Photon-counting CT (PCCT) is a frontline spectral CT modality using photon-counting detectors (PCDs). Unlike conventional detectors, PCDs possess energy-discriminating capabilities, enabling numerous clinical advantages. However, they do present many challenges, such as spectral distortion (charge sharing and pulse pileup), high pixel-to-pixel variations, and so on, and have considerable room to be improved further.

Dual-energy x-ray scans enable the extraction of density line integrals with respect to two basis material from an imaged object. This process is known as material decomposition and significantly enhances material discrimination and material-specific quantitative assessment compared to conventional single-energy x-ray imaging. As dual-energy x-ray imaging systems have been widely adopted across various clinical and industrial fields, research interest and demand continue to grow.