RESUMEN
The procedure followed by the Nuclear Metrology Laboratory (LMN) at the IPEN-CNEN/SP, in São Paulo, for the primary standardization of 166Ho is described. The activity of 166Ho was determined by the efficiency extrapolation technique applied to a 4πß(PC)-γ coincidence system using a gas flow proportional counter in 4π geometry coupled to a 76 × 76 mm NaI(Tl) crystal. The results for the γ-rays intensities at 80.57 and 1379.45 keV were 0.0651(11) and 0.00904(11), respectively.
Asunto(s)
Rayos gamma , Holmio/normas , Radioisótopos/normas , Estándares de Referencia , Espectrometría gamma/normasRESUMEN
The National Laboratory for Metrology of Ionizing Radiation (LNMRI)/Brazil acquired (166m)Ho and (243)Am/(239)Np solutions from commercial suppliers in order to realize primary standardization and therefore reducing the associated uncertainties. The method used in the standardization was the live-timed 4πß(LS)-γ(ΝaI(Tl)) anticoincidence counting. The live-timed anticoincidence system is operated since 2006 in LNMRI and is composed of two MTR2 modules donated by Laboratoire National Henri Becquerel (LNE-LNHB)/France. The data acquisition system uses a homemade LabView program and an Excel file for calculus. These systems have been used for primary standardization at LNMRI for many radionuclides and recently took part in the (124)Sb and (177)Lu International Key Comparisons with good performance.
Asunto(s)
Americio/análisis , Americio/normas , Holmio/normas , Neptunio/análisis , Neptunio/normas , Radiometría/normas , Programas Informáticos/normas , Americio/química , Brasil , Semivida , Holmio/análisis , Internacionalidad , Lenguajes de Programación , Dosis de Radiación , Estándares de Referencia , Valores de ReferenciaRESUMEN
(166)Ho is a beta-emitter (E(_max) = 1.84 MeV, T1/2 = 26.7 hours) with a mean penetration in the soft tissue of 2.2 mm and gamma-photons 81keV and 1380keV. In this paper, we present our experiences with preparation of (166)Ho-macroaggregates ((166)Ho-MA) for radiosynoviorhesis. Ho-MA were prepared by reacting the aqueous solution of holmium nitrate pentahydrate with sodium borohydride solution in 0.2 M NaOH. After centrifugation, washing, and drying at 105 degrees C, final fineness of 1-15 microm was attained using a homogenizer working at 70,000 rpm. Neutron activation was carried out in screwed titanium ampules in a nuclear reactor at the neutron flux 10E12-10E14 neutrons.cm-24.s-1. The irradiated samples were allowed to cool 24 hours before further manipulation. (166)Ho-MA were clinically tested on 20 patients suffering from gonarthrosis (15), rheumatoid arthritis (5), psoriatic arthritis (1), and gout arthropathy (1). (166)Ho-MA are currently produced under GMP and production facility allows producing radioactivity for 6 patients within one production run.