Generally speaking, it is safe to have a CT examination every six months. However, if it is necessary for the diagnosis of a disease, the number of examinations can be arranged at the discretion of the doctor according to the actual clinical needs. The principle of CT imaging is based on X-ray imaging, which has a certain ionizing effect and can cause radiation damage. However, the radiation dose of CT examination is very low, far below the dose threshold for causing damage, basically once in a while to do CT will not cause damage to the human body, for adults, once in a while the radiation dose of CT is generally negligible. Therefore, there is no need to worry too much about the damage caused by the radiation dose of CT. In clinical practice, the benefits brought by CT examination to patients are much higher than the damage caused by the radiation dose.