Band 104, Heft 5

Targeted alpha therapy (TAT) is a treatment method of increasing interest to the clinical oncology community that utilizes α -emitting radionuclides conjugated to biomolecules for the selective killing of tumor cells. Proton irradiation of thorium generates a number of α -emitting radionuclides with therapeutic potential for application via TAT. In particular, the radionuclide 230 Pa is formed via the 232 Th( p , 3 n ) nuclear reaction and partially decays to 230 U, an α emitter which has recently received attention as a possible therapy nuclide. In this study, we estimate production yields for 230 Pa and other Pa isotopes from proton-irradiated thorium based on cross section measurements. We adopt existing methods for the chromatographic separation of protactinium isotopes from proton irradiated thorium matrices to combine and optimize them for effective fission product decontamination.

A newly developed facility at the 3 MV Tandem Accelerator at Dhaka for measurement of proton induced reaction cross sections in the energy region below 5 MeV is outlined and tests for the beam characterization are described. The results were validated by comparison with the well-known excitation function of the 64 Ni(p, n) 64 Cu reaction. Excitation functions of the reactions nat Ni(p, x) 60,61 Cu, nat Ni(p, x) 55,57,58 m + g Co and nat Ni(p, x) 57 Ni were also measured from threshold to 16 MeV using the stacked-foil technique, whereby irradiations were performed with 5 MeV protons available at the Tandem Accelerator and 16.7 MeV protons at the BC 1710 cyclotron at Jülich, Germany. The radioactivity was measured using HPGe γ -ray detectors. A few results are new, the others strengthen the database. In particular, the results of the reaction nat Ni(p, x) 61 Cu below 3 MeV could serve as beam monitor.

Uranium uptake and (radio)toxicity was tested on spring wheat ( Triticum aestivum L. ) in a laboratory study using differently concentrated uranium nitrate solutions. Within these experiments, two analytical assays of uranium were comparatively tested: a fast and improved fluorimetric assay and the classical colorimetric (U(IV)–arsenazo(III) complexation) one. During the germination, the wheat seeds and plantlets supported well the uranium solutions of treatment within the entire concentration range (1E-4–5E-3 M). Uranium proved to be non (radio)toxic to wheat as compared with other natural and anthropogenic radiocations, probably because its uptake by spring wheat during the germination is low. Indeed, only a small fraction of uranium administered was located within the roots, whereas the uranium content of the stems was negligible. A high correlation between the results obtained by two analytical methods was found. However, the fluorimetric assay proved to be more reliable and fast, and accurate.

The aim of this pioneer study was to determine polonium 210 Po in the most popular magnesium supplements in Poland and estimate the possible related dose assessment to the consumers. The analyzed magnesium pharmaceutics contained organic or inorganic magnesium compounds; some from natural sources. The objectives of this research were to investigate the naturally occurring 210 Po activity concentrations in magnesium supplements, find the correlations between 210 Po concentration in medicament and magnesium chemical form, and calculate the effective radiation dose connected to analyzed magnesium supplement consumption. The highest 210 Po activity concentrations were determined in mineral tablets made from sedimentary rocks, namely dolomite – 3.84 ± 0.15 mBq g – 1 (sample Mg17). The highest annual radiation dose from 210 Po taken with 1 tablet of magnesium supplement per day or with 400 mg of pure Mg daily would come from sample Mg17 (dolomite) – 1.35  ±  0.5 and 8.44 ± 0.33 μSv year – 1 respectively.

Introduction: Recent studies show that porphyrin derivatives have interesting pharmacological and photodynamic properties and wide range of usage in photodynamic therapy treatment. This study describes the preparation, biodistribution and absorbed dose prediction of [ 111 In] labeled 5, 10, 15, 20-tetra phenyl porphyrin (TPP) in human organs, based on rats' biodistribution data. Methods: Five rats were sacrificed at each exact time intervals (2, 4 and 24 h post injection) and the percentage of injected dose per gram of each organ was measured by direct counting from rats data from 12 harvested organs. The Medical Internal Radiation Dose (MIRD) formulation was applied to extrapolate from rats to human and to project the absorbed radiation dose for various organs in humans. Results: From rat data we estimated that injection of [ 111 In] TPP into the humans would result in an estimated effective absorbed dose of 0.09 mSv/MBq in the whole body. While the highest effective absorbed dose for 111 In-TPP was in the heart wall (0.22 mSv), the organs that received the next highest doses were the Kidneys (0.06 mSv), thymus (0.04 mSv) and lungs (0.03 mSv). Conclusions: The skin dose will four times higher compare to the other 111 In compounds, which was due to magnificent skin uptakes. According to the fast wash-out, tumor avidity and the short half-life, [ 111 In] can be a suitable candidate for labeling of photo dynamic therapy (PDT) agents as a tracer for accurate biological evaluation of other PDT agents such as Photofrin and its homologs.

This study describes the preparation, biodistribution of 177 Lu-DTPA-SPIO after intravenous injection in rats. The chelator DTPA dianhydride was conjugated to SPIO NPs using a small modification of the well-known cyclic anhydride method. Conjugation was done at a 1:2 (SPIO : ccDTPA) molar ratio. Conjugation reaction was purified with Magnetic assorting column (MACs) using high gradient magnetic field following incubation, the radio labeled conjugate was checked using RTLC method for labeling and purity checked. The RTLC showed that labeling yield was above 99% after purification and the compound have good in-vitro stabilities until 48 h post injection in the presence of human serum. The biodistribution of 177 Lu-DTPA-SPIO in rats showed dramatic uptake in the reticuloendothelial system (RES) and their clearance is so fast in other organs especially in the blood. In conclusion, due to high uptakes of this radiotracer in the liver and spleen and their fast clearance from other tissues, especially in blood, it is suggested that this radiotracer would be suitable for RES studies.

Levalbuterol was successfully radiolabeled with iodine using chloramine-T as an oxidizing agent via an electrophilic substitution reaction. The reaction parameters that affecting the labeling yield such as levalbuterol concentration, chloramine-T concentration, pH of the reaction medium and reaction time were studied in details. The radiochemical yield was 97.5 ± 0.5% and the radioiodinated compound was separated by HPLC. In vitro studies showed that the iodinated levalbuterol was stable for up to 24 h. The biodistribution in experimental animals showed that the lung uptake was 68.18 ± 0.17% at 5 min post injection which decreased with time until reached to 18.7 ± 0.12% at 2 h which was higher than other recent developed radiopharmaceuticals for lung imaging. The clearance pathways from the mice appear to proceed via both hepatobiliary and renal pathways. Predosing the mice with cold levalbuterol reduced the lung uptake to 20 ± 1.3% and further confirms the high specificity and selectivity of 125 I-levalbuterol for the lung.