X-ray medical imaging. X-ray detectors.

Unlike sources, X-ray detectors have evolved significantly since the 1980s, following the path taken by digital photography with a decade's delay: time enough for manufacturers to find an economically viable technological solution to the problem of the large size of these detectors – up to 43 × 43 cm. Since around 2000, it has become clear that the future belongs to flat digital detectors, which today use a glass slab supporting amorphous silicon electronics, the same technology used in televisions and PC screens. The LCD screen industry has made this technology available for professional applications, and since around 2010, flat-panel digital detectors have ceased to be confined to high-end equipment, and are gradually making their mark on all X-ray modalities.

This article takes a look at the technologies used to produce detectors. The first section explains how the materials (photoconductors and scintillators) that transform X-rays into a signal readable by an electronic device (an electrical charge or a light signal) work: a key factor in detector performance is the performance of these materials. The reader will then be introduced to the operating principle of the detectors themselves, classified into major families whose main characteristics are described, along with a few orders of magnitude of the performance available. Older technologies such as photographic film, still in use today and used by many practising radiologists, will not be overlooked, but –and – will also cover all other techniques, ending with the most recent, flat digital detectors.