As we all know, X-ray is a ray with higher energy than ultraviolet rays, which has now been widely used in industry and medicine.Because it has a high radiation damage, it usually needs to be properly protected. The protection is roughly divided into three types, through the protection to control the dose of X-ray irradiation, so that it is maintained at a reasonable minimum level, not exceeding the dose equivalent limit stipulated in the national radiation protection standards. The principles of time protection, distance protection and shielding protection of radiation protection are as follows:
1. Time protection
The principle of time protection is that the cumulative dose of irradiation of personnel in the radiation field is proportional to time, so that in the case of constant irradiation rate, shortening the irradiation time can reduce the dose received.Or people working within a limited time may be able to ensure personal safety by placing the radiation dose they receive below the maximum permissible dose (this method is used only in extraordinary cases, and shielding protection is preferred if shielding protection can be used), thus achieving the purpose of protection. In fact, we have a similar experience in life, even if we go to the hospital to queue up for X-ray examination, please enter the examination area as soon as possible and follow the doctor’s guidance to complete the test quickly to reduce the damage of the radiation to our body.
2. Distance protection
Distance protection is an effective method of external radiation protection, the basic principle of using distance protection rays is to first use the radiation source as a point source, and the amount of irradiation and absorption dose at a certain point in the radiation field are inversely proportional to the square of the distance between the point and the source, and we call this law the inverse square law. That is, the radiation intensity changes inversely proportional to the square of the distance (in the case of a certain radiation intensity of the source, the dose rate or irradiation amount is inversely proportional to the square of the distance from the source). Increasing the distance between the radiation source and the human body can reduce the dose rate or exposure, or work outside a certain distance so that the radiation dose received by people is below the maximum allowable dose, which can ensure personal safety. So as to achieve the purpose of protection. The main point of distance protection is to maximize the distance between the human body and the radiation source.
The inverse square law shows that the intensity of rays at two points, inversely proportional to the square of their distance, will rapidly reduce the dose of irradiation as the distance increases.Note that the above relationship applies to point ray sources without air or solid material. In fact, the radiation source is a certain volume, not an idealized point source, but also must be noted that the radiation field in the air or solid material will cause the radiation to scatter or absorb, can not ignore the scattering effect of the wall or other objects near the source, so that in the actual application should be appropriately increased distance to ensure safety.
3. Shielding protection
The principle of shielding protection is: the intensity of radiation penetration of the substance will be weakened, a certain thickness of shielding material can weaken the intensity of the ray, between the radiation source and the human body set a sufficiently thick shield (shielding material).It can reduce the radiation level, so that people in the work of the dose reduced below the maximum allowable dose, to ensure personal safety, to achieve the purpose of protection. The main point of shielding protection is to place a shielding material between the radiation source and the human body that can effectively absorb rays. Common shielding materials for X-rays are lead sheets and concrete walls, or barium cement (cement with barium sulfate – also known as barite powder) walls.
Post time: Sep-01-2022
