Study of reprojection methods in terms of their resolution loss and sampling errors
- UCLA School of Medicine, Los Angeles, CA (United States)
Two reprojection methods were studied with respect to their resolution loss and sampling errors. The two methods studied were: area weighted convolution (AWC), and Gaussian pixel convolution (GPC). Both methods are based on a pixel-driven, nearest-neighbor algorithm, but with different assumptions of the pixel intensity distribution. Modulation transfer function (MTF) was used to evaluate the resolution loss, and the residual sum of squares (RSS) of the difference between the reprojected sinogram and a reference sinogram corresponding to infinite sampling was used to assess the sampling errors. The resolution loss was found to be determined by the reconstruction filter, the linear interpolation in the backprojection, and the convolution kernel. Sampling errors were found to be angle-dependent, and the angular dependency was more pronounced for the GPC. To avoid significant sampling errors, the width of the convolution kernel needs to be two times larger than the pixel distance. Large sub-binning size of the projection array leads to interpolation error, which is more pronounced for AWC than for GPC. For GPC method, with pixel size twice the pixel distance, the sampling error can be greatly reduced. The sampling error can be reduced without additional resolution loss by using a smaller pixel distance.
- DOE Contract Number:
- FC03-87ER60615
- OSTI ID:
- 6011600
- Journal Information:
- IEEE Transactions on Nuclear Science (Institute of Electrical and Electronics Engineers); (United States), Journal Name: IEEE Transactions on Nuclear Science (Institute of Electrical and Electronics Engineers); (United States) Vol. 40:4 part 1; ISSN 0018-9499; ISSN IETNAE
- Country of Publication:
- United States
- Language:
- English
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