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Purpose: Recent in vivo investigations have shown that short pulses of electrons at very high dose rates (FLASH) are less harmful to healthy tissues but just as efficient as conventional dose-rate radiation to inhibit tumor growth. In view of the potential clinical value of FLASH and the availability of modern proton therapy infrastructures to achieve this goal, we herein describe a series of technological developments required to investigate the biology of FLASH irradiation using a commercially available clinical proton therapy system., Methods and Materials: Numerical simulations and experimental dosimetric characterization of a modified clinical proton beamline, upstream from the isocenter, were performed with a Monte Carlo toolkit and different detectors. A single scattering system was optimized with a ridge filter and a high current monitoring system. In addition, a submillimetric set-up protocol based on image guidance using a digital camera and an animal positioning system was also developed., Results: The dosimetric properties of the resulting beam and monitoring system were characterized; linearity with dose rate and homogeneity for a 12 × 12 mm 2 field size were assessed. Dose rates exceeding 40 Gy/s at energies between 138 and 198 MeV were obtained, enabling uniform irradiation for radiobiology investigations of small animals in a modified clinical proton beam line., Conclusions: This approach will enable us to conduct FLASH proton therapy experiments on small animals, specifically for mouse lung irradiation. Dose rates exceeding 40 Gy/s were achieved, which was not possible with the conventional clinical mode of the existing beamline., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Protontherapy is a well-established approach to treat cancer due to the favorable ballistic properties of proton beams. Nevertheless, this treatment is today only possible with large scale accelerator facilities which are very difficult to install at existing hospitals. In this article we report on a new approach for proton acceleration up to energies within the therapeutic window between 60 and 200 MeV by using modern, high intensity and compact laser systems. By focusing such laser beams onto thin foils we obtained on target intensities of 6 x 10(19) W/cm2, which is sufficient to produce a well-collimated proton beam with an energy of up to 10 MeV. These results are in agreement with numerical simulations and indicate that proton energies within the therapeutic window should be obtained in the very near future using such economical and very compact laser systems. Hence, this approach could revolutionize cancer treatment by bringing the "lab to the hospital-rather than the hospital to the lab".

The laminarity of high-current multi-MeV proton beams produced by irradiating thin metallic foils with ultraintense lasers has been measured. For proton energies >10 MeV, the transverse and longitudinal emittance are, respectively, <0.004 mm mrad and <10(-4) eV s, i.e., at least 100-fold and may be as much as 10(4)-fold better than conventional accelerator beams. The fast acceleration being electrostatic from an initially cold surface, only collisions with the accelerating fast electrons appear to limit the beam laminarity. The ion beam source size is measured to be <15 microm (FWHM) for proton energies >10 MeV.

Progresses of the three-dimensional imageries and of the software of planning systems makes that the radiotherapy of the tumours of brain and the base of skull is increasingly precise. The set-up of the patients and the positioning of the beams are key acts whose realization can become extremely tiresome if the requirement of precision increases. This precision very often rests still on the visual comparison of digital images. In the near future, the development of the automated systems controlled by robots should allow a noticeable improvement of the precision, safety and speed of the patient set-up.