An Edge Detection Algorithm for Attenuation Correction in Emission CT

A new body edge detection algorithm is presented for attenuation compensation based on calculation in emission computed tomography. Based on the differential geometry, the edge contour on the image plane can be calculated directly from the edge detected on the projection data. A new algorithm is; (1) detect edge contour on projection data, (2) smooth noisy contour by retaining lower order Fourier coefficients and (3) transform it to the edge contour on the image. Manipulation of two dimensional array is only needed in step (1) and the rest can be done by manipulation of one dimensional array. Robustness of the algorithm was tested on the threshold level and number of Fourier coefficients. The algorithm was applied to positron emission computed tomography. It can be applied to single photon emission computed tomography as well.