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Recent progress in laser physics enabled us to generate high-flux particle pulses by laser-plasma interactions with high power laser. One of the possible applications for laser-driven beams from a compact laser system is generation of medical radioisotopes inside of hospitals. At present, many medical radioisotopes have been produced by compact proton accelerators or nuclear reactors. However, some candidates for new medical radioisotopes cannot be produced by these methods because of the lack of suitable stable isotopes as the nuclear reaction target.
We have proposed production of a medical radioisotope $^{67}$Cu using $^{67}$Zn(n, p)$^{67}$Cu and $^{68}$Zn(n, pn)$^{67}$Cu reactions with fast neutrons provided from laser-driven neutron sources (LDNSs). $^{67}$Cu-pharmaceutical is a candidate for medical diagnostic scans by gamma-rays and cancer therapy by beta-ray, but production method has not been established. Protons and deuterons were accelerated by laser-plasma interactions, and subsequently neutrons were generated by the p+$^9$Be and d+$^9$Be reactions. We measured gamma-rays from neutron irradiated samples using Ge detectors after a laser shot. We obtained the yield of (3.3±0.5)×10$^5$ atoms for $^{67}$Cu, corresponding to a radioactivity of 1.0±0.2 Bq, with a single laser shot. Using a simulation based on this result, we estimated $^{67}$Cu production with a high-frequency laser. The result suggests that it is possible to generate $^{67}$Cu with a radioactivity of 270 MBq using a future laser system with a frequency of 10 Hz and 10000-s radiation in a hospital [1].
[1] T. Mori, et al. “Feasibility study of laser-driven neutron sources for pharmaceutical applications”, High Power Laser Sci. Eng., 11, e20 (2023).
