PROSPECTS FOR THE PRODUCTION OF THERAPEUTIC RADIOISOTOPES BASED ON INSTALLED CAPACITY IN ARGENTINA AND BRAZIL

Therapeutic radioisotopes were first used in clinical practice in 1941 to treat thyroid cancer, using a mixture of 131 I/ 133 I produced in a cyclotron. Nowadays, high-purity 131 I is still used to treat thyroid disease, but it is produced in nuclear reactors. From the 1980s to the 2010s, new radioisotopes were introduced for cancer treatment, including beta (β) emitter 90 Y, 153 Sm, and 166 Ho. By the end of 2010, 177 Lu emerged as a promising radioisotope for theranostic applications, and by 2020, 161 Tb was identified as a promising new radioisotope due to its simultaneous β and Auger-electron emission. Also, the alpha emitters 211 At, 225 Ac, 212 Pb, and 213 Bi have proven effective in cancer treatment. The production of these radioisotopes depends on specific nuclear reactions requiring either high-energy charged particles or high neutron fluxes. For 225 Ac, several methods were tested, one of the oldest is 232 Th(p,x) 225 Ac, >100 MeV. However, this route is controversial because it co-produces 227 Ac, a long half-life (21.7 y) alpha emitter, that makes impossible it uses in humans; alternatively 226 Ra(p,2n) 225 Ac ≥ 30 MeV; other possibility is 226 Ra(g,n) 225 Ra (β) 225 Ac has been in use to produce 225 Ac with the higher radionuclide purity, 209 Bi(α,2n) 211 At, but with alpha particles not higher than 29-28 MeV to avoid production to 211 Po, 151 Eu( 3 He,5n) 149 Tb 40-70 MeV. Beyond the production of standard beta-emitting radioisotopes, current research focuses on the 160 Gd(n,γ) 161 Gd(β) 161 Tb (thermal neutron flux, in the range of 10 13 to 10 14 n.cm -2 .s -1 ). Argentina and Brazil have installed 10 research reactors, but only three of them, RA-3 (10 MW, neutron 1-1.4 × 10 14 ) and RA-10 (30 MW, 1.4-2.5 × 10 14 (expected to be critical in 2027), by CNEA, in Argentina, and the IEA-R1 (4.5 MW, 1 × 10 14 ) in Brazil have the capacity to produce of therapeutic radioisotopes in commercial scale. From these, Ra-3 is producing 99 Mo, 51 Cr, 131 I and 177 Lu, and 161 Tb under R&D production. Currently, the IEA-R1 is not producing radioisotopes, but it is planned to return to the production of 131 I and start the 177 Lu production in 2026. Furthermore, Brazil has begun construction of the Brazilian Multipurpose Reactor (RMB), which will operate at 30 MW and is scheduled to begin operations in 2032. There are 26 cyclotrons installed in the region, but a limited number can operate above 20 MeV, restricting the production of advanced therapeutic radionuclides. Argentina has the CP-42 (42 MeV), which is in maintenance and returning at the end of 2026, and a new center is planned to operate a 30 MeV Cyclotron in 2029, focusing on 225 Ac production for industrial applications. In Brazil, the IPEN is investing in cyclotron-based production of 225 Ac via the 225 Ra (p,2n) 225 Ac using its 30 MeV cyclotron. In parallel, IPEN has established partnerships with multinational companies to process and purify 226 Ra, supporting a sustainable and scalable 225 Ac supply chain. Conclusion: The production and distribution of emerging therapeutic radioisotopes require substantial and specialized human resources, which constrain access in the region. The commissioning of new reactors, particularly RA-10 and the RMB, is expected to significantly enhance regional capabilities, while cyclotron-based production remains largely restricted to conventional medical radionuclides.