Answer and Explanation:
FFD is the distance between the film on which the image is obtained and the center of the anode tube. The magnification and resolution of the image depends on the FFd By varying the FFD we can change the magnification and resolution of the image. The standard FFD is about 100 centimeters.
New studies have found that by changing the FFD to 130 cm the radiation dosage reduces while the image quality remains practically the same.