Atomic number resolution for three spectral CT imaging systems

J. Eric Tkaczyk; Rogerio Rodrigues; Jeffery Shaw; Jonathan Short; Yanfeng Du; Xiaoye Wu; Deborah Walter; William Leue; Daniel Harrison; Peter Edic

doi:10.1117/12.709905

16 March 2007 Atomic number resolution for three spectral CT imaging systems

J. Eric Tkaczyk, Rogerio Rodrigues, Jeffery Shaw, Jonathan Short, Yanfeng Du, Xiaoye Wu, Deborah Walter, William Leue, Daniel Harrison, Peter Edic

Author Affiliations +

Proceedings Volume 6510, Medical Imaging 2007: Physics of Medical Imaging; 651009 (2007) https://doi.org/10.1117/12.709905
Event: Medical Imaging, 2007, San Diego, CA, United States

Abstract

The material specificity of computed tomography is quantified using an experimental benchtop imaging system and a physics-based system model. The apparatus is operated with different detector and system configurations each giving X-ray energy spectral information but with different overlap among the energy-bin weightings and noise statistics. Multislice, computed tomography sinograms are acquired using dual kVp, sequential source filters or a detector with two scintillator/photodiodes layers. Basis-material and atomic number images are created by first applying a material decomposition algorithm followed by filtered backprojection. CT imaging of phantom materials with known elemental composition and density were used for model validation. X-ray scatter levels are measured with a beam-blocking technique and the impact to material accuracy is quantified. The image noise is related to the intensity and spectral characteristics of the X-ray source. For optimal energy separation adequate image noise is required. The system must be optimized to deliver the appropriate high mA at both energies. The dual kVp method supports the opportunity to separately engineer the photon flux at low and high kvp. As a result, an optimized system can achieve superior material specificity in a system with limited acquisition time or dose. In contrast, the dual-layer and sequential acquisition modes rely on a material absorption mechanism that yields weaker energy separation and lower overall performance.

Citation Download Citation

J. Eric Tkaczyk, Rogerio Rodrigues, Jeffery Shaw, Jonathan Short, Yanfeng Du, Xiaoye Wu, Deborah Walter, William Leue, Daniel Harrison, and Peter Edic "Atomic number resolution for three spectral CT imaging systems", Proc. SPIE 6510, Medical Imaging 2007: Physics of Medical Imaging, 651009 (16 March 2007); https://doi.org/10.1117/12.709905

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