Development of Porous MoO2 Pellet Target for 99Mo/99mTc Generator

Technetium-99m(99mTc) is used worldwide in 85% of nuclear medicine diagnostic imaging procedures. We developed porous MoO2 pellets as an alternative to reactor-based targets in an (n,γ) reaction for producing Technetium-99m (99mTc) in nuclear medicine. The pellets, formed through a manufacturing process involving mixing, sintering, eluting, and drying, offer advantages such as selective dissolution and improved yield. This research offers a potential solution for stable 99mTc production, focusing on porous molybdenum dioxide (MoO2) as a target material due to its insolubility in water. Using potassium molybdate (K2MoO4) as a pore former, we developed porous MoO2 pellets that facilitate efficient technetium extraction and target recycling. This approach offers control over pore formation and shows promise in addressing supply challenges and enhancing 99mTc production.

β-MoO3 Whiskers in 99Mo/99mTc Radioisotope Production and 99Mo/99mTc Extraction Using Hot Atoms

β-MoO3 whiskers prepared by a thermal evaporation method and α-MoO3 particles were irradiated in a nuclear reactor to produce 99Mo/99mTc radioisotopes via neutron capture. The irradiated targets were then dispersed in water to extract the 99Mo/99mTc isotopes. Of the 99Mo formed in the β-MoO3 whiskers, 64.0 ± 7.4% was extracted with water; by contrast, only 8.8 ± 2.6% of the 99Mo formed in α-MoO3 was extracted. By comparing these data to the 98Mo concentration dissolved in water, we confirmed the hot-atom effect on both β-MoO3 whisker and α-MoO3 particle targets to transfer 99Mo isotopes from irradiated samples to water. In addition, the β-MoO3 whiskers exhibited a prominent hot-atom effect to transfer a higher ratio of 99Mo isotopes into water. To the best of our knowledge, this research is the first demonstration of β-MoO3 being used as an irradiation target in the neutron capture method. On the basis of the results, β-MoO3 is considered a promising irradiation target for producing 99Mo/99mTc by neutron capture and using water for the radioisotope extraction process in the future.

Application of computational models to estimate organ radiation dose in rainbow trout from uptake of molybdenum-99 with comparison to iodine-131

This study compares three anatomical phantoms for rainbow trout (Oncorhynchus mykiss) for the purpose of estimating organ radiation dose and dose rates from molybdenum-99 ((99)Mo) uptake in the liver and GI tract. Model comparison and refinement is important to the process of determining accurate doses and dose rates to the whole body and the various organs. Accurate and consistent dosimetry is crucial to the determination of appropriate dose-effect relationships for use in environmental risk assessment. The computational phantoms considered are (1) a geometrically defined model employing anatomically relevant organ size and location, (2) voxel reconstruction of internal anatomy obtained from CT imaging, and (3) a new model utilizing NURBS surfaces to refine the model in (2). Dose Conversion Factors (DCFs) for whole body as well as selected organs of O. mykiss were computed using Monte Carlo modeling and combined with empirical models for predicting activity concentration to estimate dose rates and ultimately determine cumulative radiation dose (μGy) to selected organs after several half-lives of (99)Mo. The computational models provided similar results, especially for organs that were both the source and target of radiation (less than 30% difference between all models). Values in the empirical model as well as the 14 day cumulative organ doses determined from (99)Mo uptake are compared to similar models developed previously for (131)I. Finally, consideration is given to treating the GI tract as a solid organ compared to partitioning it into gut contents and GI wall, which resulted in an order of magnitude difference in estimated dose for most organs.