Radiology CT examination technology?
Many people are still very familiar with X-rays. We usually hear that someone went to the hospital to see a doctor and took an "X-ray". So, what kind of examination technology is CT scan in the hospital? Let me put it this way, X-rays flatten a person, causing many body structures to overlap. Of course, overlapping also makes it difficult to see many of our body structures clearly. CT is more powerful, as it "cuts" the human body into slices and searches for lesions layer by layer. Currently, new CT equipment and technology are developing rapidly, and the thickness of such slices has reached 1mm, allowing even smaller lesions to be detected.
How does CT work?
The process of CT imaging is very complex, and it is described too professionally, which most people may not understand. Simply put, it is a machine that emits X-rays, penetrates the human body, reaches the processor, undergoes a series of post-processing, forms images, and sends them to the computer. Radiologists use special software on the computer to look for lesions in these images, and these images are printed by a printer, which becomes what we often call CT films packaged in bags.
There are currently two imaging methods for CT: regular plain scan and enhanced scan. Regular plain scan: patients only need to lie on the "bed board" of the CT machine, and most scans can be completed within 10 seconds; Enhanced scanning: Injecting contrast agent (intravenous injection) on the basis of plain CT scan, the contrast agent will circulate to the tissues and organs throughout the body with the blood. With this contrast agent, the appearance of the diseased tissue can be highlighted, and the difference from the normal tissue of the surrounding human body can be enlarged, making it easier to detect where and how large the lesion is. Moreover, the inhalation of contrast agent in lesions often presents different "appearances" on CT images, which can also help radiologists determine the type of lesion. In summary, enhanced scanning provides a clearer and more comprehensive view.
For patients who come to see a doctor for the first time, doctors are often unclear about the condition, so they may ask the patient to undergo a regular CT plain scan first. If the lesion can be seen and a clear diagnosis can be made after the scan, then enhanced CT is not necessary. However, if the view is not so clear or the diagnosis is not so clear, then further enhanced CT should be performed. Before performing enhanced CT, it is important to remind everyone that the contrast agent injected during enhanced scanning may cause varying degrees of adverse reactions in a very small number of people. So before the examination, it is necessary to carefully read the informed consent form for contrast agent enhancement, drink more water before and after enhancement, and help the contrast agent be excreted with urine. Generally, the contrast agent will be basically emptied within 24 hours.
What are the hazards of CT scanning?
From the process of CT work, we learned that the X-rays emitted by the machine penetrate the human body. So the question is, will these X-rays cause significant harm to the human body? In fact, the hazards of CT mainly come from ionizing radiation generated by X-rays. Ionizing radiation can destroy certain large molecular structures in the human body, damage cells, and thus harm the human body. The radiation dose varies depending on the type of CT scan and the location of the CT examination. Generally, the radiation dose we receive during a CT scan is about 2mSv-10mSv. According to China's radiation protection standards, the annual dose limit for radiation workers is 50mSv; The average upper limit of radiation received each year within five years is 20mSv, therefore, the radiation dose received during a CT scan is much lower than the national radiation control value. That is to say, as long as the total radiation received is controlled within a safe range, it is relatively safe.
In fact, there are also many places and situations in life where radiation exists. For example, smoking 20 cigarettes a day is equivalent to (0.5-2) mSv per year; Passengers undergoing subway security checks may receive an annual dose of less than 0.01mSv; The dose for flying for 20 hours is approximately 0.1mSv; The natural background radiation dose that each person receives each year is approximately 2mSV. Therefore, there is no need to overly worry about the side effects and carcinogenic issues of CT scans. Occasional CT scans do not cause too much harm to the body, and doctors will assess potential risks based on the patient's specific situation to ensure that the benefits of CT scans far outweigh the risks.