Showing papers by "Andrea Attili published in 2009"

Heuristic optimization of the scanning path of particle therapy beams.

Abstract: Quasidiscrete scanning is a delivery strategy for proton and ion beam therapy in which the beam is turned off when a slice is finished and a new energy must be set but not during the scanning between consecutive spots. Different scanning paths lead to different dose distributions due to the contribution of the unintended transit dose between spots. In this work an algorithm to optimize the scanning path for quasidiscrete scanned beams is presented. The classical simulated annealing algorithm is used. It is a heuristic algorithm frequently used in combinatorial optimization problems, which allows us to obtain nearly optimal solutions in acceptable running times. A study focused on the best choice of operational parameters on which the algorithm performance depends is presented. The convergence properties of the algorithm have been further improved by using the next-neighbor algorithm to generate the starting paths. Scanning paths for two clinical treatments have been optimized. The optimized paths are found to be shorter than the back-and-forth, top-to-bottom (zigzag) paths generally provided by the treatment planning systems. The gamma method has been applied to quantify the improvement achieved on the dose distribution. Results show a reduction of the transit dose when the optimized paths are used. The benefit is clear especially when the fluence per spot is low, as in the case of repainting. The minimization of the transit dose can potentially allow the use of higher beam intensities, thus decreasing the treatment time. The algorithm implemented for this work can optimize efficiently the scanning path of quasidiscrete scanned particle beams. Optimized scanning paths decrease the transit dose and lead to better dose distributions.

Hadrontherapy: An open source, Geant4-based application for proton-ion therapy studies

Abstract: Hadrontherapy is an open source application based on the Geant4 Monte Carlo libraries. It can be downloaded with the Geant4 official code and can be found in the category of the advanced examples ($G4Install/examples/advanced folder of the Geant4 distribution). Since its original version, released in 2004, Hadrontherapy permitted the simulation of a typical proton therapy beam line, together with all it elements (collimators, scattering systems, etc.) and the calculation of the corresponding dose distribution curves in water and other materials. In this paper we will report on the newest development and improvement of Hadrontherapy as it will be released in the Geant4 9.3 version. The new version of application will furnish a set of tools useful for Users interested in studies related to proton/ion therapy. The new version of Hadrontherapy will permit, in fact, the transport of carbon beams, using the state-of-art of the Geant4 electromagnetic and hadronic models, the calculation of some basic parameters like stopping powers, or the possibility to easily change the geometrical configuration for the simulation of typical nuclear physics experiment of interest in the hadrontherapy field. Other capabilities are inserted in the new Hadrontherapy version even if not all are reported in this paper. For more information the reader can refer to the on-line manual of Hadrontherapy that can be found inside the Geant4 official website (www.cern.ch/geant4).