GB 15213-1994 Performance and test methods of medical electron accelerators
Some standard content:
National Standard of the People's Republic of China
Medical electron accelerators--Functionalperformance characteristics and test methods GB15213--94
This standard is equivalent to the international standards 1EC976 (1989) "Medical electron accelerator performance" and 1E577181/5MV "Method for the performance of electron accelerators".
1 Subject content and scope of application
This standard specifies the performance indicators and test methods of medical electron accelerators. This standard is applicable to medical electron accelerators used for treatment in the medical industry. This standard applies to medical electron accelerators that can produce x-radiation and electron radiation, with a nominal energy of 1~50M as the radiation source. The maximum dose rate at m is 0.01~1Gy, and the normal treatment distance (NTN) is 5(200 m. This standard applies to medical electronic speedometers equipped with isocentric racks. Appropriate modifications may be made to the performance and test methods of non-isocentric equipment. Unless otherwise specified in the accompanying documents, this standard applies to equipment installed and used in the following environments: a.
15~ 35 (
bh. For humidity
30%～75%
e Maximum steam pressure
7X10*--11×1nPa(700~-1 100 mbar) The accompanying documents must describe the environmental conditions for transportation and storage. The power supply must comply with the provisions of item 1.4b.2) of GB9706. The power supply must have a sufficiently low internal resistance so that the voltage fluctuation between loaded and unloaded does not exceed 5%. Note: NT is the abbreviation of the English term for positive voltage range, as described below. 2 Terms and referenced standards
2.1 Terms
\Must" means mandatory requirements to comply with the provisions of this standard. "Should" means strongly recommending rather than requiring compliance with the provisions of this standard. "Can" means allowing a specific way to meet the requirements of this standard. 2.2 Referenced standards
GB 9706.1 Medical electrical equipment - Part - General safety requirements 2BF91001 Medical electronic accelerators Terminology GH9706.5 Medical electrical equipment - Special safety requirements for medical electrical accelerators with energy of 1~50MeV 3 Performance indicators
3.1 Dose monitoring system
Approved by the State Administration of Technical Supervision on September 24, 1994 and implemented on March 1, 1995
3.1.1 Variation
GB 15213--34
Variation is characterized by the coefficient of variation. For ×-radiation and electric radiation, under the condition of indirect irradiation, the coefficient of variation of the ratio of the average dose monitoring count value to the measured low of the absorbed dose shall not exceed 0.7%. The coefficient of variation S is determined according to formula (1):
(R - R,)
Where: R, is the ratio of the monitoring count value of the absorbent obtained in the first measurement to the measured value of the absorbent, R is the average value of a measurement, originally =
H -- the number of measurements. n is 10 times.
Hereinafter, it is defined as the half-mean of the ratio of the measured count value of the absorbent obtained in 5 measurements to the minimum measured value of the absorbent. 3.1.2 Linearity
For each energy level of X-radiation and electron radiation, within the range of absorbent test and absorbent rate specified in the random documents, the relationship between the absorbent test value and the monitoring count value of the absorbent must be linear. Its maximum value shall not exceed ±2%. 3.1.3 Relationship with the change of the angle of the equipment
For X-radiation and electron radiation, within the full angle range of the machine channel and the beam limiting system, the ratio of the difference between the maximum and minimum values to the average value shall not exceed 3%.
3.1.4 Relationship with the change of the gantry rotation
For the equipment with mobile beam therapy, in the two radiation modes of X-ray and electro-radiation, within the whole angle range of the gantry rotation, the deviation between the maximum value and the minimum measured value measured at different angles in 3.1.3 when the gantry is continuously passing through different sectors shall not exceed ±2%. 3.1. 5 Relationship with the change of the radiation field
It shall be specified in the random documents. For X-ray and X-ray, the maximum deviation between the size of the radiation field of 5cm×20cm and the radiation field of 20cm×5m shall be the rated value or the maximum radiation field is less than 2cm×20cm, then the maximum size is taken. 3.1.6 Stability
3.1.6.1 Stability after irradiation
For X-radiation and electron radiation, carry out high-dose batch irradiation for 10n(y) at the normal treatment distance or run at the maximum absorption rate for 30min. Before and after high-dose irradiation, carry out axial irradiation of about 2Gy, and measure and respectively, and R, "Yuan = not allowed to give + 2%.
