Low-dose CT is a diagnostic modality that does not change other scanning parameters and reduces the radiation dose by technical means, which can be applied to lung cancer screening and so on. At present, low-dose CT can ensure the image quality as much as possible, and the means to realize the radiation dose reduction mainly include lowering the tube voltage, increasing the pitch, and choosing the CT image reconstruction algorithm. The image quality obtained by low-dose CT can fully meet the requirements of clinical diagnosis in the diagnosis and treatment of some diseases, and to a certain extent, it can make the lesion display more visual and largely reduce the radiation dose received by the examinee. Low-dose CT can be used for screening of lung cancer, review of cranial and cerebral neoplastic diseases, and so on. If there is any discomfort, it is recommended to seek prompt medical attention for diagnosis and treatment.