This standard specifies the protection requirements and equipment testing for afterloading gamma source brachytherapy (hereinafter referred to as "afterloading radiotherapy") equipment, radiotherapy rooms and afterloading radiotherapy. This standard applies to the practice of brachytherapy using sealed gamma source afterloading technology. GBZ 121-2002 Health Protection Standard for Afterloading Gamma Source Brachytherapy GBZ121-2002 Standard Download Decompression Password: www.bzxz.net

ICS13.100
National occupational health standard of the People's Republic of China GBZ121-2002
Radiological protection standards for gamma-ray afterloading brachytherapy2002-04-08 Issued
Ministry of Health of the People's Republic of China
2002-06-01 ImplementationWww.bzxZ.net
1 Scope
2 Normative references
3 Terms and definitions
4 Protection requirements for afterloading radiotherapy equipment
5 Protection requirements for afterloading radiotherapy rooms
6 Protection requirements for afterloading radiotherapy
7 Inspection of afterloading radiotherapy equipment
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 GB163641996 and this standard, this standard shall prevail. Chapters 4 to 7 of this standard are mandatory contents, and the rest are recommended contents. This standard is proposed and managed by the Ministry of Health.
The drafting unit of this standard: Institute of Radiation Medicine, Shandong Academy of Medical Sciences. The main drafters of this standard: Zong Xiyuan, Deng Daping, Sun Zuozhong, Yang Yingxiao, Qiu Yuhui. This standard is interpreted by the Ministry of Health.
GBZ121-2002
1 Scope
Health protection standard for afterloaded gamma source brachytherapy This standard specifies the protection requirements and equipment testing for afterloaded gamma source brachytherapy (hereinafter referred to as "afterloaded radiotherapy") equipment, radiotherapy rooms and afterloaded radiotherapy. This standard applies to the practice of brachytherapy using sealed gamma source afterloading technology. 2 Normative references
The clauses in the following documents become the clauses of this standard through reference in this standard. For all dated referenced documents, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties to an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For undated references, the latest version shall apply to this standard. GB2894 Safety signs
GB4076 General provisions for sealed radioactive sources
GB11806 Regulations for safe transportation of radioactive materials 3 Terms and definitions
The following terms and definitions apply to this standard. 3.1 Afterloading techniques Afterloading techniques The technique of correctly placing the source applicator at the part of the patient that needs treatment in advance, and then using automatic or manual control to input the radioactive source in the source storage device into the source applicator for treatment. 3.2 Afterloading y source brachytherapy Radiation source afterloading brachytherapy A radiotherapy method that uses afterloading technology to achieve a predetermined dose and its distribution in accordance with clinical requirements by making the y radioactive source reside in the natural cavity, duct or tissue of the human body. 3.3 Store container
A container for storing radioactive sources for afterloading therapy. It includes a transport source storage device for transporting (or temporarily storing) radiotherapy sources and a working source storage device for afterloading machines. 3.4 Applicators Radiation sources applicators are special containers that are pre-placed into human cavities, pipes or tissues for the radiation source to reside or move and to implement treatment, also known as applicators. For example, needles, tubes or applicators with other special shapes. 4 Protection requirements for afterloaded radiotherapy equipment
4.1 Radiation sources
4.1.1 The radiation sources used for afterloaded radiotherapy must comply with the provisions of GB4076. 4.1.2 The radiation source must have an instruction manual and inspection certificate provided by the manufacturer. The instruction manual should state the radiation source number, nuclide name, chemical symbol, equivalent activity, surface contamination and leakage detection date and production unit name, etc.
4.1.3 Before using the radiation source, there must be a reference point air kerma rate approved by the statutory metrology agency, and its total uncertainty shall not exceed ±5%.
4.1.4 The replacement of the radiation source must be carried out by qualified professional technicians under the supervision of radiation protection personnel.
4.1.5 The transportation of radioactive sources must comply with the provisions of GB11806. 4.1.6 Decommissioned radioactive sources must be promptly returned to the original manufacturer or sent to a designated radioactive waste repository for unified treatment or proper storage.
4.2 Storage container
4.2.1 The surface of the radioactive source storage container must be marked with the name of the radioactive nuclide, the maximum allowable loading activity and a firm and eye-catching ionizing radiation warning label (see GB2894). 4.2.2 When the transport source container (or working source container) is loaded with the maximum allowable activity, the air-specific kinetic energy rate of the leaked radiation at any position 5 cm away from the surface of the source container shall not be greater than 100uGy·h. On the spherical surface 100 cm away from the surface of the source container, the air-specific kinetic energy rate of the leaked radiation at any point shall not be greater than i0μGy.h
4.2.3 Except for transportation, the transport source container (or working source container) loaded with therapeutic radioactive sources must be stored in a radiotherapy room or a special source storage room where general personnel are restricted from entering. 4.3 Applicator
The shape, structural design and material selection of the applicator should be adapted to the characteristics of the target area, ensure that the radioactive source stays or moves normally in it, and form various predetermined dose distributions in accordance with the principles of dosimetry to maximize the protection of adjacent normal tissues and organs. 4.4 Control and transmission of radiation sources
4.4.1 The control system of the afterloading treatment equipment must be able to accurately control the irradiation conditions, and should have the source position display of the radiation source starting, transmission, residence and return to the working source storage device, as well as the display of the treatment date, channel, total irradiation time and countdown time
4.4.2 The control system of the afterloading treatment equipment should have multiple protection and interlocking devices such as safety locks. It must be able to prevent the patient from being irradiated due to electrical or mechanical failures or misoperation such as failure of timer control, radiation source transmission system, source channel or control program errors, and radiation source connection disconnection. It is strictly forbidden to operate under the condition of removing the protection and interlocking control devices. 4.4.3 During the treatment, when a power outage, source jam or accidental interruption of irradiation occurs, the radiation source must be able to automatically return to the working source storage device. The irradiation time and dose must be displayed and recorded at the same time until the next irradiation begins, and an audible and visual alarm signal should be issued. When the automatic source return device fails, manual source return measures must be taken for emergency treatment. 4.4.4 On the control console, the status of the radioactive source being output from the working source storage device and returning to the storage position must be displayed through the Y-ray monitoring
4.4.5 The timing error of controlling the irradiation time must be less than 1%. 4.4.6 The radioactive source transmission pipeline connecting each channel of the source applicator with the source applicator and the source applicator should be as smooth as possible and have an allowable minimum curvature radius to ensure unimpeded transmission of the radioactive source. 4.4.7 When connecting the source applicator with the radioactive source transmission pipeline, the joint must be tightly and firmly connected to prevent the radioactive source from rushing out or falling off.
