When it comes to radiation, most of what comes to mind is a variety of luminous substances, such as solar ultraviolet radiation, cell phone and computer screen radiation and so on. The following is to give you a talk about what is radiation, radiation is divided into several kinds.
First, what is radiation?
Radiation is the process of emitting or transmitting energy in the form of waves or particles in space or material medium. From this explanation we can see that radiation is the process of emitting or transmitting energy, which can be in the form of waves (e.g., light, sound, radio waves, etc.) or in the form of particles (e.g., neutron radiation), so that radiation is not necessarily light.
In fact, the forms of radiation include the following four:
1. Electromagnetic radiation: such as radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays, etc., which can come from the sun or from electronic devices.
2, particle radiation: such as neutron radiation and other particles in the stationary energy is not zero radiation.
3, acoustic radiation: such as ultrasound, sound waves, seismic waves, etc., these are also a kind of radiation.
4, gravitational radiation: Gravitational radiation takes the form of gravitational waves, which can also be ripples in the curvature of space-time.
In life, we are exposed to the greatest intensity of radiation is electromagnetic radiation.
At the same time, according to the different effects produced when radiation acts on matter, people will be divided into ionizing radiation and non-ionizing radiation.
Ionizing radiation includes cosmic rays, X-rays and radiation from radioactive materials; non-ionizing radiation includes ultraviolet light, thermal radiation, radio waves and microwaves.
Ionizing radiation is most commonly found in X-rays used to take pictures of children in hospitals, so hospitals put radiation protection material on the walls of radiology departments. Non-ionizing radiation is less harmful to the human body than ionizing radiation, household appliances, cell phones and these objects are sources of radiation.
In contrast to ionizing radiation, most of the radiation we are exposed to in our lives is non-ionizing radiation, such as infrared light, visible light (including light emitted from cell phone and computer screens), radio waves (such as wifi), and microwaves.
What radiation is harmful?
"Anyone who talks about radiation damage away from the dose is a rascal!" In fact, a certain safety range of radiation is not harmful to the human body. The key to whether it will cause harm to the human body is to look at the radiation dose.
Common medical tests:
1, ultrasound: no radiation
2, nuclear magnetic (MRI):
3, X-ray: radiation 0.1mSv
We take a chest X-ray examination, is about 0.1mSv (millisieverts, the amount of radiation unit). This is roughly equivalent to the radiation we receive in 10 days of daily life, or the radiation we receive on a one-way airplane ride from Tokyo to New York. Important reproductive parts of the human body are covered with lead plates.
4, CT: Radiation 2 ~ 15 mSv
CT examination principle is X-ray will be layered through the body, through the computer calculations after the second imaging, like a piece of bread into slices to see. CT examination of radiation each time about 2 ~ 15 mSv, indeed to be higher than the X-ray 10 ~ 30 times. This is related to the performance of the CT machine, the scanning area, and the clarity of the imaging.
But you don't have to be too nervous, the radiation levels of CT exams are currently within safe limits, and doctors generally control the number of CT exams their patients have.
5, nuclear medicine SPECT: radiation 0.1 ~ 5.2mSv
Nuclear medicine SPECT full name "single photon emission computed tomography", it is for the human body tissue blood flow, functional metabolism and physiological and biochemical imaging.
The principle of this test is to use micronucleus drugs, modern medical imaging technology and molecular biology combined with the new technology, highly sensitive to reflect the body's tissues and organs of the perfusion, functional metabolism and physiology and biochemistry of the imaging method.
But we do not talk about "nuclear" color! SPECT inspection radiation is not high, generally will not be around the health care workers, family members caused by radiation damage. In general, only those who have been exposed to more than 100mSv of radiation will have a significantly higher chance of developing cancer.
Overall, ultrasound and MRI are completely free of radiation, and other medical examinations even if there is radiation has not reached the level of harm to the human body, so there is no need to panic. Moreover, medical tests are performed when necessary, and if you are pregnant or breastfeeding, you should inform your doctor about the necessity of the test.
Radiation that can't be avoided on a daily basis:
Many of our little friends are also very worried about the amount of radiation they encounter in their daily lives. In recent years, there have been rumors circulating on the Internet that "sleeping with a cell phone on the pillow next to the radiation will cause cancer", "microwave ovens can cause cancer when the amount of radiation," "too long on the computer will absorb radiation and cause cancer" and so on. There are all kinds of "radiation causes cancer" and so on. These are not based on scientific evidence.
According to the test results published by the German Federal Office for Radiation Protection (Bundesanstalt für Radioprotection) in February 2019 on the radiation of a number of cell phones currently on the market, the radiation level of cell phones on the market ranges from about 0.32 to 1.75 W/kg.
But note that the unit is not millisieverts, but W/kg, which means the electromagnetic energy absorbed per unit of time and mass of a single organism. So you can rest assured that the amount of radiation from cell phones is basically negligible, and these values are within national safety limits.
What is the radiation that is harmful to our body? Microwave ovens, computers, Wifi? These are not, these radiation levels are also basically negligible.
What is unexpected is that the most harmful radiation in life should be smoking, because cigarettes contain radioactive substances. In the case of a smoker, for example, if you smoke 1 pack of cigarettes a day, you get a radiation dose of 35mSv per year, which is far greater than most medical radiation doses!