This standard specifies the overall layout and protection requirements in the design of gamma teletherapy rooms (hereinafter referred to as treatment rooms). This standard applies to the sanitary review and final acceptance of the protection facility design of newly built, rebuilt and expanded treatment rooms. GBZ/T 152-2002 Gamma teletherapy room design protection standard GBZ/T152-2002 Standard download decompression password: www.bzxz.net

Ics13.100
National occupational health standard of the People's Republic of China GBZ/T152-2002
Radiological protection requirementfor design of y-ray teletherapy rooms2002-04-08 Issued
Ministry of Health of the People's Republic of China
2002-06-01 Implementation
This standard is formulated in accordance with the "Law of the People's Republic of China on the Prevention and Control of Occupational Diseases". In case of any inconsistency between the original standard GB/T16136-1995 and this standard, this standard shall prevail. This standard is proposed and managed by the Ministry of Health.
Drafters of this standard: Qin Shizhong, Xiong Xiaoying. Drafting unit of this standard: Jiangxi Institute of Labor Hygiene and Occupational Disease Prevention and Control. The Ministry of Health is responsible for interpreting this standard.
1 Scope
Y Teletherapy Room Design Protection Standard
GBZ/T152-2002
This standard specifies the overall layout and protection requirements in the design of Y teletherapy rooms (hereinafter referred to as treatment rooms). This standard applies to the sanitary review and completion acceptance of the protection facility design of newly built, rebuilt and expanded treatment rooms. 2 Normative References
The clauses in the following documents become clauses of this standard through reference in this standard. For any dated referenced document, all subsequent amendments (excluding errata) or revised versions are not applicable to this standard. However, parties that reach an agreement based on this standard are encouraged to study whether the latest version of the document can be used. For any undated referenced document, its latest version applies to this standard.
GB4792
GB16351
3 Terms and definitions
Basic standards for radiation health protection
Radiation health protection standards for medical gamma-ray teletherapy equipment The following terms and definitions apply to this standard
3.1 Occupancy factor occupancy factor (n) indicates the degree of occupation of personnel in a certain area. The workload is multiplied by this factor to correct the occupation level of a certain area when the source is in the working position.
3.2 Utilization factor usefactor (U)
That is, the direction factor of the useful beam, which refers to the time fraction of the useful beam directed at a specific wall. 3.3 Workload workload
Refers to the degree of use of the Y source.
3.3.1 Workload of the useful beam (W)
Refers to the air kerma of the useful beam in one circle at a distance of 1m from the Y source. 3.3.2 Weekly workload of leakage radiation (W) refers to the air kerma of leakage radiation in one cycle at a distance of 1m from the y source. 4 Overall layout
4.1 The treatment room can be built separately or at one end of the ground floor of the building. 4.2 The treatment room and its auxiliary facilities, such as the operation room, examination room, waiting room, etc., should be designed at the same time and reasonably arranged according to the principles of safety, hygiene and convenience.
4.3 The treatment room should be connected to the operation room in the form of a maze. 4.4 The treatment room should have sufficient usable area, which should not be less than 30m. 4.5 When arranging the treatment machine, the useful wire bundle should not face the maze. 4.6 The treatment room should have good ventilation, generally 3 to 4 times of air change per hour. 3
5 Basic requirements for shielding protection design
5.1 Determination of shielding thickness
5.1.1 Use formula (1) to calculate the transmission of the useful wire bundle to determine its shielding thickness. B=Pd/WUT
transmission, the shielding thickness corresponding to the B value can be read from the transmission curves in Figures 1 and 2: Where: B
Distance from Y source to the examination point, m;
Working load of the useful beam, Gy·m/W: Utilization factor, read from Table 2:
Residence factor, read from Table 3:
Dose limit expressed in weekly dose equivalent, Sv/W (see Table 1). ETTTTTTTT
++++++L
Lead thickness, cm
Figure 1 Transmission curve of D-60 wide beam when passing through lead with a density of 11.35 g/cm2 (1)
10-stop
LuilLl
Radiation workers
Individuals in the public
Mixed soil thickness, cm
Figure 2 Transmission curve of Co-60 wide beam when passing through concrete with a density of 2.35 g/cm2Table 1 Dose limit P
Table 2 Utilization factor U
Useful beam fixed irradiation direction
Rotary therapy machine:||t t||Useful wire beam toward the wall
Full residence 7-1
Partial residence 7-1/4
Occasional residence T-1/16
Table 3 Residence factor T
mSv/week
Workrooms, offices, waiting rooms, residential areas and other places where people often live Public corridors, elevators operated by people, unattended parking lots and other places where people sometimes live Public bathrooms, toilets, places where a small number of pedestrians and vehicles pass by Use formula (2) to calculate the transmission of scattered rays to determine its shielding thickness Bs5.1.2
Bs=100Pds/WTS
Where: Bs||tt| | Scattered transmission, the shielding thickness corresponding to the Bs value can be read from the transmission curves of Figures 3 and 4: - The distance from the scattering radiator to the examination point, m; The percentage kinetic energy release rate of the incident radiation scattered to 1m, its value can be read from Table 4; (2)
w has the same meaning as formula (1). If the distance between the source and the scatterer is not 1m, it should be corrected according to the inverse square law; PT has the same meaning as formula (1)
Lead thickness.cm
Figure 3 Transmission curve of the diamond-60 wide beam scattered at different angles from the patient phantom when passing through the lead with a density of 11.35g/cm
Measurement conditions www.bzxz.net
Condition two
Mixed Concrete thickness, cm
Figure 4 Transmission curves of cobalt-60 wide beam gamma rays scattered from the patient phantom at different angles through concrete with a density of 2.35 g/cm2 Table 4 Percentage of kerma rate of cobalt-60 gamma rays scattered by an equivalent phantom of 400 cm2 to 1 m
Note: ① Condition 1 refers to an elliptical phantom with a major axis of 36 cm and a minor axis of 20 cm. The irradiation field area and scattering angle refer to the center of the phantom, and the beam is along the major axis:
② Condition 2 refers to irradiation on a spherical phantom with an equivalent phantom mass of 0.9~30 kg: ③ When the radiation source is placed in another room and the collimator is placed in the partition wall, the scattered radiation from the wall can be greatly eliminated. 5.1.3 Use formula (3) to calculate the Nm value of the leakage radiation to determine its shielding thickness. Nry=logioWTdp
Where: W is the weekly kerma rate of the leakage radiation in the air at 1m from the Y source: T, d and P have the same meanings as in formula (1).
