The (68)Ge/(68)Ga generator has high potential for clinical positron emission tomography (PET) imaging. However, because of the unavailability of a suitable sorbent material, the commercially available (68)Ge/(68)Ga generators are not directly adaptable for the preparation of (68)Ga-labeled radiopharmaceuticals. In view of this, a new nanoceria-polyacrylonitrile (PAN) composite sorbent has been synthesized by decomposition of a cerium oxalate precursor to cerium oxide and its subsequent incorporation in PAN matrix for the development of a clinical grade (68)Ge/(68)Ga generator. The X-ray diffraction (XRD) studies and BET nitrogen adsorption technique revealed that nanocrystalline ceria had an average particle size of approximately 10 nm, surface area of 72 +/- 3 m(2)/g and an average pore size of 3.8 +/- 0.1 A. Investigation of the distribution ratio (K(d)) values for the prepared sorbent in 0.01 N HCl medium revealed the suitability of the sorbent for the quantitative retention of (68)Ge and efficient elution of clinical grade (68)Ga. A 370 MBq (10 mCi) (68)Ge/(68)Ga chromatographic generator was developed using this sorbent. (68)Ga could be regularly eluted from this generator with >80% elution yield. The eluted (68)Ga possess high radionuclidic purity (<1 x 10(-5)% of (68)Ge impurity), chemical purity (<0.1 ppm of Ce, Fe and Mn ions) and was amenable for the preparation of (68)Ga-labeled radiopharmaceuticals. The generator gave a consistent performance with respect to the elution yield and purity of (68)Ga over an extended period of 7 months.

The present study is aimed at carrying out a comparative performance evaluation of different types of (68)Ge/(68)Ga generators to identify the best choice for use in (68)Ga-radiopharmacy. Over the 1 year period of evaluation, the elution yields from the CeO2-based and SiO2-based (68)Ge/(68) Ga generators remained almost consistent, in contrast to the sharp decrease observed in the elution yields from TiO2 and SnO2-based generators. The level of (68)Ge impurity in (68)Ga eluates from the CeO2 and SiO2-based (68)Ge/(68)Ga generator was always <10(-3)%, while this level increased from 10(-3)% to 10(-1)% in case of TiO2 and SnO2-based generators. The level of chemical impurities in (68)Ga eluates from CeO2 and SiO2-based (68)Ge/(68)Ga generators was negligibly low (<0.1 ppm) in contrast to the significantly higher level (1-20 ppm) of such impurities in eluates from other two generators. As demonstrated by radiolabeling studies carried out using DOTA-coupled dimeric cyclic RGD peptide derivative (DOTA-RGD2), CeO2-PAN and SiO2-based generators are directly amenable for radiopharmaceutical preparation, whereas the other generators can be only used after post-elution purification of (68)Ga eluates. Clinically relevant dose of (68)Ga-DOTA-RGD2 was prepared in a hospital radiopharmacy for non-invasive visualization of tumors in breast cancer patients using positron emission tomography.

This article describes the long-term evaluation of a nanoceria-polyacrylonitrile (CeO2-PAN) composite sorbent-based (68)Ge/(68)Ga generator reported. This generator used the new CeO2-PAN composite sorbent for preparation of the (68)Ge/(68)Ga generator. Since this sorbent has not been previously evaluated, a thorough long-term evaluation of the performance of the generator is necessary to ensure its applicability for clinical practice. The performance of the generator was evaluated in terms of (68)Ga yield, (68)Ge breakthrough, radioactive concentration of the (68)Ga solution, and suitability of the (68)Ga for the preparation of (68)Ga-labeled tracers. The (68)Ge/(68)Ga generator was able to provide a (68)Ga activity with consistent yields (>70%) and having acceptable radionuclidic (<10(-4)% of (68)Ge breakthrough), radiochemical, and chemical purities for an extended period of time. The eluted (68)GaCl3 is useful for the majority of the (68)Ga complexation chemistry.

No abstract

No abstract

This paper describes the utility of mesoporous alumina (MA), a high capacity nanomaterial based sorbent, for the development of a clinical grade 99Mo/99mTc generator using (n,γ)99Mo. Synthesis of MA was performed using a glucose template in an aqueous system. Structural characterization of the nanosorbent was carried out by analytical techniques such as X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), atomic force microscopy (AFM), scanning electron miscroscopy (SEM), transmission electron microscopy (TEM), thermogravimetry-differential thermal analysis (TG-DTA), Fourier transform infrared (FTIR) spectroscopy, and Brunauer–Emmett–Teller (BET) surface area analysis. The material synthesized was mesoporous and nanocrystalline, with average crystallite size of 2–3 nm with a large surface area of 230 ± 10 m2 g–1. In order to evaluate the surface charge of MA in aqueous solution, the zeta potential was determined at different pH environments. Adsorption characteristics of the sorbent such as time course of the adsorption, distribution ratios of 99Mo and 99mTc ions, Mo sorption capacity under static and dynamic conditions, 99Mo adsorption pattern and 99mTc elution pattern were determined to assess its effectiveness in the preparation of 99Mo/99mTc generator. The measured distribution ratio values indicate that 99Mo is both strongly and selectively retained by MA at acidic pH and 99mTc could be readily eluted from it, using 0.9% NaCl solution. The static sorption capacity and practical sorption capacity under dynamic conditions of MA was determined to be 225 ± 20 and 168 ± 12 mg Mo per gram of sorbent, respectively. With a view to realize the scope of developing clinical scale generator, a novel tandem column generator concept was used in which two 99Mo loaded columns were connected in series. In this method 99mTc eluted from the first column was fed to the second column to achieve higher radioactive concentration (RAC) as well as purity of 99mTc. A 26 GBq (700 mCi) 99Mo/99mTc generator was developed using (n,γ)99Mo having specific activity of ∼18.5 GBq (500 mCi)/g of Mo. The 99mTc eluted from the generator possessed high radionuclidic, radiochemical, and chemical purity and was amenable for the preparation of 99mTc-labeled radiopharmaceuticals. The technology can be adapted by those countries having research reactors with flux >1 × 1014 n·cm–2·s–1 to produce 99Mo by (n,γ) route. The capacity of the generator can be scaled up to 260 GBq (7 Ci) using (n,γ)99Mo produced from a reactor with flux >1 × 1015 n·cm–2·s–1.

A new sorbent material, polymer embedded nano crystalline titania (Titanium Polymer-TiP) has been developed, from titanium (IV) chloride and isopropyl alcohol, for the adsorption of 99Mo, which is a precursor to 99mTc, a workhorse in radio-pharmaceuticals. The infrared absorption spectra of the TiP showed peaks corresponding to Ti-O groups. X-ray diffraction pattern of the adsorbent corresponded to rutile TiO2. The surface area of this polymer was 30 m2/g with an average pore size of 40 nm. The average crystallite size of TiO2, embedded in polymer, was found to be 5 nm. TEM micrograph of the adsorbent revealed the network of polymer with dispersed titania phase. Potential of this adsorbent for the preparation of 99Mo-99mTc generator has been explored. 99Mo could be adsorbed on to the adsorbent column containing TiP at pH 1 from which 99mTC could be eluted with normal (0.9%) saline solution with an elution yield of approximately 80%. The quality of the 99mTcO4 obtained was in accordance with the international specifications applicable for radiopharmaceutical use. A process demonstration run was carried out with 1.1 GBq (30 mCi) 99Mo activity level making use of the above adsorbent and consistent results were obtained over a period of one week, which is generally the shelf life of 99MO-99mTC generator.

No abstract