Digital radiographs are one of the newest X-ray techniques around. With digital radiographs, film is replaced with a flat electronic pad or sensor. The X-rays hit the pad the same way they hit the film. But instead of developing the film in a dark room, the image is electronically sent directly to a computer where the image appears on the screen. The image can then be stored on the computer or printed out. One of the great advantages of this process is that radiographs can be digitally compared to previous radiographs in a process called subtraction radiography. The computer can digitally compare the two images, subtract out everything that is the same and give a clear image of anything that is different. This means that tiny changes that may not be noticeable with the naked eye can be caught earlier and more clearly with digital-subtraction radiography. Subtraction radiography requires a specialized projection technique and additional software.