What are the advantages of CT?

In the long-term use, people have also found some shortcomings of X-ray diagnosis technology, such as projecting human organs and tissues into a plane image, which makes all structures overlap, and the needed and unnecessary information are displayed together, which makes some needed information unclear. In addition, the lesions of human tissues with relatively small density are not easy to display. Scientists have made unremitting efforts to overcome the shortcomings of X-ray diagnosis. 1964, American nuclear physicist Colemark accidentally broke into the field of medical x-rays. He considered the reduction of X-rays in vivo and in vitro, put forward the possibility of measuring internal structure from many different angles with X-rays, and made experimental research with models made of wood and metal. 197 1 year, according to Colemark's idea, British scientist Hausfield successfully designed a new diagnostic machine, named "X-ray computed tomography camera". Because the English full name of this diagnostic machine is too long, people usually call it CT for short. The CT machine still uses the characteristics of X-rays. When X-ray beams are irradiated at multiple levels along selected parts of the body from multiple aspects, after X-rays enter and pass through the human body, some of them are absorbed and then received by the detector. The intensity of the received rays is related to the tissue density of the human body. After the detector obtains the information, it has to go through complicated calculation, because the data is about 300,000 ~1.5,000 groups, which cannot be calculated by manpower, and can only be solved by electronic computer. The computer transmits a plurality of processed pixels to the TV display device, so that the picture of the lesion can be displayed on the computer screen and the picture of the lesion can be automatically taken. CT has changed the traditional way of image acquisition and storage, and because the images displayed by CT scanning are generally cross-sectional, there is no shortcoming of overlapping before and after ordinary X-ray imaging. In addition, with the help of computer, CT has a high density resolution of human tissues, which can not only distinguish tissues with large density differences such as bones, soft tissues, water and fat, but also distinguish those tissues with small density differences, such as liver, spleen and stomach, which belong to soft tissues. Its resolution is 100 times higher than that of ordinary X-ray photos. CT is especially welcomed by doctors, because its function of identifying normal structures and abnormal pathological tissues according to different densities far exceeds that of ordinary X-ray examination. Therefore, at present, CT is often used in clinical diagnosis of diseases of brain, facial features, lung, liver, gallbladder, pancreas, spleen, kidney, bladder, uterus, ovary and prostate. For example, the pancreas is the most difficult organ in clinical and X-ray diagnosis. Although selective arteriography and fiber-optic duodenoscopy retrograde cholangiopancreatography have certain effects on the diagnosis of pancreatic lesions, these angiography are complicated, not every case can be successful, and they will also bring pain to patients. CT examination can directly see the whole picture of the pancreas. It is sometimes difficult to distinguish pancreatic cancer from chronic pancreatitis in clinical examination, and CT scanning can make some cases accurately diagnosed. At present, the accuracy of CT scanning of pancreatic tumors has reached 87%. At present, the clinical application of CT is mainly in brain diseases, accounting for about 75% of all CT examinations, and other examinations such as abdomen and chest account for 25%. CT is very effective in diagnosing tumors. For example, the diagnostic accuracy of CT for brain tumors is as high as 95%, and the differential diagnosis of renal cysts and renal tumors is as high as 100%. When doing CT, you need a bed to let the patient lie flat; A set of scaffolding, which is an instrument like a small tunnel, with X-ray emitters and detectors inside; There is also an X-ray generator and an electronic computer. These devices are all placed in a closed room. There is a window for observation on the wall of one room. On the other side of the window, an operator sits. He uses a computer to operate the scanner. Each scanned image can be quickly displayed on the monitoring equipment of the terminal. The CT computer with very fine and complex structure can not only display the structure of the fault plane at a certain angle, but also combine with the images obtained at other angles and display them on the terminal at the same time. It is convenient for the patient not to take off his clothes during the examination. CT machine has developed rapidly since it came out in 197 1. It has gone through four generations, from a scanner with a scanning time of 5 minutes per layer, which is only suitable for brain and orbit examination, to a modern device with a scanning time of only 2 seconds to 3 seconds, and can also scan any part of the body. It is meaningful to shorten the scanning time, because it can eliminate the influence of respiratory movement and other physiological activities of human body, such as gastrointestinal peristalsis, which will lead to disorder and overlap and bring difficulties to diagnosis. The invention of CT is the most important progress in medical physics since the discovery of X-ray, which makes a revolutionary leap in X-ray diagnosis technology. For this reason, its inventors, Kolmark and Hausfield, won the 1979 Nobel Prize in Medicine or Physiology.