What are the clinical applications of CT?

With the rapid development of modern computer and display technology, the first X-ray CT device was successfully trial-produced in Hounsfield, England from 65438 to 0969. Ambrose published an official report in 1972 after her clinical practice. 1974, Ledley successfully developed whole-body CT. In just 10 years, CT equipment has spread all over the world, from the first generation to the fifth generation. Most of the CT used in hospitals in China belong to the second and third generation. The appearance of CT laid the foundation of modern medical imaging and greatly improved the accuracy of early detection and diagnosis of diseases. This is one of the most important medical achievements in the 1970s. Therefore, Hausfield won the Nobel Prize in Medicine with 1979.

In fact, ct is an electronic computer plus X-axis tomography. Its advantages are: ① the examination is convenient, rapid and non-invasive, and it is easily accepted by patients; ② High density resolution. The intracranial structure and abdominal organs can be clearly displayed on the screen without injection of contrast agent. CT can also measure the CT values of various tissues and quantitatively analyze the lesions; ③CT images are clear and the anatomical relationship is clear, which is far superior to ultrasound and radionuclide scanning. By adjusting the window width and window level, the gray contrast of the image can be more suitable for the display of lesions; ④CT can provide cross-sectional images without tissue overlap, and can reconstruct coronal and sagittal images; ⑤ Enhanced scanning can not only improve the detection rate of lesions, but also make qualitative diagnosis.

What are the disadvantages of CT 1? The scanning time is too long, which is not suitable for moving organs such as heart and gastrointestinal tract; 2? Slice is too thin, which is not conducive to large-scale inspection; 3? Some special parts, such as posterior cranial fossa, upper thoracic region of lower neck, upper abdomen, etc., have excessive artifacts, which affect the observation of lesions; 4? Iodine-containing contrast agents are toxic and can cause serious reactions in individual patients. 5? The equipment is expensive, the maintenance is difficult, and the detection cost is too high.

Scope of application CT scanning has a wide range of indications and is most suitable for examining the brain, spinal cord, abdominal cavity, pelvic cavity, retroperitoneal cavity, mediastinum and great vessels. Generally, it is not suitable for the examination of gastrointestinal tract, heart and limbs.

According to the pathological changes, CT is most suitable for differentiating space-occupying lesions, such as tumors, cysts, swollen lymph nodes, hematomas, abscesses, granulomas and so on. For these lesions, CT can find out their size, shape, number and invasion range. CT can determine the staging of some organ cancers and the possibility of surgical resection.

In some cases, CT can distinguish pathological features of lesions, such as authenticity, cystic, vascular, inflammatory, calcification, fat components and so on.

Other routine examinations should be completed before CT scanning. For example, when scanning the head, the head should use plain film and tomography; Before hepatobiliary and pancreatic scanning, various laboratory examinations, abdominal plain film, cholangiography and B-ultrasound scanning should be carried out. Before renal scanning, pyelography and ultrasound should be done; Before chest scanning, plain film and tomography should be taken; Before spine scanning, spine plain film and myelography should be performed first, because CT is a part of the whole medical image.

Supplementary CT and routine X-ray examination are complementary. It is very wrong to overestimate the diagnostic ability of CT and ignore the routine X-ray examination. In fact, ct, like other X-ray methods, is only an image diagnosis, and its density resolution and spatial resolution are limited. CT is not only difficult to show minor lesions, but also has many limitations in qualitative diagnosis. Therefore, even in various diseases suitable for CT examination, the correct diagnosis rate is often less than 90%.