Abstract
The most frequently used radionuclide in diagnostic nuclear medicine, $^{99m}\mathrm{Tc}$, is generally obtained by the decay of its parent radionuclide, $^{99}\mathrm{Mo}$. Recently, concerns have been raised over shortages of $^{99}\mathrm{Mo}{/}^{99m}\mathrm{Tc}$, owing to aging of the research reactors which have been supplying practically all of the global demand for $^{99}\mathrm{Mo}$ in a centralized fashion. In an effort to prevent such $^{99}\mathrm{Mo}{/}^{99m}\mathrm{Tc}$ supply disruption and, furthermore, to ameliorate the underlying instability of the centralized $^{99}\mathrm{Mo}{/}^{99m}\mathrm{Tc}$ supply chain, we designed an $X$-band electron linear accelerator which can be distributed over multiple regions, whereby $^{99}\mathrm{Mo}{/}^{99m}\mathrm{Tc}$ can be supplied with improved accessibility. The electron beam energy was designed to be 35 MeV, at which an average beam power of 9.1 kW was calculated by the following beam dynamics analysis. Subsequent radioactivity modeling suggests that 11 of the designed electron linear accelerators can realize self-sufficiency of $^{99}\mathrm{Mo}{/}^{99m}\mathrm{Tc}$ in Japan.
Highlights
Nuclear medicine is a branch of medical imaging where active ingredients labeled with medical radionuclides, called radiopharmaceuticals, are used for examining and treating diseases in a noninvasive way [1]
In an effort to prevent such 99Mo=99mTc supply disruption and, to ameliorate the underlying instability of the centralized 99Mo=99mTc supply chain, we designed an X-band electron linear accelerator which can be distributed over multiple regions, whereby 99Mo=99mTc can be supplied with improved accessibility
99mTc emits γ-rays of 140.5 keV, by which adequate spatial resolution can be obtained with a gamma camera optimized to that energy [2,4,5], and has a physical half-life of 6 hours, which leads to balanced effective halflives of its radiopharmaceuticals and thereby allowing sufficient drug uptakes while limiting patient radiation doses [6,7]
Summary
Nuclear medicine is a branch of medical imaging where active ingredients labeled with medical radionuclides, called radiopharmaceuticals, are used for examining and treating diseases in a noninvasive way [1]. Over 80% of nuclear medicine scans are performed with technetium-99m (99mTc) across the globe [2,3], attributed to its decay characteristics and chemistry ideal for radiopharmaceuticals. 99mTc emits γ-rays of 140.5 keV, by which adequate spatial resolution can be obtained with a gamma camera optimized to that energy [2,4,5], and has a physical half-life of 6 hours, which leads to balanced effective halflives of its radiopharmaceuticals and thereby allowing sufficient drug uptakes while limiting patient radiation doses [6,7].
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