Paper detail

Production of Medical Radioisotopes with High Specific Activity in Photonuclear Reactions with $γ$ Beams of High Intensity and Large Brilliance

We study the production of radioisotopes for nuclear medicine in $(γ,x{\rm n}+y{\rm p})$ photonuclear reactions or ($γ,γ'$) photoexcitation reactions with high flux [($10^{13}-10^{15}$)$γ$/s], small diameter $\sim (100 \, μ$m$)^2$ and small band width ($ΔE/E \approx 10^{-3}-10^{-4}$) $γ$ beams produced by Compton back-scattering of laser light from relativistic brilliant electron beams. We compare them to (ion,$x$n$ + y$p) reactions with (ion=p,d,$α$) from particle accelerators like cyclotrons and (n,$γ$) or (n,f) reactions from nuclear reactors. For photonuclear reactions with a narrow $γ$ beam the energy deposition in the target can be managed by using a stack of thin target foils or wires, hence avoiding direct stopping of the Compton and pair electrons (positrons). $(γ,γ')$ isomer production via specially selected $γ$ cascades allows to produce high specific activity in multiple excitations, where no back-pumping of the isomer to the ground state occurs. We discuss in detail many specific radioisotopes for diagnostics and therapy applications. Photonuclear reactions with $γ$ beams allow to produce certain radioisotopes, e.g. $^{47}$Sc, $^{44}$Ti, $^{67}$Cu, $^{103}$Pd, $^{117m}$Sn, $^{169}$Er, $^{195m}$Pt or $^{225}$Ac, with higher specific activity and/or more economically than with classical methods. This will open the way for completely new clinical applications of radioisotopes. For example $^{195m}$Pt could be used to verify the patient's response to chemotherapy with platinum compounds before a complete treatment is performed. Also innovative isotopes like $^{47}$Sc, $^{67}$Cu and $^{225}$Ac could be produced for the first time in sufficient quantities for large-scale application in targeted radionuclide therapy.