Some standard content:
ISC13.100
National Occupational Health Standard of the People's Republic of China GBZ
GBZ131-2002
Standards for radiological protection in medical X-ray therapy
Standards for radiological protection in medical X-ray therapy2002-04-08 Issued
Ministry of Health of the People's Republic of China
Implementation on 2002-06-01
Normative references
Technical requirements for protection performance of treatment machines
Protection requirements for treatment rooms
Protection requirements for radiotherapy
Testing methods
This standard is formulated in accordance with the Law of the People's Republic of China on the Prevention and Control of Occupational Diseases. If there is any inconsistency between the original standard GB18464-2001 and this standard, this standard shall prevail. Chapters 3 to 7 of this standard are mandatory contents, and the rest are recommended contents. This standard specifies the radiation protection performance of medical X-ray therapy machines, the radiation protection conditions of the places where the therapy machines are used, and the technical requirements for radiation protection and safety of radiotherapy using therapy machines.
This standard is proposed and managed by the Ministry of Health.
The drafting unit of this standard: Beijing Institute of Radiation Health Protection. The main drafters of this standard: Wang Shijin and Ma Yongzhong. The Ministry of Health is responsible for interpreting this standard
1 Scope
Health Protection Standard for Medical X-ray Therapy
GBZ131-2002
This standard specifies the radiation protection performance of medical X-ray therapy machines and their inspection requirements, the radiation protection conditions of the treatment room, and the safe operation and quality assurance requirements for radiotherapy using therapy machines. This standard applies to the production and use of medical X-ray therapy machines (hereinafter referred to as therapy machines) with a nominal X-ray tube voltage of 10kV to 1MV.
This standard does not apply to X-ray therapy using medical accelerators. 2 Normative references
The clauses in the following documents become the clauses of this standard through reference in this standard. For all dated references, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties reaching an agreement based on this standard are encouraged to study whether the latest versions of these documents are applicable. For all undated references, the latest versions are applicable to this standard.
GB9706.10 Medical electrical equipment Part 2: Special safety requirements for therapeutic X-ray generating devices. GB9706.12 Medical electrical equipment Part 1: General safety requirements Three parallel standards: General requirements for radiation protection of diagnostic X-ray equipment.
3 General
3.1 Medical X-ray therapy must follow the basic principles of radiation protection, requiring justification of exposure, optimization of radiation protection, and ensuring that the exposure of workers and the public does not exceed the prescribed dose limit: The medical exposure received by the beneficiaries should follow the principles of justification of practice and optimization of protection.
3.2 Medical X-ray therapy must take safety measures to minimize or avoid major exposure incidents and adverse consequences.
Technical requirements for protective performance of treatment machines
4.1 Limitation of leakage radiation of treatment machines
4.1.1 In the treatment state, the leakage radiation of the X-ray source assembly shall be controlled according to Table 1. 4.1.2 In the non-treatment state, the control value of the leakage radiation and non-useful radiation of the X-ray source assembly When the X-ray source is in a non-treatment state where the treatment is manually interrupted and the X-ray tube high voltage is still energized, or the scheduled treatment is terminated and the X-ray tube high voltage is disconnected, starting from 5s after the interruption or termination of the radiation beam emission, the air kerma rate control value shall not exceed 0.02mGy/h at 1m from the focus of the X-ray tube (including the treatment beam direction): at 50mm from the surface of the X-ray source assembly, it shall not exceed 0.2mGy/h. Table 1 Control value of leakage radiation of X-ray source assembly under treatment status Rated voltage of X-ray tube, KV
≤150
Control value of air kerma rate, mGy/h
50mm from the surface of source assembly300
1m from the focus of X-ray tube10
1m from the focus of X-ray tube1
50mm from the surface of source assembly1
Note: 1) X-ray source assembly includes beam limiter fixedly mounted on the X-ray tube sleeve 2) Suitable for handheld treatment machine
4.1.3 Control level of leakage radiation of detachable beam limiter The detachable beam limiter refers only to the integral fixed part of the light collecting tube or adjustable beam limiter that is directly connected to the X-ray tube assembly but can be detached. Under the condition of full shielding of the irradiation field at the outlet of the detachable beam limiter, the relative air kerma rate outside the irradiation field of the beam limiter shall not exceed the control level in Table 2.
