47Sc production development by cyclotron irradiation of 48Ca.

The therapeutic radionuclide 47Sc was produced through the 48Ca(p,2n) channel on a proton beam accelerator. The obtained results show that the optimum proton energies are in the range of 24-17 MeV, giving the possibility to produce 47Sc radionuclide containing 7.4% of 48Sc. After activation, the powdery CaCO3 target material was dissolved in HCl and scandium isotopes were isolated from the targets. The performed separation experiments indicate that, due to the simplicity of the operations and the chemical purity of the obtained 47Sc the best separation process is when scandium radioisotopes are separated on the 0.2 µm filter.

New precipitation method for isolation of 99mTc from irradiated 100Mo target.

Technetium-99m is the most widely used radionuclide in nuclear medicine. This work describes the method to separate 99mTc from irradiated 100Mo target. For this purpose we utilized formation of ammonium molybdenum phosphate (AMP) and have optimized the four parameters of the process. The proposed process is promising and allows fast separation of macroamounts of molybdenum without co-precipitation of 99mTc. The concentration of molybdenum in solution after precipitation of AMP was lower than 300 µg ml-1. Additional purification using AnaLigTc-02 is required to obtain solution with lower concentration of molybdenum.

Sorption behaviour of Am on marl groundwater colloids.

The sorption of americium on marl colloids is studied in a comprehensive way. In Na-HCO3 groundwater conditions, americium in the concentration range 3 x 10(-11)-3 x 10(10) M sorbs onto groundwater colloids. In these tests, the colloid concentration is rather high, i.e. Ccoll 1.7+/-1.3 mg l(-1) for sizes 505000 nm or Ncoll (1.7+/-0.1) x 10(11) l(-1) for sizes larger than 100 nm. These colloids are mainly chlorite and smectite/illite with an average size smaller than 500 nm. For the groundwater (pH 8.6, [Na+]-[HCO3]-2 x 10(-2) M), Kd values in the range 1-3 x 10(6)mlg(-1) are measured. These values are compared with experimental and modelled values reported earlier in the literature.

Macrocyclic complexes of scandium radionuclides as precursors for diagnostic and therapeutic radiopharmaceuticals.

The aim of this study was to evaluate new ligands which can be applied for labeling biomolecules with scandium radionuclides. Two radionuclides of scandium, (47)Sc and (44)Sc, are perspective radioisotopes for radiotherapy and diagnostic imaging. (47)Sc decays with a half-life of 3.35 days and a maximum ß(-) energy of 600 keV and could be an alternative to carrier added (177)Lu radionuclide for targeted radionuclide therapy. Another scandium radionuclide (44)Sc (t(1/2) = 3.92 h) is an ideal ß(+) emitter for PET diagnosis. It can be obtained as a daughter of the long-lived (44)Ti (t(1/2) = 60.4 y) from (44)Ti/(44)Sc generator. For complexation of scandium radionuclides macrocyclic ligands having a cavity size similar to Sc(3+) ionic radius were selected: 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), 1,4,7-triazacyclononane-1,4,7 triacetic acid (NOTA), 1,4,7-triazacyclodecane-1,4,7 triacetic acid and 1,4,7-triazacycloundecane triacetic acid, and analogs of NOTA with 10, 11 and 12 atoms of the carbon in the ring. Our results have shown that from the studied macrocyclic ligands studied DOTA is most efficient for binding scandium radionuclides (44)Sc and (47)Sc to biomolecules. The determined stability constant of Sc-DOTA complex logK = 27.0 is comparable with stability constants for Y(3+) and heaviest lanthanides but is higher than those for In(3+) and Ga(3+). Also (46)Sc-DOTATATE conjugate exhibits high stability in-vitro studies. The (13)C NMR studies have shown that Sc-DOTA like Lu-DOTA forms in solution complexes with eight-coordination geometry. The lipophilicity of Sc-DOTATATE is nearly identical to that of Lu-DOTATATE, which suggests similar receptor affinity of both radioconjugates.