A new weighting scheme for cone-beam helical CT to reduce the image noise

• Published in: Physics in medicine & biology Vol. 49; no. 11; p. 2351
• Main Authors: Taguchi, Katsuyuki, Chiang, Be-Shan S, Silver, Michael D
• Format: Journal Article
• Language: English
• Published: England 07-06-2004
• Subjects: Algorithms; Imaging, Three-Dimensional - methods; Information Storage and Retrieval - methods; Numerical Analysis, Computer-Assisted; Phantoms, Imaging; Radiographic Image Enhancement - methods; Radiographic Image Interpretation, Computer-Assisted - methods; Reproducibility of Results; Sensitivity and Specificity; Signal Processing, Computer-Assisted; Stochastic Processes; Subtraction Technique; Tomography, Spiral Computed - instrumentation; Tomography, Spiral Computed - methods
• ISSN: 0031-9155
• DOI: 10.1088/0031-9155/49/11/016

Reducing the patient dose while keeping the image noise at the same level is desired for x-ray CT examinations. In order to achieve the goal, we propose a new weighting scheme taking the validity of the data and redundant data samples into account. The method is evaluated with a new generalized version of the Feldkamp helical reconstruction algorithm. It allows us to enlarge the projection angular range used in reconstruction, and thus, to reduce the image noise by increasing the detector utilization rate to 100% without sacrificing the image quality or z-resolution. This concept can be adapted to other exact or approximate algorithms as far as they use redundant data samples.