In fact, it is an indisputable fact that radiation from X-rays and CT tests is harmful to the human body. For a long time, scientists have been more concerned about how harmful such medical tests are to the human body.
Metro Express Fu Ling ■ Survey: 90% of Hangzhou people do not mind doing the examination
Yesterday, the reporter in the provincial people's hospital randomly interviewed 20 members of the public, of which the youngest 34 years old, the oldest 72 years old. They either had an X-ray or CT examination when seeking medical treatment, or did a chest X-ray during the physical examination, which means that all respondents without exception due to medical examinations have received X-ray radiation. The reporter designed two questions: one is whether you know that X-rays may cause cancer; the other is whether you will have doubts about the examination because of the harm of X-rays to the human body.
The survey found that: in addition to a 57-year-old woman has never heard of "X-rays may cause cancer", the other 19 citizens have said that they have heard of it. 68-year-old Uncle Qu said with great certainty: "Radiation Well, with the Japanese that Tatsunoko atomic bomb explosion, the same, to give birth to leukemia. " But the knowledge of X-ray damage, did not prevent most citizens to accept the medical examination. There are 18 members of the public believe that the hospital's inspection equipment have been rigorously inspected, the doctor also has a good idea, will not mess around, so it is very reassuring; but also two people said that the heart will be a little bit uncomfortable to do the examination. Especially if the results of the first examination are not satisfactory and need to be examined again, they will feel that the doctor did not fulfill his responsibility.
■ X-ray, CT examination of the chances of cancer how much possible to encounter radiation
Although X-rays contain harmful radiation, but when the patient's surface symptoms are not enough to diagnose the disease, or the need to further determine the extent of the disease, it is necessary to use X-rays and CT examination to help the doctor to clarify the diagnosis.
X-rays are most commonly used to detect fractures, but they can also detect abnormalities in the internal organs such as the lungs, liver, kidneys, and spleen; tumors of the ribs, clavicles, and thoracic vertebrae; and gastric ulcers and gastroenteritis-induced mucous membrane swelling, tumors, and so on. The difference is that X-ray film is a flat image of the human body, so the organs in the body will be shown before and after the overlap of the state; and CT is to take the approach of tomography, like the bread sliced into thin slices, from different points on the body to be examined by the body parts of the different photographs, thus solving part of the overlap problem. Generally speaking, diseases such as fractures can be seen clearly with X-rays, but when it comes to intracranial tumors, liver tumors, and other structurally more complex lesions, CT is needed.
How X-rays and CTs cause disease
Medical X-rays and CT exams are by far the largest source of man-made radiation to which people may be exposed, and which is capable of penetrating cells, destroying DNA, and even inducing certain cancer cells. Internationally recognized radiologist John Goffman's research has found that X-rays can damage the internal structure of cells and produce irreparable, lifelong damage to genetic molecules: of the 180,000 cases of breast cancer diagnosed each year in the United States, about two-thirds of the patients' etiology is related to medical X-rays. It has also been shown that X-rays destroy red blood cells and may induce blood disorders such as leukemia. Prof. Burlington de Gonzalez of the University of Oxford in the UK said, "In men, the disease with the highest risk associated with X-rays is bladder cancer, partly because many different kinds of X-rays irradiate the bladder. And women have a higher risk of lung and colon cancer."
Hypothetical Case - Cancer Risk in a Patient with a Fractured Rib
How many X-rays does a patient with a fracture really need? Xia Bing, director of the Department of Orthopedics at Zhejiang Provincial People's Hospital, projected it this way: once for diagnosis (if you need to further confirm the diagnosis, you have to add a CT, which is also subject to X-ray radiation), once for checking the bone reset after surgery (joint reset patients need to add one in surgery), once for a one-month review after surgery, and once for a three-month review after surgery. This is the basic number of checks, as many as six times, as few as four times, and later according to the recovery of patients with different fractures and whether the film is clear need to redo, up and down the hospital referral redo and other factors, some patients at least to do more than 10 times.
Assuming that a patient with a rib fracture is examined six times during the course of his visit, how much cancer risk will he face? Taking an X-ray chest film, when the ray is exposed in the examination area its exposure rate is about 160 mSv/hour (mSv is the unit of measuring the degree of radiation), which is about 0.045 mSv/second. At the First People's Hospital of Hangzhou, it takes about 0.5 seconds to take a chest X-ray, which means that the patient is exposed to a radiation level of about 0.023 millisieverts.
According to the standards set by the International Commission on Radiological Protection, the total risk of radiation is 0.0165/Sievert, which means that for every Sievert (1 Sievert = 1000 millisieverts) of radiation dose that the body receives, the chances of cancer increase by 0.0165. To extrapolate this, a patient with a fractured rib would have an increased risk of about 3.8/million.
