(also fluoroscopy), the roentgenologic examination of an object during which the X-ray picture of the object appears on a fluorescent screen; a principal method of roentgen diagnosis. Roentgenoscopy is usually performed in a darkened room after dark adaptation. In X-ray television transillumination, the picture is intensified by an electron-optical transducer and transmitted to a television screen.

Often combined with roentgenography, roentgenoscopy is easy to perform and can be used to examine an individual in different positions and to observe the functioning and movement of organs. Small details of a picture are harder to discern in roentgenoscopy than in roentgenography, and no permanent record, such as a photograph or curve, remains that can be reexamined to study the progression of a disease. X-ray television transillumination with a video tape recording is considered to be the optimum examination method.