GB 18464-2001 Requirements for radiation health protection in medical X-ray therapy
Some standard content:
GB18464—2001
Except Chapter 1 and Chapter 2, all other clauses of this standard are mandatory. This standard is a revision of GBW280 issued by the Ministry of Health on October 24, 1980 and implemented on a trial basis on January 1, 1981, in accordance with the Regulations on Radiation Prevention of Radioactive Isotopes and Radiation-Bearing Devices of the People's Republic of China. When revising the standard, reference was made to relevant international and national standards. New progress in the field of radiotherapy and radiological protection was noted, and relevant content on radiation safety and quality assurance was added. This standard specifies the radiation protection performance of medical X-ray therapy equipment, the radiation protection conditions of the equipment use site, and the technical requirements for radiation protection and safety of radiotherapy using the equipment. This standard shall be implemented from March 1, 2002. This standard was issued by the Ministry of Health of the People's Republic of China. The drafting unit of this standard is Beijing Radiological Protection Institute. The drafters of this standard are Shi Jin and Ma Shuizhong. This standard is entrusted by the Ministry of Health to the Ministry of Health's Industry Hygiene Laboratory for interpretation. 191
1 Scope
National Standard of the People's Republic of China
Requirements for radiological protection in medical X-ray therapy
GB 18464 - 2001
This standard specifies the radiation protection performance and inspection requirements of medical X-ray therapy machines, the radiation protection conditions of treatment rooms, and the safe operation and quality assurance requirements for radiotherapy using treatment machines. This standard applies to the production and use of medical X-ray therapy machines (hereinafter referred to as treatment machines) with a nominal X-ray tube voltage of 10 kV~1 MV, and does not apply to X-ray therapy using medical accelerators. 2 Reference standards
The provisions contained in the following standards constitute the provisions of this standard through reference in the standards. When this standard is published, the versions shown are valid. All standards will be revised. Parties using this standard should explore the possibility of using the latest versions of the following standards. GB9706.101997 Medical electrical equipment Part 2: Special safety requirements for therapeutic X-ray generating devices GB 9706. 12—1997
Medical electrical equipment Part 1: General safety requirements III. 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, require justification of exposure, optimization of radiation protection, and ensure that the exposure of workers and the public does not exceed the prescribed dose limit; the medical exposure received by patients 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 the occurrence of major exposure incidents and adverse consequences. 4 Technical requirements for the protection performance of treatment machines
4. 1 Limitation of leakage radiation of treatment machines
4. 1. 1 Under treatment status, the leakage radiation of X-ray source components shall be in accordance with Table 1 Table 1 Control value of leakage radiation of X-ray source assembly 1 under treatment state Rated voltage of X-ray tube, kV
Air kerma This control value, mGy/l
50 mm from the surface of source assembly300
1 m from the X-ray renal focus10
1 m from the focus of X-ray tube1
50 mm from the surface of source assemblyt
1) The X-ray source assembly includes a beam limiter fixedly mounted on the X-ray tube sleeve2) Suitable for handheld treatment equipment.
4.1.2 Control values of leakage radiation and non-useful radiation of X-ray source assembly in non-treatment state When the X-ray source is in 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 powered off, the air kerma rate control value shall not exceed 0.02mGy/h at a distance of 1m from the focus of the X-ray tube (including the treatment beam direction) and 0.2mGy/h at a distance of 50mm from the surface of the X-ray source assembly from 5s after the interruption or termination of the radiation beam emission: 41.3 Removable beam limiter refers to the fixed part of the optics or adjustable beam limiter which is directly connected to the X-ray tube assembly but can be removed. Under the condition of full shielding of the irradiation field after 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 detachable 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.
Relative leakage radiation control level of the detachable beam limiter, %
1) The maximum air kerma rate at any position 20mm away from the edge of the lead plate accounts for the white fraction 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 components other than the X-ray source assembly Except for the X-ray source assembly, the air kerma rate shall not exceed 0.02 at any position 50mml away from the surface of any component of the X-ray machine. mGy/h.
