Photon-counting detector computed tomography (PCD-CT) is an innovative technology in X-ray CT, providing direct photon detection and inherent spectral differentiation superior to traditional energy-integrating detectors (EIDs). A review and analytical evaluation examined 30 clinical and scientific CT data sets and 100 peer-reviewed articles (2010–2025) to analyze the effects of PCD-CT on image quality, optimization of radiation dose, and diagnostic performance. Technological advancements such as high atomic number semiconductors (CdTe, CZT), sub-millimetre pixel design, and charge-sharing correction were demonstrated to improve 10–20% spatial resolution and contrast-to-noise ratio (CNR) by 15–25% compared with EID-CT. Capabilities in differentiating between photon energies enabled multi-energy reconstructions like monoenergetic imaging and material decomposition without the need for extra dual-energy hardware, dramatically enhancing lesion conspicuity in cardiovascular, thoracic, and musculoskeletal imaging. Radiation dose analyses yielded 20–35% decreases with maintained or enhanced image quality via energy weighting and low-keV iodine optimization for improved patient safety. Technical limitations remained, including pulse pileup, charge sharing, and incomplete charge collection, despite these benefits, requiring more sophisticated calibration, detector cooling, and complex reconstruction algorithms to retain spectral fidelity and quantitative accuracy. Together, the results confirm that PCD-CT provides synergistic advantages of improved spatial resolution, enhanced spectral imaging, and maximum dose efficiency, a milestone toward more accurate and safer diagnostic imaging. Ongoing studies in system optimization and artifact removal are still critical to achieve the complete clinical value of this next-generation CT technology.