A Harmonic Decomposition Reconstruction Algorithm for Spatially-Varying Focal Length Collimators

—Spatially varying focal length fan-beam collimators can be used in single photon emission computed tomography to improve detection efficiency and to reduce reconstruction artifacts resulting from the truncation of projection data. It has been proven that there exists no convolution backprojection algorithm for this type of collimator, so a complicated interpolation between two nonparallel projection rays is necessary for existing algorithms. The interpolation may generate blurring and artifacts in the reconstructed images. Based on a harmonic decomposition technique and the translation property of Fourier series, a semifrequency resampling technique is proposed to avoid the above mentioned interpolations. By this technique, the harmonic decomposition of projection data for spatially varying focal length fan-beam collimators has the same form as that for parallel-beam collimators in the semifrequency domain (Fourier transform with respect to angular variables only). An alternative v...

• Type: Journal
• Year: 1998
• Where: TMI
• Authors: Jiangsheng You, Zhengrong Liang, Shanglian Bao
• Keywords: Focal Length Fan-beam, Length Fan-beam Collimators, Projection Data, TMI 1998