ABSTRACT
Purpose: [177Lu]Lu-DOTATATE and [177Lu]Lu-PSMA-617 used for targeted radionuclide therapy are very often prepared in the hospital radiopharmacy. The preparation parameters vary depending upon the specific activity of the 177Lu used. The aim of this study was to develop optimized protocols to be used in the nuclear medicine department for the preparation of patient doses of the above radiopharmaceuticals. Method: 177Lu (CA and NCA) were used for radiolabeling DOTATATE and PSMA-617. Parameters studied are 177Lu of different specific activity and different peptide concentrations and two different buffer systems. Paper and thin layer chromatography systems were used for estimating the radiochemical yield as well as radiochemical purity. Solid-phase extraction was used for the purification of the labeled tracers. Results: [177Lu]Lu-DOTATATE was prepared with CA 177Lu (n = 13) and NCA177Lu (n = 6). Four batches each of [177Lu]Lu-PSMA-617 were prepared using CA and NCA 177Lu. Radiochemical yields > 80% and final product with less than < 1% radiochemical impurity could be obtained in all batches which were used for therapy. Conclusion: Robust protocols for the preparation of clinical doses of [177Lu]Lu-DOTATATE and [177Lu]Lu-PSMA-617 were developed and used for the preparation of clinical doses. The quality of the SPECT images of both the tracers are consistent with the expected uptake in respective diseases.
ABSTRACT
Purpose: The clinical demand of 6-l-[ 18F] FDOPA is gaining rapidly for imaging neurodegenerative diseases by using positron emission tomography. Hence, large-scale production of 6-l-[18F] FDOPA is necessary. This paper describes our experience on the production of 6-l-[18F]FDOPA via nucleophilic synthesis using NEPTIS module and a commercially available cassette based chemistry. Method: 6-l-[18F]FDOPA production could be completed in three synthetic steps by using ABX nitro precursor. The precursor is first labeled with18F by replacing a -NO2 leaving group followed by purification using a solid phase cartridge. In the subsequent step, the radiolabeled precursor is oxidized using meta chloroperoxy benzoic acid hydrolyzed to remove the four different protecting groups. The product is finally purified in a series of solid phase cartridges to yield radiochemically pure 6-l-[18F]FDOPA. Results: Total 36 batches of 6-l-[18F]FDOPA were produced. The decay uncorrected yield were 5.5 ± 1.5% (n = 33) which corresponds to a decay corrected yield of 11.8 ± 3.2% (n = 33). The radiochemical purity of the product obtained is always > 95%. Conclusion: The yields obtained are low and hence there is a need to improve synthetic chemistry. In order to understand the efficiency of each step, a detailed analysis using the radioactive traces obtained from the automated module was carried out. The radiolabeling yield of precursor is only about 50% and there is subsequent reduction in activity in the oxidation as well as hydrolysis steps. Despite the low radiochemical yields, the product obtained was suitable for imaging.
ABSTRACT
Reprocessed high-level nuclear waste (HLW) contains range of radioactive components. Crystalline oxyphosphate apatite ceramic of the formula LaSr4(PO4)3O [LSS] was investigated as a host for HLW immobilisation. The systematic study of solid solubility limit of individual rare earth ion substitution leads to the formulation of simulated wasteform of the formula La0.6Pr0.1Nd0.1Sm0.1Gd0.1Sr4(PO4)3O (WF1) with the waste loading of 17.95 wt% of rare-earth ions. Both parent and WF1 were synthesized by precipitation method. The thermal stress and groundwater inventory at the repository site can severely affect the wasteform performance, in addition to radiation and mechanical effects. Hence, the fabricated composition with high-level nuclear waste loading must be screened basically for chemical, thermal and radiation resistance. The present study investigated the thermal stability (by TGA), thermal expansion behaviour (by HT-XRD) and chemical durability (MCC-5) of the composition (WF1). The weight loss of WF1 being 2.2% and the average thermal expansion co-efficient (αavg) of 10.7 ± 1.2 × 10-6 K-1 in the temperature range (298-973 K) were comparatively lower than the parent phase, LaSr4(PO4)3O. The WF1 showed resistance to leaching of RE3+ and P5+ with only the leaching of Sr2+ ion whose leach rate was of the order 10-3-10-4 gm-2d-1.
ABSTRACT
The present study reports on CuO-assisted reduction of Cr(VI) under ambient conditions using sodium borohydride and its complete removal. The confirmation of the reductive removal of Cr(VI) was assisted by powder X-ray diffraction, Fourier transform infrared, scanning electron microscopy, mic absorption spectro, UV-vis, and UV-vis-diffuse reflectance spectroscopy techniques. The analysis revealed that the process involved adsorption of dichromate ion on the surface of copper oxide, reduction of Cr(VI), and precipitation of Cr(III) as its hydroxide. Cr(VI) reduction capacity of CuO was found to be around 27.2 mmol/(g h). The residue collected showed promising reusability for 3 to 4 cycles, and the exhausted residue was finally converted into a black composite, CuO/CuCr2O4. The composite showed positive response for the photodegradation of methyl orange. Thus, the current protocol proposed a complete package of cost-effective reduction of Cr(VI) to Cr(III), precipitation into its hydroxide, and the conversion of the residue into a photoactive composite.
ABSTRACT
The oxysilicate apatite host CaLa4(SiO4)3O has been explored for immobilization of radioactive nuclides. Divalent ion, trivalent rare earth ion, and combined ionic substitutions in the silicate oxyapatite were carried out to optimize the simulated wasteform composition. The phases were characterized by powder X-ray diffraction, FT-IR, TGA, SEM-EDS, and HT-XRD techniques. The results revealed the effect of ionic substitutions on the structure and thermal expansion behavior. The investigation resulted in the formulation of simulated wasteforms such as La3.4Ce0.1Pr0.1Nd0.1Sm0.1Gd0.1Y0.1(SiO4)3O (WF-1) and Ca0.8Sr0.1Pb0.1La3.4Ce0.1Pr0.1Nd0.1Sm0.1Gd0.1Y0.1(SiO4)3O (WF-2). In comparison to the average axial thermal expansion coefficients of the hexagonal unit cell of the parent CaLa4(SiO4)3O measured in the temperature range 298-1073 K (α' a = 9.74 × 10-6 K-1 and α' c = 10.10 × 10-6 K-1), rare earth ion substitution decreases the thermal expansion coefficients, as in the case of La3.4Ce0.1Pr0.1Nd0.1Sm0.1Gd0.1Y0.1(SiO4)3O (α' a = 8.67 × 10-6 K-1 and α' c = 7.94 × 10-6 K-1). However, the phase Ca0.8Sr0.1Pb0.1La3.4Ce0.1Pr0.1Nd0.1Sm0.1Gd0.1Y0.1(SiO4)3O shows an increase in the values of thermal expansion coefficients: α' a = 11.74 × 10-6 K-1 and α' c = 11.70 × 10-6 K-1.
