This invention relates generally to methods and apparatus for computed tomography (CT), and more particularly to methods and apparatus for generating thick images in cone beam volumetric CT.
Generation of a tomographic image with a slice thickness larger than the nominal detector row width (referred to herein, as a “thick image”) is of clinical importance in neuro- and trauma-CT imaging. A straightforward way to generate thick images is the weighted summation of tomographic images with the slice thickness equal to the detector row width (namely thin image) in the image domain. This approach generates a thick image with uniform slice thickness, but is computationally expensive because each thin image contributing to the thick image has to be reconstructed respectively in advance. Another way is to filter projection data along the z-direction, which is equivalent to increasing the nominal detector row width. This approach is computationally efficient, but may result in a non-uniform slice thickness. To have a balance between slice thickness uniformity and computational efficiency, an approach of generating a thick image using tracked and re-sampled virtual plane projection is disclosed below.