Three dimensional computed tomography (CT) algorithms for a planar object

Abstract

Recently modern X-ray computed tomography (CT) scanner is rapidly moving towards cone-beam geometry. One of the important advantages of the cone-beam CT is its fast volumetric scanning capability. Also it provides the opportunity for tomographic image reconstruction with magnified resolution. This opportunity is applicable for Emission CT (ECT) scanner with a convergent collimator, which functions as cone beam geometry. However, in a cone-beam image reconstruction, current existing reconstruction algorithms put limitations from long object problems due to the nature of insufficient data or limited source scanning. Therefore, the algorithms that is based on cone-beam geometry and free from limited source scanning highly demanded these days. In this study, for planar object, we have developed full and half-scan algorithms based on approximated cone-beam back-projection. For solving long object problems, many other reconstruction algorithms have been adopted by several helical CT scanners that are composed of a micro-focus X-ray tube and flat panel detector. Although these efforts make the long object problem solved, it remains for planar object as ever due to limited source scanning such as non-isocentric circular orbit. Prior to the algorithmic development, we report digital tomosynthesis (DT) called laminography using geometric projection methods for reconstructing arbitrary cross-section images as well as three dimensional laminography images for cone-beam CT. Digital laminography are advantageous in terms of temporal resolution, and widely used only with a few number of projection data on cone-beam geometry. While existing laminography algorithms use the geometric projection methods, in this dissertation we substitute back-projection technique instead of the geometric projection. Both of laminography without filtering and weighting steps have similar results except for the complexity between their algorithms but it makes the blurring and other severe ...