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WS 674-2020: (Medical electronic linear accelerator quality control inspection specification)
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(Medical electronic linear accelerator quality control inspection specification)
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WS 674-2020
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Basic data | Standard ID | WS 674-2020 (WS674-2020) | | Description (Translated English) | (Medical electronic linear accelerator quality control inspection specification) | | Sector / Industry | Health Industry Standard | | Classification of Chinese Standard | C57 | | Word Count Estimation | 36,327 | | Date of Issue | 2020-04-03 | | Date of Implementation | 2020-10-01 | | Older Standard (superseded by this standard) | GBZ 126-2011 (Partly) | | Regulation (derived from) | State-health communication (2020) No. 4 | | Issuing agency(ies) | National Health Commission | WS 674-2020: (Medical electronic linear accelerator quality control inspection specification)---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Specification for testing of quality control in medical linear accelerator
ICS 13.280
C 57
WS
People's Republic of China Health Industry Standard
Partially replace GBZ 126-2011
Specification for quality control and testing of medical electronic linear accelerator
2020-04-03 released
2020-10-01 implementation
Issued by the National Health Commission of the People's Republic of China
Table of contents
Foreword...II
1 Scope...1
2 Normative references...1
3 Terms and definitions...1
4 Equipment protection performance requirements...2
5 Equipment quality control requirements...7
6 Equipment quality control testing methods...8
Appendix A (Normative Appendix) Testing methods for technical indicators of stray radiation (including induced radioactivity)...17
Appendix B (Normative Appendix) Test areas related to accelerator leakage radiation measurement...22
Appendix C (Normative Appendix) Equipment Quality Control Test Items and Technical Requirements...23
Appendix D (Normative Appendix) The best layout of phantom position and measurement center in quality control testing...25
Appendix E (Normative Appendix) Testing Conditions for Equipment Quality Control...27
Appendix F (informative appendix) Schematic diagram of uniformity and symmetry of radiation field...29
Appendix G (informative appendix) Rotating frame diagram...32
References...33
Foreword
Chapter 4, Chapter 5, Appendix A, Appendix B, Appendix C, Appendix D and Appendix E of this standard are mandatory clauses, and the rest are recommended
Terms.
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard replaces the equipment protection performance and equipment quality control of GBZ 126-2011 "Radiation Protection Requirements for Electron Accelerator Radiotherapy"
section. Compared with the equipment protection performance and equipment quality control part of GBZ 126-2011, except for editorial changes, the main technical changes
as follows.
-Modified the scope of standard application (see Chapter 1, Chapter 1 of the.2011 edition);
--Modified some terms and definitions (see 3.1, 3.3 and 3.6, 3.1, 3.6 and 3.12 of the.2011 version);
--- Added quality control testing requirements and testing methods (see Chapter 5 and Chapter 6);
- Deleted the dose monitoring system calibration control test items, the maximum absorbed dose rate test items, and the X-ray field of the wedge filter
Detection items, the light field of the irradiation field indicates the detection items, the position of the radiation beam axis on the patient's exit surface indicates the detection items,
Indicating test items for the distance to the radiation source, and test items for the coincidence of the front and back irradiation fields (see Appendix E of the.2011 edition);
--Modified the items and testing cycle of acceptance testing, status testing and stability testing (see Appendix C, Appendix E of the.2011 edition);
--Increase the inspection index and recommended index of acceptance inspection and stability inspection, and the zero-scale position detection items of the rotating movement scale
And its requirements, the testing items and requirements of the treatment bed movement accuracy, and the testing items and requirements of the treatment bed stiffness (see Appendix C);
-Added the best layout of the phantom position and measurement center in quality control testing (see Appendix D);
--Increase the testing conditions for quality control (see Appendix E);
--- Added a schematic diagram of the uniformity and symmetry of the radiation field (see Appendix F);
- Added a schematic diagram of the rotating frame (see Appendix G).
Drafting organizations of this standard. Institute of Radiation Medicine, Chinese Academy of Medical Sciences, Peking University Cancer Hospital, Chinese Center for Disease Control and Prevention
Institute of Radiological Protection and Nuclear Safety Medicine, Sichuan Provincial Center for Disease Control and Prevention.