3.1.6.2 [Stability
For X-radiation and electron radiation, the equipment produces about 1y of absorption at the normal treatment distance at a typical absorption rate, then stops irradiation for 10min, and continues to run for B hours in this cycle. Before and after the operation, carry out irradiation of about 2(y), respectively. K shall be measured separately, and it shall not exceed ±2%.
3.1.6.3 Weekly qualitative
For ×-ray electron radiation, the measurement shall be carried out for 5 consecutive days after the equipment has been in standby state for at least 30 minutes and reaches the ready state. The ratio of the sum of the maximum and minimum values of K measured within 5 days shall not be greater than 12%. 3.1.7 Stability of mobile beam therapy
For ×-ray electron radiation, the absorption rate and the unit dose shall be within the pre-selected range. If the mobile beam therapy is carried out by rotating the frame to terminate the irradiation, the dose error of the auxiliary irradiation shall not exceed ±5%. Where: 4p-dose error;
U-dose monitoring count value;
D, -—unit angle dose;
A——gantry rotation angle.
GB 15213-94
UD·Ａ
4. =
If the mobile beam therapy is terminated by the dose monitoring system, the rotation angle error shall not exceed ±3°. D,
Where: △A——rotation angle error;
A——gantry rotation angle;
D.—preset dose;
D.—unit angle dose.
3.2 Depth absorption dose characteristics
3.2. 1 X-radiation
3.2.1.1 Depth dose curve
-(2)
The random documents must give the absorbed dose percentage diagrams along the radiation table axis for 10cm×10cm and the maximum radiation field. These diagrams must correspond to each level of X-radiation nominal energy under standard test conditions. The following indicators must be given for each nominal energy: a Nominal energy of X-radiation:
10cm×10cm and the maximum absorbed dose depth of the maximum X-radiation field (in centimeters) ) b.
10cm×10cmX-radiation field penetration (in centimeters) The maximum deviation between the actual value of penetration and the specified value, this deviation shall not exceed ±3% or 3mm d.
e. Quality index.
The quality index is defined as the ratio of the absorbed dose measured at a depth of 20ctm in the phantom to the absorbed dose measured at a depth of 10cm for X-radiation, with the radiation detector located at the normal treatment distance on the axis of the radiation beam. 3.2.1-2 Surface dose
Corresponding to the nominal energy of each level of X-radiation, the following must be specified in the random documents: a. Relative surface absorbed dose of 10 cm×10 ctm radiation field; b. Relative surface absorbed dose of the maximum radiation field e. Must meet the requirements of Article 29.2.2 of GB9706.5. 3.2.1.3 Depth isodose curve
Under standard test conditions, corresponding to each X-radiation nominal energy, the random documents must provide a typical depth isodose curve on one or two planes including the radiation beam axis and any principal axis. The depth isodose curve must be given along the radiation beam axis, from 10% to 100% of the maximum absorbed dose (100%), every 10%. Each depth isodose curve must be marked: This value is only a typical value and cannot be used in the patient's treatment plan unless it has been verified.
3.2.2 Electron radiation
3.2.2.1 Depth dose curve
Under standard test conditions, corresponding to each electron radiation nominal energy, the random documents must provide a depth dose curve of 10cm×10cm and along the radiation beam axis under the maximum radiation field. GB 15213--94
Corresponding to each nominal energy, the following indicators must be given: a.10cm×10cm and the maximum absorbed dose depth of the maximum radiation field (in centimeters). The maximum absorbed dose depth shall not be less than 0.1 cm
h. The ratio of the actual range under 10 cm×10 cm and the maximum radiation field to the depth of 80% absorbed dose. For medical electron accelerators with a nominal energy greater than 20MeV, the ratio shall not be greater than 1.6: c. The actual range of the 10cm×10cm radiation field (in meters); d. The penetration of the 10 cm×10 cm radiation field (in centimeters) e. The maximum deviation of the actual value of the penetration from the specified value, which must not exceed 3% or ±2mm. 3.2.2.2 Stability of penetration
In the entire range of absorbed dose rate and gantry rotation angle, the maximum deviation of the penetration of electron radiation due to random gantry angle changes shall not exceed ±2mm or ±3%.
