Estimation-reconstruction approach for image reconstruction in halfscan computed tomography

Abstract

The fan-beam filtered backprojection (FFBP) algorithm has been widely used for image reconstruction in fan-beam computed tomography (CT). We have also developed fullscan-hybrid algorithms for image reconstruction in fan-beam CT. Numerical evaluation indicates that such fullscan-hybrid algorithms possess computational and noise properties superior to those of the FFBP algorithm. However, because these fullscan-hybrid algorithms involve the calculation of the Fourier series expansion of the fan-beam data, they require fullscan data acquired over an angular range of 2(pi) . Therefore, these fullscan-hybrid algorithms cannot be applied directly to a halfscan fan-beam data that are acquired only over an angular range of (pi) plus the fan angle. In this work, we present new reconstruction algorithms -- the halfscan-hybrid algorithms -- for image reconstruction in halfscan CT. These halfscan-hybrid algorithms have properties that are similar to those of the full-scan hybrid algorithms and that are superior to those of the widely used halfscan-FFBP algorithm. Such properties of the halfscan-hybrid algorithms may have significant implications to the accuracy and precision of lesion detection and parameter estimation in noisy CT images without increasing the radiation dose to the patient.