Review of X-ray dark-field imaging under development is presented. Its goal is its application to clinical diagnosis of organs that have been invisible by the ordinary techniques. In order to clinically visualize tiss...Review of X-ray dark-field imaging under development is presented. Its goal is its application to clinical diagnosis of organs that have been invisible by the ordinary techniques. In order to clinically visualize tissues in detail one needs high contrast and high spatial resolution say ～50 μm. This X-ray optics comprises a Bragg asymmetric monochro-collimator and a Bragg case or a Laue case filter with capability of analyzing angle in a parallel position. Their diffraction index is 4,4,0 and the X-ray energy 35 keV (λ= 0.0354 nm). The filter has 0.6 mm thickness in the Bragg case or 1.075 mm or 2.15 mm thickness in the Laue case. Under this condition only the refracted X-rays from object can transmit through the filter while the beam that may receive absorption and/or phase change will not. Soft tissues at human joints thus taken show high contrast images so that the DFI is promising for clinical diagnosis. Preliminary X-ray absorption images of another clinical candidates of ear bones are also shown.展开更多
This paper presents the derivation of Gauss-Newton filter in linear cases and an analysis of its properties. Based on the minimum variance theorem, the Gauss-Newton filter is constructed and derived, including its sta...This paper presents the derivation of Gauss-Newton filter in linear cases and an analysis of its properties. Based on the minimum variance theorem, the Gauss-Newton filter is constructed and derived, including its state transition equation, observation equation and filtering process. Then, the delicate relationship between the Gauss-Aitken filter and the Kalman filter is discussed and it is verified that without process noise the two filters are equivalent. Finally, some simulations are conducted. The result shows that the Gauss-Aitken filter is superior to the Kalman filter in some aspects.展开更多
文摘Review of X-ray dark-field imaging under development is presented. Its goal is its application to clinical diagnosis of organs that have been invisible by the ordinary techniques. In order to clinically visualize tissues in detail one needs high contrast and high spatial resolution say ～50 μm. This X-ray optics comprises a Bragg asymmetric monochro-collimator and a Bragg case or a Laue case filter with capability of analyzing angle in a parallel position. Their diffraction index is 4,4,0 and the X-ray energy 35 keV (λ= 0.0354 nm). The filter has 0.6 mm thickness in the Bragg case or 1.075 mm or 2.15 mm thickness in the Laue case. Under this condition only the refracted X-rays from object can transmit through the filter while the beam that may receive absorption and/or phase change will not. Soft tissues at human joints thus taken show high contrast images so that the DFI is promising for clinical diagnosis. Preliminary X-ray absorption images of another clinical candidates of ear bones are also shown.
文摘This paper presents the derivation of Gauss-Newton filter in linear cases and an analysis of its properties. Based on the minimum variance theorem, the Gauss-Newton filter is constructed and derived, including its state transition equation, observation equation and filtering process. Then, the delicate relationship between the Gauss-Aitken filter and the Kalman filter is discussed and it is verified that without process noise the two filters are equivalent. Finally, some simulations are conducted. The result shows that the Gauss-Aitken filter is superior to the Kalman filter in some aspects.