3.2.2.3 Surface dose
Under standard test conditions, for each nominal energy of the electronic radiation, the maximum value of the relative surface dose must be specified in the random documents at 10 cm×10 cm and the maximum radiation field.
3.2.2.4 Depth isodose diagram
Under standard test conditions, for each nominal energy of the electronic radiation, the random documents must give typical depth isodose curves on one or two planes including the radiation beam axis and any principal axis. The isodose diagram must be given along the radiation beam axis, from 10% to 100% of the maximum dose (as 100%), every 10%. Each isodose diagram must indicate that this value is only a typical value and cannot be used in the treatment plan of the patient unless it has been verified. 3.3 Uniformity of radiation field
3.3.1 X-ray radiation
3.3.1.1 Uniformity of square X-ray radiation field
Under standard test conditions, within the full range of absorbed dose rates, for each nominal energy, the ratio of the absorbed dose (not greater than the average value within an area of 1 cm) of the maximum absorbent wall point in the radiation field to the minimum absorbed dose point within the uniform area of the radiation field (see Figure 4) is: a. For radiation fields from 5 cm×5 cm to 30 cm×30 cm, it shall not be greater than 106%; b. For square fields from 30 cm×30 cm to the maximum person, it shall not be greater than 110% (see Figure 5). 3.3.1.2 Variation of the dose distribution of the X-radiation field with angle Under standard test conditions, within the entire angular range of the frame and the beam limiting system, for the entire X-radiation field larger than 5 cm × 5 cm, the variation in the ratio of the absorbed dose of the absorbent at any point in the uniform area (not greater than the average value within 1 cm) to the absorbed dose at the axis of the radiation beam is: a. It shall not exceed ± 3% when the nominal energy is less than 30 MeV; b. It shall not exceed ± 4% when the nominal energy is equal to 30 MeV. 3.3.1.3 Symmetry of square X-radiation field
Under standard test conditions, when the gantry and beam limiting system are at 0 or 90° respectively, the maximum ratio (large to small) of the absorbent dose (average value within an area not greater than 1 cm\) of any two points symmetrical to the radiation beam axis in the uniform area of all X-radiation fields of 5cm×5cm for a person shall not be greater than 103%
3.3.1.4 Maximum absorbed dose ratio
When the gantry and beam limiting system are at 0\ or 90°, on the plane perpendicular to the radiation beam axis at the maximum absorbed dose depth, the ratio of the absorbed dose at the maximum absorbed dose point in the uniform area (average value within an area not greater than -1cm\) to the maximum absorbed dose on the radiation beam axis is: a. for radiation fields of 5cm×5cm to 30cm×30cm, it should be less than 107%; b. for square radiation fields of 30cm×30cm, it should be less than 109%. 3.3.1.5 The X-radiation field of the wedge filter shall not exceed ±2° within the rotation angle range of the rack and the beam limiting system. (See Figure 6) The difference between the measured value and the nominal value of the wedge angle shall not exceed ±2% of the measured value of the wedge GB1521394
shape factor. The maximum radiation field of each shape filter must be given in the random documents. 3.3-2 Electron radiation
3.3.2-1 Uniformity of electron radiation field
Under standard test conditions, for each nominal energy and all electron radiation fields not less than 5 cm×5 cm: a. At the reference depth, the distance between the 80% isodose line on the two main axes and the edge of the geometric field projection should not be greater than 15 mm; b. At the standard test depth, the distance between the 90% isodose line on the two main axes and the edge of the geometric field projection shall not be greater than 10 mm; the distance between the 90% isodose line on the two diagonals and the edge of the geometric field projection shall not be greater than 20 mm; c. The random documents must give the ratio of the maximum absorbed dose (average value within a 1 cm area) in the radiation field at the standard test depth to the absorbed dose at the depth of maximum absorbed dose on the radiation beam axis (see Figure 7). 3.3.2.2 Relationship between the dose distribution of the electron radiation field and the angular position At the standard test depth, within the full range of the rotation angle of the rack and the beam limiting system, for all electron radiation fields, the ratio of the absorbed dose at any point within the uniform area of 1 cm pushed inside the 90% isodose curve (the average value within an area of not more than 1 cm) to the absorbed dose at the axis of the radiation beam shall not exceed ±3%.