4.2 Technical requirements related to useful beam radiation output 4.2.1 Repeatability of cumulative radiation output
The repeatability of the cumulative air kerma of the useful beam in the irradiation field should not be greater than 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 should not be greater than 5%. 4.3 Treatment machine console
The console should have the following safety control devices: 4.3.1+power lock,
4.3.2 Preset irradiation condition confirmation device, 4.3.3 Device for starting irradiation after confirming that the irradiation conditions are correct. 4.3.4 Device for interrupting irradiation in emergency. 4.3.5 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: 4.4.1 When the treatment machine is equipped with two timers or two dose monitors, they must be configured in parallel or in a master/slave combination. Each of them must be able to terminate irradiation independently. 4.4.2 When the preset value is reached, the two systems in the column combination or the main system in the master/slave combination must terminate irradiation . If the irradiation is not terminated due to a failure of the main system of the primary and 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 (.1Gy, the secondary system must immediately terminate the irradiation. 4.5 Radiation safety and interlock requirements
4.5.1 The treatment machine must have a safety device that can interrupt the irradiation and display the corresponding fault when any error or failure in 4.5.2 to 4.5.5 occurs.
4.5.2 Protection against failure of the mobile device of the X-ray source assembly When the treatment machine is irradiating, if the mobile device of the X-ray source assembly relative to the patient is stuck, blocked or has other movement failures during the execution of the preset movement instructions, the protection device should be activated to automatically interrupt the irradiation. 4.5.3 Prevent accidental irradiation when the X-ray tube is powered on193
GR 18464—2001
This equipment is called radiation absorption component (such as shutter) and its work should be: 4.5.3.1 If the absorption component does not work properly, it is impossible to power on the X-ray tube. 4.5.3.2 When the X-ray tube is powered on, the failure of the absorption component should cause the X-ray tube to be powered off. 4.5.3.3 When the radiation beam stops emitting, the absorption component should work properly. 4.5.4 Preventing mis-exposure when the combined irradiation conditions are misplaced The combined irradiation conditions include the combination of X-ray tube voltage, X-ray tube current, fixed and additional filters, beam limiters (adjustable beam limiters or light collectors), and X-ray source assembly mobile devices and other irradiation conditions related to patient treatment. When the combined irradiation conditions set by the console have one of the following conditions, the treatment machine cannot output radiation: 4.5.4.1 Not preset according to the treatment plan.
4.5.4.2 The preset exceeds the performance indicators of the equipment. 4.5.4.3 The setting conditions are not correct (e.g., the filter or beam limiter is not placed in the right position or in the wrong direction). 4.5.4.4 When the combined irradiation conditions can be set at the console inside and outside the treatment room, the setting at the console is inconsistent with the setting at the machine.
4.5.4.5 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 operating 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. Precautions should be taken to prevent the protective door from being accidentally opened during irradiation, and there should be a corresponding indication on the console at this time.
4.6 Starting and stopping the emission of radiation beams
4.6.1 Under normal circumstances, the combination conditions described in Article 4.5.4 must be set in sequence, and after the console confirms that the settings are correct, the irradiation is started by the "Start" button. After the preset irradiation is completed, the irradiation is automatically terminated. 4.6.2 Under normal circumstances, the radiation beam is emitted again, and the above steps must be reset and operated. 4.6.3 Under abnormal circumstances, the irradiation is interrupted by the safety device in Article 4.5. At this time, the irradiation can be started by the "Start" button only after the fault is eliminated and the console is restored to continue to complete the preset irradiation; or the irradiation can be started again after resetting. 4.7 Special requirements for handheld therapy machines
4.7. 1 The nominal voltage of the X-ray tube of the therapy machine shall not be greater than 50 kV. 4.7.2 In addition to being handheld, the X-ray tube assembly shall have other fixing methods. 4.7.3 The power on of the X-ray tube can only be controlled by the staff holding the X-ray tube assembly: 4.7.4 There must be sound and light signals to indicate that the X-ray tube is not electrostatic. 4.7.5 The therapy machine must be equipped with personal protective hats, gowns and skirts, whose attenuation of X-rays is not less than 0.25mm lead equivalent, and the ball phase test industry should be asked to ask the applicant to sit on the industrial product ticket. 4.8 Component specification marking and random documents
4.8.1 Component specification marking
The therapy machine and its components must have firm, clear and recognizable markings as follows: 4.8.1.1 On the surface of the X-ray source assembly, mark the position of the focus and the material and thickness of the fixed filter. 48.1.2 Material, thickness, insertion direction mark and working status indication after insertion of the removable additional filter. 4.8.1.3 Nominal size of the irradiation field at the far end exit of the treatment beam focusing tube and the distance from the focus to the far end. 4.8.1.4 Size of the irradiation field of the adjustable beam limiter and the nominal focal length 4.8.1.5 Equivalent order or attenuation factor of X-ray attenuation of protective equipment accessories. 5 Protection requirements for treatment rooms
GB 184642001
5.1 The setting of the treatment room must fully consider the safety of the surrounding area and personnel. It is generally 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 less than 24 m. No debris unrelated to treatment should be placed inside. 5.2 The walls of the treatment room in the direction of the useful beam irradiation should be designed according to the requirements for X-ray shielding, and the buildings in other directions should be designed according to the requirements for leakage radiation and radiation corridor shielding.
