18 March 2015 Energy calibration of photon counting detectors using x-ray tube potential as a reference for material decomposition applications
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Abstract
Photon counting spectral detectors (PCSD) with smaller pixels and efficient sensors are desirable in applications like material decomposition and phase contrast x-ray imaging where discrimination of small signals and fine structure may be desired. Charge sharing in PCSD increases with decreasing pixel sizes and increasing sensor thickness such that the energy calibration or utility of spectral information can become a major hurdle. Utility of a combination of high Z sensors and small pixel sizes in PCSD is limited without efficient threshold calibration and charge sharing mitigation. Here we explore the utility of x-ray tube kVp as a reference to achieve efficient and fast calibration of PCSDs. This calibration method itself does not require rearranging the imaging setup and is not impacted by charge sharing. Our preliminary results indicate that this method can be useful even in scenarios where metal fluorescence and radioactive source based calibration techniques may be practically impossible. Our results are validated using x-ray fluorescence based calibration for a Silicon detector with moderate charge sharing. Calibration of a particularly challenging case of a Medipix2 detector (55 μm pixel size) with a 1 mm thick CdTe sensor and a Medipix3 detector with CdTe sensor is also demonstrated. A cross validation with K-edge identification of Gd is also presented here.
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Mini Das, Bigyan Kandel, Chan Soo Park, Zhihua Liang, "Energy calibration of photon counting detectors using x-ray tube potential as a reference for material decomposition applications", Proc. SPIE 9412, Medical Imaging 2015: Physics of Medical Imaging, 941214 (18 March 2015); doi: 10.1117/12.2082979; https://doi.org/10.1117/12.2082979
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