Future Prospects of Spectral CT: Photon Counting
Dual-energy spectral CT has demonstrated numerous clinical benefits, yet there is potential to further improve the quantity and quality of acquired spectral data. Clinical dual-energy CT scanners are limited to two spectral measurements that overlap in spectral content. Photon-counting detectors use direct-conversion semiconductors, combined with pulse-height analysis electronics, to sort detected photons into energy bins. Photon-counting detectors can acquire more than two spectral measurements simultaneously, while also acquiring a nonspectral CT image. In addition to the spectral acquisition capabilities, photon-counting detectors have the additional benefits of higher spatial resolution and improved dose efficiency, compared to conventional CT detectors. This chapter explains the basic operation of photon-counting detectors and describes the potential benefits of photon-counting CT (PCCT), as well as the challenges of photon-counting technology. Examples are provided demonstrating the improved nonspectral CT images and new material decomposition applications made possible by PCCT.
KeywordsPhoton counting Spectral CT Material decomposition Detector Detective quantum efficiency Contrast-to-noise ratio Charge sharing Pulse pileup
The author thanks David Cormode (University of Pennsylvania), Mats Danielsson (KTH Royal Institute of Technology and Prismatic Sensors), Cynthia McCollough (Mayo Clinic), Salim Si-Mohamed (Hospices Civils de Lyon), and Yoad Yagil (Philips Healthcare) for sharing images and information for this chapter.
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