5.3 The treatment room must be equipped with equipment for observing the treatment (such as industrial television or observation window). The observation window should be set on the wall not in the direction of the useful beam and have the same side wall as the screen effect.
5.4 Equipment for forcible termination of irradiation for emergency use should be installed at an appropriate position 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 screen effect as the same side wall. 5.6 There should be a component next to the inner door of the treatment room for emergency opening of the door. 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 clear 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 arc holes, curved paths or trenches should be used. 6. Protection requirements for radiotherapy
6.1 Legitimacy requirements for radiotherapy
Radiotherapy must establish a prescription management system, and only qualified prescribing physicians can order X-ray treatment. Prescribing physicians must analyze and judge the appropriateness 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 Optimizing treatment plans should include: analyzing the radiation and non-radiation treatments that the patient has already undergone; formulating single irradiation fields or superimposed irradiation according to the conditions of the lesion and the dose given to the lesion tissue for each irradiation; selecting treatment irradiation conditions; taking shielding and reasonably planned irradiation measures to protect the patient's normal tissues and important organs. 6.3 Safety and Operation Requirements
6.3.1 The operator must be proficient in and strictly follow the operating regulations. Important safety operation contents must be clearly displayed in the control room of the treatment machine.
6.3.2 If a personal dosimeter must be worn during radiotherapy, the operator must always monitor the console and the patient during the treatment process and eliminate unexpected situations in a timely manner.
6-3.3 The operator shall not remove the auxiliary radiation safety and interlocking equipment without authorization. When maintenance is required, it must be approved by the responsible personnel and the treatment machine must be clearly displayed at the console that it is under maintenance. After maintenance, the safety and interlocking equipment must be restored in time, and its control function must be checked to be normal. Radiotherapy can only be carried out after confirmation by the responsible personnel.
6.3. When the treatment machine above 450kV is irradiating, no other personnel should stay in the treatment room except the patient. 6.3.5 When using a radiation therapy machine with a voltage below 50 kV, the operator must wear a radiation shield and an apron with a lead equivalent of not less than 0.25 mm, and stay as far away from the X-ray tube 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, and technicians. 6.4.2 Radiotherapy should establish a quality assurance management organization and formulate quality assurance guidelines, 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 absorbed dose received by the target tissue of the filter does not deviate from the prescribed dose.
6.5 Quality control inspection requirements for treatment machines
GB 18464 --2001
6.5.1 Before daily radiotherapy, the start and end of irradiation and the corresponding irradiation status display and the interlock of the treatment room door should be inspected. 6.5.2 The treatment unit should conduct experimental inspections on the combined irradiation conditions of the treatment machine (Article 4.J.4) and the emergency interruption irradiation equipment (Articles 4.3 (4) and 5.4) every week: use a radiotherapy agent meter to check the radiation output. 6.5.3 The type test and management department of the treatment machine manufacturer shall inspect the finalized products in accordance with the requirements of GB 9706.10 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 acceptance inspection and management department shall be carried out to check the repeatability, linearity of the radiation output and the radiation leakage of the treatment machine (once every two years). See Chapter 1 for the inspection method. In addition, the safety interlocks in Articles 1.5.2 and 1.5.3 should be verified by simulation experiments. 6.5.5 After the X-ray tube is replaced or other major repairs are carried out on 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.
