A study on the accuracy of polynomial fitting for direct computation of material lengths from projection data in dual energy CT
Haase V, Stierstorfer K, Maier A, Noo F (2023)
Publication Type: Conference contribution
Publication year: 2023
Journal
Publisher: SPIE
Book Volume: 12463
Conference Proceedings Title: Progress in Biomedical Optics and Imaging - Proceedings of SPIE
Event location: San Diego, CA, USA
ISBN: 9781510660311
DOI: 10.1117/12.2654340
Abstract
Dual energy (DE) CT is on the path to dramatically improve the impact of CT on patient healthcare. We are particularly interested in accurate estimation of tissue attenuation values, a key potential of DECT yet to be achieved. In many implementations of DECT, the two scans can be decomposed in the projection domain before image reconstruction. This decomposition amounts to solving a pair of non-linear equations for each measurement line. A computationally efficient approach addressing this problem is to directly express the solution with a polynomial fit. Most often, a cubic order is deemed sufficient, and the polynomial coefficients are found with calibration scans through combinations of positive lengths of the basis materials. Alternatively, when the energy response of the measurements is known, calibration scans are not needed, and both negative and positive material lengths can be considered. Negative material lengths can be useful to account for quantum noise and partial volume effects, and to enrich the set of tissues that can be exactly represented by the basis materials. In this work, we study the accuracy of the polynomial fitting assuming that the measurements have been corrected for scatter and the energy responses are known, using a data processing pipeline we recently published. Experimental results based on CT scans of the ACR phantom show that negative lengths are not uncommon, that fitting based on positive lengths therefore inherently involve unsafe extrapolation, and that quintic polynomial fitting with negative and positive material lengths yield robust and accurate results.
Authors with CRIS profile
Involved external institutions
Germany (DE)
United States (USA) (US)How to cite
APA:
Haase, V., Stierstorfer, K., Maier, A., & Noo, F. (2023). A study on the accuracy of polynomial fitting for direct computation of material lengths from projection data in dual energy CT. In Lifeng Yu, Rebecca Fahrig, John M. Sabol (Eds.), Progress in Biomedical Optics and Imaging - Proceedings of SPIE. San Diego, CA, USA: SPIE.
MLA:
Haase, V., et al. "A study on the accuracy of polynomial fitting for direct computation of material lengths from projection data in dual energy CT." Proceedings of the Medical Imaging 2023: Physics of Medical Imaging, San Diego, CA, USA Ed. Lifeng Yu, Rebecca Fahrig, John M. Sabol, SPIE, 2023.
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