Speaker
Description
The radionuclides used in targeted radionuclide therapy emit charged particles, such as α, β- and Auger electron, that makes possible the delivery of a significant dose to the tumour cells while sparring the healthy tissues surrounding them. The radioisotope 111Ag (T1/2 = 7.45 days, Emax,β- = 1.04 MeV) is a β- emitter that is promising for this kind of application. Its low energy β- has a medium tissue penetration of average 1.8 mm which enables the targeting of medium tumours. Additionally, its γ-rays at 245 keV (1.3 %) and 342 keV (6.7 %) are well suited for SPECT imaging which is helpful for monitoring more precisely the in vivo dose delivered. Several routes have been studied to produce
111Ag either with research reactors, cyclotrons or photonuclear reactions. The production cross sections of natPd(α,x)111Ag, one of the reaction for the alpha route, has only been measured by two teams. However, these measurements do not cover the whole region of the peak and what’s happening after it.
For this reason, several measurements of the production cross section of the natPd(α,x)111Ag reaction have been performed at the GIP ARRONAX with an alpha beam of 68 MeV to get experimental data above 40 MeV. The area of the peak will be thus better defined and the shape of the curve after the peak will be known. The “stacked-foils” method has been used during our experiments. The intensity of the beam has been monitored through the natAl(α,x)24Na and natAl(α,x)22Na nuclear reactions. HPGe detectors were used to perform the γ-spectrometry of each foil: short acquisitions
were done directly after the irradiation to measure short-lived radionuclides and longer acquisitions days after to measure 111Ag and the contaminants 105Ag, 106mAg and 110mAg. The analysis of the spectra was performed using multiple γ-rays for each radionuclide when possible.
The measurement made at the GIP ARRONAX of the natPd(α,x)111Ag cross sections up to 68 MeV will be presented. The experimental data obtained will be confronted with the literature and with TENDL 2023. Furthermore, the excitation function obtained with the new measurements and with the literature makes it possible to pick optimal parameters for the production of 111Ag. Thus, allowing its comparison with the other production routes in terms of yield, purity and specific activity.
These new experimental data could also help in refining the theoretical models to better describe the nuclear reactions.
