Photon-counting detector computed tomography (PCD-CT) is an emerging technology that offers several advantages over conventional energy-integrating detector CT, including improved spatial resolution, reduced image noise, and intrinsic spectral capabilities. This chapter reviews the current and potential clinical applications of PCD-CT in adult and pediatric oncology. Key areas where PCD-CT shows promise include improved lesion detection and characterization, reduced radiation dose, enhanced tumor staging, and quantitative assessment of treatment response. In pancreatic cancer imaging, PCD-CT enables superior delineation of tumor margins and vascular involvement, facilitating more accurate staging and surgical planning. The improved contrast resolution of PCD-CT also enhances the visibility of neuroendocrine tumors, potentially leading to earlier detection and better characterization of these lesions. For musculoskeletal oncology, PCD-CT offers exquisite detail in evaluating bone lesions, with particular benefits in multiple myeloma imaging. The technology’s ability to better visualize trabecular bone structure may allow for earlier detection of marrow infiltration and more precise assessment of lytic lesions. In head and neck oncology, PCD-CT significantly reduces dental metallic artifacts, improving the evaluation of oral cavity and oropharyngeal tumors. This reduction in artifacts, combined with the enhanced spatial resolution, allows for more accurate assessment of tumor extent and invasion of adjacent structures. Specific applications in thoracic and abdominal oncology are also discussed, including improved lung nodule detection and liver lesion characterization. In pediatric oncology, PCD-CT’s dose reduction capabilities and enhanced image quality offer particular advantages for frequent follow-up imaging. While further research is needed, initial clinical studies demonstrate that PCD-CT has the potential to significantly impact cancer imaging across multiple organ systems and improve patient care through more accurate diagnosis, staging, and treatment monitoring.