Table 2 Relative leakage radiation control level of removable beam limiter The size of the shielding lead plate at the beam limiter outlet is a multiple of the corresponding size in the horizontal (vertical) direction of the irradiation field 1.5 times
Relative leakage radiation of removable beam limiter!
Control level, %
Note: 1) The maximum air kerma rate at any position 20mm away from the edge of the lead plate accounts for the percentage of the air kerma rate at the midpoint of the beam when there is no lead plate on the same plane 4.1.4 Leakage radiation control values of other components except X-ray source assembly Except for the X-ray source assembly, the air kerma rate at any position 50mm away from the surface of any component of the X-ray machine shall not exceed 0.02mGy/h.
4.2 Technical requirements related to the radiation output of the useful beam 4.2.1 Repeatability of cumulative radiation output
The repeatability of the cumulative air kerma of the useful beam in the irradiation field shall not exceed 5% (X-ray tube voltage ≤ 150kV) and 3% (X-ray tube voltage > 150kV).
4.2.2 Linearity of cumulative radiation output
The nonlinearity of the cumulative air kerma of the useful beam in the irradiation field shall not exceed 5% 4.3 Treatment machine console
The console shall have the following safety control devices: (1I) Main power lock.
(2) Confirmation device for preset irradiation conditions. (3) Device for starting irradiation after confirming that the irradiation conditions are correct. (4) Device for interrupting irradiation in an emergency. (5) Radiation safety and interlocking device (see Section 4.5 for details). 4.4 Timer and dose monitor
The timer and dose monitor of the treatment machine should be able to prevent accidental failures that automatically terminate irradiation. The requirements are as follows: (1) When the treatment machine is equipped with two timers or two dose monitors, they must be configured in parallel or in a primary/secondary combination. Each of them must be able to terminate irradiation independently. (2) When the preset value is reached, the two systems in the parallel combination or the main system of the primary/secondary combination must terminate irradiation. If the irradiation is not terminated due to a failure of the main system of the primary/secondary combination and exceeds 10% of the preset value, or the timer exceeds 0.1min, or the absorbed dose of the dose monitor at the corresponding nominal distance exceeds 0.1Gy, the secondary system must immediately terminate irradiation. 4.5 Radiation safety and interlock requirements
4.5.1 The treatment machine must have safety equipment that can interrupt irradiation and display the corresponding fault when any error or failure in Articles 4.5.2-4.5.5 occurs.
4.5.2 Protection against failure of mobile device of X-ray source assembly When the treatment machine is irradiating, if the mobile device of X-ray source assembly relative to the patient is stuck, blocked or has other movement failures during the execution of preset movement instructions, the protection device shall automatically interrupt the irradiation. 4.5.3 Prevention of accidental irradiation when the X-ray tube is powered on This device may be a radiation absorbing component such as a shutter, and its operation shall be as follows: (1) If the absorbing component does not work properly, it is impossible to power on the X-ray tube. 5
(2) When the tube is powered on, failure of the absorbing component shall cause the X-ray tube to be powered off. (3) When the radiation beam stops emitting, the absorbing component shall work properly. 4.5.4 Prevention of accidental irradiation when combined irradiation conditions are misplaced Combined irradiation conditions include X-ray tube voltage, X-ray tube current, fixed and additional filters, beam limiter (adjustable beam limiter or light collecting tube), and X-ray source assembly mobile device and other irradiation conditions related to patient treatment. When the combined irradiation conditions set by the control console have any of the following conditions, the treatment machine cannot output radiation: (1) Not preset according to the treatment plan.
(2) The preset exceeds the performance index of the equipment. (3) The preset conditions are incorrect (such as improper placement of filters and beam limiters or wrong placement directions). (4) When the combined irradiation conditions can be set at the console inside and outside the treatment room, the settings at the console are inconsistent with the settings at the machine.
