June 16, 2024

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Radiation issue: X-ray CT B-ultrasound MRI

Radiation issue: X-ray CT B-ultrasound MRI


Radiation issue: X-ray CT B-ultrasound MRI. X-ray.  CT, B-ultrasound, Magnetic Resonance Imaging, which one has the most radiation? For our common medical examinations, including CT, X-ray, Magnetic Resonance Imaging, etc., everyone is worried about radiation. So, are these examinations dangerous? Does too much radiation cause cancer?

Radiation issue: X-ray CT B-ultrasound MRI

X-ray CT, B-ultrasound, Magnetic Resonance Imaging, are there any radiation risks?

You may have done these checks, but you don’t know very well. Today, we will give you a brief introduction.


The principle is to use X-rays to penetrate the body to form an image, just like taking a photo.

Radiation size

The radiation dose of X-ray examination is almost 20-100 microsieverts, which is similar to the radiation received in a 20-hour flight.

Main inspection content

The most common X-ray examination is to take chest radiographs to screen for lung diseases. In addition, you can also take pictures of the skull, abdomen, bones and joints of the limbs.


CT also uses radiation to penetrate the body, but unlike X-ray examinations, multi-slice spiral CT examinations are now imaging by collecting every voxel of the human body within the scanning range. To put it bluntly, it is to divide the area to be inspected into countless volumes less than one. The tiny squares of cubic millimeters can be seen more closely, and very subtle lesions can also be found.

Radiation size

The radiation dose of a normal chest CT examination is about 2000-5000 microsieverts, and the radiation dose of a low-dose CT examination of the chest is about 200-500 microsieverts, which is almost 10 times that of X-rays.

Main inspection content

CT is most commonly used in the examination of head, chest, abdomen, and spine diseases. When some limbs and bones are not clearly seen by X-ray examination, CT can also be selected.


B-ultrasound examination uses sound reflections to obtain different echoes to form images, which is almost the same as throwing rocks into the water to hear echoes to measure depth.

Radiation size

Ultrasound inspection uses sound reflection imaging, no radiation!

Main inspection content

B-ultrasound mainly screens the abdominal and pelvic organs for disease, including: breast, thyroid, liver, kidney, pancreas, gallbladder, spleen, bladder, uterus, ovaries, etc.

Magnetic Resonance Imaging

Magnetic Resonance Imaging (MRI) is often referred to as nuclear magnetism. Don’t look at the name it sounds a bit scary. In fact, this nucleus refers to the hydrogen nucleus. Magnetic Resonance Imaging is to artificially create a magnetic field to let the human body lie in it. In the magnetic field, the hydrogen nuclei in the human body can move regularly, processed by a computer to form an image.

Radiation size

Magnetic Resonance Imaging is the use of electromagnetic signals for imaging, and there is no radiation!

Main inspection content

There are many parts that can be examined by MRI, including the brain, blood vessels, muscles, ligaments, spine and so on.

Therefore, in fact, NMR and B-ultrasound do not use X-rays in the inspection process, and will not produce ionizing radiation, so these two inspections are quite safe.

As for X-ray and CT, although X-rays are used, the radiation dose is not high, and there is no problem in general. However, if you are pregnant women, children, or special populations who have recently undergone imaging tests, please tell your doctor when you see a doctor. The doctor will choose the appropriate examination plan according to the patient’s physical condition.

What needs special attention is that if you are clearly a high-risk group of certain diseases and need to do these tests, but you do not do it because you are afraid of radiation, you will delay your illness, and the consequences will be more serious.

Small science on medical examination

1 Why do I need to apply a layer of gel before doing B advance?

This sticky gel is called a coupling agent. Because it is difficult for ultrasound to penetrate the air, it is applied to the skin to expel the air between the ultrasound probe and the skin for easy observation.

The coupling agent will not cause harm to the human body, and the ingredients it contains are non-toxic and tasteless, so you can rest assured.

2 Why do I have to hold back urine when doing a B-ultrasound?

Women who do transabdominal B overtime generally require holding back urine, the purpose is to fill the bladder. Because women’s uterus, ovaries and other organs exist deep in the pelvic cavity, surrounded by the intestines, holding back urine can push the intestines away, so that the uterus, ovaries and other organs can be clearly displayed, making the examination results more accurate.

3 Why do I need to breathe in and hold my breath when taking a chest radiograph?

Taking a big breath when taking a chest radiograph can enlarge the lung volume, which is convenient for observation.

You can never guess the most radiant place in the world!

Speaking of the strongest radiation in the world, is the Chernobyl nuclear power plant? Or the Fukushima nuclear power plant in Japan? Actually neither! It’s the lungs of smokers!

Before, a physicist named Derek Muller once visited all over the world to find the place with the strongest radiation in the world. Let’s take a look with him:

  • In our daily life, we cannot avoid radiation. The amount of radiation that we naturally receive daily is about 0.1 to 0.2 microsieverts/hour.
  • The United States dropped an atomic bomb on Hiroshima, Japan. Today, 70 years later, the radiation intensity at the explosion site is 0.3 microsieverts/hour.
  • More than 30 years ago, a leak occurred at the Chernobyl nuclear power plant, and today there is still 5 microsieverts/hour of radiation.
  • Eight years ago, the Fukushima nuclear power plant in Japan was leaked due to the tsunami. Today, the radiation in the local isolation area is still 5-10 microsieverts/hour.
  • And the last stop is the basement of Pripyat Hospital. There are piles of firefighting suits taken off by the firefighters who dealt with the Chernobyl nuclear power plant accident more than 30 years ago and entered the basement. The data soared to 1500 microS. Eph/hour. You read that right, this is one of the places with the highest radiation levels in the world.


Of course, this is not the end, because you have not seen the amount of radiation in the lungs of smokers.

Every smoker’s lungs receive an average of about 160,000 microsieverts of radiation every year! This is equivalent to taking nearly 1,600 chest X-rays in a year!

Therefore, it is better to quit smoking for fear of radiation!

What is the harm of smoking?

Some people may say, “What is the meaning of life without smoking” “My grandfather will be fine after smoking for most of his life”… But, have you ever thought about smoking, besides affecting yourself, it can also hurt People around you, such as family, children.

For example, if a husband smokes, his wife and children are the most important passive smokers. Passively absorbs more than twice the nicotine, three times the tar, five times the carbon monoxide, and fifty times the carcinogen.

For his children, there is twice the chance of contracting respiratory diseases, such as colds, tonsillitis, bronchitis, asthma, etc. Not only that, parental smoking may also cause children’s growth, mental retardation, and decline in academic performance. At the same time, children are more likely to become addicted to smoking.

So, for your family and children, quit smoking!



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