Investigations of proton and deuteron induced nuclear reactions on natural and enriched Titanium, Calcium and Vanadium targets, with special reference to the production of 47Sc.

47Sc could be used in SPECT imaging and also suitable for targeted therapy of small tumors. The excitation functions for the production of 47Sc and accompanying impurities via proton and deuteron bombardment of Calcium, Titanium and Vanadium targets were evaluated by three nuclear codes, ALICE, TALYS and EMPIRE. Therefrom, integral yields of 47Sc and also 46gSc as a main impurity were calculated. The various production routes of 47Sc were compared together. The results consistency with available experimental data was checked for each reaction. Based on the results, the 46Ca(d,n)47Sc reaction can leads to the high purity 47Sc with the moderate yield.

Study on a new design of Tehran Research Reactor for radionuclide production based on fast neutrons using MCNPX code.

The aim of this work is to increase the magnitude of the fast neutron flux inside the flux trap where radionuclides are produced. For this purpose, three new designs of the flux trap are proposed and the obtained fast and thermal neutron fluxes compared with each other. The first and second proposed designs were a sealed cube contained air and D2O, respectively. The results of calculated production yield all indicated the superiority of the latter by a factor of 55% in comparison to the first proposed design. The third proposed design was based on changing the surrounding of the sealed cube by locating two fuel plates near that. In this case, the production yield increased up to 70%.

Theoretical assessment and targeted modeling of TiO2 in reactor towards the scandium radioisotopes estimation.

47Sc radioisotope with beta particle emission can be used for targeted radionuclide therapy in nuclear medicine and can be produced by nuclear reactor (with high activities) and accelerator. In this work, the specific activity of 47Sc with the isotopic impurities produced through irradiating the enriched 47Tio2 and natural TiO2 targets have been calculated by the MCNPX-2.6 and the TALYS-1.8 codes and also theoretical approach in a fast neutron flux 3×1013ncm-2s-1 in the reactor. In addition, the cross sections of 46Ti(n,p)46Sc reaction have been interpolated in the 1-10MeV energy range and compared with the corresponding experimental data, as well. Moreover, the average cross sections of 46Ti(n,p)46Sc, 47Ti(n,p)47Sc and 48Ti(n,p)48Sc reactions were reproduced. Acceptable agreement between the experimental data and calculated results confirms the ability of the used methods to design and predict the production process in reactor.

Development of a Radiolabeled Amlodipine Analog for L-type Calcium Channel Imaging.

PURPOSE: The non-invasive imaging and quantification of L-type calcium channels (also known as dihydropyridine channels) in living tissues is of great interest in diagnosis of congestive heart failure, myocardial hypertrophy, irritable bowel syndrome etc. METHODS: Technetium-99m labeled amlodipine conjugate ([99mTc]-DTPA-AMLO) was prepared starting freshly eluted (<1 h) 99mTechnetium pertechnetate (86.5 MBq) and conjugated DTPAAMLO at pH 5 in 30 min at room temperature in high radiochemical purity (>99%, RTLC; specific activity: 55-60 GBq/mmol). The calcium channel blockade activity (CCBA) and apoptosis/necrosis assay of DTPA-amlodipine conjugate evaluations were performed for the conjugate. Log P, stability, bio-distribution and imaging studies were performed for the tracer followed by biodistribution studies as well as imaging. RESULTS: The conjugate demonstrated low toxicity on MCF-7 cells and CCBA (at µm level) compared to the amlodipine. The tracer was stable up to 4 h in final production and presence of human serum and log P (-0.49) was consistent with a water soluble complex. The tracer was excreted through kidneys and liver as expected for dihydropyridines; excluding excretory organs, calcium channel rich smooth muscle cells; including colon, intestine and lungs which demonstrated significant uptake. SPECT images supported the bio-distribution data up to 4 h. CONCLUSION: significant uptake of [99mTc]-DTPA-AMLO was obtained in calcium channel rich organs. The complex can be a candidate for further SPECT imaging for L-type calcium channels.

Preparation and preclinical evaluation of 68Ga-DOTA-amlodipine for L-type calcium channel imaging.

AIM: In order to develop a possible tracer for L-type calcium channel imaging, we here report the development of a Ga-68 amlodipine derivative for possible PET imaging. MATERIALS AND METHODS: Amlodipine DOTA conjugate was synthesized, characterized and went through calcium channel blockade, toxicity, apoptosis/necrosis tests. [68Ga] DOTA AMLO was prepared at optimized conditions followed by stability tests, partition coefficient determination and biodistribution studies using tissue counting and co incidence imaging up to 2 h. RESULTS: [68Ga] DOTA AMLO was prepared at pH 4-5 in 7-10 min at 95°C in high radiochemical purity (>99%, radio thin layer chromatography; specific activity: 1.9-2.1 GBq/mmol) and was stable up to 4 h with a log P of -0.94. Calcium channel rich tissues including myocardium, and tissues with smooth muscle cells such as colon, intestine, and lungs demonstrated significant uptake. Co incidence images supported the biodistribution data up to 2 h. CONCLUSIONS: The complex can be a candidate for further positron emission tomography imaging for L type calcium channels.

Production and modeling of radioactive gold nanoparticles in Tehran research reactor.

Gold has two medically useful radioactive isotopes, 198Au and 199Au, for locally irradiating and killing tumor cells. 198Au radionuclide has been produced through the irradiation of the pure gold via 197Au(n,γ)198Au reaction in the Tehran Research Reactor at a thermal neutron flux of 4.5×1013ncm-2s-1 for the different irradiation times. In this paper, the activity of 198Au radionuclide has been determined using MCNPX-2.6 and TALYS-1.6 codes and also the theoretical approach. The calculated results were compared with the corresponding experimental values. The calculated results were in good agreement with the experimental data, thus the used codes can be used as a powerful tool to predict and optimize production conditions in reactor.

In vivo SPECT imaging of tumors by 198,199Au-labeled graphene oxide nanostructures.

Graphene oxide (GO) sheets functionalized by aminopropylsilyl groups (8.0 wt.%) were labeled by (198,199)Au nanoparticle radioisotopes (obtained through reduction of HAuCl4 in sodium citrate solution followed by thermal neutron irradiation) for fast in vivo targeting and SPECT imaging (high purity germanium-spectrometry) of tumors. Using instant thin layer chromatography method, the physicochemical properties of the amino-functionalized GO sheets labeled by (198,199)Au NPs ((198,199)Au@AF-GO) were found to be highly stable enough in organic phases, e.g. a human serum, to be reliably used in bioapplications. In vivo biodistribution of the (198,199)Au@AF-GO composite was investigated in rats bearing fibrosarcoma tumor after various post-injection periods of time. The (198,199)Au@AF-GO nanostructure exhibited a rapid as well as high tumor uptake (with uptake ratio of tumor to muscle of 167 after 4h intravenous injection) that resulted in an efficient tumor targeting/imaging. Meantime, the low lipophilicity of the (198,199)Au@AF-GO caused to its fast excretion (~24 h) throughout the body by the kidneys (as also confirmed by the urinary tract). Because of the short half-life of (198,199)Au radioisotopes, the (198,199)Au@AF-GO with an excellent tumor targeting/imaging and fast washing out from the body can be suggested as one of the most effective and promising nanomaterials in nanotechnology-based cancer diagnosis and therapy.