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.
Animals ; China ; Cyclotrons ; Iodine Radioisotopes/standards* ; Mice ; Positron Emission Tomography Computed Tomography ; Quality Control ; Radiochemistry ; Radiopharmaceuticals/standards* ; Thyroid Gland/diagnostic imaging* ; Tomography, Emission-Computed