Ms. Liu, 50 years old, accompanied her father, who was suffering from lung cancer, to the PLA 306 Hospital. On the recommendation of the doctor, a low-dose spiral CT of the chest was done, and a ground glass nodule of 25px in diameter was found; three months later, the lesion was reexamined, and there was no significant change. While the patient was happy, he had many doubts in his mind, why was he found to have a problem in such a short period of time, and it was cancer! In fact, all this is thanks to the role of low-dose spiral CT screening of the chest. Let’s have a brief understanding of the early diagnosis of lung cancer. Lung cancer is currently the most threatening malignant tumor to human beings. Its mortality rate is the highest among male and female malignant tumors in China. Among all cancer types, lung cancer has the lowest overall 5-year survival rate of 16%-17%; however, if it can be diagnosed in the early stage of the disease, the 5-year survival rate will be significantly increased to 54%. However, only 15% of lung cancer cases are diagnosed in the early stage, and most of the patients are already in the middle or late stage when they are diagnosed because the clinical symptoms of early stage lung cancer are not obvious. In contrast, regular (annual) screening of high-risk groups for lung cancer using low-dose CT is expected to increase the diagnosis rate of early-stage lung cancer, improve the prognosis and treatment outcome of high-risk individuals, and is expected to significantly reduce the number of lung cancer-related deaths. There has been widespread interest from patients, clinicians and academia on how to conduct more effective lung cancer screening in healthy populations. Conventional radiographs and chest CT are the two major screening methods for lung diseases, but conventional radiographs have high leakage rate, especially low detection rate for lesions smaller than 25px, while CT improves the positive rate but its higher radiation dose is daunting. In the early 1990s, Naidich et al. first proposed the concept of low-dose spiral CT (LDCT) of the chest. Due to the high contrast between air and lung lesions, reducing the tube current within a certain range results in a significant decrease in radiation dose, which does not significantly affect the detection and diagnostic accuracy of lung lesions, although it increases noise. A landmark National Lung Cancer Institute sponsored National Lung Cancer Screening Trial (NLST) was conducted at 33 U.S. medical facilities involving more than 53,000 elderly individuals at high risk for lung cancer. Half of the participants were screened with low-dose CT (LDCT) and the other half were screened with chest X-rays. The data showed that low-dose CT (LDCT) screening resulted in a 20% reduction in lung cancer mortality compared to chest X-ray screening. In addition, low-dose CT screening also resulted in a significant 6.7 percent reduction in national mortality. Several leading U.S. medical organizations have issued lung cancer screening guidelines between 2011-2013, recommending LDCT lung cancer screening in high-risk populations. The U.S. Preventive Services Task Force (USPSTF) and the Centers for Medicare and Medicaid Services (CMS) have recommended annual low-dose CT screening for eligible populations, and low-dose CT should be used as a routine lung cancer screening program. In addition, Medicare has approved insurance reimbursement for low-dose CT lung cancer screening in high-risk patients. The “Expert Consensus on Low-Dose Spiral CT Lung Cancer Screening” issued by the Cardiothoracic Group of the Radiology Branch of the Chinese Medical Association in 2015 recommends lung cancer screening in high-risk groups, which defines high-risk groups as: (1) aged 50-75 years; (2) combined with at least one of the following Risk factors: (1) smoking ≥20 packs/year, including former smokers who have quit for less than 15 years; (2) passive smokers; (3) history of occupational exposure (asbestos, beryllium, uranium, radon, etc.); (4) history of malignancy or family history of lung cancer; (5) history of COPD or diffuse lung fibrosis. Lung cancer is not incurable. As long as we can achieve the three catches, namely early (early stage), small (less than 25px) and accurate (accurate diagnosis), the cure of lung cancer is entirely possible. To achieve these, low-dose spiral CT of the chest provides an optimal choice with its low dose, high positive rate and high accuracy, especially for high-risk groups. Let’s change our inner perception of CT: it is not the only way to get CT if you have a disease; low-dose CT screening in special populations can save the lives of many, many high-risk patients.