The main hazards of CT are ionizing radiation and the side effects of iodine. Generally follow the doctor’s instructions, under normal circumstances to do CT examination, usually will not cause harm to the human body. 1. When patients are exposed to CT radiation for a long time, the ionizing radiation produced by X-rays can destroy the molecular structure of a part of the human body, damage the cells in the human body and cause harm to the human body. However, the radiation dose of ct examination is within the safe range, generally will not cause great harm to the human body. 2. When patients need to do enhanced CT, iodine contrast agent needs to be injected, and some patients may have allergic reactions. However, usually drink more water, the iodine agent is discharged with urine within a day, and the adverse reaction will disappear.