Assuntos
Neoplasias/radioterapia , Comitê de Profissionais/organização & administração , Radioterapia (Especialidade)/organização & administração , Projetos de Pesquisa , Braquiterapia , Fracionamento da Dose de Radiação , Previsões , Humanos , Fenômenos Físicos , Física , Radioterapia (Especialidade)/normas , Radioterapia (Especialidade)/tendências , Radiocirurgia , Radioterapia ConformacionalRESUMO
A global registration algorithm using only two CT slices was developed to transform target points known in the Brown-Roberts-Wells frame back to a CT-simulator coordinate system. The algorithm uses exact solutions to determine all of the points of interest based on BRW pins in the two CT-slices. In comparison with the algorithms based on individual slices, there is no requirement of digitization of BRW pins in every CT slice. There is no approximation (or linear interpolation) for determination of the target points that fell in between two CT slices. Results in 60 clinical cases demonstrate that the accuracy and precision of the isocentric positions are within the digitization uncertainty. Application of this global image registration can simplify the coordinate transformation in stereotactic radiation therapy.
Assuntos
Radiocirurgia/métodos , Técnicas Estereotáxicas , Tomografia Computadorizada por Raios X/métodos , Algoritmos , Encéfalo , Humanos , Planejamento da Radioterapia Assistida por Computador , Reprodutibilidade dos TestesRESUMO
To evaluate their usefulness as chemical indicators of cumulative oxidative damage to proteins, we studied the kinetics and extent of formation of ortho-tyrosine (o-Tyr), dityrosine (DT), and dityrosine-like fluorescence (Ex = 317 nm, Em = 407 nm) in the model proteins RNase and lysozyme exposed to radiolytic and metal-catalyzed (H2O2/Cu2+) oxidation (MCO). Although there were protein-dependent differences, o-Tyr, DT, and fluorescence increased coordinately during oxidation of the proteins in both oxidation systems. The contribution of DT to total dityrosine-like fluorescence in oxidized proteins varied from 2-100%, depending on the protein, type of oxidation, and extent of oxidative damage. In proteins exposed to MCO, DT typically accounted for > 50% of the fluorescence at DT wavelengths. These studies indicate that o-Tyr and DT should be useful chemical markers of cumulative exposure of proteins to MCO in vitro and in vivo.
Assuntos
Proteínas/química , Tirosina/análogos & derivados , Relação Dose-Resposta a Droga , Relação Dose-Resposta à Radiação , Peróxido de Hidrogênio/farmacologia , Isomerismo , Cinética , Muramidase/química , Muramidase/efeitos dos fármacos , Muramidase/efeitos da radiação , Oxirredução , Proteínas/efeitos dos fármacos , Proteínas/efeitos da radiação , Ribonucleases/química , Ribonucleases/efeitos dos fármacos , Ribonucleases/efeitos da radiaçãoAssuntos
Computadores , Departamentos Hospitalares/normas , Pacientes , Doses de Radiação , Serviço Hospitalar de Radiologia/normas , Educação Médica , Exposição Ambiental , Humanos , Dente Molar/diagnóstico por imagem , Prática Privada/normas , Lesões por Radiação/prevenção & controle , Radiografia Torácica , Radiologia/educação , Serviço Hospitalar de Radiologia/tendências , Coluna Vertebral/diagnóstico por imagem , Tecnologia Radiológica/educação , Recursos Humanos , Raios XRESUMO
The performance of a compact and efficient neutron generator, using the 3H(d, n) reaction and a gas target, is reported. The target is formed in a windowless, differentially pumped vessel pressurised to 7.5 Torr. An extended source of 15 MeV neutrons is produced when the target is bombarded by a 10 mA beam of 210 keV deuterons. Measurements are reported of the neutron energy spectra, neutron and gamma-ray dose rates, target lifetime and tritium handling. The neutron flux distribution of the extended target was measured and compared with the predictions of a simple beam-gas interaction model. The measured neutron source strength is 1.7 +/- 0.4 X 10(12) neutrons per second. The source output is limited by target beam current, not target power considerations.
