[Update of clinical programs using hadrontherapy 2008-2012]. / Évolution des indications cliniques en hadronthérapie 2008-2012.

Hadrontherapy, a type of radiation therapy dealing with heavy charged particles, has become for the past decade one of the most sophisticated and attractive approach in the management of cancer. This is related with major technological innovations that have made available, at a relatively cheap cost, compact proton accelerators equipped with rotational gantries. The implementation of pencil beam scanning should also make treatment planning and delivery much easier and faster than conventional approaches. Until now, approximately 100,000 patients have been treated with protons worldwide. Due to more complex technological and biological challenges, light ion therapy - mainly carbon ions - has developed at a lower pace, except in Japan where most of the 15,000 treated patients have been enrolled. Current indications for protons include firstly, locally aggressive tumours non or incompletely resected, that are located close to critical normal structures: ocular melanomas, skull base and spinal canal low grade sarcomas, selected ENT carcinomas (like adenoid cystic); secondly, improvement of tolerance to radiations: delayed, mainly in paediatric malignancies, due to the exquisite sensitivity of organs under development (including to carcinogenesis); immediate, on bone marrow, mucosae… mainly in concomitant radiation-chemotherapy interactions (tested in esophagus, and lung). Most promising indications for carbon ions include inoperable highly radioresistant primaries, such as mucosal melanomas, high grade bone and soft part sarcomas, and pancreatic carcinomas. Altered fractionations are also of interests that could translate in clinical and economical benefits. Controversies have risen whether more common indications, like prostate, should also be explored.

Monte Carlo modelling of the treatment line of the Proton Therapy Center in Orsay.

This paper presents the main results of a Monte Carlo simulation describing the Orsay Proton Therapy Center (CPO) beam line. The project aimed to obtain a prediction of the dose distribution in a water phantom within 2% accuracy in the dose value and a 2 mm of range. The simulation tool used was MCNPX, version 2.5.0, and included all the elements of the CPO beam line. A new algorithm of multiple Coulomb scattering has been incorporated in MCNPX, resulting in a better prediction of the spatial dose distribution and absolute values of the deposited energy. The simulations of 3D dose profiles in water show a very good agreement with measured data to within 2%. We first performed a comparative analysis of the dosimetry in heterogeneous phantoms between the pencil beam algorithm and MCNPX. The simulations give a better agreement with experimental data compared to the pencil beam approach. In a second phase, we simulated the patient-dependent fields along with the spatial dose distributions in a water phantom. The simulated response of a Pixel chamber located 2 m upstream of the water phantom revealed a good agreement with the measured data to within 1%. The results presented herein support the applicability of Monte Carlo models for absolute dosimetry and for design purposes regarding existing and new beam lines at CPO. This work completes a series of publications reporting the progress in the development of a Monte Carlo simulation tool for the CPO beam line dedicated for the treatment of head and neck tumours.