Experimental excitation functions for PD-103 produced by deuteron beams

Brachytherapy was developed to treat prostate cancer 50 years ago. It consists in the implantation of Ti or SS seeds containing suitable radionuclides: nowadays only three radionuclides are available for use in low dose rate – LDR - prostate brachytherapy: I-125 (T1/2 = 59.4 d, mean photon energy emitted: 21 keV), Pd-103 (T1/2 = 17 d, mean photon energy emitted: 27 keV), and Cs-131 (T1/2 = 9.7 d, mean photon energy emitted: 29 keV). Pd-103 is an effective alternative to I-125 for high grade, rapidly growing cancer because of its faster dose rate that also raise thanks to possible differences in external tissue complications. So it is important to study the production optimization of Pd-103 radionuclide. Nowadays Pd-103 production by accelerator is based exclusively on the irradiation of rhodium metal targets with 18 MeV protons via Rh-103(p, n)Pd-103 reaction. We have studied the possibility to produce it by deuteron beams irradiation, which presents indisputable advantages. A new set of excitation functions for Rh-103(d,2 n)Pd-103 was measured and compared with the only other two sets present in the literature. The thin-target yields have been plotted as a function of their average energy into the targets and were fitted with the best mathematical functions. By integration of these functions the calculated thick-target yields were obtained, in order to find the optimized couple of irradiation energy and energy loss inside the thick target to maximize the production of the radionuclide of interest.