4.4.8 The deviation of the radioactive source from being transmitted to the stationary position in the source applicator shall not be greater than ±1mm. 4.4.9 The maximum number of safe transmission times of the radioactive source given by the manufacturer must be within the range without any faults such as the radioactive source falling off or getting stuck.
4.4.10 The maximum transmission time of the radioactive source from the source storage device to the source applicator must be given in the documents accompanying the radiotherapy machine.
5 Protection requirements for afterloading radiotherapy rooms
5.1 The radiotherapy room must be designed by professionals, and the treatment room must be separated from the preparation room and the control room. The usable area of ​​the treatment room should not be less than 20m. 5.2 The entrance to the treatment room must adopt a maze design, with door interlocks, and sound and light alarms on the door of the treatment room. An emergency switch and a radiation source monitor should be installed in the treatment room to quickly return the radiation source to the source storage device.
5.3 The shielding thickness of the walls and protective doors of the treatment room should comply with the principle of optimal protection to ensure that the radiation dose of the staff and the public is less than the corresponding annual dose limit. 5.4 An observation window (or monitor) and an intercom should be installed between the control room and the treatment room. 6 Protection requirements for afterloading radiotherapy
6.1 A quality assurance plan must be formulated and implemented to ensure accurate doses. It can not only enable the treatment area to obtain a reasonable dose and its distribution, but also minimize the radiation dose and range of normal tissues. 6.2 During treatment, the technicians must closely monitor the various displays of the control system and the patient's condition in order to promptly detect and eliminate abnormal conditions.
6.3 During radiotherapy, the treatment date, treatment method, treatment source type, activity, number, channel, irradiation time, single irradiation dose and total dose, and the location of the radiation source in the applicator and irradiation length must be recorded in detail, and a schematic diagram must be drawn for archiving.
6.4 During treatment, no one except the patient may stay in the treatment room. 7 Inspection of after-loading radiotherapy equipment
7.1 Acceptance test Before the newly installed or overhauled aftertreatment equipment is officially put into use, professional technicians must be organized to conduct acceptance tests. The test items are as follows: a) Measurement of the leakage radiation air kerma rate at any position 5 cm away from the source surface and at any point 100 cm away from the source surface; Note: 1) When measuring at 5 cm away from the source surface, the average value of the leakage radiation air kerma rate should be taken within a range of no more than 10 cm.
2) When measuring at 100 cm away from the source surface, the average value of the leakage radiation air kerma rate should be taken within a range of no more than 100 cm.
b) Inspection of the source position indication, sound and light alarm, dose monitoring, monitor, intercom and timer operation functions of the afterloader console;
c) Measurement of the air kerma rate of the reference point of the radiation source: d) Functional inspection of the movement state (residence, stepping and oscillation) of the radiation source in the transmission system and the applicator and the return to the reservoir:
e) Determination of the transmission time of the radiation source from the reservoir to the predetermined position in the applicator; f) Error inspection of the afterloader control timer: Note: Select 5 preset irradiation times (not less than 1% of the maximum preset value), measure and calculate the average percentage error of the actual duration of each preset time, and then calculate the average of the average percentage errors of the 5 preset irradiation times.
g) Calibration of the radiation dose monitoring instrument; h) Surface contamination and leakage of the radiation source, surface contamination detection of the applicator, treatment bed and other equipment; i) Deviation inspection of the resident position of the radiation source in the applicator; j) Measurement of the radiation level in the treatment room and its surrounding environment. 7.2 Regular Inspection
The treatment equipment in use must be inspected regularly. The inspection items and cycles are as follows: Items a), c), f), g), and h) in 7.1 once a year; Items e), f), and i) in 7.1 once a month; Items b) and d) in 7.1 once a day. When any of them is suspected of being damaged or having problems or other issues, inspections should be carried out at any time. 7.3 Source Replacement Inspection After each replacement of the radiation source in the after-treatment machine, items a), c), h), i), and j) in 7.1 should be inspected once.
7.4 Decay correction of the effective activity of the radiation source and the reference point air kerma rate, 19Ir once before each irradiation; \Co once a month, 13Cs once every six months.
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