DR examination and CT examination are two different examination methods, both are scanned and imaged by X-rays, both have radiation. For example, the radiation dose of an ordinary chest DR film is 0.02mSv, while the radiation dose of a chest CT is 8mSv, so it is obvious that the radiation dose of CT is higher than that of DR. In addition, CT can show the lesion from different angles through 3D reconstruction, while DR can not.