A new energy spectrum reconstruction method for time-of-flight diagnostics of high-energy laser-driven protons.

The Time-of-Flight (TOF) technique coupled with semiconductorlike detectors, as silicon carbide and diamond, is one of the most promising diagnostic methods for high-energy, high repetition rate, laser-accelerated ions allowing a full on-line beam spectral characterization. A new analysis method for reconstructing the energy spectrum of high-energy laser-driven ion beams from TOF signals is hereby presented and discussed. The proposed method takes into account the detector's working principle, through the accurate calculation of the energy loss in the detector active layer, using Monte Carlo simulations. The analysis method was validated against well-established diagnostics, such as the Thomson parabola spectrometer, during an experimental campaign carried out at the Rutherford Appleton Laboratory (UK) with the high-energy laser-driven protons accelerated by the VULCAN Petawatt laser.

Transversal dose distribution optimization for laser-accelerated proton beam medical applications by means of Geant4.

The main purpose of this paper is to quantitatively study the possibility of delivering dose distributions of clinical relevance with laser-driven proton beams. A Monte Carlo application has been developed with the Geant4 toolkit, simulating the ELIMED (MEDical and multidisciplinary application at ELI-Beamlines) transport and dosimetry beam line which is being currently installed at the ELI-Beamlines in Prague (CZ). The beam line will be used to perform irradiations for multidisciplinary studies, with the purpose of demonstrating the possible use of optically accelerated ion beams for therapeutic purposes. The ELIMED Geant4-based application, already validated against reference transport codes, accurately simulates each single element of the beam line, necessary to collect the accelerated beams and to select them in energy. Transversal dose distributions at the irradiation point have been studied and optimized to try to quantitatively answer the question if such kind of beam lines, and specifically the systems developed for ELIMED in Prague, will be actually able to transport ion beams not only for multidisciplinary applications, such as pitcher-catcher nuclear reactions (e.g. neutrons), PIXE analysis for cultural heritage and space radiation, but also for delivering dose patterns of clinical relevance in a future perspective of possible medical applications.

First experimental proof of Proton Boron Capture Therapy (PBCT) to enhance protontherapy effectiveness.

Protontherapy is hadrontherapy's fastest-growing modality and a pillar in the battle against cancer. Hadrontherapy's superiority lies in its inverted depth-dose profile, hence tumour-confined irradiation. Protons, however, lack distinct radiobiological advantages over photons or electrons. Higher LET (Linear Energy Transfer) 12C-ions can overcome cancer radioresistance: DNA lesion complexity increases with LET, resulting in efficient cell killing, i.e. higher Relative Biological Effectiveness (RBE). However, economic and radiobiological issues hamper 12C-ion clinical amenability. Thus, enhancing proton RBE is desirable. To this end, we exploited the p + 11B → 3α reaction to generate high-LET alpha particles with a clinical proton beam. To maximize the reaction rate, we used sodium borocaptate (BSH) with natural boron content. Boron-Neutron Capture Therapy (BNCT) uses 10B-enriched BSH for neutron irradiation-triggered alpha particles. We recorded significantly increased cellular lethality and chromosome aberration complexity. A strategy combining protontherapy's ballistic precision with the higher RBE promised by BNCT and 12C-ion therapy is thus demonstrated.