Speaker
Description
Photon-counting computed tomography (PCCT) has recently emerged as the next-generation CT technology, offering multi-energy and low-dose imaging capabilities that provides significant advantages over conventional energy-integrating detectors. Especially, PCCT using CdTe-based semiconductor detectors has already entered clinical use.
However, several practical limitations remain. For instance, semiconductors are difficult to fabricate in thick layers, which limits detection efficiency for high-energy photons. Moreover, small pixel sizes (typically 0.2–0.4 mm) are required to read out high-count-rate signals in PCCT, due to slow mobility of electron-hole pairs. While CdTe offers excellent energy resolution, such fine spectral resolution is generally not required in material decomposition in current multi-color CT imaging based on 4-6 energy bins.
To address these issues, we propose a novel PCCT system employing a dual-layer scintillator detector. Scintillators can be easily manufactured with variable thicknesses and allow flexible multilayer configurations, providing high detection efficiency across a broad energy range. Our design features a thin front layer optimized for low-energy photon detection and a thicker rear layer for high-energy photons. To overcome the spatial resolution limitations typical of scintillator-based CT (~1 mm), we introduce sub-pixel shifts between the two layers to enhance resolution via super-resolution techniques.
We constructed a prototype dual-layer detector and conducted imaging experiments using contrast agent and resolution phantoms. The results demonstrated improved image quality across a wide energy range and enhanced spatial resolution compared to a single-layer system, validating the concept.
This study highlights the potential of dual-layer scintillator-based PCCT as a practical, low-cost alternative to CdTe-based systems, with performance suitable for advanced spectral and high-resolution PCCT imaging.