For other medical tests, the general limbs do an X-ray to receive a radiation dose of 0.01 mSv, the abdomen is 0.54 mSv, the pelvis is 0.66 mSv, the lumbar spine is 1.4 mSv, and the upper gastrointestinal tract is 2.55 mSv. Using this, the risk of developing cancer in a healthy population because of a medical examination is between 1 in 10 million and 1 in 100,000
To be sure, radiation screening that can be omitted should be omitted. The patient needs to be accompanied by a family member who does not have to go along with the examination, so that the radiation is completely unnecessary.
However, it is not necessary to even dare to enter the area of the hospital radiology department. When taking chest X-rays, X-rays in the examination of the regional exposure rate of about 160 mSv / h, two meters away from the 80 microsievert / h, about 1/2000 of the center point, the chance of cancer at this time is about one in a million; and in the distance from the center of the point of the 6 meters away from the radiation is 1.5 microsievert / h, about one in five million of the center point, the chance of cancer is very small.
Vulnerable people - pregnant women, newborns
Although X-rays and CT checks during pregnancy do not absolutely lead to fetal malformations, Chen Wenhui, chairman of the Clinical Radiology and Interventional Branch of the Hangzhou Medical Association and director of the Department of Radiology at Hangzhou Hospital No. 1, still suggests that pregnant women Should try to avoid such examinations, especially in the first trimester of pregnancy. Because this is the critical period of the formation of important fetal organs, X-ray may make these cells and tissues have not yet developed a stereotyped mutation, the incidence of congenital malformation of the fetus will also increase.
It has also been shown that CT scanning of newborns with head injuries can have an impact on later learning and logical reasoning, but not on spatial recognition. Sensitive parts --- gonads
Cells in various parts of the human body react to X-rays to varying degrees, with the gonads being the most sensitive. Prof. Zhang Shizheng said, foreign hospitals do this point better, in the lower abdomen for the patient to do X-ray or CT examination, will be used to cover the gonads with a lead sleeve or other protection to improve the insurance factor. But most hospitals in the country do not have this kind of protection.
Position of responsibility - doctors
British researchers found that X-ray examinations have been on the rise in 15 countries surveyed, including Japan, over the past 20 years, and at least 30% are unnecessary. Professor Zheng Junzheng of the Chinese Center for Disease Control and Prevention's Institute of Radiation Protection and Nuclear Safety Medicine also pointed out that medical staff should not ignore the protection of patients and examinees because they come to the hospital just once for a checkup; examinees also need to be aware of self-protection, and reject unreasonable medical exposures.
■ Eat more kelp When it comes to dietary care, Chen Hui, director of the profession for 20 years, shook his head and said "no" twice, and then added with some hesitation: "Eat more kelp and other iodine-containing things may be useful, which can absorb some of the rays. "
■ The latest spiral CT at Shaw Hospital
Next week, the newest 16-slice spiral CT in Asia will be officially opened at Shaw Hospital. The new $900,000 CT, of which only eight have been installed in hospitals around the world, is capable of scanning a full circle of the area to be examined in 0.37 seconds and obtaining 16 images taken from different locations. In the past two days, Prof. Zhang Shizheng is working with his colleagues on how to maximize the power of the new CT. After nearly 40 years in the field, he has lost count of how many times he has embraced new technological innovations.
In 1975, CT was formally introduced to clinical practice. Shortly thereafter, as the first generation of CT people in China, Prof. Zhang Shizheng went to Germany for six months to learn how to use this new instrument. At that time, the X-ray examination, which has a history of nearly 80 years, was no longer the original instrument that took half an hour to take a film; and in less than 30 years since then, CT technology has also been advancing by leaps and bounds. The first generation of CT machines to complete a scan takes 4-5 minutes; and with two X-ray tube composition of the second generation of CT machine products, each scan only needs to use 30-120 seconds; the third generation of CT machine products with more than one X-ray tube composition, with 2.5 seconds on the completion of a scan; to the fourth generation of CT machines, the scanning time is reduced to only 1 second. And the various new CT machines that have been created since then have kept the time to less than 1 second. Similarly, the speed of X-ray examination is also rapidly improving, today a common chest X-ray imaging as long as 0.1 seconds, other parts of the general 0.5 seconds.
X-ray and CT scan imaging, from the initial film projection, and later computerized imaging, has moved to the most fashionable digital era. Modern X-ray and CT examination machines revere sensitive digital receivers. Prof. Zhang said confidently, "Sensitive receivers and rapidly increasing imaging speeds mean less radiation and safer examinations for patients."