The recent introduction of nuclear active materials and their rapidly expanding use in scientific and technical fields have revived and sharpened interest in the pathogenic properties of all types of short-wave-length photon energy. While much work has been done on exposures and safe practices in the use of nuclear reactive materials, very little definite recent information exists on the danger to technicians and roentgenologic personnel from exposures to x-rays in normal diagnostic studies. Motivated by this lack of knowledge and by the new developments and renewed interest in the hazards associated with roentgenologic procedures, the Division of Industrial Health of the Michigan Department of Health made a study of the operation of fluoroscopic and roentgenographic installations in the eleven state mental hospitals, in a effort to determine whether personnel were being subjected to hazardous amounts of radiation, and if so, to devise control measures. Mental institutions in Michigan perform practically ...