CT is also called computed tomography, and there is no clear requirement as to how often it can be done a second time. According to the needs of the condition, the next day can be examined, routine physical examination can generally be done once in one to two years or so. If you do the same location of the examination, the recent need for a second computerized tomography examination to help diagnose the condition, such as brain hemorrhage patients with changes in the condition of the next day can be examined. If it is a routine physical examination and nothing is found during the first computed tomography scan, it can be done once a year or two years. In cases where there is a tumor or other space-occupying lesion, a review can usually be done once every three to six months. The number of times a computed tomography scan is done also depends on the patient’s own tumor condition such as the size of the tumor and other factors to determine the examination interval. Computed tomography scan belongs to X-ray examination, generally the ionizing radiation of computed tomography scan will cause certain impact on human body, because it is based on the number of times of irradiation per year to assess the degree of radiation hazard, so occasionally do it once on human body is not much, patients do not need to worry too much. Computed tomography scanning how often can be done the second time must follow the doctor’s instructions, not to decide on their own, so as not to be too frequent to do the examination and affect the health of the body.