If the diagnosis and treatment of disease needs, CT can be done 5~10 times a year, generally does not have a great impact on health, if it is to enhance the ct is recommended to 2~3 times a year for the degree of special conditions need to weigh the pros and cons of the person. The radiation dose of ct scanning is about 5~10mSv. Generally speaking, it is safe for the human body to receive a radiation dose of 50mSv or less in a year. If CT is needed for diagnosis and treatment of diseases, it will not have much effect on the body if it is done 5~10 times in a year, and if it is for routine medical checkups, 1~2 times of CT in a year will be enough. The radiation dose of enhanced CT is 2~3 times higher than that of plain scanning, so it is recommended not to do enhanced CT more than 3 times in a year. For patients with special conditions, such as tumor patients, may be in a short period of time to carry out frequent CT examination, at this time should be based on their own condition to weigh the pros and cons, in general, even if more than a few times to do CT on the human body is not very harmful, can be evaluated under the guidance of the physician.