%0 Generic
%A Sánchez Parcerisa, Daniel
%D 2012
%F heidok:13619
%K hadrontherapy , particle therapy , dosimetry , ionization chambers , stopping power ratio
%R 10.11588/heidok.00013619
%T Experimental and computational investigation of water-to-air stopping power ratio for ion chamber dosimetry in carbon ion radiotherapy
%U https://archiv.ub.uni-heidelberg.de/volltextserver/13619/
%X Particle therapy is an advanced modality of cancer radiotherapy which allows the delivery of a highly conformal dose to the tumour while considerably sparing healthy tissue. This work aims at improving the accuracy of ion chamber dosimetry for particle therapy with carbon ion beams. The readout of air-filled ionization chambers is affected by a number of correction factors, some of which are known only with limited accuracy. This study deals with one of this beam quality correction factors, the stopping power ratio between water and air, or sw,air. On a first step, we planned and carried out experimental measurements to determine the value of water-to-air stopping power ratio in monoenergetic carbon ion beams. Then, we used the Monte Carlo code FLUKA to extend the results of those measurements to realistic treatment beams, and to develop a model to calculate sw,air for any given position in a treatment field. Finally, we tested the developed model in patient cases, to study its possible application in absolute dosimetry and patient plan verification. The obtained results are promising and can, if incorporated in the recommended dosimetry protocols, reduce the uncertainty margins in the determination of absorbed dose for carbon ion beam radiotherapy.