Abstract: An X-ray detection device for providing an output signal the value of which can be used to determine the radiation received at a selected region of an object, such as a patient, comprising a transmitter for being energized by X-rays, said transmitter producing radiation of a wavelength different from that of said X-rays, said transmitter aligned with X-ray film to be exposed, and wherein said transmitter is of substantially the same cross-sectional area of said X-ray film, a detector for detecting said radiation wherein said detector is substantially transparent to incident X-ray radiation, and a sensor connected to said detector, said sensor generating an output signal related to said radiation, the value of said output signal which can be used to determine the x-ray radiation received at said transmitter to provide X-ray exposure output readings at one or more selected locations of a patient's body.