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Conference Paper
Over-exposure Correction in Knee Cone-Beam CT Imaging with Automatic Exposure Control using a Partial Low Dose Scan
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- Authors
- Jang-Hwan Choi, Kerstin Muller, Scott Hsieh, Andreas Maier, Garry Gold, Marc Levenston, Rebecca Fahrig
- Issue Date
- 2016-02
- Citation
- Medical Imaging 2016 (SPIE 9783), v.9783, pp.1-6
- Publisher
- SPIE
- Language
- English
- Type
- Conference Paper
- Abstract
- C-arm-based cone-beam CT (CBCT) systems with flat-panel detectors are suitable for diagnostic knee imaging due to their potentially flexible selection of CT trajectories and wide volumetric beam coverage. In knee CT imaging, over-exposure artifacts can occur because of limitations in the dynamic range of the flat panel detectors present on most CBCT systems. We developed a straightforward but effective method for correction and detection of over-exposure for an Automatic Exposure Control (AEC)-enabled standard knee scan incorporating a prior low dose scan. The radiation dose associated with the low dose scan was negligible (0.0042mSv, 2.8% increase) which was enabled by partially sampling the projection images considering the geometry of the knees and lowering the dose further to be able to just see the skin-air interface. We combined the line integrals from the AEC and low dose scans after detecting over-exposed regions by comparing the line profiles of the two scans detector row-wise. The combined line integrals were reconstructed into a volumetric image using filtered back projection. We evaluated our method using in vivo human subject knee data. The proposed method effectively corrected and detected over-exposure, and thus recovered the visibility of exterior tissues (e.g., the shape and density of the patella, and the patellar tendon), incorporating a prior low dose scan with a negligible increase in radiation exposure.
- KSP Keywords
- Air interface, Back projection(BP), C-arm, CT imaging, Human subjects, Line profile, Low-dose, Over-exposure correction, automatic exposure control, beam coverage, cone-beam CT