Dose prescription in carbon ion radiotherapy: How to compare two different RBE-weighted dose calculation systems

Silvia Molinelli, Giuseppe Magro, Andrea Mairani, Naruhiro Matsufuji, Nobuyuki Kanematsu, Taku Inaniwa, Alfredo Mirandola, Stefania Russo, Edoardo Mastella, Azusa Hasegawa, Hiroshi Tsuji, Shigeru Yamada, Barbara Vischioni, Viviana Vitolo, Alfredo Ferrari, Mario Ciocca, Tadashi Kamada, Hirohiko Tsujii, Roberto Orecchia, Piero Fossati

Research output: Journal article (peer-reviewed)Journal article

63 Citations (Scopus)


BACKGROUND AND PURPOSE: 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.

MATERIAL AND METHODS: 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.

RESULTS: 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.

CONCLUSIONS: 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.

Original languageEnglish
Pages (from-to)307-312
Number of pages6
JournalRadiotherapy and Oncology
Issue number2
Publication statusPublished - Aug 2016
Externally publishedYes


  • Carbon/therapeutic use
  • Heavy Ion Radiotherapy/methods
  • Humans
  • Models, Biological
  • Monte Carlo Method
  • Neoplasms/radiotherapy
  • Radiotherapy Dosage
  • Radiotherapy Planning, Computer-Assisted/methods
  • Relative Biological Effectiveness


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