The hazards of various radiation sources to human body in hospitals are carried out by invisible rays, which are difficult to detect, and therefore easy to be ignored. In order to ensure the safety of medical staff, patients and other personnel, it is necessary to do a good job of radiation protection in hospital construction. If the protection is not in place, it will not only threaten the safety of the relevant personnel, but also make the corresponding functional areas unable to pass the acceptance check and acceptance, resulting in the unavailability of use, thus bringing losses to the hospital.
Areas requiring radiation protection
Because radiation is harmful to human body and environment, the areas where radiation is produced need to be protected. As far as departments are concerned, radiology, nuclear medicine and radiotherapy all produce radiation. With the development of technology, hybrid operating rooms have emerged, and X-ray-producing equipment such as CT has entered the operating room, so this kind of operating room needs to be protected. In addition, some hospital laboratories will use radiopharmaceuticals, but also need a certain degree of protective treatment.
Types of radiation
According to the different sources of radiation, hospital radiation can be divided into active radiation and passive radiation.
Radiology department's DR, CT, gastrointestinal machine and other equipment only produce X-ray in the working process, X-ray radiation to the human body. This is called passive radiation.
Radioactive drugs are often used in radiotherapy and nuclear medicine. These drugs produce radiation at any time and anywhere, such as technetium-99, iodine-131, fluorine-18, etc. In addition, some equipment still has correction sources, and the radioactive materials used in correction sources are also producing radiation at any time and anywhere. These two conditions are called active radiation. At the same time, passive radiation also exists in these two departments because of the use of equipment capable of producing radiation. Taking PET-CT in nuclear medicine as an example, it is the combination of active radiation and passive radiation. Its active radiation comes from drug sources and correction sources, including radiopharmaceuticals such as fluorine-18. The correction sources are germanium 68 (one is a cylinder about 5 cm in diameter and 45 cm in length, the other is a semi-cylinder about 30 cm in diameter and 40 cm in length); the passive radiation comes from CT.
Requirements for radiation protection
Radiation protection in hospitals must meet the requirements of national laws, regulations and standards. For example, the area of various computer rooms can not be less than the provisions of relevant standards, as long as the corresponding area is reached, it can play a certain protective effect. According to the requirements of "Radiation Protection Requirements for Medical_-ray Diagnosis" (GBZ130-2013), the minimum effective use area of CT room is not less than 30 square meters, and the minimum unilateral length of the room is 4.5 meters.
In addition to meeting the requirements of area and unilateral length, some high-density materials should be used for protection in order to meet the requirements of relevant laws, regulations and standards.
Common protective materials
There are three commonly used materials for radiation protection: reinforced concrete, barium sulfate and lead skin. These three materials have their own characteristics.
Nowadays, many hospitals use lead skin as protection, which has the advantages of convenient construction, good protection effect and easy disassembly and alteration. The disadvantage is that the cost is relatively high, but not particularly high.
The advantages of cast-in-situ reinforced concrete are easy construction and low cost. The biggest disadvantage of cast-in-situ reinforced concrete is that it is very difficult to demolish the reinforced concrete once the function of the house needs to be rebuilt.
The use of barium sulfate as protection has the advantages of low cost and easy disassembly and modification; the biggest problem is that cracking occurs easily over time. Because the exterior of the wall usually has decorative layer, even if cracks occur, it is difficult to find from the exterior. Once the radiation leakage is detected, the machine must be shut down, and then the protective layer is dismantled and repaired, which will bring great losses to the hospital.
The author suggests that lead skin should be used as far as possible in the protection of Radiology and nuclear medicine. Considering the protection effect, the difficulty of decoration and reconstruction, the cost-effective ratio of lead-skin protection is relatively high. If cast-in-situ concrete or barium sulfate is used, some money will be saved at first, but in the long run, it is not necessarily cost-effective.
For radiotherapy department, reinforced concrete should be used for radiation protection. Radiotherapy Department has set up a variety of radiotherapy equipment, in order to meet the requirements, the wall thickness of equipment room is also different, generally about 2 meters. For this thickness of reinforced concrete wall, if the same protective effect is achieved with lead plate, then the cost is too high.

Common Problems of Radiation Protection in Hospitals
The most direct result of inadequate radiation protection in hospitals is that they can not pass the acceptance test, which prevents the corresponding departments from being put into use.
To sum up, there are two reasons that lead to the failure of acceptance of radiation protection projects in hospitals: one is that the area and unilateral size do not meet the requirements; the other is that the radiation leakage is caused by problems in design, construction and materials.
For the room area of all kinds of equipment that can generate radiation, the relevant standards and specifications have clear requirements. For this kind of request, basically can satisfy. But it is worth noting that while meeting the area requirements, the size of the room should be easy to use. Although the area of some rooms is up to the standard, it is very inconvenient to use because of the unreasonable shape. In addition, if the computer room wants to be put into normal use, it also needs some auxiliary rooms and facilities, which must be taken into account in the design process.
In addition to area, the requirement of minimum one-sided size should be paid attention to, especially when there are pillars with prominent wall in the computer room that change the shape of the edge of the room, it is necessary to ensure that the dimensions of each one-sided meet the requirements, otherwise the acceptance can not pass. The requirement of minimum unilateral dimension not only limits the shape of the room to a certain extent, makes the room easy to use, but also plays a certain distance protection effect.
Designers should fully understand the basic starting point of the requirements of the standards and specifications, so as to make a more reasonable design.
The cause of radiation leakage is the problem of radiation protection in the final analysis. Whether radiation protection can achieve the desired effect depends on many factors such as design, construction, materials and so on. For example, the protection level of the design does not meet the requirements, the lead sheet joints, window frames and doorframes in the construction process are not properly handled, and the quality of the selected protective doors and windows is not up to the standard.
In the radiation protection project of the hospital, the designer may not be very familiar with the work flow of the hospital and the protection requirements of each area, and the builder often knows little about the radiation protection. Therefore, in order to ensure the quality and effect of the radiation protection project, the hospital needs to send a person who has all the relevant knowledge. Personnel who must know will participate in the whole process, find out problems in time, and put forward opinions and suggestions.
Source: China Hospital Architecture and Equipment Magazine
Author: Kang Yadong, Peking University People's Hospital