X-ray CT Imaging And Multimodality Imaging

Modern medical imaging techniques play an increasingly important role in ourdaily lives. They provide non-invasive detection and visual images for medical di-agnosis. Medical imaging techniques are generally classifed into structural imagingtechniques and functional imaging technology. Common structural imaging tech-niques include X-ray computed tomography (XCT), magnetic resonance imaging(MRI) and ultrasound imaging. Common functional imaging techniques includefunctional magnetic resonance imaging (fMRI), single photon emission computedtomography (SPECT), positron emission tomography (PET) and optical tomogra-phy.Diferent imaging modalities provide various highly complementary images.For example, CT and MRI can provide anatomic changes, but can not be used forpathological diagnosis directly; SPECT, PET and optical imaging techniques cap-ture functional or metabolism changes, but can not ofer the exact location of lesions.Multi-modality imaging techniques aimed at fusion of several imaging modalities,which could provide more comprehensive information for medical diagnostics.This dissertation will focus on the fusion of XCT and optical tomography. Atpresent, XCT imaging has been widely used in nondestructive testing and medicaldiagnosis. Optical tomography is a non-radioactive and low-cost imaging technique. It has developed rapidly in recent years, and become more and more attractive.Optical tomography includes difuse optical tomography (DOT), bioluminescencetomography (BLT) and florescence molecular tomography (FMT).In this dissertation, multi-modality imaging techniques, including XCT calibra-tion method, XCT reconstruction algorithm and XCT/DOT dual-modality imagingsystem, are studied as follows.1. XCT and DOT techniques are introduced into an existing imaging system. Af-ter detailed analysis of the Kodak in-vivo imaging system FX, system improve-ment programs are proposed including the objects multidimensional movementmechanism and near-infrared imaging module.2. The XCT calibration and system correction methods are studied. Accordingto diferent sources of geometric parameters, all parameters are divided intothree groups with smaller coupling relationship. Parameters of each groupare analytical calibrated using appropriate phantoms, respectively. Numericalsimulations verify the proposed method. The calibration process of Kodaksystem and experimental results are provided.3. The reconstruction algorithm for the two-circles-plus-one-line trajectory arestudied. It is proved that the two-circles-plus-one-line trajectory is preferablein a limited space. Then, the reconstruction algorithm for the two-circles-plus-one-line trajectory is given by applying the M-line reconstruction method.The usage of redundant data and computation of derivatives are discussed.Numerical studies and preliminary physical phantom experiment demonstratethe feasibility of the proposed design and reconstruction algorithm.4. The XCT/DOT dual-modality imaging problems are studied. The parametersfor DOT imaging are calibrated using both X-ray and optical imaging. Then,the relation between XCT and DOT in the system is discussed. The fabri-cation method for dual-modality imaging phantoms are also provided. Theexperimental results of XCT and DOT verify the proposed system design.