Introduction Molybdenum-99 (Mo-99) and technetium-99m (Tc-99m) are used in about 80 percent of all nuclear medicine procedures worldwide. Not only using for diagnostic imaging, Tc-99m is used for the detection of disease and for the study of organ structure and function. Tc-99m is especially useful for nuclear medicine procedures because it can be chemically incorporated into small molecule ligands and proteins that concentrate in specific organs or tissues when injected into the body. Almost all of the Tc-99m in nuclear medicine today is produced by radioactive decay of Mo-99. About 88 percent of the Mo-99 decays (red line) produce Tc-99m via the pathway depicted in the Figure 1.
One technique to produce Mo-99 which is used in Tc-99 generators is based on neutron activation of a stable nuclide Mo-98 through the neutron capture reaction:
𝑀𝑜4298 + 𝑛01 → 𝑀𝑜4299
In our preliminary work, the water solubility of MoO3 was found to be increased after the neutron irradiation. This phenomenon can lead the reacted Mo-99 / Tc-99m separated and recovered by water. Besides, if MoO3 powder is more micronized to increase the surface area, the solubility of Mo-99 and Tc-99m in water may be increased. From this point, if a porous MoO3 target can be produced, it is not necessary to dissolve all the target, and it is possible to recover Mo-99 and Tc-99m simply by pouring water. Furthermore, if it is possible to keep the target in the reactor, a new method can be proposed to recover the reacted Mo-99/Tc-99m simply by circulating water.
In order to produce porous ceramics, there is a known a method of mixing and sintering ceramic powder with NaCl powder and dissolving NaCl in water. In this study, the preparation of porous MoO3 targets that are water-permeable are described.
