u Ram

Nanoceria-PAN composite-based advanced sorbent material: a major step forward in the field of clinical-grade 68Ge/68Ga generator.

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.

Development of a nano-zirconia based 68Ge/68Ga generator for biomedical applications.

INTRODUCTION Most of the commercially available (68)Ge/(68)Ga generator systems are not optimally designed for direct applications in a clinical context. We have developed a nano-zirconia based (68)Ge/(68)Ga generator system for accessing (68)Ga amenable for the preparation of radiopharmaceuticals. METHODS Nano-zirconia was synthesized by the in situ reaction of zirconyl chloride with ammonium hydroxide in alkaline medium. The physical characteristics of the material were studied by various analytical techniques. A 740 MBq (20 mCi) (68)Ge/(68)Ga generator was developed using this sorbent and its performance was evaluated for a period of 1 year. The suitability of (68)Ga for labeling biomolecules was ascertained by labeling DOTA-TATE with (68)Ga. RESULTS The material synthesized was nanocrystalline with average particle size of ~7 nm, pore-size of ~4 Å and a high surface area of 340±10 m(2) g(-1). (68)Ga could be regularly eluted from this generator in 0.01N HCl medium with an overall radiochemical yield >80% and with high radionuclidic (<10(-5)% of (68)Ge impurity) and chemical purity (<0.1 ppm of Zr, Fe and Mn ions). The compatibility of the product for preparation of (68)Ga-labeled DOTA-TATE under the optimized reaction conditions was found to be satisfactory in terms of high labeling yields (>99%). The generator gave a consistent performance with respect to the elution yield and purity of (68)Ga over a period of 1 year. CONCLUSIONS The feasibility of preparing an efficient (68)Ge/(68)Ga generator which can directly be used for biomedical applications has been demonstrated.

Exploitation of nano alumina for the chromatographic separation of clinical grade 188Re from 188W: a renaissance of the 188W/188Re generator technology.

The (188)W/(188)Re generator using an acidic alumina column for chromatographic separation of (188)Re has remained the most popular procedure world over. The capacity of bulk alumina for taking up tungstate ions is limited (∼50 mg W/g) necessitating the use of very high specific activity (188)W (185-370 GBq/g), which can be produced only in very few high flux reactors available in the world. In this context, the use of high-capacity sorbents would not only mitigate the requirement of high specific activity (188)W but also facilitate easy access to (188)Re. A solid state mechanochemical approach to synthesize nanocrystalline γ-Al(2)O(3) possessing very high W-sorption capacity (500 mg W/g) was developed. The structural and other investigations of the material were carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer Emmett Teller (BET) surface area analysis, thermogravimetric-differential thermal analysis (TG-DTA), and dynamic light scattering (DLS) techniques. The synthesized material had an average crystallite size of ∼5 nm and surface area of 252 ± 10 m(2)/g. Sorption characteristics such as distribution ratios (K(d)), capacity, breakthrough profile, and elution behavior were investigated to ensure quantitative uptake of (188)W and selective elution of (188)Re. A 11.1 GBq (300 mCi) (188)W/(188)Re generator was developed using nanocrystalline γ-Al(2)O(3), and its performance was evaluated for a period of 6 months. The overall yield of (188)Re was >80%, with >99.999% radionuclidic purity and >99% radiochemical purity. The eluted (188)Re possessed appreciably high radioactive concentration and was compatible for the preparation of (188)Re labeled radiopharmaceuticals.

Long-Term Evaluation of ‘BARC 68Ge/68Ga Generator’ Based on the Nanoceria-Polyacrylonitrile Composite Sorbent

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.

Ammonium molybdophosphate impregnated alumina microspheres as a new generation sorbent for chromatographic 137Cs/137mBa generator

Barium-137m availed from a (137)Cs/(137m)Ba generator is an attractive industrial radiotracer for liquid flow rate measurement owing to its short half-life (T(1/2)=2.5 min) and emission of highly energetic gamma radiation (E(γ)=661.7 keV). Ammonium molybdophosphate (AMP) impregnated alumina microspheres (AMP-Al(2)O(3)), an engineered form of sorbent material was synthesized by Gel Entrapment Technique (GET). The utility of the material in the preparation of (137)Cs/(137m)Ba generator was evaluated. Various experimental parameters were optimized for efficient retention of (137)Cs and selective elution of (137m)Ba. A chromatographic 0.74 GBq (20 mCi) (137)Cs/(137m)Ba generator was developed using this material and its performance was evaluated for 6 months. Barium-137m could be eluted from the generator using 0.1 M NH(4)NO(3)+0.5 M HNO(3) solution with >80% yield and with acceptable radionuclidic purity suitable for industrial radiotracer investigations.

