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Proceedings Paper

Attenuation and image noise level based online z-axis tube current modulation for CT scans independent with localizer radiograph: simulation study and results
Author(s): Yi Tian; Mahao Chen; Jun Kong
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Paper Abstract

With the online z-axis tube current modulation (OZTCM) technique proposed by this work, full automatic exposure control (AEC) for CT systems could be realized with online feedback not only for angular tube current modulation (TCM) but also for z-axis TCM either. Then the localizer radiograph was not required for TCM any more. OZTCM could be implemented with 2 schemes as attenuation based μ-OZTCM and image noise level based μ-OZTCM. Respectively the maximum attenuation of projection readings and standard deviation of reconstructed images can be used to modulate the tube current level in z-axis adaptively for each half (180 degree) or full (360 degree) rotation. Simulation results showed that OZTCM achieved better noise level than constant tube current scan case by using same total dose in mAs. The OZTCM can provide optimized base tube current level for angular TCM to realize an effective auto exposure control when localizer radiograph is not available or need to be skipped for simplified scan protocol in case of emergency procedure or children scan, etc.

Paper Details

Date Published: 13 March 2009
PDF: 9 pages
Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 72582U (13 March 2009); doi: 10.1117/12.811640
Show Author Affiliations
Yi Tian, Siemens Shanghai Medical Equipment Ltd. (China)
Mahao Chen, Siemens Shanghai Medical Equipment Ltd. (China)
Jun Kong, Siemens Shanghai Medical Equipment Ltd. (China)


Published in SPIE Proceedings Vol. 7258:
Medical Imaging 2009: Physics of Medical Imaging
Ehsan Samei; Jiang Hsieh, Editor(s)

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