Men can prepare for pregnancy 3 months after chest CT. CT examination belongs to the examination with radiation, it is X-ray tomography, which has certain ray damage to human cells, and may affect the function of testicular spermatogenic epithelium, resulting in malformation of male semen or weak sperm, dead sperm, etc., which is not conducive to eugenics. The process of sperm formation, development, maturation in the epididymis and storage in the epididymis and vas deferens in men takes about 3 months, so it is usually better to wait until 3 months after the examination to prepare for pregnancy, which is conducive to eugenics. After the chest CT examination need to delay the preparation for pregnancy, during this period of time to do a good job of pre-pregnancy examination, to avoid re-exposure to radioactive examination, women should supplement folic acid and so on.