Extended imaging volume in cone-beam x-ray tomography using the weighted simultaneous iterative reconstruction...

Area of Science:

• Medical Imaging
• Computational Imaging
• X-ray Tomography

Background:

• Limited detector size in computerized x-ray tomography restricts the field of view (FOV).
• Lateral detector offset increases effective FOV but introduces artifacts due to projection truncation and data redundancy.
• Redundancy weighting is a technique to address these artifacts in reconstruction algorithms.

Purpose of the Study:

• To implement redundancy weighting within the simultaneous iterative reconstruction technique (SIRT).
• To develop and validate a weighted SIRT (W-SIRT) method for improved image reconstruction in CXT.
• To accelerate the W-SIRT algorithm for reduced computation time.

Main Methods:

• Implementation of redundancy weighting in SIRT to create the W-SIRT algorithm.
• Validation using geometric phantoms and a rabbit specimen via simulations and physical experiments.
• Development of an accelerated version (aW-SIRT) by incorporating a relaxation parameter.

Main Results:

• W-SIRT achieved higher contrast-to-noise ratio compared to weighted SART in simulations.
• aW-SIRT demonstrated comparable results to W-SIRT with half the iterations, significantly reducing computation time.
• aW-SIRT outperformed the Feldkamp-David-Kress algorithm in small overlap regions and achieved >75% effective FOV increase.

Conclusions:

• The W-SIRT algorithm effectively addresses artifacts caused by detector offset in CXT.
• The accelerated aW-SIRT provides a faster and efficient method for reconstructing larger volumes.
• The developed methods are applicable to various detector types, including XRIIs and flat-panel detectors.