关键词: 固体靶核素, 碘-124生产, 碲-124靶片, 分子显像

Abstract: Objective：To provide useful information for the further production and application of this novel radio-nuclide for potential clinical application. Methods:124Te(p,n)124I nuclide reaction was used for the 124I production. Firstly, the target material, 124TeO2 (200 mg) and Al2O3 (30 mg) mixture, were compressed into the round platinum based solid target by tablet device. HM-20 medical cyclotron was applied to irradiate the solid target slice for 6－10 h with helium and water cooling. Then, the radiated solid target was placed for 12 h (overnight) to decay the radioactive impurity; finally, 124I was be purified by dry distillation using 1 mL/min nitrogen for about 6 hours and radiochemical separation methods. Micro-PET imaging studies were performed to investigate the metabolism properties and thyroid imaging ability of 124I.After 740 kBq  124I was injected intravenously into the tail vein of the normal mice, the animals were imaged with micro-PET and infused with CT. The micro-PET/CT infusion imaging revealed actual state 124I’s metabolism in the mice. Results: It was been successfully applied for 200 mg 124TeO2 plating by the tablet device on the surface of platinum. It showed smooth, dense surface and without obviously pits and cracks. The enriched 124Te target was irradiated for 6 to 10 hours at about 12.0 MeV with 20 μA current on HM-20 cyclotron. Then 370-1 110 MBq 124I could be produced on the solid target after irradiation and 370-740 MBq high specific activity could be collected afterdry distillation separation and radio-chemical purification.124I product was finally dissolved in 0.01 mol/L NaOH for the future distribution. The gamma spectrum of the produced 124I-solution showed that radionuclide purity was over 80.0%. The micro-PET imaging of 124I in the normal mice exhibited the thyroid and stomach accumulations and kidney metabolism, the bladder could also be clearly visible, which was in accordance with what was previously reported. To the best of our knowledge, it was the first production of 124I report in China. Conclusion: In this study, the preparation of 124TeO2 solid target was successfully carried out by using the tablet device. After irradiation of the 124TeO2 solid target and radio-chemical purification, we successfully produced 370-740 MBq high specific activity 124I by a cyclotron for biomedical application, and microPET imaging of 124I in normal mice exhibited the thyroid accumulations. Also, slight uptake in stomach were also monitored with almost nonuptake in other organs in the micro-PET imaging. The production of 124I is expected to provide a new solid target radionuclide for the scientific research and potential clinical application of our country.

Key words: Solid target radionuclide, Iodine-124 production, Tellurium-124 solid target, Molecular imaging