A radiographic system comprising an X-ray source disposed to direct an X-ray beam through an adjustable shutter aperture in an aligned collimator and onto an image receptor in a holder located at a preselected distance from the source; and automatic means for preventing an X-ray exposure until prescribed operating conditions have been satisfied, the automatic means including read-only-memory means for storing the prescribed conditions therein and ascertaining whether or not the prescribed conditions have been met.
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