The main drafters of this standard. Zhang Wenyi, Wu Hao, Zhang Liangan, Ding Yanqiu, Jiao Ling, He Ling, Yang Yi.
The previous editions of the standard replaced by this standard are as follows.
--GB 16369-1996;
--GBZ 126-2002;
--GBZ 126-2011.
Specification for quality control and testing of medical electronic linear accelerator
1 Scope
This standard specifies the requirements and methods for the protective performance and quality control testing of medical electronic linear accelerators.
This standard applies to the quality control testing of medical electronic linear accelerators.
2 Normative references
The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this document.
For undated references, the latest version (including all amendments) applies to this document.
GB 9706.5-2008 Medical electrical equipment Part 2.Special requirements for the safety of electron accelerators with energy from 1 MeV to 50 MeV
GB 15213-2016 Medical electron accelerator performance and test methods
3 Terms and definitions
The following terms and definitions defined in GB 9706.5-2008 and GB 15213-2016 apply to this document.
3.1
Normal treatment distance; NTD
In the case of an electronic wire, it is the distance measured along the useful wire beam axis from the electron wire window along the radiation beam axis to the end of the beam limiter or the specified plane; X
For ray, it is the distance measured from the front surface of the target along the radiation beam axis to the isocenter; for non-isocentric equipment, it is the distance to the specified plane
from.
3.2
Isocentre
In radiology equipment, the reference axis of various motions moves around a common center point, and the radiation beam is centered on the smallest sphere inside the
However, this point is the isocenter.
3.3
Nominal energy
It is given by the manufacturer to characterize the energy of the radiation beam.
Note. referred to as energy in this document.
3.4
Flatteness
A performance index that measures whether the absorbed dose rate at each point in the irradiation field at a specified irradiation distance is uniform.
3.5
In the plane of the patient, the area is centered on the useful beam axis and the maximum irradiation field is the boundary.
3.6
Patient plane
When using an accelerator to treat patients, the normal treatment distance is parallel to the treatment table and the vertical distance to the treatment table is 7.5 cm
Plane.
3.7
Test area in patient plane
On the patient's plane, the area with a radius of 2 m from the center of the useful harness, excluding the M area.
3.8
Maximum absorbed dose
The maximum absorbed dose measured along the axis of the radiation beam in a water model under the condition of a normal treatment distance and an irradiation field of 10 cm×10 cm.
3.9
Stray radiation
Except for useful radiation beams, all radiations mainly include stray X-rays during electron therapy, and X-ray therapy causes patients’ relative appearance.
Stray radiation and stray neutrons with increased surface dose.
4 Equipment protection performance requirements
4.1 General requirements
4.1.1 When applying for acceptance testing, a medical institution shall provide the testing institution with random documents from the manufacturer of radiotherapy equipment.
4.1.2 The leakage radiation and stray radiation of the equipment (including the induced radioactivity of accelerator treatment) should be accepted and tested. Under normal circumstances
The status and stability test may not be performed; however, when the beam limiting equipment is replaced, modified or repaired, the leakage radiation and stray radiation shall be tested.
4.2 Control of absorbed dose
4.2.1 Monitoring and control of absorbed dose
4.2.1.1 The equipment used should have an independent dual-channel dose monitoring system, the output of which is displayed as the dose monitoring value, and should be able to be used to calculate the
Illuminate the dose at a reference point in the target volume.
4.2.1.2 The dual-channel dose monitoring system shall meet the following requirements.
a) The dual-channel dose monitoring system can be either a redundant dose monitoring combination or a primary-secondary dose monitoring combination. In redundant dose monitoring
When testing the combination, both dose monitoring should reach the performance specified in the manufacturer’s technical specification; when the primary-secondary dose monitoring is combined, the
The low-main-dose monitoring system should reach the performance specified in the manufacturer's technical specification;
b) When a certain dose monitoring system fails, the other one should be guaranteed to work normally; each dose monitoring system should be able to independently
Termination of irradiation; in the case of redundant dose monitoring combination, each channel should be set to terminate the irradiation when the preset parameters are reached; primary-secondary dose monitoring
When measuring the combination, the main channel should be set to terminate the irradiation when the preset parameters are reached, and the secondary channel should be set to terminate when the preset parameters are exceeded.