7 Inspection methods
7.1 Inspection of radiation leakage from the treatment machine
7.1.1 Inspection conditions and requirements
7.1.1.1 Inspection must be carried out under the conditions that can cause the maximum radiation leakage within the performance indicator 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 results shall be deducted from the pre-determined background value and corrected to the air kerma rate in units of \mGy/h\ according to the coefficients regularly calibrated by the national legal metrology verification department. 7.1.1.2 The energy response and reading range of the detection instrument shall meet the requirements of the corresponding measurement. The basic error of the instrument shall be less than 15, and the expanded uncertainty of the detection shall be less than 30%.
7.1.1.3 The detection at the position 1 I away from the X-ray tube focus must be averaged over an area of 100 cm with a long axis dimension not greater than 20 cm on the measuring plane perpendicular to the central axis of the X-ray beam. 7.1.1.4 In Article 4.1, the detection at 20 mm and 50 mm away from the corresponding boundary must be averaged over an area of 10 ctm with a long axis dimension not greater than 4t:In on the measuring 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 components in treatment state 7.1.2.1. The radiation beam outlet of the X-ray tube housing must be tightly covered with a shielding body, and its degree should have an attenuation of not less than 10° of the air kerma rate on the useful beam axis. Its geometric dimensions shall not exceed 5mm outside the radiation beam boundary. 7.1.2.2 The detection points shall include: the useful beam center axis, the long axis of the X-ray tube, and the axis perpendicular to this axis form a three-dimensional coordinate system with the X-ray tube focus as the center. The angle between each two axes is 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°, corresponding to Table 1 in Article 4.1.1. Specified position, 7.1.2.3 Irradiation conditions are the same as those in Article 7.1.1.1. Detection can be performed by direct dose rate reading or by calculating the cumulative dose by timing. Direct reading should use a dose rate meter that can be read at a long distance. Cumulative dose can use a thermoluminescent dosimeter or an integrating dosimeter. 7.1.2.4 Evaluation criteria; see Table 1.
7.1.3 Leakage radiation and non-useful radiation of X-ray source components in non-therapeutic state 7.1.3.1 The treatment machine irradiates under the conditions of Article 7.1.1.1. After the irradiation is terminated, it is directly measured and read with an air kerma patrol meter at the position specified in Article 4.1.2.
7.1.3.2 Evaluation criteria: see Article 4.1.2. 7. 1.4 Leakage radiation of removable beam limiters
7.1.4.1 Inspect all removable beam limiters used with the treatment machine one by one. 7.1.4.2 Adjust the beam limiters and make measurements at the specified adjustment positions of the irradiation field. 7.1.4.3 Remove the radiation-transmitting end cap at the far end of the beam limiter and connect the beam limiter directly to the X-ray tube assembly. 7.1.4.4 Test under irradiation conditions corresponding to Article 7.1.1.1 and with the specified maximum filter reduction. 7.1.4.5 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. 196
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GB 18464 -2001
7.1.4.6 Cover the exit of the beam limiter tightly with an almost round lead plate that has an attenuation of not less than 101 on the air kerma rate on the central axis of the 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. 7.1.4.7 On the outer side of the lead plate required in Table 2, 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 of the detection point. For a circular beam limiter, select eight detection points evenly. For a rectangular beam limiter, select two detection points at the positions of 1/4, 1/2, 3/4 of the corresponding edge length along each side. 7.1.4.8 Calculate the ratio of 7.1.4.7 to 7.1.4.5, according to Table 2 of 4.1.3. Evaluation, 7.1.5 Radiation of components other than X-ray source assembly 7.1.5.1 Other components usually refer to high voltage generator. 7.1.5.2 Irradiation conditions are the same as those in 7.1.1.1. Use air kerma rate survey meter to directly scan and measure at the position required by 4.1.4. 7.1.5.3 Evaluation criteria are as in 4.1.4. 7.2 Repeatability and linearity test of cumulative radiation output 7.2.1 Test conditions and requirements
7.2.1.1 General test system is the same as that in G9706.10 50.101, 7.2.1.2 The dose of ionization chamber used for test - should meet the requirements of working-level dosimeter. 7.2.1.3 All test results must be deducted from the background value measured in advance. Except for relative measurements, the test results must be calibrated to standard conditions (20°C, 101.3 kPa) according to the ambient temperature and air pressure at the location of the ionizer at the time of testing, and converted into the corresponding "SI\ unit value" according to the coefficients regularly calibrated by the national statutory metrology verification department. The uncertainty of the measurement should be less than 3%. 7.2.2 "Production" type testwwW.bzxz.Net
The inspection method and evaluation are the same as those in Article 50.2 and Articles 50.101 to 50.104 of GB9706.10-1997: 7.2.3 Other acceptance inspections and status inspections
When the power supply voltage is 220 Under the conditions of 99% 101 of V and the most commonly used beam limiter and total filtering (the sum of the existing filtering and additional filtering), check the repeatability and linearity of the cumulative radiation output as follows. 7.2.3.1 Under the rated X-ray tube voltage, measure the reading of the cumulative irradiation reaching 0.2 full-scale value. Repeat the measurement 10 times. Calculate the average value K of the first five readings and the average value K1 of the ten readings K1: and their relative standard deviation C, see formula (1) F(K-Ke*
7.2.3.2 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 K.
