Final answer:
A flat panel detector in cassette-less digital radiography contains millions of individual detectors known as pixels, which capture x-ray radiation to produce detailed images.
Step-by-step explanation:
Cassette-less digital radiography uses a flat panel detector to capture the x-ray image, which is made up of numerous individual detectors known as pixels. These detectors work similarly to those found in charge-coupled devices (CCDs), commonly seen in digital cameras and video camcorders. Each pixel on a flat panel detector corresponds to a tiny detector that captures photons of the x-ray radiation and converts them into a stream of electrons. These electrons are then counted and processed into an image. The exact number of pixels (and therefore individual detectors) can vary based on the resolution of the flat panel detector. Typically, modern detectors can have millions of pixels or megapixels (MPs), enabling the rendering of highly detailed images. X-ray computed tomography (CT) and single-photon-emission computed tomography (SPECT) are examples of advanced imaging techniques that use an array of detectors to produce complex images, including three-dimensional reconstructions.