Irradiate. If the exceeding value is used as a percentage, it should not exceed 10% of the preset parameters; if the absolute dose value is used, it will be in the normal treatment
The distance does not exceed the equivalent value of 0.25 Gy; it is optional, and the smallest difference with the preset parameters should be selected;
c) When the dose monitoring reading changes by more than 5% caused by any reason, the irradiation should be automatically terminated;
d) When calibrating the dual-channel dose monitoring system, the readings of the same dose in the dual-channel dose monitoring system should be consistent;
e) When power failure or component failure causes interruption or termination, the preselected parameters and dose data displayed by the two-channel dose monitoring system should be maintained
No change, the pre-selected parameters and dose readings at the time of failure should be stored in a readable manner for at least 20 minutes;
f) After the interruption or termination, the display should be reset to zero, and the next irradiation can be started; the preselected parameters of the dose monitoring system are determined on the console
Before, irradiation should not be started.
4.2.1.3 The radiation detector shall meet the following requirements.
a) Two radiation detectors should be installed in the radiation head, at least one of which should be a transmission detector, located in the leveling filter and beam divergence
The patient side of the injection filter, with its center on the reference axis;
b) It can be fixed or mobile. The fixed type should only be removed with tools, and the mobile application interlocking device prevents positioning errors.
During irradiation, if the radiation detector deviates from the reference axis, the irradiation should be terminated;
c) The sealed radiation detector should be individually sealed and accompanied by a certificate of seal integrity (including test date).
4.2.1.4 The requirements for the selection and display of dose monitoring are as follows.
a) The display of the dual-channel dose monitoring system should be clear and easy to read, close together and placed on the treatment console to display the preselected dose monitoring value.
Show nearby
b) If a display terminal is used, two independent display terminals or a dual-channel dose monitoring system should be used to display on the same terminal.
However, there should be a spare display terminal or a common display to display at least one piece of data;
c) Any combination of primary-secondary dose monitoring should have clear and identifiable displays;
d) The dose monitoring value should display the increase of the count to show the overdose reading and the preselected dose monitoring value. Interruption or termination of irradiation
After that, these two counts should be kept;
e) The display value should be reset to zero before starting the next new irradiation; before confirming the dose monitoring count from the treatment console,
Should not start exposure;
f) When the irradiation is interrupted or terminated due to power failure or device failure, the dose monitoring count at this time should be stored in a readable manner.
And keep it for at least 20 min.
4.2.1.5 The safety interlock of the dose monitoring system shall meet the following requirements.
a) Each dose monitoring system should be able to terminate the exposure independently. When the dual-channel dose monitoring system constitutes a redundant dose monitoring system combination,
Each channel should be able to be set to terminate the irradiation when the dose monitoring count reaches the preset value;
b) In the combination of primary-secondary dose monitoring system, the primary dose monitoring system should be able to be set to terminate the exposure when the dose monitoring count reaches the preselected value.
The sub-dose monitoring system should be able to be set to terminate the irradiation when the dose monitoring count exceeds 10% of the preselected value;
c) The interlocking device should ensure that between two exposures or before exposure, the dose monitoring system that did not cause the termination of exposure verifies its termination of exposure.
The ability to shoot.
4.2.1.6 Monitoring of absorbed dose distribution shall meet the following requirements.
a) The radiation detector should be able to monitor different parts of the radiation beam in order to detect the symmetrical and asymmetrical changes in the dose distribution;
b) Measures should be provided. At the specified depth of uniformity measurement, when the absorbed dose distribution distortion exceeds 10% or the radiation detector absorber
When the quantity distribution detection signal indicates that the change is greater than 10%, before the increased absorbed dose reaches 0.25 Gy, this measure makes the irradiation end
only.
4.2.2 Timer control
4.2.2.1 A control timer should be configured on the treatment console, and the control timer should meet the following requirements.
a) It is an incremental timer;
b) Synchronize with the start and stop of irradiation;
c) Keep the reading after the irradiation is interrupted or terminated;
d) After the irradiation is terminated, it can be reset to zero before starting the next irradiation;
e) In order to prevent the dose monitoring system from failing, when the preselected time is reached, the irradiation is terminated;
f) Independent of any other systems or subsystems that control the termination of exposure.
