Having 12 CTs in a month is more harmful to the body. CT is a scanning of the human body level with X-ray beams, which carries a certain amount of radiation. Frequent CT is also subjected to a higher amount of radiation, which may be more harmful to the body’s blood system, reproductive system or thyroid gland. Frequent CT may affect the blood system, leading to a drop in white blood cells, which reduces one’s immunity and makes one susceptible to various infectious diseases, as well as abnormalities in the quantity and quality of blood cells; the reproductive system is highly sensitive to radiation, which may cause abnormalities in reproduction, leading to infertility or teratology, etc. In addition, there is also the possibility of affecting the function of the thyroid gland. In general, 2 to 3 times a year for adults to do enhanced CT usually does not cause great harm to the human body. It is recommended that the examination be conducted under the guidance of a doctor.