Title :
Can the backprojection filtering algorithm be as accurate as the filtered backprojection algorithm?
Author :
Zeng, Gengsheng L. ; Gullberg, Grant T.
Author_Institution :
Dept. of Radiol., Utah Univ., Salt Lake City, UT, USA
fDate :
30 Oct-5 Nov 1994
Abstract :
For many years people have realized that the image reconstructed by the filtered backprojection (FBP) algorithm is more accurate than the image reconstructed by the backprojection filtering (BpjF) algorithm. The FBP algorithm is implemented in two steps: (1) convolve the projections with a kernel function, then (2) backproject the modified projections. The BpjF algorithm is also implemented in two steps: (1) backproject the projections, then (2) filter the backprojected image in the frequency domain with a two-dimensional ramp filter. The major drawback of BpjF is that the mean value of the reconstruction is not correct. This error is caused by the way the two-dimensional discrete ramp-filter is formed by sampling the continuous ramp-filter, which results in zeroing the DC component. The Nyquist Theorem is used to show that this approach of forming a discrete ramp-filter is not accurate and a new method to form the discrete ramp-filter is developed. The newly developed filter is the same as the commonly used discrete ramp-filter except for the DC value and preserves the correct mean value of the image
Keywords :
computerised tomography; image reconstruction; medical image processing; 2D discrete ramp-filter; DC value; Nyquist Theorem; backprojection filtering algorithm; correct mean value preservation; filtered backprojection algorithm; frequency domain; image filtering; medical diagnostic imaging; projections convolution; reconstructed image accuracy; tomographic imaging; Cities and towns; Convolvers; Filtering algorithms; Filters; Fourier transforms; Frequency domain analysis; Image reconstruction; Kernel; Radiology; Sampling methods;
Conference_Titel :
Nuclear Science Symposium and Medical Imaging Conference, 1994., 1994 IEEE Conference Record
Conference_Location :
Norfolk, VA
Print_ISBN :
0-7803-2544-3
DOI :
10.1109/NSSMIC.1994.474603