gms | German Medical Science

48th Meeting of the Particle Therapy Co-Operative Group

Particle Therapy Co-Operative Group (PTCOG)

28.09. - 03.10.2009, Heidelberg

Investigation on the impact of ripple filters on the biological modeling of the beam delivery line for active scan irradiation technique in heavy-ion radiotherapy

Meeting Abstract

  • F. Bourhaleb - Depatment of Experimental Physics, University of Turin, Turin, Italy
  • A. Attili - INFN - Istituto Nazionale di Fisica Nucleare, Turin, Italy
  • G. Russo - Depatment of Experimental Physics, University of Turin, Turin, Italy
  • E. Schmitt - Depatment of Experimental Physics, University of Turin, Turin, Italy
  • F. Marchetto - INFN - Istituto Nazionale di Fisica Nucleare, Turin, Italy
  • S. Giordanengo - INFN - Istituto Nazionale di Fisica Nucleare, Turin, Italy
  • V. Monaco - Depatment of Experimental Physics, University of Turin, Turin, Italy
  • R. Sacchi - Depatment of Experimental Physics, University of Turin, Turin, Italy
  • R. Cirio - Depatment of Experimental Physics, University of Turin, Turin, Italy
  • C. Peroni - Depatment of Experimental Physics, University of Turin, Turin, Italy
  • M. Donetti - CNAO (Centro Nazionale di Adroterapia Oncologica) Foundation, Milan, Italy
  • M. A. Garella - CNAO (Centro Nazionale di Adroterapia Oncologica) Foundation, Milan, Italy

PTCOG 48. Meeting of the Particle Therapy Co-Operative Group. Heidelberg, 28.09.-03.10.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc09ptcog023

DOI: 10.3205/09ptcog023, URN: urn:nbn:de:0183-09ptcog0237

Published: September 24, 2009

© 2009 Bourhaleb et al.
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Outline

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Background: The beam delivery line of the active scanning irradiation system for proton and carbon ion radiation therapy requires ripple filters to broad the very sharp Bragg peak at low kinetic energies. Usually the ripple filters are optimized only for physical dose profiles. However, it is necessary to consider the biological effect and their impact on the dose distribution, especially in the Bragg peak region for a correct estimation of the peak spread.

Materials and methods: A full beam delivery line of the national center of oncologic hadrontherapy (CNAO) is simulated with the Monte Carlo package GEANT4 to get the actual distribution in the treated volume of particles and fragments and the corresponding energies. The evaluation of biological effects was studied using a code based on the Local Effect Model (LEM). The computational effort was performed using the distributed INFN Grid computing resources.

Results: We estimate the impact on the relative biological effectiveness (RBE) and the biological dose distribution of the ripple filters as well as all the passive elements of the beam delivery line. The shape of the physical dose at Bragg peak is different from the corresponding biological dose. We verified that the transfer functions characterizing each of the element should involve a rigorous evaluation of the biological effects.

Conclusions: A full understanding of the impact of the biological effect on the shape of the Bragg peak dose distribution is necessary to evaluate the right equivalent effective dose delivered. A biological transfer function can be a flexible tool in the treatment planning system for a complete modeling of the effect of ripple filters for both proton and carbon ion beams.