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内容記述 |
Introduction: There are several hundred radionuclides emitting Auger electron via their decay process. However, it is rare to fulfill the criteria for ideal targeted radiotherapy by Auger electron supposed by Bernhart et al.1, i.e. the radionuclide has suitable half-life and emit Auger electron necessary for treatment without unnecessary X or gamma radiation. 103mRh (T1/2 56 min, IT 100%) is selected as one of the five optimum radionuclides for Auger therapy. The feasible supply of 103mRh for clinical application should be achieved by generator because of its short half-life. We recently developed a 103Pd/103mRh generator with performance as the same as ones previously reported. However, there were many drawbacks needed to be improved, such as low yield, large volume of recovered extractant, and long operation time. In this study, we have demonstrated a new type of generator to clear up those problems and discuss feasibility of the generator.Methods: 100 mg of rhodium pellet was irradiated with accelerator, then no carrier added 103Pd was separated from the Rh-target2. The two types of generator (about 10 MBq) developed with nca-103Pd were prepared. Conventional: 3 ml of anion exchange resin (SA11AL: Mitsubishi Chemical) was packed in the column (Φ 8.8 mm, L 66 mm Fig. 1). 103Pd dissolved in 2–5 mL of 0.1 M HCl solution was loaded onto the column. For milking, 6 mL of 0.1 M HCl solution was loaded on the column. New: About 20 particles of SA11AL were soaked and shaking in the same 103Pd–HCl solution overnight. Resin beads were packed into the reservoir with extract (Fig. 1). For milking, 300 μl of 0.1 M HCl solution was flushed through the reservoir. The measurement of the yield of 103mRh and contamination of 103Pd in 103mRh fraction were carried out using liquid scintillation counter and HPGe-detector, respectively2.Results: The contamination rate of 103Pd in the new-type generator was about double than that of conventional, however, the new-type is beneficial; e.g., minimize volume of extract, shorten the operation time, and higher recovery of 103mRh. As a result, concentration of 103mRh in the product fraction was about 16 times higher than the conventional that would be effective in further labelling process. Moreover, the product activities of new-type obtained for every milking were higher than that of conventional-type. Conclusions: New-type generator has much potential. We will evaluate the long-term availability of this generator system with special emphasis of radiolysis effect of the packed resin. |
