The magnitude of radiation dose is always a matter of relativity. Generally speaking the radiation dose for oral related imaging is relatively small. A general oral panoramic film, also known as an oral surface tomogram, has a radiation dose of about 22 microsieverts. If compared with small dental films, the radiation dose is definitely higher. Because the radiation amount of general small dental film is only 1 microsievert, one oral panoramic film is equivalent to 22 small dental films, of course, oral panoramic film is also much larger than small dental films. However, if we compare the oral panoramic film with CBCT, which is often done in dentistry, it is about the same as CT film. The oral panoramic film is about one half of the CT film, and the radiation amount of one oral CBCT is about 50 microsieverts. However, there is a big difference between the CBCT of dentistry and the large spiral CT which is commonly done, and a large spiral CT is 40 times more radiation than the CBCT of dentistry. From this point of view, the oral panoramic film is equivalent to one eightieth of the radiation dose of large CT.