Comparison of MCNPX and GEANT4 to Predict the Contribution of Non-elastic Nuclear Interactions to Absorbed Dose in Water, PMMA and A150

摘要

Proton induced non-elastic nuclear reactions play an important role in the dosedistribution of clinically used proton beams as they deposit dose of high biological effectivenessboth within the primary beam path as well as outside the beam to untargeted tissues. Non-elasticnuclear reactions can be evaluated using transport codes based on the Monte Carlo method. Inthis work, we have utilized the Los Alamos code MCNPX and the CERN GEANT4 toolkit,which are currently the most widely used Monte Carlo programs for proton radiation transportsimulations in medical physics, to study the contribution of non-elastic nuclear interactions tothe absorbed dose of proton beams in the therapeutic energy range. The impact of differentavailable theoretical models to address the nuclear reaction process was investigated. Thecontribution of secondary particles from non-elastic nuclear reactions was calculated in threematerials relevant in radiotherapy applications: water, PMMA and A150. The results evidencethat there are differences in the calculated contribution of the secondary particles heavier thanprotons to the absorbed dose, with different approaches to model the nuclear reactions. TheMCNPX calculation give rise to a larger contribution of d, t, a ~3Heto the total dose compared tothe GEANT4 physical models chosen in this work.