An X-ray, or general radiology, is a painless, non-invasive procedure that creates images of a patient's internal organs or bones to aid in diagnosis and treatment...
X-rays are a form of electromagnetic radiation, similar to visible light. Unlike light, however, x-rays have higher energy and can pass through most objects, including the body. Medical x-rays are used to generate images of tissues and structures inside the body. If x-rays traveling through the body also pass through an x-ray detector on the other side of the patient, an image will be formed that represents the "shadows" formed by the objects inside the body.
There are three common mechanisms for the production of X-rays: the acceleration of a charged particle, atomic transitions between discrete energy levels, and the radioactive decay of some atomic nuclei. Each mechanism leads to a characteristic spectrum of X-ray radiation.
Photographic film was used by Röntgen as one of the first X-ray detectors, and this simple technique remains in wide use in medical applications. The process of exposure is initiated by X-ray photons ionizing radiation-sensitive silver halide crystals in an emulsion on the film surface.