Detailed evaluation of different 68Ge/68Ga generators: an attempt toward achieving efficient 68Ga radiopharmacy

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.

Bioevaluation studies of 32P incorporated mould brachytherapy sources for potential application in treatment of superficial tumors.

AimTo prepare 32P-based user-friendly mould brachytherpy sources for the treatment of superficial tumors. Methods32P as orthophosphoric acid was adsorbed on 15–25 mm (diameter) circular sheets of cellulose-based adsorbent paper to prepare sources containing approximately 37–74 MBq of 32P per cm2 of strip. The sources were immobilized between plastic sheets of 40 μm thickness. Autoradiography studies were carried out to determine the uniformity of 32P deposition in the source. Dosimetric evaluation of the sources was also carried out. Bioevaluation studies were carried out in C57BL6 mice bearing melanoma using 37–74 MBq sources. ResultsCellulose-based sources containing 37–74 MBq of 32P per cm2 could be prepared from which no radioactivity leakage could be detected in water or saline. Autoradiography studies revealed 32P to be uniformly distributed in these sources. Dosimetric evaluation showed that the contact dose imparted was 10 Gy/h, sufficient for treatment of superficial tumors. In mice bearing melanoma, complete tumor regression could be achieved with two applications of 37–74 MBq sources, at an interval of 3 days. Histopathological examination of the skin tissue from the treated area proved the absence of tumor as compared with the controls. ConclusionPreparation of 32P sources of various shapes and sizes (based on the tumor size) having uniform 32P activity distribution could be achieved. Efficacy of these sources in treating melanoma tumors could be established in the animal model.

Comparative Assessment of Nanostructured Metal Oxides: A Potential Step Forward to Develop Clinically Useful 99Mo/99mTc Generators using (n,γ)99Mo

While the use of nanostructured metal oxides such as nanotitania, nanozirconia, nanoalumina, and mesoporous alumina, as column matrices constitutes a successful paradigm in the development of chromatographic 99Mo/99mTc generators using (n,γ)99Mo, a comparative assessment of their properties is essential not only to determine the merits and bottlenecks of each sorbent but also to evaluate their usefulness commensurate with the specific activity of (n,γ)99Mo obtained from different sources. Characteristics which were compared included the sorption capacity, zeta potential, shelf-life of the generator, radioactive concentration and purity of 99mTc for radiopharmaceutical applications, and recovery of decayed Mo from spent generators. Mesoporous alumina was identified as the most suitable sorbent for ensuring sustainable production of clinical grade 99Mo/99mTc generators using low specific activity 99Mo.

Fabrication of Cesium-137 Brachytherapy Sources Using Vitrification Technology

137Cs source in solid matrix encapsulated in stainless-steel at MBq (mCi) levels are widely used as brachytherapy sources for the treatment of carcinoma of cervix uteri. This article describes the large-scale preparation of such sources. The process of fabrication includes vitrification of 137Cs-sodium borosilicate glass, its transformation into spheres of 5-6 mm diameter, casting of glass spheres into a cylinder of 1.5 mm (varphi) x 80 mm (l) in a platinum mould, cutting of the moulds into 5-mm-long pieces, silver coating on the sources, and finally, encapsulation in stainless steel capsules. Development of safety precautions used to trap 137Cs escaping during borosilicate glass preparation is also described. The leach rates of the radioactive sources prepared by the above technology were within permissible limits, and the sources could be used for encapsulation in stainless steel capsules and supplied for brachytherapy applications. This development was aimed at promoting the potential utility of 137Cs-brachytherapy sources in the country and reducing the users reliance on imported sources. Since its development, more than 1000 such sources have been made by using 4.66 TBq(126 Ci) of 137Cs.

Recovery of 137Cs from Laboratory Waste using Solvent Extraction with Sodium Tetraphenylboron (TPB)

The paper describes a method for the recovery of 137Cs from an aqueous radioactive laboratory waste solution containing 137Cs (2 µg/mL) in the presence of high concentration of Na+ using solvent extraction technique. The method comprises of adjustment of pH to the acidic range (pH = 2), contacting the aqueous radioactive solution with sodium tetraphenylboron (TPB) in nitrobenzene, whereby 137Cs binds with tetraphenylboron anions and gets separated. Results of this investigation indicate that 137Cs could be efficiently and selectively extracted from an aqueous solution media containing high concentration of Na+ under mildly acidic pH into an organic phase and back extracted with small volume of 3 M HNO3, thus enabling concentration. The proposed method was successfully applied in real samples.