Simulation studies on a pseudo-three-dimensional reconstruction algorithm for volume imaging in multi-ring PET.
The imaging performance of a pseudo-three-dimensional (3D) reconstruction algorithm has been investigated. The algorithm is based on ID filtering followed by 3D backprojection. High- and low-frequency components of the image are reconstructed separately, and oblique projections are used only for reconstructing the high-frequency component. The cross talk between different slices due to oblique backprojection is eliminated by high-pass filtering. 'Variable filters', the cut-off frequencies of which are proportional to the tilt angles of projections, provide higher signal-to-noise ratio than 'fixed filters' with similar capability for cross-talk rejection. The maximum ring difference used in the reconstruction of each slice is extended as far as possible, while still satisfying the requirement that the total density of backprojection beams deposited in the slice is approximately uniform in the field of view. This allows the use of almost all available projection data to improve signal-to-noise ratio in peripheral slices. The root mean square noise of the reconstructed images evaluated with simulation studies is in good agreement with numerical calculations, and it is shown that the loss in signal-to-noise ratio caused by discarding the low-frequency component of oblique projections is negligibly small as long as suitable variable filters are used.
Tanaka
E
E
Hamamatsu Photonics KK, Mori-Building No 33, 5F, 3-8-21, Toranomon, Minato-ku, Tokyo, Japan.
Mori
S
S
Yamashita
T
T
D000465:Algorithms; D003198:Computer Simulation; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D015233:Models, Statistical; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000379:methods*; D013223:Statistics as Topic; D014055:Tomography, Emission-Computed / Q000379:methods