Beam shaping systems for small animal proton therapy

Pre-clinical research using small animal models is of crucial importance in cancer research. Small animal radiotherapy platforms have been established allowing the evaluation of therapies and treatment plans in the pre-clinical setting before applying them in human radiotherapy. This work is done in the aim of developing a proton therapy treatment plan for small animals. It deals in particular with the optimization, using Monte Carlo simulations, of a beam shaping device that conforms the dose profile to a subcutaneous tumor five millimeters deep. Three models are compared: A range compensator, attenuator slabs each with a specific collimator, and attenuator slabs with a fixed-size collimator. Using Aluminium slabs of different thicknesses, that can be inserted manually one by one before the tumor in a way to cover all the tumor volume, with a collimator to shield unwanted protons, is judged to be the best method considering the available equipment and the simple mechanical feasibility of such a system.