Volume 108, Issue 8

Despite its insufficient availability, Copper-67 is currently attracting much attention for its enormous potential for cancer therapy as theranostic radionuclide. This work aims to accurately measure the unexplored cross section 70 Zn(p,x) 67 Cu in the energy range 45–70 MeV and to evaluate its potential advantages in the case of high-intensity proton beams provided by compact cyclotrons. Thin target foils of enriched 70 Zn were manufactured by lamination at the INFN-LNL and irradiated at the ARRONAX facility using the stacked-foils method. A radiochemical procedure for the separation of Cu, Ga and Zn contaminants and the isolation of 67 Cu from the irradiated material was developed. The efficiency of the chemical processing was determined for each foil by monitoring the activity of selected tracer radionuclides ( 61 Cu, 66 Ga and 69m Zn) through γ-spectrometry. Experimental data of the 70 Zn(p,x) 67 Cu, 64 Cu, 67 Ga, 66 Ga, 69m Zn, 65 Zn cross sections were measured for the first time in the energy range 45–70 MeV and compared with the theoretical results obtained by using the TALYS code. The 67 Cu production yield by using enriched 70 Zn thick targets was compared with the results obtained by using 68 Zn targets in the same irradiation conditions.

Ruthenium recovery from the alkaline media was attempted using solid phase extraction. UV-Vis and X-ray absorption studies were performed to understand the ruthenium speciation under different conditions relevant to its extraction from alkaline medium. Since Ru forms anionic complex in the alkaline solution, an anion exchange resin (Dowex 1x8) was selected for its recovery from alkaline media. The precipitation of black RuO 2 at the resin surface hinders its back exaction. Experimental conditions were optimized for the quantitative uptake of Ru from alkaline feed and its subsequent back extraction by a series of batch studies. About 90 % of the Ruthenium was back extracted from the resin using alkaline hypochlorite solution and nitric acid solution at different stages in the Ru back extraction cycle. The column studies were done under the optimized condition and showed ~80 % Ru recovery with 5 mL of the eluent (8 M HNO 3 ) and ~90 % recovery in 10 mL including the tailing. The mechanism for the ruthenium extraction from alkaline medium and its back extraction from the resin was proposed.

Thirty liters of highly acidic spent nuclear fuel solutions need to be disposed at the “Hot Laboratory (hotlab)” facility in Paul Scherrer Institut (PSI), Switzerland. In order to significantly reduce the γ dose rate before proper disposal treatment, 137 Cs must be removed. In the here presented sub-project, the ion-exchange method was evaluated. Two promising sorbents, CLEVASOL ® and AMP (ammonium molybdophosphate), and two derived products AMP_PAN (AMP immobilized in polyacrylonitrile) and AMP/SiO 2 (AMP immobilized on silica gel) were tested by the batch method using model solutions of important high-yield fission products (Cs, Eu, Zr, Ru, Pd and Ag), as well as U and Pu. The results showed that AMP, AMP/SiO 2 and AMP_PAN have higher selectivity for Cs than CLEVASOL ® in 0.1–8 M (mol/L) HNO 3 solutions. 4 M HNO 3 solution was identified as the most suitable condition for Cs-removal with AMP, AMP_PAN and AMP/SiO 2 due to the still sufficiently high separation factor of Cs from other metal ions and an acceptable volume increase factor after dilution. The follow-up kinetic studies on AMP, AMP_PAN and AMP/SiO 2 indicated that although Cs exchange on AMP and AMP/SiO 2 is faster than on AMP_PAN in the first 5 min, they all nearly reach equilibrium after 30 min of contacting time. The isotherm curves of Cs adsorption on AMP, AMP_PAN and AMP/SiO 2 in 4 M HNO 3 showed that the maximum sorption capacity of Cs is reached asymptotically. The results from Langmuir isotherm modeling agree with results from other publications.