(5) The preset is not confirmed and tested by the console. 4.5.5 Preventing people from entering the treatment room by mistake
The protective door of the treatment room must be interlocked with the working state of the treatment machine. Irradiation can only be carried out when the door of the treatment room is closed; if the protective door is accidentally opened during the irradiation state of the treatment machine, the irradiation will be interrupted. Preventive measures should be taken to prevent the protective door from being accidentally opened during irradiation, and the console should have a corresponding display at this time. 4.6 Starting and stopping radiation beam emission
(1) Under normal circumstances, the combination conditions described in Article 4.5.4 must be set in sequence, and after the console confirms and verifies that the settings are correct, the irradiation is started by the "Start" button. The irradiation is automatically terminated after the preset irradiation is completed. (2) Under normal circumstances, the radiation beam must be emitted again, and the above steps must be reset and operated. (3) Under abnormal circumstances, the safety device in Article 4.5 will interrupt the irradiation. At this time, the irradiation can only be started by the "Start" button after the fault is eliminated and the console is "restored" to continue to complete the original preset irradiation; or the irradiation can be started again after resetting.
4.7 Special requirements for handheld therapeutic devices
(1) The nominal voltage of the X-ray tube of the therapeutic device shall not be greater than 50kV(2) The X-ray tube assembly shall have other fixing methods besides hand-held. (3) The power on of the X-ray tube can only be controlled by the staff holding the X-ray tube assembly. (4) There must be sound and light warning signals indicating that the X-ray tube is powered on. (5) The therapeutic device must be equipped with personal protective hats, gloves and aprons, whose attenuation of X-rays is not less than 0.25mm lead equivalent, and the requirements for reminding the operator to use these protective equipment are given in the random documents. 4.8 Component specification marking and random documents
4.8.1 Component specification marking
The therapeutic device and its components must have the following firm, clear and recognizable markings: 1) On the surface of the X-ray source assembly, mark the position of the focus and the material and thickness of the fixed filter. (2) The material, thickness, insertion direction mark and working status indication after insertion of the removable additional filter. (3) The nominal size of the irradiation field at the far end of the treatment beam focusing tube and the distance from the focus to the far end. (4) The size of the irradiation field of the adjustable beam limiter and the indication of the nominal focal-skin distance. (5) The equivalent thickness or attenuation factor of the protective equipment accessories for X-ray attenuation. 4.8.2 Random documents
The random documents of the treatment machine must comply with the requirements of GB9706.10. 4.9 Irradiation field and others
The irradiation field and others shall comply with the applicable general requirements for radiation protection in GB9706.12. 5
Protection requirements for treatment rooms
5.1 The setting of the treatment room must fully consider the safety of the surrounding area and personnel, and it can generally be located at one end of the ground floor of the building. The treatment room of the treatment machine above 50kV must be separated from the control room. The treatment room should generally be no less than 24m2. No sundries unrelated to treatment should be placed in the room.
5.2 The walls of the treatment room in the direction of the useful beam shall be designed according to the main ray shielding requirements, and the buildings in other directions shall be designed according to the leakage and scattered ray shielding requirements.
5.3 The treatment room must have equipment for observation of treatment (such as industrial television or observation window). The observation window should be set on the wall in the direction of the non-useful beam and have the shielding effect of the same side wall. 5.4 Equipment for forced termination of irradiation for emergency use should be installed at an appropriate location in the treatment room. 5.5 The door of the treatment room should be set away from the irradiation of the useful beam. The door of the treatment room without maze must have the same screening effect as the same side wall.
5.6 There should be a component next to the door of the treatment room for emergency opening of the door of the treatment room. 5.7 The door of the treatment room must be equipped with the interlocking device of Article 4.5.5, and there should be a conspicuous irradiation status indicator light and ionizing radiation warning sign near the door.
5.8 The treatment room should be well ventilated. The holes for cables, pipes, etc. passing through the walls of the treatment room should avoid useful wire bundles and control consoles where personnel often stay, and use arc holes, curved paths or trenches. Protection requirements for implementing radiotherapy
6.1 Requirements for the legitimacy of radiotherapy
A prescription management system must be established for radiotherapy, and only qualified prescribing physicians can apply for X-ray treatment. Prescribing physicians must analyze and judge the legitimacy of X-ray treatment based on the patient's condition to avoid improper X-ray treatment. 6.2 Optimizing treatment plans
6.2.1 While applying the required dose to the target volume planned for irradiation, the irradiation of normal tissues during radiotherapy should be kept at the lowest level that can be reasonably achieved. 6.2.2 The optimization of treatment plans should include: analyzing the radiation and non-radiation treatments that the patient has undergone; formulating single irradiation fields or superimposed irradiation fields and the dose given to the lesion tissue by each irradiation field according to the lesion conditions; selecting treatment irradiation conditions: taking shielding and reasonably planned irradiation measures to protect the patient's normal tissues and important organs. 6.3 Requirements for protective safety operation
(1) Operators must be proficient in and strictly follow the operating procedures. Important safety operation contents must be prominently displayed in the control room of the treatment machine.
