When you go to the hospital to see a doctor, whether it's headache, stomach pain, or cough to lung pain, the doctor said that it's very common to take a CT first.
However, some people said, "if you do CT once, the radiation you receive is equivalent to taking 400 X-rays", "if you do too much CT, it is easy for cells to mutate into cancer cells?" Indeed, many people have such concerns. Does CT have any impact on health?
1、 What is CT first?
What is CT? CT is an examination item that uses the "X" harness to scan after penetrating human parts. The imaging shows the distribution of sectional tissue, just like a cake roll. CT is responsible for cutting the cake into pieces, mainly reflecting the cross-sectional organs.
At present, CT is divided into plain CT and enhanced CT.
Plain scan CT: also known as ordinary plain scan CT, patients can scan as long as lying flat on the CT machine. There is no need to create shadow agent, and it is convenient and fast. Generally, plain scan CT can be used as the primary examination item of initial examination and acute disease.
Enhanced CT: on the basis of plain CT, enhanced CT is to inject contrast agent into the patient's vein. The contrast agent flows through various organs of the body through blood circulation, which can more accurately analyze the pathological problems of organ tissues and tissues with rich bleeding fluid circulation.
It should be noted here that the contrast agent used for enhanced CT is usually iodine contrast agent, which is not applicable to all patients. For example, patients with hyperthyroidism will have the risk of allergy when using iodine contrast agent, so enhanced CT can only be carried out after being evaluated by doctors.
So where can CT check the body? CT is widely used. In neurosurgery, there are many problems that need to be assisted by CT, such as cerebral infarction, craniocerebral trauma and brain tumors. In addition, heart problems, dry liver, gallbladder, kidney and other substantive organs can also be clearly seen by CT.
2、 Did CT do harm to your body? How many times will it cause cancer?
First of all, CT does have radiation, mainly from ionizing radiation produced by X-ray. Ionizing radiation will release free radicals that damage DNA, which may cause cell carcinogenesis. However, the prerequisite is to pay attention to the dose, and it is safe not to exceed the dose.
So, what dose of radiation can cause cancer?
In a study in 2013, scientists compared 680000 children who received CT with 10million children of the same age who had not received CT. Then scientists estimated that the radiation dose per 1msv would increase the probability of cancer by 0.0017%~0.002%.
Rough calculation, for example, if the radiation dose of a chest X-ray is 0.1msv, the cancer rate will increase by 0.00017%~0.0002%.
Clinical practice believes that a single dose of 50msv or a lifetime dose of 100msv will not cause health risks, and this dose is also the upper limit of the dose of diagnostic imaging examination.
Effective dose of radiation that can be borne by tissues in different parts of the body (source: Tencent medical code)
In fact, many things in life have radiation:
Smoking 20 cigarettes a day, 0.5~2msv radiation per year
The radiation dose of flying for 20 hours reaches 0.1msv
When subway security checks passengers, the annual acceptable radiation dose is <0.01msv
Each person receives about 2msv of natural background radiation every year
Therefore, don't worry too much about the side effects and carcinogenesis of CT examination. It won't be too harmful to experience CT examination once or several times occasionally.
Basically, diseases can "die of light" through CT scanning, especially patients with tumors, vascular diseases, inflammation and traumatic diseases. CT examination is an important means to help doctors analyze patients' conditions and make clear diagnosis.
However, although CT is powerful, there are still some patients who are not suitable for CT examination, such as heart disease patients, such as infants under 1 year old and the elderly over 60 years old, as well as patients with renal insufficiency, allergic constitution, asthma and eczema diseases.
3、 CT or MRI, how to choose?
Some patients may wonder why the doctor doesn't directly ask me to have an MRI, but to take a CT first.
In fact, CT and MRI have their own advantages.
Although CT has certain radiation, its manifestation of human lung, bone and other diseases is very clear, and the CT scanning time is short. Usually, the examination can be completed in a few minutes, and the patient's cooperation will also become higher.
Although MRI has no radiation, it is not suitable for the examination of any part. Usually, MRI mainly examines the lesions of human brain and soft tissue. For lung lesions, in fact, MRI is not clear.
In addition, MRI examination takes a long time. Sometimes patients even have to lie on the examination machine and remain motionless for at least ten minutes. Some examinations also need the cooperation of patients to hold their breath.
Therefore, both CT and MRI have their own advantages and disadvantages. Doctors will choose them according to the actual situation of patients. For patients who come to see a doctor for the first time, the doctor does not know how their condition is actually, and may ask them to have a general CT examination first.
CT is a common clinical examination method. Although there is radiation, the amount is very low. Occasionally going through one or two CT examinations will not cause much harm. In fact, the majority of medical staff are the people who face radiation all year round. Therefore, if the doctor advises you to do CT according to your condition, then as a patient, as long as you cooperate, you don't need to worry too much about cancer caused by radiation.
Reference material:
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[2]《“CT检查会致癌”被夸大了！做一次没有那么恐怖》.腾讯医典.2022-02-24
[3]《做个CT检查，对身体的伤害有多大？》.中国医学论坛报.2021-10-14
[4]《CT检查辐射大吗？真的会致癌吗？》.人卫健康.2020-04-17
[5]Drozdovitch V . Radiation Exposure to the Thyroid After the Chernobyl Accident[J]. Frontiers in Endocrinology, 2021, 11.
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[7]《做一次CT，对人体的伤害有多大？医生终于说了实话！》.DrX说.2021-10-1
Original link:
https://mp.weixin.qq.com/s/PTYGbfznbX7LZRh1D9R28w
