Evaluation ofMo99andTc99mProductions Based on a High-Performance Cyclotron

Abstract

Following preliminary feasibility studies which started at Legnaro National Laboratories (LNL) in 2011, the Italian National Institute for Nuclear Physics (INFN) research activities are underway aiming at the alternative, accelerator-driven,Mo99/Tc99mproduction routes. One of the most promising approaches is to use100Mo-enriched (i.e., >99%) molybdenum metallic targets, bombarded with high-beam-current, high-energy proton cyclotrons. In order to get a comprehensive map of radionuclides expected, a detailed theoretical investigation has been carried out using the TALYS-TENDL 2012 excitation functions extended up to (p,6n), (p,p5n), and (p,2p4n) levels. A series of quality parameters have thus been calculated both at the end of beam (EOB) and at longer times. Results point out that accelerator-99Mo is of limited interest for a possible massive production because of the quite low specific activity with respect to reactor-99Mo. Accelerator-Tc99mquality parameters (i.e., radionuclidic purity (RNP), isotopic purity (IP), and specific activities) calculated are instead quite close to the generator-Tc. Calculations at 15, 20, and 25 MeV have thus been performed to assess the best operative irradiation condition forTc99mproduction while minimizing both the short-lived and long-lived Tc contaminant radionuclides. Although present in minimum quantities, Tc contaminants may indeed have an impact either on the pharmaceutical labeling procedures or on contributing to patient radiation dose during the diagnostic procedures.

Experimental cross section evaluation for innovative 99Mo production via the (α,n) reaction on 96Zr target

“…This is an interesting solution that, however, could meet only local needs and poses some issues still under investigation, mainly relying on the production of other Tc-isotopes [2,10]. They may indeed affect the final image quality and increase the radiation dose to patients; for these reasons, a careful analysis of irradiation conditions is mandatory [5,25,26].…”

“…In 2009-2010 both reactors have experienced long scheduled/ unscheduled shutdowns, thus causing a temporary shortage of 99 Mo and 99m Tc on the radionuclides' international market. Such an event has prompted the international scientific community to investigate new production routes for these vital radionuclides [4][5][6][7][8].…”

“…The second one, with a variable exit energy (from 30 to 70 MeV), will be used for applied research in physics and isotope production. In such a framework, the production of 99 Mo and 99m Tc has been investigated and compared through both proton-induced reactions on 100 Mo-enriched targets [5,11] and the ainduced reaction on 96 Zr targets.…”

14 MeV Neutrons for 99Mo/99mTc Production: Experiments, Simulations and Perspectives

“…The automatable module developed and properly optimized for this project (Figure 8) involves five main steps: (1) dissolution of the irradiated target and basification of the solution; (2) solvent extraction of pertechnetate with MEK from the aqueous alkaline solution; (3) separation of the MEK phase, containing pertechnetate, from aqueous solution containing molybdate and by-products; (4) purification of the extracted pertechnetate by column chromatography with a silica and an alumina cartridges and finally; (5) elution of sodium pertechnetate [ 99m Tc]NaTcO 4 from the alumina column with saline [26,27,28]. The dissolution, extraction and purification processes were performed the day after sample irradiation to achieve the equilibrium between 99m Tc and the parent nuclide 99 Mo.…”

“…The procedure takes about 45 min, comprehensive of the dissolution step, and allows to obtain 99m Tc in high yield with minimum activity losses. This technique was also recently applied for the high yield separation of 99m Tc directly produced by proton irradiation with cyclotron on an enriched 100 Mo sample [26,27]. A detailed quality control analysis of the final pertechnetate solution was performed, to determine isotopes and impurity amounts, Mo breakthrough, percentage of organic solvent etc.…”