(2) Radiotherapy operators must wear personal dosimeters. During the treatment process, operators must always monitor the console and patients and eliminate unexpected situations in a timely manner. (3) Operators must not remove radiation safety and interlocking devices without authorization. When maintenance is required, it must be approved by the responsible personnel and a notice must be posted on the console that the treatment machine is under maintenance. After maintenance, the safety and interlocking devices must be restored in a timely manner, and their control functions must be checked to be normal. Radiotherapy irradiation can only be carried out after confirmation by the responsible personnel. (4) When irradiating with a treatment machine above 50kV, no other personnel should stay in the treatment room except the patient. (5) When using a handheld treatment machine below 50 kV, the operator must wear protective gloves and an apron with a lead equivalent of not less than 0.25 mm, and stay as far away from the X-ray tube assembly of the treatment machine as possible. 6.4 General requirements for quality assurance
6.4.1 Radiotherapy should be equipped with qualified personnel such as corresponding treatment physicians, physicists, technicians, etc. 6.4.2 Radiotherapy should establish a quality assurance management organization and formulate a quality assurance outline, establish a verification system for the implementation of treatment plans, and keep treatment records intact.
6.4.3 Radiotherapy must frequently and regularly check the radiation output of the treatment machine to ensure that the deviation between the absorbed dose received by the patient's target tissue and the prescribed dose is no more than 5%. 6.5 Quality control inspection requirements for treatment machines
6.5.1 Before daily radiotherapy, the start and end of irradiation and its corresponding irradiation status display and the treatment room door interlock should be checked.
6.5.2 The treatment unit shall conduct experimental inspections on the combined irradiation conditions of the treatment machine (Article 4.5.4) and the emergency interruption irradiation equipment (Articles 4.3 (4) and 5.4) every week: Use a radiotherapy dose meter to check the radiation output. 6.5.3 The type test of the treatment machine manufacturer and the inspection of the finalized products by the management department shall be carried out in accordance with the requirements of GB9706.10 and this standard.
6.5.4 In addition to the inspections in Articles 6.5.1 and 6.5.2, the annual inspection of the treatment machine in use by the user acceptance inspection and management department shall inspect the repeatability, linearity of the radiation output and the leakage radiation of the treatment machine (once every three years). The inspection method is shown in Chapter 7. In addition, the safety interlocks in Articles 4.5.2 and 4.5.3 shall be verified by simulation experiments. 6.5.5 After the replacement of the X-ray tube or other major repairs of the treatment machine, the maintenance department, the user and the management department shall conduct corresponding inspections on the performance indicators of the treatment machine affected.
Test method
7.1 Test for radiation leakage from treatment machine
7.1.1 Test conditions and requirements
(1) The test must be carried out under the conditions that can lead to maximum radiation leakage within the performance index range of the treatment machine given in the random documents (i.e. the rated X-ray tube voltage and the corresponding maximum tube current). The test result is deducted from the pre-determined background value and corrected to the air kerma rate in "mGy/h" according to the coefficient regularly calibrated by the national statutory metrology verification department (2) The energy response and reading range of the detection instrument should be able to meet the requirements of the corresponding measurement. The basic error of the instrument should be less than 15%, and the expanded uncertainty of the test should be less than 30%. (3) For the test at a position 1m away from the focus of the X-ray tube, the average value must be taken over an area of 100cm with a long axis not greater than 20cm on the measurement plane perpendicular to the central axis of the X-ray beam. (4) In 4.1, the detection at 20mm and 50mm from the corresponding boundary must be averaged over a 10cm area with a long axis dimension not greater than 4cm on the measurement plane perpendicular to the central axis of the X-ray beam. When the detection instrument cannot actually reach the required position, the detection can be carried out at a distance as close to the required distance as possible and it can be used as the result of the required position. 7.1.2 Leakage radiation of X-ray source assembly under treatment state (1) The radiation beam outlet of the X-ray tube housing must be tightly covered by a shielding body, the thickness of which should have an attenuation of the air kerma rate on the useful beam axis of not less than 10°, and its geometric dimensions shall not exceed 5mm outside the radiation beam boundary (2) The detection points shall include: a three-dimensional coordinate system centered on the X-ray tube focus, the useful beam center axis, the X-ray tube long axis, and the axes perpendicular to these two axes, with the angles between each two axes being 0°, 45°, 90°135°, 180°225°, 270°, and 315°, corresponding to the positions specified in Table 1 in Article 4.1.1. (3) The irradiation conditions are the same as those in Article 7.1.1 (1). The detection can be carried out by direct dose rate measurement or by calculating the timed cumulative dose. Direct measurement should use a dose rate meter that can be read at a long distance. The cumulative dose can be measured by a thermoluminescent dosimeter or an integrating dosimeter.
