CT scans the whole body in a single fine scan in just a few seconds, and through post-processing, the scanned images and lesions can be visualized in three dimensions. It can be used for early diagnosis of tumor and follow-up examination of efficacy after treatment, acute diagnosis of cerebral hemorrhage, examination of systemic vascular lesions such as vascular disease, forecasting and detection of various cardiovascular and myocardial diseases such as cardiac coronary arteriosclerosis, analysis of systemic vascular stenosis, pre-stent placement planning and post-placement evaluation, thus bringing CT clinical application to a new level. For patients with clinically suspected cerebral infarction, cerebral perfusion imaging with contrast injection can lead to a clear diagnosis within one hour, allowing patients to receive timely treatment and reduce sequelae. Aneurysm rupture is the main factor of subarachnoid hemorrhage, and the condition is dangerous and often life-threatening. With the application of multilayer spiral CT, it is possible to observe the lesioned vessels and intracavity from multiple angles without intubation and fast scanning speed, and it can show aneurysms of about 3 mm in diameter with the use of post-processing technology, and it is also effective in examining cerebrovascular malformations. The laryngeal anatomy can be better displayed with the post-processing technology, and the results can be similar for patients who are not convenient for laryngoscopy, which can bring convenience to clinicians and patients. It also provides a better view of the middle ear structure and the orbital area. Dental software provides the best basis for orthodontics. The use of CT has greatly improved the early diagnosis of small lung cancer. It can detect lesions of several millimeters, and for patients who cannot be bronchoscopically performed, the trachea and bronchi can be better displayed using simulated endoscopic techniques, and it is painless and can be done in ten seconds or less. The detection rate of microscopic hepatocellular carcinoma is significantly improved by the use of thin-layer and three-stage scanning. The detection of small lesions in the pancreas and kidney is significantly improved. In addition, simulated endoscopy of the stomach and colon has expanded the value of CT in the field of gastrointestinal tract. Coronary angiography can be done in a few seconds or more than ten seconds by injecting contrast into the vein. It can show whether there is calcification or stenosis in the coronary arteries, evaluate the ischemia of the myocardium after stenting or bypass surgery, and the thickening of the myocardium in myocarditis, and clearly show the location of the rupture of the entrapped aneurysm. Post-processing can show microfractures, soft tissue contusions, fracture fragments in relation to the surrounding area, arbitrary spine angles, burst fractures, circumferential fractures, and bone tumors better than ordinary CT. In addition, CT bone densitometry can evaluate bone calcification at all ages to reflect the nutritional status of the subject and the degree of physical aging.