7.2.3.3 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 reading 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 value, and. 7. 2. 3. 4 Calculate the ratio M of the above measured mean value K and the preset value Q: K
7.2.3.5 Evaluation criteria for cumulative radiation output repeatability experiment: Relative standard deviation C, for therapeutic machines with rated X-ray tube voltage greater than 150 kV, shall not exceed 0.03; for therapeutic machines with rated X-ray tube voltage not greater than 150 kV, shall not exceed 0.05. 7.2.3.6 Evaluation criteria for cumulative radiation output linearity test: [M--Mz.0.025|M,M and
[Ms - M 0.025IM - M,2 The dose of the ionization chamber used for inspection shall meet the requirements of the working-level dosimeter. 7.2.1.3 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 testing, 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 "Production" type test
The inspection method and evaluation are the same as Article 50.2 and Articles 50.101~50.104 of GB9706.10-1997: 7.2.3 Other acceptance inspections and status inspections
When the power supply voltage is 220 Under the conditions of 99% 101 of V and the most commonly used beam limiter and total filtering (the sum of the existing filtering and additional filtering), check the repeatability and linearity of the cumulative radiation output as follows. 7.2.3.1 Under the rated X-ray tube voltage, measure the reading of the cumulative irradiation reaching 0.2 full-scale value. Repeat the measurement 10 times. Calculate the average value K of the first five readings and the average value K1 of the ten readings K1: and their relative standard deviation C, see formula (1) F(K-Ke*
7.2.3.2 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 K.
7.2.3.3 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 reading 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 value, and. 7. 2. 3. 4 Calculate the ratio M of the above measured mean value K and the preset value Q: K
7.2.3.5 Evaluation criteria for cumulative radiation output repeatability experiment: Relative standard deviation C, for therapeutic machines with rated X-ray tube voltage greater than 150 kV, shall not exceed 0.03; for therapeutic machines with rated X-ray tube voltage not greater than 150 kV, shall not exceed 0.05. 7.2.3.6 Evaluation criteria for cumulative radiation output linearity test: [M--Mz.0.025|M,M and
[Ms - M 0.025IM - M,2 The dose of the ionization chamber used for inspection shall meet the requirements of the working-level dosimeter. 7.2.1.3 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 testing, 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 "Production" type test
The inspection method and evaluation are the same as Article 50.2 and Articles 50.101~50.104 of GB9706.10-1997: 7.2.3 Other acceptance inspections and status inspections
When the power supply voltage is 220 Under the conditions of 99% 101 of V and the most commonly used beam limiter and total filtering (the sum of the existing filtering and additional filtering), check the repeatability and linearity of the cumulative radiation output as follows. 7.2.3.1 Under the rated X-ray tube voltage, measure the reading of the cumulative irradiation reaching 0.2 full-scale value. Repeat the measurement 10 times. Calculate the average value K of the first five readings and the average value K1 of the ten readings K1: and their relative standard deviation C, see formula (1) F(K-Ke*
7.2.3.2 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 K.
7.2.3.3 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 reading 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 value, and. 7. 2. 3. 4 Calculate the ratio M of the above measured mean value K and the preset value Q: K
7.2.3.5 Evaluation criteria for cumulative radiation output repeatability experiment: Relative standard deviation C, for therapeutic machines with rated X-ray tube voltage greater than 150 kV, shall not exceed 0.03; for therapeutic machines with rated X-ray tube voltage not greater than 150 kV, shall not exceed 0.05. 7.2.3.6 Evaluation criteria for cumulative radiation output linearity test: [M--Mz.0.025|M,M and
[Ms - M 0.025IM - M,
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