Post-doc 24 months - Monte-Carlo simulations for low energy photon beam

Postdoctoral position – 24 months

Monte-Carlo simulations for low energy photon beam


Project context

The proposed position is part of the MC-SMART project (Monte-Carlo Small Animal Radiation Therapy), funded by the “Physi-Cancer” call for project (INCA, AVIESAN). It is a collaboration between IRT (Institut de Recherche Thérapeutique, INSERM, Nantes) and CREATIS (medical imaging, CNRS, Lyon) laboratories.

Scientific context

Preclinical irradiation studies on small animals are essential in the fight against cancer. They generally consist in delivering a single high dose with an anterior beam port. However, dose calculation provided by commercial systems is limited to an estimation of the entrance dose rate because the involved physics deal with low energy photon beams (50 kVp to 300 kVp). Today, no treatment planning system similar to human clinical practice exists for small animal treatments. The current simplistic calculation yields to a difficult interpretation of the observed results. In particular, a dose effect relationship is hard to establish with confidence. The goal of the MC SMART project is to provide a reference Monte Carlo based 3D dose distribution platform for preclinical irradiations using the GATE software, based on Geant4.  It will serve as a reference dose calculation engine and will be used for quality assessment of current and future treatment devices that will allow a more complex ballistic.

Tasks

The recruited person will be involved in two main tasks. The first one consists in calibrating the preclinical Cone-Beam associated with the irradiator XRAD225Cx in order to correlate  voxel values to the composition of the materials. Gate will then be able to calculate 3D dose distribution using the CBCT images, taking into account this calibration. A sensitivity study will be performed to analyze the impact of the calibration on the dose distribution, which is not well known for small fields at low energy (~200 keV).
The second task consists in increasing the simulation speed by developing a method based on the hybrid approach previously developed in the team.  Hybrid approaches consist in dividing the computation into two parts: (a) the dose deposited by primary radiation (coming directly from the incident X-ray beam) is calculated in a deterministic way using ray casting techniques and energy-absorption coefficient tables and (b) the dose deposited by secondary radiation (Rayleigh and Compton scattering, fluorescence) is computed using a hybrid algorithm combining Monte Carlo and deterministic calculations. The integration and the validation of this method in Gate will allow the computation of accurate dose distributions in a time compatible with interactive usage (forward planning, adjustment of irradiation parameters).

Skills

The candidate must hold a PhD in physics, medical imaging or computer sciences.

  • Programming skills: C++.
  • Monte-Carlo simulation, ideally Geant4, Gate

Details

  • Location : CREATIS, Léon Bérard cancer center, Lyon, France
  • Salary gross : 2000-2500 € / month
  • Duration : 24 months, starting ideally November 2012

Contact

Send a CV and motivation letter to: