Future prospects of spectral CT: Photon counting

Abstract

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.