@article{oai:repo.qst.go.jp:00058512,
 author = {田中, 泉 and 石原, 弘 and 田中 泉 and 石原 弘},
 journal = {National Institute of Radiological Sciences Annual Report 2013},
 month = {Aug},
 note = {Objectives
Radiocesium nuclides generated during nuclear fission are contained in used nuclear fuels and nuclear wastes. For people who work in or around nuclear-related plants, there is some risk of accidental absorption of a large amount of radiocesium. The risk of internal contamination also present, since improper operations or acts of terrorism can result in release of 137Cs from the strongly reinforced containers that are used in industries and in hospitals as gamma-ray sources. When internal radiocesium contamination occurs in humans, and the committed dose of the internal exposure reaches more than 300 mSv [1], decorporation treatment by the use of Prussian blue should be considered. Although Radiogardase is available as an approved drug, improvement of the drug preparation is possible. We propose an example drug preparation of Prussian blue for radiocesium decorporation, based on the current concept to minimize the risk with the use of a drug.
\nIntroduction
Cesium is an alkaline metal and it exists as an ionic watersoluble form in the body. Ingested radiocesium moves rapidly into the circulation system, is distributed in the body, and is accumulated in cells. Due to the difference in the tissue-specific retention time, cesium migrates among organs via the circulation system. Because intracellular cesium in skeletal muscle cannot be easily excreted, the biological half-time of the body-burden is long. The major excretion pathway of intracorporeal radiocesium is via the urinary excretion system from the circulation system. Although certain amounts of radiocesium are secreted into the gastrointestinal (GI)-tract, most of the radiocesium is reabsorbed in the intestine and returned to the circulation system. When insoluble carrier that can tightly bind with the radiocesium flows through the GI-tract cavity to become feces, the total excretion rate of radiocesium is enhanced. The reinforcement of the excretion pathway accelerates total excretion of radiocesium, and contributes to a decrease in the level of internal exposure. In the 137Cs internal contamination accident in Goiania in 1987, Prussian blue was given to patients as the insoluble carrier to remove radiocesium, and its efficacy has been proven [2].
Radiogardase_x1113088_ capsule, the only approved drug for humans for radiocesium decorporation, have been developed in 1970s. However, with the current pharmaceutical concept that seeks the comfort of patients and protection of nursing staff and the natural environment, the drug is considered to have two problems. First, a Radiogardase capsule contains multiform rectangular parallelepiped and rigid minerals in various sizes from approximately 0.1 μm to 5 mm of Prussian blue crystals (chemical formula: Fe(III)4[Fe(II) (CN)6]3 -14 to 16 H2O), and this physical form is irritating to the mucosal tissue of the GI-tract in the patients. Second, after treatment of a patient, radioactive air-borne particles may be produced from the patient’s excreted feces which contain nano-sized crystals bound with radiocesium. This occurs because the Prussian blue crystals in the radioactive feces are not always stable based on the chemical equilibrium of the crystal coordination lattice.},
 pages = {74--75},
 title = {Preparation of agarose beads containing Prussian blue and magnetite for internal decorporation of radiocesium},
 year = {2014}
}