ИСТИНА

Alpha-particle therapy is a new and promising treatment for many forms of cancer. 225Ac and 213Bi are the most of perspective among of α-emitters. 225Ac may be produced from natural thorium irradiated with protons in the energy range 200-60 MeV [1]. The irradiated thorium was dissolved in 4 - 6 M HNO3 with the addition of catalytic quantity 0,004 M HF. Although the radionuclide composition of the irradiated target comprises several tens of various elements, the main difficulties was to separate Ac(III) from Th(IV) and rare earth elements (REE) especially La(III) and Ce(III). Thorium was extracted by di(2-ethyl-hexyl)orthophosphoric acid [HDEHP] with toluene (1:1). For radiochemical separation of Ac(III) from REE(III) and other radionuclides we investigated extraction chromatography sorbents produced by TrisKem company: TRU (octylphenyl-N,N-di-isobutyl carbomoylphosphine oxide), Ln Resin (di(2- ethylhexyl)orthophosphoric acid), DGA Resin (N,N,N`,N`tetroctyldiglicolamide). Capacity factor for Ac(III), La(III), Ce(III) on DGA Resin, Ln Resin, TRU Resin was determinated in static conditionsin range 0,01 M – 9M HNO3. We used DGA Resin to adsorb Ac(III) and REE(III) from HNO3 solution of favorable acidity, while mono- and divalent ions (Cs+, Ra2+, Ba2+, Sr2+) as well as most of Ru, Zr, Nb, and others were washed out of the column. TRU Resin and Ln Resin we used for separate Ac(III) and REE(III). Chemical yield of the obtained 225Ac fraction was not less than 87% and radionuclidic purity of final product was better than 99.5%. But 225Ac has chemical inseparable impurity of 227Ac. The obtained 225Ac can not be used for direct medicine application. So generator systems 225Ac – 213Bi were determinated. There are some works about such systems [2]. Ac Resin (P,P,- di(2-ethylhexyl)methanediphosponic acid) was used for elution 213Bi in 0,5 M HCLO4. Thus, the actinium isolation comprises three main steps: 1) separation from macro-amounts of thorium; 2) pre-concentration of the fraction containing Ac(III) and REE(III); 3) separation of Ac(III) from REE(III). Method of obtaining of 213Bi was developed.