Regular paper

[OPTICAL REVIEW Vol. 5, No. 5 (1998) 275-279]

Correction of Nonuniform Response in the Reconstruction for Single Photon Emission Computed Tomography with a Spatially Varying Focal Length Collimator

Masahiro MIMURA,^1,2 Takashi OBI,^1,* Masahiro YAMAGUCHI¹ and Nagaaki OHYAMA¹

¹Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, 4259, Nagatsuta, Midori-ku, Yokohama, 226-8503 Japan, ²Cancer Information and Epidemiology Division, National Cancer Center Research Institute, 5-1-1, Tsukiji, Chuo-ku, Tokyo, 104-0045 Japan

(Received December 22, 1997; Revised June 15, 1998; Accepted July 2, 1998)

SPECT (single photon emission computed tomography) images can visualize physiological functions directly and are diagnostically useful. The reconstruction methods based on the Continuous-Discrete (C-D) mapping model have an immediate effect on SPECT imaging because they employ photon detection kernels describing the photon transport from the body to the detector. However, in a spatially varying focal length geometry, the concentration of the sensitivity around the center of rotation of the detector causes a change in the response from the original image to the reconstructed image. As a result, a false hot spot often appears around the center of rotation. This paper presents a convenient method to repress the change by correcting the resolving kernels. Numerical simulations show that the method can reduce the false hot spots.

Key words: SPECT, NPD, GARDS, SVFLC

* obi@isl.titech.ac.jp

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