David J Brenner et al 2009 Phys. Med. Biol. 54 6065 doi:10.1088/0031-9155/54/20/003
David J Brenner1,3, Carl D Elliston1, Eric J Hall1 and Harald Paganetti2
Show affiliationsProton radiotherapy represents a potential major advance in cancer therapy. Most current proton beams are spread out to cover the tumor using passive scattering and collimation, resulting in an extra whole-body high-energy neutron dose, primarily from proton interactions with the final collimator. There is considerable uncertainty as to the carcinogenic potential of low doses of high-energy neutrons, and thus we investigate whether this neutron dose can be significantly reduced without major modifications to passively scattered proton beam lines. Our goal is to optimize the design features of a patient-specific collimator or pre-collimator/collimator assembly. There are a number of often contradictory design features, in terms of geometry and material, involved in an optimal design. For example, plastic or hybrid plastic/metal collimators have a number of advantages. We quantify these design issues, and investigate the practical balances that can be achieved to significantly reduce the neutron dose without major alterations to the beamline design or function. Given that the majority of proton therapy treatments, at least for the next few years, will use passive scattering techniques, reducing the associated neutron-related risks by simple modifications of the collimator assembly design is a desirable goal.
General scientific summary. Hospital-based proton facilities represent a potential major advance in radiation therapy. Most current proton beams are spread out to cover the tumor by using passive scattering and collimation, which result in an extra whole-body high-energy neutron dose, primarily due to interactions of the protons with the final collimator. There is uncertainty as to the carcinogenic potential of these high-energy neutrons, and thus our goal is to investigate whether this external neutron dose can be significantly reduced without major modifications to passively-scattered proton beam lines. An optimized collimator/pre-collimator can significantly reduce this neutron dose. Given that the majority of proton therapy treatments, at least for the next few years, will be accomplished using passive scattering techniques, reducing the associated neutron-related second-cancer risks by a simple modification of the collimator assembly design is a highly desirable goal.
For more information on this article see medicalphysicsweb.org
Issue 20 (21 October 2009)
Received 10 July 2009, in final form 4 August 2009
Published 24 September 2009
David J Brenner et al 2009 Phys. Med. Biol. 54 6065
Martin Heiß et al 2009 Nanotechnology 20 075603
Neil J Cornish and Shane L Larson 2001 Class. Quantum Grav. 18 3473
G Tarjus et al 2005 J. Phys.: Condens. Matter 17 R1143
Steven Vogel 2009 Bioinspir. Biomim. 4 046004
R J Needs et al 2010 J. Phys.: Condens. Matter 22 023201
Andrew M Lance et al 2003 New J. Phys. 5 4
G Charpak et al 2009 JINST 4 P12007
Thomas V Marcella 2002 Eur. J. Phys. 23 615
A Fowler 1911 Proc. Phys. Soc. London 24 168