Dissertation > Excellent graduate degree dissertation topics show

Research on Extraction Methods of Phase Information and CT Reconstruction Algorithms in Diffraction Enhanced Imaging

Author: HuangZhiFeng
Tutor: KangKeJun;LiZheng
School: Tsinghua University
Course: Nuclear Science and Technology
Keywords: Phase-contrast imaging Diffraction enhanced imaging Extraction method of phase information CT reconstruction algorithm
CLC: O434.19
Type: PhD thesis
Year: 2006
Downloads: 391
Quote: 3
Read: Download Dissertation


Diffraction enhanced imaging (DEI) is one of up-to-date subjects in the X-ray imaging field. It can inspect weakly absorbing low-Z samples and its spacial resolution is on the order of microns or even sub-microns. So DEI has its particular advantages over traditional X-ray absorption imaging technology. The primary experiments on DEI have been done sucessfully in medical, biological and material fields. Thus, the research on DEI has significant value and perspective.This dissertation focuses on the research of extraction methods of phase information and reconstruction algorithms of DEI-CT based on the solution of the DEI’s computer simulation experiment model. The research results are all proved by the real experimental data from the DEI setup at the Beijing synchrotron radiation facility. The main work and the originality of the dissertation are summarized as follows:Firstly, the equivalent rectilinear propagation model of the computer simulation experiment is presented according to the geometric-optics approximation theory of X-ray diffraction by a perfect crystal with symmetrical Bragg geometry. The new model partly simplifies the geometric structure of the beam path and is applied to analyze quantificationally the position offsets of the DEI images in the different positons of the rocking curve. The correction method is proposed to correct the images of the computer simulation experiment and ensure the validity of the simulated results computed by the extraction methods of phase information and CT reconstruction algorithms.Secondly, in the research on extraction methods of phase information, the limitation of the current methods, such as the geometric-optics approximation method and the multiple-images statistical method, are analyzed detailedly, and three more effective methods are presented here, including the statisticalgeometric-optics-approximation method, the maximum refraction-angle method and the Gaussian curve-fitting method. A strategy how to select appropriate extraction methods in the real experiment is drawn up. More accurate results of refraction angle information can be obtained by these new methods than current methods in the simulation and real experiments.Finally, in the research on reconstruction algorithms of DEI-CT, a direct filtered backprojection algorithm based on refraction angle information for the scan type of the CT rotation axis parallel to the lattice plane of the analyzer crystal is presented here, which can reconstruct the distribution of the sample’s diffractive index decrement in one step. The results of the simulation and real experiments indicate that the new algorithm based on the new extraction methods can reconstruct the distribution of the sample’s diffractive index decrement quite accurately, whose calculation precision and image quality are better than those obtained by the CT reconstruction algorithms based on the current extraction methods.

Related Dissertations

  1. Study on Phase Retrieval Algorithms of X-ray In-line and Grating-based Phase-Contrast Imaging,O435.1
  2. The Study on Cone-beam CT Reconstruction Algorithm Acceleration,TP391.41
  3. Phase Aberration Compensation in Digital Holographic Microscopy for Biological Cells,O438.1
  4. Study on Differential Phase Extraction in Phase-contrast Imaging,O434.12
  5. Study on the Morphology of Microvessels by Synchrotron Radiation,R73-3
  6. Synchrotron radiation X-ray tumorigenesis, vascular imaging and phase contrast imaging theory,R730.4
  7. Hard X-ray diffraction enhanced imaging CT,TN27
  8. Thermal neutron phase contrast imaging technology research,TL99
  9. Investigation of the Performance of Digital Holographic System When Used for Microscoptic Image,O438.1
  10. Research of Quality Assessment and Image Processing of In-line X-ray Phase-contrast Imaging,O434.1
  11. X-ray phase contrast imaging simulation and experimental study of the principles of,TP391.41
  12. Research on Methods and Technologies for Grating-based Imaging with Conventional X-ray Sources,TP391.41
  13. Study on Phase Contrast Imaging for Micro Objects by Digital Holographic Microscopy,O438.1
  14. Detection of Angiogenesis after Stem Cell Transplantation in a Rat Model of Hindlimb Ischemia Using Synchrotron Radiation,R654.3
  15. X-ray phase contrast imaging and CT studies,TP391.41
  16. Coaxial and differential phase contrast imaging theory and numerical analysis,TP274.5
  17. Experiment Study of the Phase-Contrast Technique in Medical Imaging,R814.4
  18. Research on Optical Problems Related to X-ray Phase Contrast Imaging,O434.1
  19. Preliminary Experiment Study on In-situ XRF Technique Applied in RoHS Certification,O434.19
  20. Using the condenser lens to obtain a high brightness source of soft X-ray technology,O434.19
  21. Study on Some Characteristic of X-Ray Laser and Extreme Ultraviolet Lithographic Source in Capillary Discharge,O434.19

CLC: > Mathematical sciences and chemical > Physics > Optics > X-ray,ultraviolet, infrared > X-ray > Application
© 2012 www.DissertationTopic.Net  Mobile