Pulmonary embolism (PE) is a clinical and pathological syndrome in which endogenous or exogenous emboli embolize the pulmonary arteries and cause pulmonary circulation disorders, of which thromboembolism accounts for 85%. Most patients with pulmonary embolism lack specificity in clinical symptoms and signs, especially in elderly patients, and are very easy to be misdiagnosed or missed clinically because they are often associated with other cardiopulmonary vascular disorders. The diagnosis of this disease mainly relies on imaging examination. In recent years, with the rapid development of CT technology, CT pulmonary angiography (CTPA) has gradually become the first choice for clinical diagnosis of pulmonary vascular disease, and has almost replaced traditional pulmonary angiography as the “gold standard” for the diagnosis of pulmonary embolism. On the other hand, in clinical emergencies and elderly patients, dyspnea and right heart insufficiency due to pulmonary embolism, especially in elderly patients with chronic pulmonary diseases, cannot meet the 7-9s breath-holding time during CTPA examination, which greatly reduces the quality of CTPA imaging and directly affects the clinical diagnosis or even can only abandon the examination. 320-layer CT has an ultra-wide detector, a high spatial resolution of 0.5 mm, and a high spatial resolution of 0.5 mm. With a high spatial resolution of 0.5mm and a high temporal resolution of 175ms, the Z-axis of a single volume scan can reach 160mm, which can completely include the pulmonary artery branches within 5 levels and complete all scans in 1s, making it unique in pulmonary artery imaging. Applying the advantages of 320-layer CT ultra-wide detector, the feasibility and clinical application value of 320-layer CT single-volume pulmonary artery imaging were investigated for the characteristics of pulmonary embolism in elderly patients. The results showed that: 1. 320-layer CT single-volume scanning mode, the scanning time is only 1s, and all breath-holding time is only 2s, even without strict breath-holding, to complete the examination and obtain satisfactory images. This scanning mode meets the requirements of clinical examination for patients with breath-holding difficulties, and at the same time, for patients with rapid heart rate, there is no need to increase the amount of contrast agent. Therefore, there is almost no contraindication to this examination for patients with non-iodine contrast allergy. 2.The Z-axis field of view of the 320-layer CT volume scan is 160mm, and there is no need to move the scanning bed during the scanning process, and the imaging delay time does not need to consider the difference between the scanning time and the peak time of contrast agent. This makes it easier for the operator to grasp and control the contrast concentration in the pulmonary artery, thus obtaining high quality images and eliminating various hidden dangers that cause scan failure. 3.Low dosage of contrast agent. The application of high dose contrast agent can obtain high quality images, but it is easy to induce contrast nephropathy. Therefore, it is clinically important to reduce the amount of iodine contrast agent. 320-layer CT single volume scanning mode requires only 45 ml of contrast agent throughout, even in patients with rapid heart rate, the total amount of contrast agent is only 50 ml, which has the incomparable advantage of traditional CTPA. 4.Small dose of radiation. The effective radiation dose for a single examination is only 3mSv, which is significantly lower than the radiation dose of conventional CTPA scan. In conclusion, the application of 320-layer CT single-volume pulmonary artery imaging can accurately display the pulmonary artery segment and the pulmonary vessels above the segment, providing accurate imaging data for the diagnosis of clinical pulmonary embolism. In addition, the advantages of high speed, large range, low contrast dose and low radiation damage of this method are more suitable for patients with acute and elderly combined cardiopulmonary diseases, which can help the early diagnosis of clinical pulmonary embolism.