Fractional scan algorithms for low-dose perfusion CT

One of the key considerations in CT perfusion is the X-ray dose received by the patient, since cine acquisition mode is typically used in which repeated x-ray exposure occurs at the same anatomical location. In this technical note, we propose a new approach for dose reduction in which the X-ray tube current is maintained and the number of projection views is reduced per gantry rotation. A projection interpolation algorithm and an image prediction algorithm are developed to address the incompleteness of such projection data. Both algorithms utilize a priori knowledge that the contrast-uptake in perfusion images is gradual and predictable. As a result, excellent perfusion images can be reconstructed at a fraction of the nominal radiation dose. (C) 2004 American Association of Physicists in Medicine.