Founded in March 1950, macheng people's hospital is a modern comprehensive hospital integrating medical treatment, teaching, prevention, health care, rehabilitation, first aid and community services. The hospital has strong technical force, advanced medical equipment and complete clinical departments.
In order to meet the treatment of tumor patients, the hospital built a new three-storey radiotherapy building in early 2014, and introduced medical linear accelerator, radiation therapy simulator and other radiotherapy and treatment equipment to carry out the tumor radiation treatment project. Now the building has been completed, the equipment has been installed and debugged, and all the protective facilities have been reformed and put in place.
X-ray linear accelerator, radiation therapy, simulator, X-ray useful wire can effectively improve the diagnosis of disease and treatment of tumors, but they are also one of the occupational-disease-inductive factors, the construction unit may entrust in hubei province in 2015, to science and technology co., LTD. (hereinafter referred to as the company) of the construction project occupational disease hazard control effect on radiological protection.
The new medical linear accelerator, radiation therapy simulator, CT simulator positioning machine room, operation control room and corresponding auxiliary room are newly built in the new radiation therapy building of the people's hospital of macheng. Precise Precise accelerator, GE LIGHTSPEED PLUS CT simulator locator and shandong xinhua SL-IC radiation therapy simulator are installed respectively.
The evaluation scope of this evaluation report includes two control areas and supervision areas of the medical linear accelerator machine room and the radiation therapy simulation machine room of the construction project. The control areas of the project include the medical accelerator treatment room, the diagnostic room of the radiation therapy simulator, the monitoring area including the control room and the related auxiliary rooms. The personnel involved include radiation workers and the public who may enter the surveillance area.
In the future, the occupational-disease-inductive factors caused by the change of equipment and protective facilities in this project will not be included in the evaluation scope of this report.
Analysis of occupational-disease-inductive factors
1. analysis of radioactive hazard factors
The main radiation produced is x-rays, as well as electron lines, neutrons and induced radioactivity.
2. non-radioactive hazard factor analysis
The main products are ozone (O3) and nitrogen oxides (NO and NO2).
Radiation protection measures
1 verification of protective shielding facilities
1.1 accelerator room:
(1) shielding thickness: the accelerator treatment room has been built with an area of about 67.2m2 (including the maze) and a floor height of 4.20m. The maze length and width are set at 9.2m and 2.0m. The linear accelerator machine room is built on one floor, and there is no building on the top of the machine room. All the surrounding walls, baffles and ceiling of the accelerator room are irrigated with barite concrete (3.5t/m3) once, and the protective door is shielded with 15mmPb, 4mm steel plate and 76mm 5% boropolyethylene, effectively preventing neutron leakage.
(2) protective measures against poisonous and harmful gases: the machine room adopts upper air supply and lower air discharge to organize ventilation. When the central air conditioner is used to supply the air, the air inlet is set on the upper part of the west side of the machine room. The ventilation and ventilation times of the mechanical ventilation system of the new air unit are designed according to 8 times per hour. The inlet pipe is "Z", which enters the machine room from the labyrinth top of the machine room into the machine room. The outlet is located under the east side wall with 2 outlets. Two doors are set between the treatment room and the maintenance room, and the upper and lower parts of each door are used to exchange indoor air with a hundred window.
(3) protective safety device
In order to ensure the safety of treatment process, a series of safety interlocking devices and safety measures are set up in the linear accelerator site: (1) interlocking of protective door, lamp and machine: interlocking of infrared control door and machine. (2) timer - source switch interlock: there are two timers, primary and secondary. The main timer terminates radiation when the preset time is reached. When the primary timer fails, the slave timer can also independently terminate the irradiation. (3) emergency stop switch. There are 7 emergency switch buttons in the accelerator treatment room (3 treatment rooms, 1 lost, 2 treatment beds and 1 control room). (4) the equipment is equipped with standby power source (UPS). When the power supply is suddenly interrupted, the standby power supply can continue to power for 10 minutes and send a prompt signal at the same time. (5) a fixed radiation monitor is installed in the control room, and when the dose is more than 2.5 oxidation Sv/h, a sound and light alarm signal is issued.
1.2 radiation therapy simulation machine room:
(1) shielding thickness: the radiation therapy simulation machine room is located on the first floor of the radiotherapy department, with the common wall between the west wall and the accelerator machine room and the area of the radiation therapy simulation machine room: 30.86m2, 6.2 meters long, 5.3 meters wide and 3.05 meters high. The surrounding walls are made of 200 mm thick concrete (density > 2.35t/m3) cast-in-place bricks with barium sulfate 30 mm single-side brush. The protective door of the machine room USES 4mmPb, and the observation window USES 4mmPb lead glass.
(2) protective measures against toxic and harmful gases: central air conditioning is adopted in the room of the radiation therapy simulator (FIG. 4-5) to regulate indoor air, which can effectively eliminate ozone and nitrogen oxides caused by radiation.
Radiation monitoring and evaluation
The rating agencies use IBA dosed 1 treatment DOSE meter, SRT - 200 standard water filling die bodies and use TN12000 dosimeter and die bodies of form a complete set, on the accelerator and radiotherapy simulator for the protective performance testing, using 451 p pressurized ionization chamber survey instrument of radiological diagnosis and treatment of two levels of workplace protection detection, validation of the protective effect of shielding measures testing results show that the radiation protection equipment protective performance index and the workplace level are accord with the requirement of radiological health standard, verify the shielding effect is ideal, The requirements of the construction unit on the constraint value of dose management are realized.
The main occupational-disease-inductive factor of this construction project is high-energy X-ray. According to article 4 of article 25 , the construction project belongs to the construction project with serious hazards, which was issued by the former ministry of health in accordance with the regulations on the hygienic examination and management of the construction project of radiation diagnosis and treatment. The site of the construction project has a reasonable layout. Ventilation, protective door, wall shield thickness, test hole cable hole and dose alarm are all in place. Shielding and protection facilities such as walls, ceiling, ground and protective doors, ventilation, safety interlock, warning signs and other safety facilities around the control area of the radiation workplace can effectively control the occupational disease hazards caused by the project during normal operation and comply with relevant laws, regulations and standards