The Study Of OCT-based Projected Index Computed Tomography

Projected Index Computed Tomography (PICT) has been recently developed as a promising technique of high resolution microscopy. Based on the theory of image reconstruction from projection, PICT combines the principles of optical coherence tomography and computed tomography. It allows for non-invasive mapping of sample's refractive indices. The refractive index mapping of tissues is of key importance to study light distribution and propagation in tissue, and the light-tissue interactions. Therefore, PICT has great potential application in biomedical field.We designed the PICT system on the basis of a fiber OCT system. In this system, the rotated CT projection scanning device enables collecting sample projection images from several view angles. Our system has high space resolution and is sensitive to the refractive index change. The resultant PICT images are free of the spatial distortion that is inherent in standard optical images and correspond well to the dimensions of the experiment sample we made.In this project, we design the image reconstruction software in PICT. Following PICT imaging model, we devised a sample to simulate the process of refractive index projection collection in PICT. By using convolution back projection algorithm (CBP), we reconstructed the images of the devised sample to test the performance of the software. In addition, we analyzed the influence of some factors on the quality of PICT images, such as the filter functions, the number of projection angles etc. We also provided a rapid CBP algorithm, which could reduce the image reconstruction time by 15 percent.This thesis includes five parts. The first chapter includes the development of PICT, an overview of index imaging techniques and the meaning of our project. The second chapter introduces PICT. The third chapter discusses the details of PICT system we built and the realization of PICT image reconstruction. In the fourth chapter, the experimental results are stated and analyzed. Finally, a conclusion of our work and the prospect of future work are presented in the fifth chapter.