Four methods for 90 Sr separation from spent ion-exchange resin samples were carried out, offering a useful methodology to achieve interferences free 90 Sr fractions. The four methods consist in resin sample decomposition, pre-treatment and selective separation of 90 Sr by using: (a) a single chromatographic extraction process, (b) double chromatographic extraction, (c) a single chromatographic extraction process followed in sequence by two precipitations, and (d) ion-exchange chromatography, followed by extraction chromatography and precipitation. Mineralization by microwave acid digestion and the four 90 Sr separation methods thoroughly presented are available. Data processing methods (adjustable modified efficiency tracing – a new improved approach for the efficiency tracing LSC technique, non-linear regression and α - β discrimination) to obtain the activities values of α , β - γ , pure β emitters and the evaluation of chemical recovery yield of strontium were presented. A discussion about activity assessment in 90 Sr purified fractions, providing a convincing argument to support the accuracy of the 90 Sr separation methods, is also offered.

We studied the simple separation of radiosilvers from proton- or deuteron-irradiated natural palladium ( nat Pd) targets, and successfully separated radiorhodium, radiosilver and radiopalladium using an anion-exchange resin. The yields of radiosilvers were 105 Ag: 1.0 ± 0.32 MBq/μAh; 106m Ag: 2.0 ± 0.64 MBq/μAh; 110m Ag: 0.019 ± 0.0063 MBq/μAh ( n  = 4) at the end of bombardment with a total recovery rate of 98 % under the following irradiation conditions (deuteron beam energy: 20 MeV; beam current: 10 μA; irradiation time: 2.25 ± 0.50 h). We also evaluated the recycling of the palladium target.

In this investigation, a novel application of Aliquat 336 (tricaprylmethylammonium chloride)-impregnated chitosan (AICS) for the separation and purification of 99 Mo from some fission products, such as 137 Cs, 85 Sr and 131 I, in alkaline solution is presented. Before impregnation, pristine chitosan experienced no adsorption affinity for Mo. However, this situation dramatically changed after the impregnation. The structure of AICS was elucidated by FTIR, SEM and EDX spectra. The influence of contact time, solution pH, weight of AICS, initial Mo concentration and temperature on the adsorption process was studied. Kinetic studies revealed that the rate of adsorption was impressively very fast and only 3 min were sufficient to reach equilibrium. The pH influence showed that Mo could be effectively adsorbed over a wide range of pH 3–11. The equilibrium data fitting to isotherms models followed the order Langmuir > Freundlich > Dubinin-Radushkevich. Based on the Langmuir model, the maximum adsorption capacity was computed at 60.1 mg/L. Thermodynamic studies indicated that the adsorption process is spontaneous and endothermic in nature. Finally, a pure solution of 99 Mo with a purity >99 % was obtained from a real sample. The data obtained confirmed that AICS is a promising candidate for separation and purification of 99 Mo from alkaline media.

Radiolabeled macrocyclic bisphosphonate ligands have recently been demonstrated to be highly efficacious in treatment of patients with painful bone metastases. Herein, we report a robust protocol for formulation of therapeutically relevant doses of 177 Lu-labeled bisphosphonate amide of DOTA (BPAMD) using moderate specific activity 177 Lu produced by direct (n,γ) route and its preliminary investigation in human patients. Doses (2.8 ± 0.2 GBq) were formulated with high radiochemical purity (98.3 ± 0.4 %) using a protocol optimized after extensive radiochemical studies. In vitro binding studies with mineralized osteosarcoma cells demonstrated specific binding of the radiotracer. Biodistribution studies in healthy Wistar rats demonstrated rapid skeletal accumulation with fast clearance from the non-target organs. In a patient administered with 555 MBq dose of 177 Lu-BPAMD, intense radiotracer uptake was observed in the metastatic skeletal lesions with insignificant uptake in any other major non-targeted organs. Preliminary clinical investigations carried out after administration of 2.6 GBq of 177 Lu-BPAMD revealed significant reduction in pain after 1 week without any adverse effects. The developed protocol for formulation of 177 Lu-BPAMD doses using moderate specific activity carrier added 177 Lu has been found to be effective and warrants wider investigations in patients with painful skeletal metastases.

Aqueous solution of pH indicator dye tetrabromophenolphthalein ethyl ester containing chloral hydrate was studied for its possibility to be used as a liquid dosimeter. The useful measuring range was found to be (0.5–2 kGy) depending on the concentration of both dye and chloral hydrate added. The system has good stability before and after irradiation under different storage conditions. A comparison study between direct irradiation of the dye containing chloral hydrate and indirect method that executed through avoiding exposure of the dye to irradiation and irradiate the chloral hydrate only followed by outputs for interaction with dye was investigated seeking to extend the dose range up to 5 kGy.