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Alpha, beta, gamma rays, X-rays, neutron rays. Among the routine examinations in the hospital, B-ultrasound and MRI are non-ionizing radiation examination methods and do not contain radiation.
Radiation can be roughly divided into two types: ionizing radiation and electromagnetic radiation .
ionizing radiation
electromagnetic radiation
Features
◆Higher energy
◆Can ionize substances
◆Can cause damage to cells and even DNA
◆ is more dangerous
◆In daily life The energy exposed is lower
◆There is no ionized substance Ability
◆ It is difficult to cause direct harm to people
◆ Relatively safe
represents
α, β, , gamma rays, , , , neutrons Rays
induction cookers, microwave ovens, etc., mainly generate heat energy
In routine examinations in hospitals, B ultrasound , Nuclear Magnetic Resonance (MRI), is a non-ionizing radiation examination method with no radiation. X-ray, CT, PET-CT will produce ionizing radiation.
We are receiving radiation every day
Let’s not talk about radiation discoloration first.
We generally use millisievert (mSv) to measure the harm of radiation. Only when exposed to a radiation dose of more than 100mSv, the probability of human cancer will increase significantly.
We also encounter ionizing radiation in our daily life, but the dose of radiation is extremely small.
This is the ray emitted from cosmic rays and natural radionuclides . The dose received by each person per year is about .4mSv, which is called background radiation .
In some places in the world, the surface radioactive material content is relatively high (such as near uranium/thorium deposits and associated radioactive rare earth deposits) , which becomes high background areas . For example, (6.0mSv) in Yangjiang, Guangdong Province, my country, and Guarapari, Brazil (5.5mSv) , etc.
A large number of surveys have shown that background radiation levels have no impact on health.
Are there any radiation in medical imaging examinations?
In the hospital, we often find the following signs: "Far away, close at hand".
In the hospital, in order to clarify the diseased organ, location, and lesion size for precise treatment, clinicians often require patients to go to the radiology department for various imaging examinations, including ultrasound, X-rays, CT, MRI (magnetic resonance), etc. . Do these examinations have a big impact on the patient's health? Let us analyze it in detail:
Magnetic Resonance Imaging (MRI) Radiation: None
Magnetic Resonance Imaging (MRI) is sometimes called " MRI ", It does not "Nuclear", no radiation! ! ! Its developing principle is to "shake" the water molecules in the body to vibrate them, and then calm down again, so as to detect changes in the water molecules. The place with lots of water is the place where magnetic resonance imaging signal is strongest. The brain, spinal cord, intervertebral disc , articular cartilage are the favorite parts of magnetic resonance imaging. B Ultrasound Radiation: None The principle of B Ultrasound is to use ultrasonic waves to penetrate the human body. When the sound waves encounter human tissue, they will produce reflected waves , and the reflected waves will be imaged by calculating them. Just like picking a watermelon , tapping and looking at the lesions shows that has no radiation at all.
A chest X-ray is roughly equivalent to the amount of radiation you would receive in 10 days of daily life, or a one-way plane ride from Tokyo to New York. X-rays will pass through the human body and will not be exposed on the film when they encounter blocked parts. After the film is developed, this part will turn white.
Nuclear medicine examination SPECT Radiation: Yes, not much, 0.1-5.2mSv
Don’t talk about “nuclear” discoloration! SPECT stands for "single photon emission computed tomography", which is aimed at tissue blood flow, functional metabolism and physiological and biochemical imaging in the human body.
Its inspection principle is based on the new technology that combines trace nuclide drugs , modern medical imaging technology and molecular biology to highly sensitively reflect the blood perfusion, functional metabolism and physiological biochemistry of tissues and organs in the human body. imaging method. The SPECT examination has a wide range of uses . It is mainly used to early infer the functional changes of brain, heart, kidney, liver, lung, parathyroid glands and other human organs, as well as changes in blood supply and metabolism etc. Such as:
. Whole body bone imaging (4.2mSv): A single examination can scan the whole body bones, and the sensitivity for various benign and malignant bone diseases is very high ( can detect more than 90% of the lesions ).
. Thyroid scan (3.6 mSv): is suitable for the diagnosis and differential diagnosis of hyperthyroidism, hypothyroidism and various thyroiditis and thyroid nodule diseases.
SPECT radiation dose is not high and will not cause radiation damage to surrounding medical staff and family members.
Whole-body bone scintigraphy can detect bone metastases 3-6 months earlier than X-ray and other imaging examinations. In the picture above, the X-ray is negative (right), but the bone scintigraphy (left) shows bone metastases in the upper end of the right femur.
CT Radiation: relatively high, 2-15 mSv
CT The inspection principle is that X-rays will pass through the human body in layers, and the computer will calculate the secondary image, just like cutting a piece of bread into slices. The amount of radiation in CT examination is 10 times, 30 times, or even hundreds of times higher than that of high . But don’t be too nervous. Currently, the amount of radiation in CT examinations is within the safe range, and the X-ray tubes in CT equipment are like daily lamps, with different wattages and adjustable brightness, so the amount of radiation It's not constant, it's adjustable.
Nuclear medicine examination PET/CT Radiation: Yes, the radiation dose of PET and CT is superimposed, and the maximum is only 15mSv
PET/CT scientific name is "positron emission tomography/computed tomography". Different from the local examination of SPECT, it targets It is full body examination ! As the most advanced molecular imaging examination at present, can focus on systemic tumor search and efficacy evaluation . But , are self-funded and more expensive! The glucose metabolism of most tumors is increased. PET/CT can clarify the metabolism of the whole body in one examination. can detect lesions before the morphology changes. is jokingly called the "artifact for screening tumors" and is Nuclear medicine top "high, rich and handsome".
To summarize
How harmful is radiation to people?
The impact of rays on the human body is divided into determined impact and random impact .
The determined impact means that after the human body receives a radiation dose that reaches a certain value, it will definitely suffer from certain diseases, such as hair loss, leukemia and infertility etc.
For example, the threshold dose for cataracts is 5000mGy. If the dose is lower than this value, cataracts will not occur due to radiation.
Random effects refer to: The probability of radiation damage (disease) is related to the dose, but the severity has nothing to do with the dose, and there is no threshold dose .
As for cancer, There is currently no clear study confirming the relationship between radiation dose and cancer.
There is a type of radiation that may be more worthy of your attention than medical examinations.
In summary, the radiation dose of conventional X-ray films is quite low and can be considered completely safe.
CT examinations bear a higher radiation dose. However, like other treatments and examination methods, CT examination is also a choice made after weighing the pros and cons. Just pay attention to the number of radiographs taken.
Generally speaking, most radiological examinations below the background radiation level involve very trace amounts of radiation. As long as the examination is not excessive, it will have no impact on human health.
Instead, what many people need to really focus on is another source of radiation - smoking.
Cigarettes contain a radioactive substance called polonium 210, which can release α rays . If you smoke 30 cigarettes a day, the annual radiation is about 13mSv. This is equivalent to 6.5 head CT examinations or 650 chest X-rays !
"Alpha, beta, gamma rays, X-rays, neutron rays. Among the routine examinations in the hospital, B-ultrasound and MRI are non-ionizing radiation examination methods and do not contain radiation." Related video
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