Limits on increasing the sensitivity of x-ray diagnostic screens

The irradiation dose for patients is proportional to that necessary to receive sufficiently informative image. The minimum value of this dose for different examination methods (roentgenography, photoroentgenography and roentgenoscopy) is evaluated by comparing the quantum fluctuation level with the visual "noise" and other components of the threshold contrast. The role of these components balance and the optimization of conditions and hardware for X-ray examination have been discussed.