4.2.2.2 Corresponding measures shall be provided to ensure that the set value of the control timer does not exceed the limit given in the instruction manual, and this value is not greater than
At the expected dose rate, 120% of the time required for the exposure to reach the dose monitoring preset value or additional 0.1 min, whichever is greater.
4.2.2.3 Measures shall be taken to ensure the ability to test the control timer to terminate the exposure between two exposures or before exposure.
4.2.2.4 The control timer shall be scaled in minutes and tenths of minutes or in seconds. These two scales cannot be mixed.
4.2.3 Control of absorbed dose rate
4.2.3.1 A dose rate monitoring system should be configured, and its readings (dose monitoring counts per second or per minute) should be displayed on the treatment console.
From this reading, the absorbed dose rate at a reference point within the treatment volume should be calculated.
4.2.3.2 In any faulty maintenance state, if the equipment can produce a maximum value than specified in the technical specification at a normal treatment distance
If the absorbed dose rate is twice as high as the value, a measure should be provided so that when the absorbed dose rate exceeds the maximum specified value and is not more than twice the value
Stop the irradiation. The technical specification should have an absorbed dose rate value that can terminate the exposure.
4.2.4 Selection and display of radiation types
For equipment that can generate both X-rays and electronic wires, the following requirements shall be met.
a) After the irradiation is terminated, the next irradiation should be blocked before reselecting the radiation type on the treatment console;
b) When it is required to select radiation types in the treatment room and on the treatment console, the selection in one place should not be displayed in the other
Come out, only after the two selections are completed will it be displayed;
c) When the choice in the treatment room is inconsistent with the choice of the treatment console, the irradiation should be prevented;
d) During and before irradiation, the type of irradiation used should be displayed on the treatment console;
e) The interlocking device should ensure that only the selected type of irradiation can be carried out;
f) The interlocking device should ensure that when the accessories specified for electron irradiation, such as the electron beam limiter, are in place, X irradiation should not be generated;
It is stipulated that the accessories used for X-ray shall not generate electronic wires;
g) X-rays should be blocked when it is specified as an electronic line; electronic lines should be blocked when it is specified as an X-ray.
4.2.5 Selection and display of energy
4.2.5.1 Except for equipment that can only generate one energy radiation beam, after the irradiation is terminated, before reselecting the energy on the treatment console,
The next exposure should be prevented.
4.2.5.2 When it is required to select energy operation in both the treatment room and the treatment console, the selection in one place should not be displayed in the other
Come, it will show up only after you have finished selecting both places.
4.2.5.3 When the selection in the treatment room is inconsistent with the selection on the treatment console, the irradiation should be prevented.
4.2.5.4 Equipment capable of generating radiation beams of different energy should be displayed on the treatment console during and before the irradiation in the instructions for use
The energy value specified in the book.
4.2.5.5 During normal operation, the radiation generated under the selected operating mode and energy conditions should end up in any of the following situations.
Stop irradiation.
--When the deviation of the average energy of electron bombardment on the X-ray target exceeds ±20%;
--When the deviation of the average energy of electron bombardment on the electron wire window exceeds ±20% or ±2 MeV (whichever is less).
4.2.6 Selection and type of wedge filter
4.2.6.1 Before starting the irradiation, the irradiation cannot be started until a specified wedge filter or no wedge filter is selected on the console.
4.2.6.2 When this type of selection is required to be made in both the treatment room and on the console, it can be displayed on the console only after the selection in both places is completed.
It shows that when the two choices are inconsistent, there is also an interlock that cannot be illuminated.
4.2.6.3 Equipment equipped with wedge filters should be able to display the wedge filters in use on the console, and each wedge filter should
There are clear identification marks; if the selected wedge filter is not positioned correctly, there should be two independent interlocking devices to prevent or terminate the irradiation.
4.2.7 Interlock of irradiation beam limiting device
When the X-ray beam limiting device is used as a part of the electronic wire beam limiting system, there should be an interlock. When its actual position is relative to the required position
When the difference exceeds 10 cm (at the normal treatment distance), the electronic line is blocked.