(4) Evaluation criteria: See Table 1 in Section 4.1.1. 7.1.3 Leakage radiation and non-useful radiation of X-ray source assembly in non-treatment state (1) The treatment machine irradiates under the conditions of Section 7.1.1(1). Immediately after termination of irradiation, the air kerma meter shall be used to directly measure the radiation at the position specified in Section 4.1.2. (2) Evaluation criteria: See Section 4.1.2.
7.1.4 Leakage radiation of removable beam limiter
(1) All removable beam limiters matched with the treatment machine shall be inspected one by one. 8
(2) For adjustable beam limiters, the measurement shall be carried out at each specified adjustment position of the irradiation field. (3) Remove the radiation-transmitting curved end cap at the far end of the beam limiter and connect the beam limiter directly to the X-ray tube assembly. (4) Test under the irradiation conditions corresponding to Article 7.1.11) and with the specified maximum attenuation filtering (5) Measure the air kerma rate at the geometric center of the irradiation field at the far end exit of the beam limiter. The measurement method is the same as that of Article 7.1.2(3).
(6) Cover the exit of the beam limiter tightly with a flat lead plate with an attenuation of not less than 10 on the air kerma rate on the central axis of the useful beam. The shape of the lead plate is the same as the shape of the irradiation field at the exit, and the geometric dimensions meet the requirements of Table 2 of Article 4.1.3. (7) On the outer plane of the lead plate required in Table 2 of Article 4.1.3, 20 mm away from the edge of the lead plate, use a thermoluminescent dosimeter to detect the leakage radiation of the beam limiter and calculate the leakage radiation air kerma rate at the detection point. For a circular beam limiter, select eight detection points evenly. For a rectangular beam limiter, select three detection points along each side at the positions of 1/4, 1/2, and 3/4 of the corresponding side length.
(8) Calculate the ratio of (7) to (5) of this clause and evaluate according to Table 2 of Clause 4.1.3. 7.1.5 Radiation of components other than X-ray source assembly (1) Other components usually refer to high voltage generators. (2) Irradiation conditions are the same as those of Clause 7.1.1(1). Direct scanning measurement is performed at the position required by Clause 4.1.4 using an air kerma rate survey meter.
(3) Evaluation criteria are as in Clause 4.1.4.
7.2 Repeatability and linearity test of cumulative radiation output 7.2.1 Test conditions and requirements
(1) General experimental conditions are the same as those of Clause 50.101 of GB9706.10 (2) The ionization chamber dosimeter used for the test shall meet the requirements of a working-level dosimeter. (3) All test results must deduct the background value measured in advance. Except for relative measurements, the test results must be calibrated to standard conditions (20℃, 101.3kPa) according to the ambient temperature and atmospheric pressure at the location of the ionization chamber at the time of the test, and converted into the corresponding "SI" unit value according to the coefficients regularly calibrated by the national legal metrology verification department. The uncertainty of the measurement should be less than 3%.
