RESUMO
A method for assessing the impurity 210At in cyclotron-produced 211At via isotope dilution alpha spectrometry is presented. The activity of 210At is quantified by measuring the activity of daughter nuclide 210Po. Counting sources are prepared by spontaneous deposition of Po on a silver disc. Activity of 210At (at the time of 210Po maximum activity) is found to be 83.5+/-9.0 Bq, corresponding to an atom ratio (210At:211At at the time of distillation) of 0.010+/-0.007% (k=2). The method produces high-quality alpha spectra, with baseline alpha-peak resolution and chemical yields of greater than 85%.
Assuntos
Partículas alfa , Astato/análise , Polônio/análise , Técnica de Diluição de Radioisótopos , Radiometria/métodos , Análise Espectral/métodos , Astato/química , Astato/uso terapêutico , Avaliação de Medicamentos/métodos , Polônio/química , Doses de Radiação , Compostos Radiofarmacêuticos/análise , Compostos Radiofarmacêuticos/síntese química , Compostos Radiofarmacêuticos/uso terapêutico , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
Samples of 24Na, 42K, 76As and 198Au were produced by irradiation in the National Institute of Standards and Technology (NIST) reactor, and examined for impurities before and after measurement. Half-life measurements were carried out in the NIST 4pigamma pressurized ionization chamber. The results are compared to presently accepted values and previous NIST measurements.
Assuntos
Algoritmos , Meia-Vida , Modelos Químicos , Radioisótopos/análise , Radioisótopos/normas , Radiometria/instrumentação , Radiometria/normas , Astato/análise , Astato/química , Astato/normas , Calibragem/normas , Desenho de Equipamento , Radioisótopos de Ouro/análise , Radioisótopos de Ouro/química , Radioisótopos de Ouro/normas , Radioisótopos de Potássio/análise , Radioisótopos de Potássio/química , Radioisótopos de Potássio/normas , Radioisótopos/química , Radiometria/métodos , Padrões de Referência , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Radioisótopos de Sódio/análise , Radioisótopos de Sódio/química , Radioisótopos de Sódio/normasRESUMO
Four different chemical forms of the alpha-particle emitting radionuclide 211At were injected intraperitoneally in mice inoculated intraperitoneally 30 hr in advance with 10(6) cells of the K13 murine hybridoma cell line. The different 211At forms were (a) free 211At, (b) 211At-labeled TP-3 nonspecific monoclonal antibody (211At-TP-3), (c) 211At-labeled human IgG kappa (211At-hIgG kappa), and (d) 211At-labeled monodisperse polymer particles (211At-MDPP). A significantly prolonged survival (P < 0.05) was observed with injected doses down to 7 kBq for the 211At-MDPP, and down to 25 kBq for 211At-hIgG kappa. There were no significant differences in survival between 211At-MDPP, 211At-hIgG kappa, and 211At-TP-3 at the dose level of 200 kBq. The group receiving 250 kBq free 211At per animal had a shorter survival than the three other forms at 200 kBq. The groups treated with 500, 200, and 65 kBq 211At-MDPP had a similar survival. The group given the highest dose of 211At-hIgG kappa (275 kBq) had the highest fraction (50%) of long-term survivors of all groups. Biodistribution measurements and total body scintigrams in mice without tumor revealed that the free 211At was distributed all over the body within 10 min after injection while at 2 hr a high fraction of the 211At-TP-3 and 211At-hIgG kappa was still present intraperitoneally. In conclusion this study indicates that 211At-labeled MDPP and 211At-labeled IgG's may be efficient tools for treatment of intraperitoneal superficial tumor cells and malignant ascites.
Assuntos
Anticorpos Monoclonais/uso terapêutico , Astato/uso terapêutico , Hibridomas/efeitos da radiação , Imunoglobulina G/uso terapêutico , Animais , Anticorpos Monoclonais/análise , Anticorpos Monoclonais/farmacocinética , Astato/análise , Astato/farmacocinética , Modelos Animais de Doenças , Relação Dose-Resposta à Radiação , Feminino , Hibridomas/química , Hibridomas/diagnóstico por imagem , Imunoglobulina G/análise , Injeções Intraperitoneais , Camundongos , Camundongos Endogâmicos BALB C , Polímeros , Cintilografia , Taxa de Sobrevida , Fatores de Tempo , Distribuição Tecidual , Células Tumorais CultivadasRESUMO
We have evaluated SPECT and two planar imaging methods, geometric mean (GM) and buildup factor (BF), for their potential to quantitate in vivo 211At distributions in rat spinal subarachnoid spaces using phantom studies. The use of medium-energy collimators and the small diameter (3 mm) of the subarachnoid space complicate quantitation. Net activities from distributions in various backgrounds were obtained using a large region of interest with background subtraction. Results showed quantitation accuracy within 10% for SPECT and BF in low backgrounds increasing to 25% at higher background levels while GM errors ranged from 20 to 45%. We have also obtained images of [211At]astatide distributions, administered intrathecally, in rats.
Assuntos
Astato/análise , Radiometria/métodos , Animais , Astato/farmacocinética , Astato/uso terapêutico , Feminino , Ratos , Tomografia Computadorizada de Emissão de Fóton ÚnicoRESUMO
The concentrations of 211At and 125I were measured in various tissues in nude mice bearing xenografts of human thyroid tissue (fetal and malignant). The relative concentration of the two halogens was obtained at 4 and 24 h after injection. Samples were taken of the host blood, muscle and thyroid gland and the grafted tissues. The mouse thyroid concentrated 125I more efficiently than 211At but the human grafts concentrated both halogens about equally.
