A filtered backprojection algorithm with ray-by-ray noise weighting

• Published in: Medical physics (Lancaster) Vol. 40; no. 3; pp. 031113 - n/a
• Main Authors: Zeng, Gengsheng L., Zamyatin, Alex
• Format: Journal Article
• Language: English
• Published: United States American Association of Physicists in Medicine 01.03.2013
• Subjects: Algorithms; Analysis of texture; analytical reconstruction algorithm; Artifacts and distortion; Cadaver; Computed tomography; Computer simulation; Computerised tomographs; computerised tomography; Cone-Beam Computed Tomography - methods; Digital computing or data processing equipment or methods, specially adapted for specific applications; edge‐preserving filtering; Fourier transforms; Humans; Image data processing or generation, in general; image denoising; Image enhancement or restoration, e.g. from bit‐mapped to bit‐mapped creating a similar image; Image Processing, Computer-Assisted - methods; image reconstruction; image texture; Medical image noise; medical image processing; Medical image reconstruction; Medical imaging; Medical X‐ray imaging; Models, Theoretical; Noise; noise modeling; phantoms; Radiation Dosage; ray tracing; Reconstruction; tomography; Transmission measurement; X-RAY COMPUTED TOMOGRAPHY: 2012 ADVANCES IN IMAGE FORMATION (Online only); X‐ray imaging; analytical reconstruction algorithm; noise modeling; CT; image reconstruction; edge-preserving filtering; tomography
• ISSN: 0094-2405; 2473-4209; 1522-8541; 2473-4209
• DOI: 10.1118/1.4790696

Purpose: This paper derives a ray-by-ray weighted filtered backprojection (rFBP) algorithm, based on our recently developed view-by-view weighted, filtered backprojection (vFBP) algorithm. Methods: The rFBP algorithm directly extends the vFBP algorithm by letting the noise weighting vary from channel to channel within each view. The projection data can be weighted in inverse proportion to their noise variances. Also, an edge-preserving bilateral filter is suggested to perform post filtering to further reduce the noise. The proposed algorithm has been implemented for the circular-orbit cone-beam geometry based on Feldkamp's algorithm. Results: Image reconstructions with computer simulations and clinical cadaver data are presented to illustrate the effectiveness and feasibility of the proposed algorithm. The new FBP-type algorithm is able to significantly reduce or remove the noise texture, which the conventional FBP is unable to do. The computation time of the proposed rFBP algorithm is approximately the same as the conventional FBP algorithm. Conclusions: A ray-based noise-weighting scheme is introduced to the FBP algorithm. This new FBP-type algorithm significantly reduces or removes the streaking artifacts in low-dose CT.