Study for band artifact correction for photon counting detector CT

Abstract

Photon Counting Detector CT (PCD-CT) is expected to provide new possibilities by its capability of energy decomposition. However, because of non-ideal phenomena like the finite widths of individual energy windows of the detector or the scattered radiation, PCD-CT can have artifacts of not only dark but bright bands in some images. Therefore, we developed a correction method to reduce both dark and bright bands and verified it with data acquired with a prototype machine. The correction is performed on the material decomposition images, and acrylic and iodine images were employed. The dark band observed in the iodine image was corrected with the method used in the Energy Integrated Detector CT system. To suppress the bright band seen in the acrylic image, several virtual monochromatic images were created from the material decomposition images, and the energy was sought at which the dark and bright bands were cancelled. The bright band correction was performed using this energy and the correction amount of the dark band in the iodine image. It was demonstrated with the prototype machine data that the dark and bright bands were reduced in the material decomposition image and the virtual monochromatic image, and it was shown that the artifacts of both dark and bright bands can be corrected by the proposed method.