7.2.2 Manufacturer type test
The inspection method and evaluation are the same as those in Article 50.2 and Article 50.101-50.104 of GB9706.10-1997. 7.2.3 Other acceptance inspections and status inspections
Under the conditions of 99-101% of the power supply voltage of 220V and the most commonly used beam limiter and total filtration (the sum of inherent filtration and additional filtration), the repeatability and linearity of the cumulative radiation output are inspected according to the following method. (1) Measure the reading when the cumulative irradiation reaches 0.2 full-scale value under the conditions of rated X-ray tube voltage. Repeat the measurement 10 times. Calculate the average value Ki of the first five readings and the average value K1o of the ten readings K, and their relative standard deviation Cv[-
(2) Under the rated X-ray tube voltage, measure the readings when the cumulative irradiation reaches 0.05 full-scale value, repeat the measurement 5 times, and calculate the average value K2.
(3) When the X-ray tube voltage is a "lower value" (i.e. 50% of the rated value or the specified minimum value, whichever is higher), measure the readings when the cumulative irradiation reaches 0.05 full-scale value and 0.2 full-scale value. Repeat the measurement 5 times and calculate the average values K3 and K4. (4) Calculate the ratio of the above-mentioned average reading K, to the preset value Q; M9
Evaluation criteria for the repeatability experiment of cumulative radiation output: the relative standard deviation C does not exceed (5)
0.03-for treatment machines with a rated X-ray tube voltage greater than 150KV; 0.05-for treatment machines with a rated X-ray tube voltage not greater than 150KV. (6) Evaluation criteria for cumulative radiation output linearity test: "Mr-M2|≤0.025|Mi+M2| and
[M3-M4≤0.025|M3+M43 Other acceptance tests and condition tests
Under the conditions of 99-101% of the power supply voltage of 220V and the most commonly used beam limiter and total filtering (the sum of inherent filtering and additional filtering), check the repeatability and linearity of the cumulative radiation output as follows. (1) Measure the reading of the cumulative irradiation reaching 0.2 full-scale value under the rated X-ray tube voltage. Repeat the measurement 10 times. Calculate the average value Ki of the first five readings and the average value K1o of the ten readings K and their relative standard deviation Cv[-
(2) Under the rated X-ray tube voltage, measure the reading of the cumulative irradiation reaching 0.05 full-scale value, repeat the measurement 5 times, and calculate the average value K2.
(3) When the X-ray tube voltage is a "lower value" (i.e. 50% of the rated value or the specified minimum value, whichever is higher), measure the readings of the cumulative irradiation reaching 0.05 full-scale value and 0.2 full-scale value. Repeat the measurement 5 times and calculate the average values K3 and K4. (4) Calculate the ratio of the above measured mean value K to the preset value Q; M9
Cumulative radiation output repeatability test evaluation criteria: relative standard deviation C does not exceed (5) bzxz.net
0.03 - for treatment machines with rated X-ray tube voltage greater than 150KV; 0.05 - for treatment machines with rated X-ray tube voltage not greater than 150KV. (6) Evaluation criteria for cumulative radiation output linearity test: "Mr-M2|≤0.025|Mi+M2| and
[M3-M4≤0.025|M3+M43 Other acceptance tests and condition tests
Under the conditions of 99-101% of the power supply voltage of 220V and the most commonly used beam limiter and total filtering (the sum of inherent filtering and additional filtering), check the repeatability and linearity of the cumulative radiation output as follows. (1) Measure the reading of the cumulative irradiation reaching 0.2 full-scale value under the rated X-ray tube voltage. Repeat the measurement 10 times. Calculate the average value Ki of the first five readings and the average value K1o of the ten readings K and their relative standard deviation Cv[-
(2) Under the rated X-ray tube voltage, measure the reading of the cumulative irradiation reaching 0.05 full-scale value, repeat the measurement 5 times, and calculate the average value K2.
(3) When the X-ray tube voltage is a "lower value" (i.e. 50% of the rated value or the specified minimum value, whichever is higher), measure the readings of the cumulative irradiation reaching 0.05 full-scale value and 0.2 full-scale value. Repeat the measurement 5 times and calculate the average values K3 and K4. (4) Calculate the ratio of the above measured mean value K to the preset value Q; M9
Cumulative radiation output repeatability test evaluation criteria: relative standard deviation C does not exceed (5)
0.03 - for treatment machines with rated X-ray tube voltage greater than 150KV; 0.05 - for treatment machines with rated X-ray tube voltage not greater than 150KV. (6) Evaluation criteria for cumulative radiation output linearity test: "Mr-M2|≤0.025|Mi+M2| and
[M3-M4≤0.025|M3+M4
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