ABSTRACT
The radionuclide zirconium-89 can be employed for the positron emission tomography (PET). In this study 89Zr excitation function via 89Y(p,n)89Zr reaction was calculated by the TALYS-1.8 code based on microscopic level density model. The formation of 89Zr was simulated using the Monte Carlo simulation code MCNPX to calculate the integral yield in the 89Y target body for threshold up to 40MeV incident-proton energy. The target thickness was based on calculation of the stopping power using the SRIM-2013 code matched to any incident-proton energy. The production yield of the 89Zr simulated with the Monte Carlo method for the 89Y(p,n)89Zr, 89Y(d,2n)89Zr, natSr(α,xn)89Zr and natZr(p,pxn)89Zr reactions and the results were in good agreement with published experimental results for the optimum energy range. An experimental yield of 53.1MB/µA for the 15MeV proton-induced on Y2O3 powder as a disk-target obtained for 1h irradiation at the AMIRS cyclotron.
ABSTRACT
PURPOSE: Development of a gallium-68-labeled renal tracer can be a good substitute for Tc-99m, a known SPECT tracer. In this study, effort was made to develop (68)Ga-ethylenecysteamine cysteine ((68)Ga-ECC). METHODS: Ga-ECC was prepared using generator-based (68)GaCl3 and ethylenecysteamine cysteine (ECC) at optimized conditions. Stability of the complex was checked in human serum followed by partition coefficient determination of the tracer. The biodistribution of the tracer in rats was studied using tissue counting and PET/CT imaging up to 120 min. RESULTS: Ga-ECC was prepared at optimized conditions in 15 min at 90 °C (radiochemical purity ≈97 ± 0.88 % ITLC, >99 % HPLC, specific activity: 210 ± 5 GBq/mM). (68)Ga-ECC was a water-soluble complex based on partition coefficient data (log P; -1.378) and was stable in the presence of human serum for 2 h at 37 °C. The biodistribution of the tracer demonstrated high kidney excretion of the tracer in 10-20 min. The SUVmax ratios of the liver to left kidney were 0.38 and 0.39 for 30 and 90 min, respectively, indicating high kidney uptake. CONCLUSION: Initial biodistribution results showed significant kidney and urinary excretion of the tracer comparable to that of the homologous (99m)Tc compound. The complex could be a possible PET kidney imaging agent with a fast imaging time.
ABSTRACT
OBJECTIVES: In nuclear medicine studies, gallium-68 ((8)Ga) citrate has been recently known as a suitable infection agent in positron emission tomography (PET). In this study, by applying an in-house produced (68)Ge/(68)Ga generator, a simple technique for the synthesis and quality control of (68)Ga-citrate was introduced; followed by preliminary animal studies. METHODS: (68)GaCl3 eluted from the generator was studied in terms of quality control factors including radiochemical purity (assessed by HPLC and RTLC), chemical purity (assessed by ICP-EOS), radionuclide purity (evaluated by HPGe), and breakthrough. (68)Ga-citrate was prepared from eluted (68)GaCl3 and sodium citrate under various reaction conditions. Stability of the complex was evaluated in human serum for 2 h at 370C, followed by biodistribution studies in rats for 120 min. RESULTS: (68)Ga-citrate was prepared with acceptable radiochemical purity (>97 ITLC and >98% HPLC), specific activity (4-6 GBq/mM), chemical purity (Sn, Fe<0.3 ppm and Zn<0.2 ppm) within 15 min at 500C. The biodistribution of (68)Ga-citrate was consistent with former reports up to 120 minutes. CONCLUSION: This study demonstrated the possible in-house preparation and quality control of (68)Ga-citrate, using a commercially available (68)Ge/(68)Ga generator for PET imaging throughout the country.
ABSTRACT
AIM: Due to the interesting pharmacologic properties of porphyrins, the idea of developing a possible tumor imaging agent using PET by incorporating (68)Ga into a suitable porphyrin ligand was investigated. METHODS: (68)Ga-labeled 5,10,15,20-tetrakis(pentafluoro-13 phenyl) porphyrin ((68)Ga-TFPP) was prepared using freshly eluted [(68)Ga]GaCl3 obtained from a 68Ge/68Ga generator developed in-house and 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (H2TFPP) for 60 min at 100°C. RESULTS: The complex was prepared with high radiochemical purity (>99% ITLC, >99% HPLC, specific activity: 13-14 GBq/mmol). Stability of the complex was checked in the final formulation and in human serum for 5 h. The partition coefficient was calculated for the compound (log P = 0.62). The biodistribution of the labeled compound in vital organs of Swiss mice bearing fibrosarcoma tumors was studied using scarification studies and SPECT imaging up to 1 h. The complex was mostly washed out from the circulation through kidneys and liver. The tumor-to-muscle ratio 1 h post injection was 5.13. CONCLUSION: The radiolabeled porphyrin complex demonstrated potential for further imaging studies in other tumor models.
