CT technology has been developed for more than 30 years since its birth, from the earliest non-spiral CT to single-layer and multi-layer spiral CT, to today’s 64-row 64-layer spiral CT, which realizes the true sense of volume data acquisition, i.e. volume CT or VCT. This technology has created a brand new field in non-invasive diagnostic imaging, and has become one of the indispensable examination means. Spiral CT breaks through the traditional CT design by using slip-ring technology, which connects the power cable and some signal lines to different metal rings in the fixed frame. The tube and detector are not limited by the length of the cable and rotate continuously and uniformly along the long axis of the body, and the scanning bed is synchronized with uniform progression (the traditional CT scanning bed is stationary during scanning), and the scanning trajectory is spiral forward, which can complete volume scanning quickly and without interruption. Spiral CT can be named as how many rows of CT or how many layers of CT due to the number of detectors and data acquisition systems, multiple “rows” refers to the arrangement of multiple detectors in the longitudinal axis; multiple “layers” refers to the combination of detectors in the longitudinal axis including how many data acquisition systems ( DAS). Instead of just depending on how many rows of detectors are in the longitudinal axis, how many DASs determine how many consecutive layers of images can be obtained for each week of rotation. For example, Toshiba’s 4-layer CT has 34 rows of detectors, but only four DASs. So it can only be called 4 “layers”. Compared with the previous multi-layer spiral CT, LightSpeed VCT (64-layer spiral CT) has the following technical features: First, the longitudinal axis coverage based on high spatial resolution (sub-millimeter) is greatly increased, and 64 layers of sub-millimeter layer thickness can be acquired at the same time, and the maximum coverage of one week of rotation is nearly 40 mm; VCT thin layer scanning achieves true volumetric data VCT thin-layer scanning enables true volumetric data acquisition, isotropic image resolution, and image reconstruction in any plane such as cross-sectional, sagittal, coronal, etc. We can perform multi-planar imaging (MPR) on the acquired images, which means we only need to scan once. Multiple directions are adjusted to obtain arbitrary cross-sectional images, allowing us to better understand the details of the lesion and spatial anatomical relationships. Second, the unprecedented improvement in time resolution, weekly rotation can be shortened to 0.33 S. Acquisition of the same volume of data, the scan time is greatly reduced, a breath-holding 20 s, you can complete the body scan; scan unit time coverage is significantly improved, the patient receives a significant reduction in radiation dose; the shortening of the scan time makes the amount of contrast agent significantly reduced in the enhancement scan. The contrast agent that maintains a certain pressure has to be injected until the scan is completed to ensure the enhancement effect. For example, CT aortic imaging, even with a 4-layer CT, requires a scan of about 60 s. A 2 ml/s injection rate requires at least 120 ml of contrast. A 64-layer CT requires at most 20 s. The same injection rate. Only about 6O ml (including delay time) of contrast agent is needed to achieve the same effect. Third, the imaging software has been improved, and the acquired data can be used for both conventional image display and post-processing in the workstation to complete 3D stereo reconstruction, multi-level reconstruction, organ surface reconstruction, etc. It can be displayed in real time or near real time, and by adjusting the reconstruction threshold, soft tissue and bony structures can be displayed layer by layer, especially for the display of 3D structures of the head, maxillofacial region, spine, bone and joint, etc. It is especially suitable for the display of three-dimensional structures of the head, maxillofacial region, spine, bone and joint, etc., and can obtain more detailed three-dimensional images. In addition, due to the isotropic resolution of VCT, it can obtain the internal structure information of the lumen similar to endoscopy while obtaining the results of conventional cross-sectional images, which is suitable for the display of the lumen structure of paranasal sinus, tracheobronchus, gastrointestinal tract and blood vessels. LightSpeed VCT (64-layer spiral CT) technical breakthroughs have brought about breakthroughs in clinical applications, mainly in the following areas: 1. Cardiovascular examination Compared with previous spiral CT, 64-layer spiral CT has obvious advantages in the diagnosis of cardiac coronary artery disease. The machine can clearly show the presence or absence of atherosclerotic plaque, the size and shape of the plaque, the presence or absence of stenosis and the degree of stenosis in the coronary arteries, which can be used for the screening of coronary heart disease and the examination of patients with coronary heart disease before and after treatment or before and after surgery. VCT can show the structure of coronary arteries, heart chambers and valves at the level of electron beam CT, and can perform myocardial perfusion, myocardial stress perfusion, myocardial blood flow storage determination and other cardiac function examinations. It is capable of evaluating coronary artery disease, myocardial survival after myocardial infarction, and cardiac function, and can clearly diagnose most congenital heart diseases (including infants and children). Comparison with previous invasive cardiovascular angiography. In the angiographic examination of pulmonary arteries and peripheral vessels such as carotid arteries, abdominal arteries, limb arteries and their corresponding veins, a large range of vessels can be shown with a single injection of contrast agent, which reduces the amount of contrast agent injected and the dose of radiation, overcomes the anterior and posterior overlap of structures during invasive angiography, and clearly shows the lesion and its relationship with the surrounding tissues, and provides detailed morphology of large and small vessels before and after surgery, organ transplantation and vascular transplantation. It provides detailed information on the morphology of small, medium and large blood vessels and their anatomical relationships, helping doctors to fully understand the situation of the organs surrounding the lesion, reducing surgical bleeding and risks, and avoiding damage to the surrounding important organs. 2.In emergency medicine Ultra-fast high-resolution wide-area scan makes it possible to complete CT examination of any part or the whole body in a short time even in severe trauma and other serious cases (such as aortic coarctation) or less cooperative patients (such as stroke), with few respiratory and motion artifacts, clear images and lesions not easily missed. 3, in the evaluation of organ physiological function CT perfusion scanning technology can truly reflect the blood perfusion situation of the tissue. For stroke, brain tumor and other diseases, 64-layer spiral CT can realize simultaneous acquisition of CT angiography (CTA) and perfusion scan data. A single injection of contrast agent can acquire pure arterial phase images, dynamic CT angiography images, and at the same time, it can complete tissue perfusion examination, which facilitates the scanning of a single organ in one second, and also enables 64-layer spiral CT to perform functional perfusion imaging of organs, assess changes in microvascular perfusion of organs as a whole, and understand the blood supply of lesion sites, so as to achieve a comprehensive analysis and diagnosis of parenchymal organs and their diseases. 4.VCT is applied to health checkup 64-layer spiral CT can be used for coronary CT imaging to show whether there is atherosclerotic plaque in coronary artery and its involvement range, whether there is stenosis in coronary artery and its degree of stenosis, which can be used for screening of coronary heart disease and early intervention of coronary heart disease. Low-dose (20-30mA) scanning of the chest can obtain images of the same quality as conventional high mA conditions, allowing for cross-sectional, coronal sagittal and arbitrary planar and three-dimensional reconstruction as needed, enabling early detection and diagnosis of lung tumors, and reducing X-ray radiation. In general, the performance and function of 64-layer spiral CT is definitely superior to ordinary CT, but the higher examination price also makes many patients afraid, according to our experience, most of the examinations, ordinary CT is able to achieve, only some of the special examinations need to use 64-layer spiral CT. hope for domestic physicians and patients to select 64-layer spiral CT examination purposefully, so that it is in line with radiation protection It is hoped that the selection of 64-layer spiral CT for domestic physicians and patients can be made in a purposeful manner so that it is consistent with radiation protection and health economics.