4.3 Control and detection of stray radiation
4.3.1 Stray X-rays during electrotherapy
On the reference axis, at a depth of 100 mm outside the actual electron range, the percentage of absorbed dose due to X-rays should not exceed the table
1 The value given. Should be measured in a phantom, the incident surface is perpendicular to the reference axis, and at the normal treatment distance, each side is at least 5 cm larger than the irradiation field;
The depth of the phantom is at least 5 cm greater than the measured depth.
Note. The data in this table is from GB 9706.5-2008.
4.3.2 Relative surface dose during X-ray treatment
Use 30 cm×30 cm irradiation field, or use the largest rectangular irradiation field possible (when the maximum irradiation field is less than 30 cm×30 cm),
The surface dose should not exceed the value in Table 2.
The measurement should be carried out in a phantom, whose size and position are as described in 4.3.1.All beam shaping devices that can be removed without tools should be removed from
Move away from the radiation beam, and all leveling filters should stay in their prescribed positions.
4.3.3 Stray neutrons
4.3.3.1 Stray neutrons are only applicable to equipment with electron energy exceeding 10 MeV.
4.3.3.2 Under normal conditions of use, outside the M area, the ratio of the absorbed dose of neutrons to the maximum absorbed dose should be ≤0.05%, and the average
The ratio of the value (the mean value on the area of ≤800 cm2) to the maximum absorbed dose should be ≤0.02%.
4.3.4 Detection of stray radiation
The detection of stray radiation should be carried out in accordance with Appendix A.
4.4 Leakage radiation control and detection of beam limiting device
4.4.1 X-ray beam limiting device
4.4.1.1 The leakage radiation passing through all combinations of beam limiting devices shall be measured. X-ray leakage radiation test area through beam limiting device is mainly
It is carried out in area M (see Figure B.1 in Appendix B).
4.4.1.2 For any beam limiting device or its combination, the following requirements shall apply to each independent device or a combined device that is simultaneously measured together.
a) Except for the conditions applicable to 4.4.1.2 c), if any beam limiting device is located anywhere in the M area, the air absorbed dose of the leaked radiation is equal to
The ratio of the maximum absorbed dose ≤ 2%;
b) For any size of irradiation field, the leakage radiation passes through any beam limiting device, the average absorbed dose and maximum absorption in the M area
The ratio of the dose is ≤0.75%;
c) If a multiple beam limiting device cannot meet the requirements of 4.4.1.2 a) and b), an adjustable or interchangeable beam limiting device must be overlapped
In order to meet the requirements, these beam limiting devices should be automatically adjusted to the smallest size rectangular irradiation field, surrounded by the multiple beam limiting devices
Around the limited radiation field;
d) The absorbed dose caused by the leakage radiation that is projected through the multi-element beam limiting device into the rectangular irradiation field automatically formed in 4.4.1.2 c) and
The ratio of the maximum absorbed dose is ≤5%.
4.4.2 Electronic wire harness limiting device
4.4.2.1 It should be equipped with adjustable or interchangeable beam limiting devices and (or) electron beam limiters, which should be able to limit the exposure of electron beams in the field.
To meet the following requirements at the same time.
a) In the area from 2 cm outside the boundary of the geometric irradiation field to the boundary of the M zone, the ratio of the absorbed dose to the maximum absorbed dose is ≤10%;
b) The average absorbed dose and maximum absorber of leakage radiation in the area from 4 cm outside the boundary of the geometric irradiation field to the boundary of zone M
Ratio of amount.
1) When the electron energy is ≤10 MeV, ≤1%;
2) When the electron energy is ≥35 MeV, ≤1.8%;
3) When 10 MeV< electron energy< 35 MeV, ≤a%, where a=1 0.032(Ee-10), Ee is the electron energy in MeV.
4.4.2.2 Extrapolate 2 cm from the outer surface of any electron beam limiter, or from the end of the beam limiter to 10 cm away from the housing, the measured absorbent
The ratio to the maximum absorbed dose is ≤10%.
4.4.2.3 When the X-ray beam limiting device is used as a part of the electronic wire beam limiting system, there should be interlocking facilities. When its actual location and requirements
When the position difference of 10 cm (at the normal treatment distance), it should be able to stop the electronic wire.
4.4.3 Leakage radiation outside M area (except neutrons)
4.4.3.1 The equipment should provide protec...
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