Dosimetric verification of PENSSART, a new Monte Carlo dose calculation system based on PENELOPE and dedicated to patient-specific treatment quality control in radiotherapy
Résumé
Beam delivery in radiotherapy has become increasingly complex since the advance of 3D conformational radiotherapy (3DCRT), intensity modulated radiotherapy (IMRT) and stereotactic body radiotherapy (SBRT). With these high precision modalities, accurate dose calculations are essential for radiotherapy planning since the accuracy of the absorbed dose as prescribed determines the clinical outcome. However, in presence of air cavities or inhomogeneities in the patient anatomy, commercial treatment planning systems (TPSs), in particular those based on the pencil beam algorithm, often fail to predict accurate dose distributions. Systematic errors exceeding 10 % in the thoracic area have been reported. To obtain accurate dose calculations in Monte Carlo simulations, tissues have to be correctly characterized. Indeed, it has been reported that to overcome significant dose artifacts.
In this work, we present a new MC dose calculation system called PENSSART (PENELOPE Simulation for the Safety in Radiotherapy). Prior to dose calculation, we have developed an accurate characterization of biological tissues thanks to a conversion method similar to the one proposed by Vanderstraeten et al., based on a stoichiometric calibration method and making used of dosimetrically equivalent tissues subsets. A special attention has been given to bone and lung materials. The schemes obtained for a GE LightSpeed scanner have been introduced in PENSSART and validated with a slab phantom.
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