Photon-counting detector CT: technology overview and radiation dose reduction

Photon-counting detector CT (PCD-CT) represents a transformative advancement in CT technology, overcoming limitations of conventional energy-integrating detector (EID) based systems. It uses semiconductor materials such as cadmium telluride, cadmium zinc telluride, and silicon to directly count X-ray photons while resolving their energy levels. This energy-resolving capability ensures equal weighting of low- and high-energy photons, eliminates electronic noise, and enables material-specific imaging. The absence of physical septa in the detector-used in EIDs to prevent light photon cross-talk-results in smaller effective detector pixels in PCD-CT, enhancing detection efficiency and spatial resolution. These innovations collectively enhance diagnostic accuracy while enabling significant radiation dose reduction. This article provides a comprehensive overview of PCD-CT technology, comparing it with EID-based systems. It highlights key advantages such as superior spatial and contrast resolution, spectral imaging, and noise reduction. Additionally, the review discusses PCD-CT's radiation dose reduction across cardiovascular, thoracic, abdominal, musculoskeletal, neuroimaging, and paediatric applications. Despite its promise, PCD-CT faces challenges, including non-ideal detector performance, increased electronic complexity, and calibration requirements to maintain accuracy. Addressing these issues will be crucial for widespread clinical adoption. As research progresses and technology improves, PCD-CT is expected to reshape clinical practice by integrating high diagnostic accuracy with improved radiation efficiency.