An evaluation of the various aspects of the progress in clinical applications of laser driven ionizing radiation

There has been a vast development of laser-driven particle acceleration (LDPA) using high power lasers. This has initiated by the radiation oncology community to use the dose distribution and biological advantages of proton/heavy ion therapy in cancer treatment with a much greater accessibility than currently possible with cyclotron/synchrotron acceleration. Up to now, preclinical experiments have only been performed at a few LDPA facilities; technical solutions for clinical LDPA have been theoretically developed but there is still a long way to go for the clinical introduction of LDPA. Therefore, to explore the further potential bio-medical advantages of LDPA has pronounced importance. The main characteristics of LDPA are the ultra-high beam intensity, the flexibility in beam size reduction and the potential particle and energy selection whilst conventional accelerators generate single particle, quasi mono-energetic beams. There is a growing number of studies on the potential advantages and applications of Energy Modulated X-ray Radiotherapy, Modulated Electron Radiotherapy and Very High Energy Electron (VHEE) delivery system. Furthermore, the ultra-high space and/or time resolution of super-intense beams are under intensive investigation at synchrotrons (microbeam radiation and very high dose rate (> 40 Gy/s) electron accelerator flash irradiation) with growing evidence of significant improvement of the therapeutic index. Boron Neutron Capture Therapy (BNCT) is an advanced cell targeted binary treatment modality. Because of the high linear energy transfer (LET) of the two particles (Li-7 and He-4) released by (BNC)-B-10 reaction, all of the energy is deposited inside the tumour cells, killing them with high probability, while the neighbouring cells are not damaged. The limited availability of appropriate neutron sources, prevent the more extensive exploration of clinical benefit of BNCT. Another boron-based novel binary approach is the B-11-Proton Fusion, which result in the release of three high LET alpha particles. These promising, innovative approaches for cancer therapy present huge challenges for dose calculation, dosimetry and for investigation of the biological effects. The planned LDPA (photons, VHEE, protons, carbon ions) at ELI facilities has the unique property of ultra-high dose rate (> Gy/s(-10)), short pulses, and at ELI-ALPS high repetition rate, have the potential to develop and establish encouraging novel methods working towards compact hospital-based clinical applications.