Optimized small animal tumor model for the radiobiological characterization of low-energy laser accelerated protons

The long-term aim of developing laser based particle acceleration (protons, heavier ions) towards clinical radiotherapy application requires not only substantial technological progress, but also the radiobiological characterization of the resulting ultra-short and ultra-intensive particle beam pulses. Already obtained in vitro data reveal similar effects of laser accelerated versus conventional proton beams on clonogenic cell survival and DNA double-strand breaks. To proceed in the translational chain, these effects have to be further verified by radiobiological experiments in vivo. However, as the proton energies currently available by laser driven acceleration are still too low to penetrate standard tumor models on mouse legs, a small animal tumor model allowing the delivery of a homogeneous 3D dose distribution with low energy protons (<30 MeV) was established. In the present work, the optimization of this small animal model towards its applicability in a full scale radiobiological experiment at a laser driven proton accelerator will be shown.