Medical Application Studies at ELI-NP

We study the production of radioisotopes for nuclear medicine in (γ, γ′) photoexcitation reactions or (γ, xn+yp) photonuclear reactions for the examples of 195mPt,117mSn and 44Ti with high flux [(1013 − 1015)γ/s], small beam diameter and small energy band width (ΔE/E ≈ 10−3 − 10−4) γ beams. In order to realize an optimum γ-focal spot, a refractive γ-lens consisting of a stack of many concave micro-lenses will be used. It allows for the production of a high specific activity and the use of enriched isotopes. For photonuclear reactions with a narrow γ beam, the energy deposition in the target can be reduced by using a stack of thin target wires, hence avoiding direct stopping of the Compton electrons and e+e − pairs. The well-defined initial excitation energy of the compound nucleus leads to a small number of reaction channels and enables new combinations of target isotope and final radioisotope. The narrow-bandwidth γ excitation may make use of collective resonances in γ-width, leading to increased cross sections. (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. The produced isotopes will open the way for completely new clinical applications of radioisotopes. For example 195mPt could be used to verify the patient’s response to chemotherapy with platinum compounds before a complete treatment is performed. In targeted radionuclide therapy the short-range Auger and conversion electrons of 195mPt and 117mSn enable a very local treatment. The generator 44Ti allows for a PET with an additional γ-quantum (γ-PET), resulting in a reduced dose or better spatial resolution