Photon-counting CT scan. Coloured photon-counting computed tomography (CT) scan of a section through the abdomen of a research subject. Photon-counting CT scanners are a new generation of CT scanner that use a photon-counting detector (PCD), which registers the interactions of individual photons with the body's tissues. The prototype technology is expected to replicate the image quality of conventional CT scanning, but may also provide health care specialists with an enhanced look inside the body through multi-energy imaging. Radiotherapy patients could receive a minimum amount of radiation, while the maximal amount of information needed would be delivered to health care providers.