....(3)
The corresponding calculated N value multiplied by the value given in Table 5 is the shielding thickness of the leakage radiation. Table 5 Approximate half-value thickness and one-tenth value thickness of cobalt-60 wide beam radiation Material
Concrete
Half-value thickness, cm
One-tenth value thickness, cm
5.2 According to the optimization principle, the dose limit P in Table 1 is used as the starting point for the shielding thickness calculation, and the P value is gradually reduced to calculate the shielding thickness 7
: Calculate the corresponding shielding cost and its increased cost according to each shielding thickness: Then calculate the corresponding reduction in collective dose equivalent (person·Sieve) and the cost per unit collective dose equivalent according to the service life of the treatment room and the expected maximum number of staff. Finally, determine the shielding thickness required to reduce the radiation to an acceptable level. 5.3 In the shielding protection design, the maximum workload of the equipment and the number of staff should be used. 5.4 The maximum possible values ​​of the residence factor and the utilization factor should be selected based on the natural conditions around the treatment room, the activities and distribution of personnel, etc.
5.5 When calculating the shielding thickness required for the useful beam, movable objects (such as simulation bodies and patients) that may absorb part of the radiation should not be taken into account.
5.6 When calculating the shielding thickness required for scattered and leaked radiation, the expected use conditions that produce the maximum scattered and leaked radiation should be used.
5.7 When the calculated shielding thickness of scattered and leaked radiation differs by a value of 1/10 or more, the thicker shielding should be used; if the difference is less than a value of 1/10, the thicker shielding should be used and enhanced by a half value of thickness.
5.8 When concrete is used as the shielding material, the material should be fully uniform and the shielding layer should not have cavities or gaps. If the density of concrete is not 2.35 g/cm, the formula (4) should be used for correction: the actual required concrete thickness
2.35×thickness required by the chart
actual density of concrete used
. (4)
5.9 The openings and conduits in the protective wall of the treatment room should be as far away from the radiation source and the position of the staff as possible: the hollow pipes in the protective wall must be bent.
5.10 When installing equipment, it must be ensured that the shielding of joints, nails, bolts or installation pipes and conduits is not affected. If the shielding performance is weakened by the pipes through the wall, shielding compensation should be increased. 6 Labyrinth, protective doors and ceiling
6.1 The height and width of the labyrinth and protective doors should be suitable for the convenience of the treatment machine and the patient stretcher trolley to enter and exit. 6.2 When the inner wall of the labyrinth (near the treatment machine) and the outer wall jointly protect the safety of a certain area outside the labyrinth, the shielding thickness can be calculated as a whole, and then divided equally between the inner and outer walls, and the inner wall can be appropriately made slightly thicker. If the inner and outer walls protect the safety of a certain area respectively, the shielding thickness should be calculated separately
6.3 The protective door should be equipped with an interlocking device between the radiation source control system and the protective door to ensure that the machine can only be turned on after the door is locked. After the machine is turned on, the door cannot be opened, but the door can be opened from the irradiation room. 6.4 Sound and light alarm devices should be installed outside the protective door. 6.5 The protective door should be able to effectively shield scattered rays so that the radiation level outside the door meets the corresponding protection requirements. 6.6 The shielding thickness of the ceiling of the treatment room in a single-story building should be designed based on the impact of the rays penetrating the ceiling on the ground through air scattering, and the impact of the rays at a 45-degree angle of the Y source on nearby buildings or workplaces that are higher than the ceiling of the treatment room. If the treatment room is built on the ground floor of a building, the shielding thickness of its ceiling should be calculated based on the usage of the adjacent rooms. 6.7 The treatment room should not have windows. If it is necessary to open a window, a small window should be opened on the ceiling of a single-room building or on a high wall where no useful beam is projected, and its shielding compensation should be calculated.
6.8 The operation room should be equipped with monitoring and intercom devices for the treatment room.
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