia, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Ciocca
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kamada
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Tsujii
authors.affiliation: CNAO Foundation, Pavia, Italy; Istituto Europeo di Oncologia, Milano, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Orecchia
authors.affiliation: CNAO Foundation, Pavia, Italy; Istituto Europeo di Oncologia, Milano, Italy.
authors.forename: Piero
authors.initials: P
authors.lastname: Fossati
mesh_terms: D002244:Carbon / Q000627:therapeutic use; D063193:Heavy Ion Radiotherapy / Q000379:methods*; D006801:Humans; D008954:Models, Biological; D009010:Monte Carlo Method; D009369:Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012062:Relative Biological Effectiveness
chemical_list: D002244:Carbon
keywords: Carbon ion radiotherapy; RBE-weighted dose; Radiobiological models