About the radiation problem of CT examination, it is a recent concern and a more professional issue, the following is some knowledge about ionizing radiation, I hope it will help you. 1, radiological examination, including dilation X-ray, CT, PET-CT is ionizing radiation, the dose varies depending on the examination site and method, some examination equipment will indicate the total dose of the examination. 2.The main sensitive organs of ionizing radiation are gonads, hematopoietic system, thyroid, vitreous, etc. The degree of sensitivity varies from person to person, and pregnant women and children are relatively sensitive. 3, normal adults receive the total dose of ionizing radiation has an upper limit, this includes the earth’s background radiation, so we should try to stay away from radiation sources to avoid unnecessary damage. But in life, radiation is everywhere, soil, burning cigarette butts, etc. have radiation, we are receiving radiation all the time, but the dose is very small. 4, for patients, now the mainstream understanding is – patients are not subject to radiation dose limits. Of course, we need to try to avoid unnecessary repeat examinations. After all, early diagnosis and early treatment is the primary way to deal with the disease, which has an important impact on the regression of the disease, so the examination that helps in the diagnosis of the disease is necessary, unless there are clear contraindications. 5.Commonly used radiological examinations are safe and the radiation is within a controlled range. X-ray examinations have a history of more than 100 years and no clear reports of radiation-related diseases in patients due to single radiological examinations have been seen so far. Radiation-related diseases mainly occur among radiation workers and are legal occupational diseases. 6, the rapid development of modern imaging equipment, examination speed is becoming faster and faster, image quality is becoming clearer and clearer, providing more and more help to clinical diagnosis, especially CT, rapid development, has become a routine clinical examination methods for a variety of diseases. 7, the direction of equipment development: improve image clarity, reduce radiation dose.