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Feldkamp-based cone-beam reconstruction for gantry-tilted helical multislice CT
Ilmar Hein1, Katsuyuki Taguchi, Michael D Silver
1Bio-Imaging Research, Inc., 425 Barclay Boulevard, Lincolnshire, Illinois 60069, USA. ihein@birinc.com
Medical Physics
|January 10, 2004
Summary
Gantry tilt in helical CT imaging requires algorithm modification to prevent artifacts. A generalized Feldkamp algorithm successfully accounts for tilt, improving image quality in multislice systems.
Area of Science:
- Medical Imaging
- Computed Tomography
- Image Reconstruction
Background:
- Gantry tilt is clinically necessary in X-ray CT systems.
- Single-slice fan-beam systems tolerate tilt without artifacts.
- Multislice helical CT requires modified reconstruction algorithms for tilted gantry imaging to avoid image degradation.
Purpose of the Study:
- To present a generalized helical cone-beam Feldkamp-based algorithm for CT image reconstruction.
- To validate the algorithm for both tilted and nontilted gantry orientations.
- To address image artifacts caused by gantry tilt in multislice helical CT.
Main Methods:
- Developed a generalized helical cone-beam Feldkamp-based algorithm.
- Incorporated modifications to account for gantry tilt, including calculating and applying a lateral shift.
- Integrated the tilt-generalized algorithm into a 16-slice CT scanner (Aquilion).
Main Results:
- The generalized Feldkamp algorithm effectively handles gantry tilt without significant computational increase.
- Gantry tilt introduces a calculable lateral shift in the reconstructed image isocenter.
- The developed algorithm demonstrated successful incorporation and verification in a clinical CT system.
Conclusions:
- A generalized helical Feldkamp algorithm provides accurate CT image reconstruction with gantry tilt.
- The algorithm mitigates artifacts like smearing and double-imaging in tilted helical CT.
- This approach simplifies the adaptation of CT systems for tilted gantry applications.