Experimental study of medical isotopes Cu-62,Cu-64 and Ga-68 production using intense picosecond laser pulse

Radioisotopes are indispensable agents in medical diagnosis and treatment, among which copper-62, 64 (Cu-62,Cu-64) and gallium-68 (Ga-68) are medical isotopes widely used in positron emission tomography (PET) imaging. Experiments that generate these radioisotopes via laser-induced photonuclear reactions were performed on the XingGuangIII laser facility of the Laser Fusion Research Center in Mianyang. High-charge (Q(e) similar to 40 nC) MeV electron (e(-)) beams were generated with 100 terawatts, picosecond laser pulses. The e(-) beams were then impinged on a metal stack composed of Ta foil and activation plates (natural Cu and Ga2O3), producing high-energy bremsstrahlung x-rays and medical isotopes Cu-62,Cu-64 and Ga-68, respectively. The characteristic emissions of the produced Cu-62,Cu-64 and Ga-68 were detected off-line , and the production yields of Cu-62,Cu-64 and Ga-68 were obtained to be of the order of 10(6) per laser shot. For electrons with energy higher than 8 MeV, the dependence of isotope production efficiency (per e(-)) on electron temperature (T-e) is investigated through Geant4 simulations. It is found that the production efficiency increases with the T-e. At T-e similar to 10 MeV, the values are 10(-4) for Cu-62 and 2 x 10(-5) for Ga-68, respectively. The prospect of producing the medical isotopes Cu-62,Cu-64 and Ga-68 are further evaluated using a table-top femtosecond laser system of high repetition. With a repetition rate of 100 Hz, their activity is expected to reach 0.2 GBq for Cu-62, 0.1 GBq for Cu-64 and 0.05 GBq for Ga-68, respectively. Such activity would meet the required dose for clinical PET imaging, indicating the great potential to produce medical isotopes with an all-optical, high-repetition laser system.