Program Information
Optimal CT Scan Mode and Reconstruction Kernel Selection for Bone Fracture Detection Task Under Both Centered and Off-Centered Conditions
J Cruz Bastida*, D Gomez-Cardona , K Li , T Szczykutowicz , G-H Chen , University of Wisconsin, Madison, WI
Presentations
SU-F-207-12 (Sunday, July 12, 2015) 4:00 PM - 6:00 PM Room: 207
Purpose:
Hi-Res(olution) mode was introduced in some state-of-the-art CT systems to reduce aliasing and improve spatial resolution. The Hi-Res data can be reconstructed using either the conventional kernels or HD kernels. Since high spatial resolution is often associated with a tremendous increase in image noise, the introduction of Hi-Res has confounded the scan protocol optimization. This work investigated how to use the task-driven optimization framework to optimize the selection of Hi-Res mode and reconstruction kernel for bone fracture detection tasks.
Methods:
The dependence of spatial resolution on scan mode, reconstruction kernel and off-center position was quantified via MTF measurements. For certain edge enhancing Hi-Res kernels, accuracy of the measurements was confounded by both high image noise and potential CT number saturations. These challenges were addressed by a combined use of repeated scanning and thick-slice reconstructions. Similarly, the NPS was measured under different conditions from repeated scans. The frequency-dependent detectability analysis was used to combine imaging task, MTF, and NPS to quantify the dependence of the overall imaging performance and optimize scan mode and reconstruction kernel selection.
Results:
(1) For a conventional kernel, the use of Hi-Res significantly improved the MTF at off-centered position. (2) The combined use of Hi-Res mode and HD kernel improved MTF at both the centered and off-centered positions. (3) The use of HD kernels increased noise magnitude and pushed the NPS to higher frequencies, and a model-observer analysis demonstrated that the optimal kernel and scan mode strongly depends on patient position and the nature of the task. This was confirmed by ex vivo animal (bovine bone) experiment.
Conclusion:
Optimal use of the Hi-Res mode and its associated HD kernels depends on patient positioning and the imaging task. Optimal decision making for its use can be achieved based on the framework developed in this work.
Funding Support, Disclosures, and Conflict of Interest: J. P. Cruz Bastida, D. Gomez-Cardona, K. Li: Nothing to disclose. T. P. Szczykutowicz: Equipment support, General Electric Company Research Grant, Siemens AG. G.-H. Chen: Research funded, GE Healthcare; Research funded, Siemens AX.
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