Medical science has evolved along with science and technology. In 150 A.D., Galen of ancient Rome began vivisection, but it bordered on cruelty because the means of anesthesia were not yet available. By 185 A.D., China's Hua Tuo invented anaesthesia, and only then was anaesthesia surgery possible. But want to use medical instruments to understand the lesions of the organs in the body, without surgery, and after nearly a full 1700 years, that is, to 1895, the German R?ntgen discovered X-rays to be possible to observe from outside the body to the changes in the internal organs of the human body. This method of diagnosis using X-rays is still commonly used in hospitals today.
Roentgen in 1895 found that X-rays are very unexpected, he was studying the discharge phenomenon of low vacuum tube, found that placed 2 meters away from the vacuum discharge tube coated with barium cyanide-oxygen platinum acid fluorescent screen also emits fluorescence. He moved the fluorescent screen far away, and even wrapped the vacuum tube in black paper, the fluorescent screen still fluorescent. After repeated studies, it was determined that this invisible light was emitted by the vacuum tube when it was discharged, and was able to be displayed on the special fluorescent screen. R?ntgen experimented with his own palm, and for the first time saw the bones of his hand on the fluorescent screen. R?ntgen's discovery was soon used in the practice of medicine. For the first time, doctors were able to see lesions and injuries in the human body without surgery. Prior to this, physicians could only rely on the patient's body surface to reflect, check and diagnose some obvious symptoms, while the use of X-rays, the body's internal lesions can be reflected on the fluorescent screen. However, the use of X-ray diagnosis also has shortcomings. X-rays penetrate the body tissues, the overlapping image of the body tissues seen on the fluorescent screen, the doctor is not easy to accurately determine the true situation of the lesion from the overlapping image, even if two or three or even more directions of the shooting, not the body organs can not be accurately fluoroscopy, especially for the soft organs, soft tissues, X-rays fluoroscopy in fact, there is no practical effect. There is not much change in density between healthy and diseased tissue, so it is difficult to detect lesions in soft tissue, including tumors. People's research on this subject continued for nearly 80 more years. By 1971, Horsfield in the United Kingdom finally succeeded in launching a diagnostic scanning machine with a computerized X-ray tomography - X-CT, or computerized tomography X-ray scanner (CT).
Early CT scanners had a radiation source and detector mounted at either end of a C-shaped magnetic wheel. Scanning was performed by rotating the source and detector around the patient to obtain images of an area viewed from multiple angles. The soft tissue density values reflected in these images are then fed into a computer, where they are processed by the computer to form a two-dimensional image, which is then displayed as a gray shaded image on the system monitor and recorded by the computer. This lamination process is like using a light knife to slice off the human body, including the internal organs, piece by piece. The slices are usually only a few millimeters thick, and soft-tissue lesions are detected by comparing the front and back of the slices, and the sliced portion with the adjacent portion.
In the original CT scanners, scans took a long time, typically 1 to 3 minutes, and used a single narrow-beam radiation source and detector. Due to the long scanning time, during the scanning process, by the patient's breathing, digestive system peristalsis, etc., often make the image change. In order to solve this problem, and the invention of multiple detectors and fan-shaped ray beam source. 800 detectors on the CT scanner, so that it around the patient's body for the arc arrangement, this layout is also known as the bridge table. With this system, the entire scan takes only about 8 seconds and is not affected by the patient's movement, which significantly improves the results.
While such CT scanners have been able to correctly reflect soft tissues, they sometimes miss findings such as tumor masses. Especially for the diagnosis of brain tumors, this time due to the limitations of the patient and the direction of the bridge-shaped table, only with the spine perpendicular to the plane of axial scanning, to produce the best imaging results.
British CT machine in order to solve the CT scanning problems, on behalf of the 1990s international level of science and technology of the new diagnostic technology - nuclear magnetic **** vibration imaging system NMR was born.
Nuclear magnetic **** vibration scanner shape and CT scanner is similar. But instead of X-ray equipment, the ring into which the patient is propelled contains a powerful electromagnet, a radio wave transmitter and a radio wave receiver. When the electromagnet is energized, it produces a very strong magnetic field, and the hydrogen atoms, which are the most abundant in the molecules of human tissues, are able to force the spin axes of the hydrogen nuclei in the patient's body to align in the same direction under the action of the strong magnetic field, and then the radio transmitter is turned on, allowing it to emit low-frequency radio waves, and the hydrogen nuclei absorb the energy from such radio waves. When the transmitter is turned off, the hydrogen nucleus releases the absorbed energy in the form of a signal. Using the radio signals emitted by the hydrogen atoms in the tissues of a healthy organism, which are not of the same frequency and intensity as those emitted by the tissues with lesions, and then using a computer to turn the different signals from the hydrogen nuclei into images, a diagnosis can be made. It is important to mention here that the use of NMR***Vibration not only allows for better detection of tumors, but also for early detection and early diagnosis of diseases that the patient does not feel. This is because the process of nuclear magnetic **** vibration imaging, is a stable strong magnetic field with the imaging site of each body tissue is not the same, different physiological conditions will also be reflected in the picture. In this way, even if the patient's disease is still in the biochemical stage, in the pathology, physiology, biochemical disorders and symptoms do not appear, from the image can also be reflected. Nuclear magnetic **** vibration NMR has another advantage over CT, that is, there are no significant side effects, and the bones of the ray interference is significantly reduced, into the test and diagnosis of brain, liver, kidney, heart, nervous system diseases of the newest and safest method.