Adsorption of radon on silver exchanged zeolites at ambient temperatures.

Since more than 100 years, the adsorption of the radioactive noble gas radon (222Rn) is performed on activated charcoal at cryogenic temperatures. There is little-if any-progress in the field of radon adsorption at ambient conditions to facilitate the development of simple and compact radon adsorption systems. We report here on the truly remarkable property of the synthetic silver-exchanged zeolites Ag-ETS-10 and Ag-ZSM-5 to strongly adsorb radon gas at room temperature. 222Rn breakthrough experiments in nitrogen carrier gas have shown that these materials exhibit radon adsorption coefficients exceeding 3000 m3/kg at 293 K, more than two orders of magnitude larger than any noble gas adsorbent known to date. Water vapor and carrier gas type were found to strongly influence radon adsorption, practically qualifying these silver exchanged materials as a new class of radon adsorbents. Our results demonstrate that Ag-ETS-10 and Ag-ZSM-5 are materials that show high affinity towards radon gas at ambient temperatures making them candidate materials for environmental and industrial 222Rn mitigation applications. Adsorption systems based on silver loaded zeolites have the potential to replace activated charcoal as material of choice in many radon related research areas by avoiding the necessity of cryogenic cooling.

Resonant laser ionization and mass separation of 225Ac.

[Formula: see text]Ac is a radio-isotope that can be linked to biological vector molecules to treat certain distributed cancers using targeted alpha therapy. However, developing [Formula: see text]Ac-labelled radiopharmaceuticals remains a challenge due to the supply shortage of pure [Formula: see text]Ac itself. Several techniques to obtain pure [Formula: see text]Ac are being investigated, amongst which is the high-energy proton spallation of thorium or uranium combined with resonant laser ionization and mass separation. As a proof-of-principle, we perform off-line resonant ionization mass spectrometry on two samples of [Formula: see text]Ac, each with a known activity, in different chemical environments. We report overall operational collection efficiencies of 10.1(2)% and 9.9(8)% for the cases in which the [Formula: see text]Ac was deposited on a rhenium surface and a ThO[Formula: see text] mimic target matrix respectively. The bottleneck of the technique was the laser ionization efficiency, which was deduced to be 15.1(6)%.

Nuclear Cross-Section of Proton-Induced Reactions on Enriched 48Ti Targets for the Production of Theranostic 47Sc Radionuclide, 46cSc, 44mSc, 44gSc, 43Sc, and 48V.

The cross-sections of the 48Ti(p,x)47Sc, 46cSc, 44mSc, 44gSc, 43Sc, and 48V nuclear reactions were measured from 18 to 70 MeV, with particular attention to 47Sc production. Enriched 48Ti powder was deposited on an aluminum backing and the obtained targets were characterized via elastic backscattering spectroscopy at the INFN-LNL. Targets were exposed to low-intensity proton irradiation using the stacked-foils technique at the ARRONAX facility. Activated samples were measured using γ-spectrometry; the results were compared with the data int he literature and the theoretical TALYS-based values. A regular trend in the new values obtained from the different irradiation runs was noted, as well as a good agreement with the literature data, for all the radionuclides of interest: 47Sc, 46cSc, 44mSc, 44gSc, 43Sc, and 48V. 47Sc production was also discussed, considering yield and radionuclidic purity, for different 47Sc production scenarios.

LARAMED: A Laboratory for Radioisotopes of Medical Interest.

The widespread availability of novel radioactive isotopes showing nuclear characteristics suitable for diagnostic and therapeutic applications in nuclear medicine (NM) has experienced a great development in the last years, particularly as a result of key advancements of cyclotron-based radioisotope production technologies. At Legnaro National Laboratories of the National Institute of Nuclear Physics (LNL-INFN), Italy, a 70-MeV high current cyclotron has been recently installed. This cyclotron will be dedicated not only to pursuing fundamental nuclear physics studies, but also to research related to other scientific fields with an emphasis on medical applications. LARAMED project was established a few years ago at LNL-INFN as a new research line aimed at exploiting the scientific power of nuclear physics for developing innovative applications to medicine. The goal of this program is to elect LNL as a worldwide recognized hub for the development of production methods of novel medical radionuclides, still unavailable for the scientific and clinical community. Although the research facility is yet to become fully operative, the LARAMED team has already started working on the cyclotron production of conventional medical radionuclides, such as Tc-99m, and on emerging radionuclides of high potential medical interest, such as Cu-67, Sc-47, and Mn-52.

Innovative Target for Production of Technetium-99m by Biomedical Cyclotron.

Technetium-99m (99mTc) is the most used radionuclide worldwide in nuclear medicine for diagnostic imaging procedures. 99mTc is typically extracted from portable generators containing 99Mo, which is produced normally in nuclear reactors as a fission product of highly enriched Uranium material. Due to unexpected outages or planned and unplanned reactor shutdown, significant 99mTc shortages appeared as a problem since 2008 The alternative cyclotron-based approach through the 100Mo(p,2n)99mTc reaction is considered one of the most promising routes for direct 99mTc production in order to mitigate potential 99Mo shortages. The design and manufacturing of appropriate cyclotron targets for the production of significant amounts of a radiopharmaceutical for medical use is a technological challenge. In this work, a novel solid target preparation method was developed, including sputter deposition of a dense, adherent, and non-oxidized Mo target material onto a complex backing plate. The latter included either chemically resistant sapphire or synthetic diamond brazed in vacuum conditions to copper. The target thermo-mechanical stability tests were performed under 15.6 MeV proton energy and different beam intensities, up to the maximum provided by the available GE Healthcare (Chicago, IL, USA) PET trace medical cyclotron. The targets resisted proton beam currents up to 60 µA (corresponding to a heat power density of about 1 kW/cm²) without damage or Mo deposited layer delamination. The chemical stability of the proposed backing materials was proven by gamma-spectroscopy analysis of the solution obtained after the standard dissolution procedure of irradiated targets in H2O2.

In-house cyclotron production of high-purity Tc-99m and Tc-99m radiopharmaceuticals.

In the last years, the technology for producing the important medical radionuclide technetium-99m by cyclotrons has become sufficiently mature to justify its introduction as an alternative source of the starting precursor [99mTc][TcO4]- ubiquitously employed for the production of 99mTc-radiopharmaceuticals in hospitals. These technologies make use almost exclusively of the nuclear reaction 100Mo(p,2n)99mTc that allows direct production of Tc-99m. In this study, it is conjectured that this alternative production route will not replace the current supply chain based on the distribution of 99Mo/99mTc generators, but could become a convenient emergency source of Tc-99m only for in-house hospitals equipped with a conventional, low-energy, medical cyclotron. On this ground, an outline of the essential steps that should be implemented for setting up a hospital radiopharmacy aimed at the occasional production of Tc-99m by a small cyclotron is discussed. These include (1) target production, (2) irradiation conditions, (3) separation/purification procedures, (4) terminal sterilization, (5) quality control, and (6) Mo-100 recovery. To address these issues, a comprehensive technology for cyclotron-production of Tc-99m, developed at the Legnaro National Laboratories of the Italian National Institute of Nuclear Physics (LNL-INFN), will be used as a reference example.