3.3.2.3 Symmetry of the electron radiation field
Under standard test conditions, when the rack and the beam limiting system are at 0 or 90°, for all electron radiation fields not less than 5cmX5cm, at the standard test depth, the ratio (large to small) of the absorbed dose at any two points symmetrical to the axis of the radiation beam within the uniform area of 1 cm pushed inside the 90% isodose line (the average value within an area of not more than 1 cm) shall not exceed 105%. 3.3.2.4 Ratio of Maximum Absorbed Dose
The ratio of the absorbed dose at the point of maximum absorbed dose in the radiation field at a depth of 0.5 mm (average value over an area not greater than 1 cm) to the maximum absorbed dose on the axis of the radiation beam shall not be greater than 109%. 3.3.3 Planar Shadow of Radiation Field
Under standard test conditions, for each nominal energy of X-radiation and electron radiation, the Random Documents must give the distance (in millimeters) between the 80% absorbed dose point and the 20% absorbed dose point on the two principal axes. The 80% point and the 20% point are relative to the absorbed dose at the standard test depth on the axis of the radiation beam.
3.4 Indication of Radiation Field
3.4.1 X-radiation
3.4.1.1 Digital Indication of Radiation Field
All equipment should be equipped with a digital indicator to indicate the size of the X-radiation field at the normal treatment distance. Within the rotation angle range of the gantry and beam limiting system, for each rated energy, at the normal treatment distance, the deviation of the radiation field size on the two main axes from the indication of the digital indication device shall be: a. For the radiation field of 5cm×5cm to 20cm×20cm, it shall not exceed ±3mm or ±1.5% b. For the radiation field of 20cmX20cm to the maximum, it shall not exceed ±5mm or ±1.5%. The radiation field size is determined by the 50% absorbed dose line described in the test method. 3.4.1.2 Light field indication of radiation field
All equipment must be equipped with a light field indication device to indicate the size of the X-radiation field at the incident surface. Within the rotation angle range of the gantry and beam limiting system, for each nominal energy level, on the two main axes, the distance between the edge of the light field and the edge of the radiation field (determined by the 50% dose line) is:
At normal treatment distance:
a. For radiation fields from 5cm×5cm to 20cm×20cm, it shall not be greater than 2mm or 1%; b. For fields from 20cm×20cm to the maximum square field, it shall not be greater than 3rm or 1%. At 1.5 times the normal treatment distance:
a. For radiation fields from 5cm×5cm to 20cm×20cm, it shall not be greater than 4mm or 2%; b. For fields from 20cm×20cm to the maximum square field, it shall not be greater than 6mm or 2%. The distance between the center of the light field and the center of the radiation field: GB 15213-94
a. At normal treatment distance, it shall not be greater than 2 mm; b. At 1.5 times the normal treatment distance, it shall not be greater than 4mm. 3.4.1.3 Repeatability
When the radiation field is repeatedly established at the same digital indication, the maximum deviation of the radiation field size determined by the 50% absorbed dose point on the two main axes shall not exceed ±2mm, and the distance between the edge of the light field and the edge of the X-radiation field shall not be greater than 2mm. 3.4.2 Electronic radiation
3.4.2.1 Digital indication of radiation field
All equipment should be equipped with a digital indication device to indicate the size of electronic radiation. For all nominal energies and radiation fields, the deviation between the size of the radiation field at the standard test depth and the digital indication value of the radiation field shall not exceed ±2mⅡ. The size of the radiation field is determined by the distance between the 50% isodose points on the two main axes when the phantom surface is at the normal treatment distance.
3.4.2.2 Light field indication of radiation field
All equipment must be equipped with a light field indication device to indicate the size of the electron radiation field (on the incident surface). At the normal treatment distance, the deviation between the distance between the opposite sides of the light field and the digital indication value shall not exceed ±2mm. 3.4.3 Geometry of the beam system under X-ray radiation mode - The maximum deviation of the parallelism of the opposite sides of the radiation field shall not be greater than 0.5°, and the maximum deviation of the adjacent perpendicularity shall not be less than 0.5° 3.4.4 Illumination and contrast of the light field
On the plane perpendicular to the axis of the radiation beam at the normal treatment distance, the average value of the illumination in the light field shall not be less than 401x. The contrast along the periphery of the light field shall not be less than 4%. The contrast is the ratio of the illumination of a point within the periphery of the light field to the illumination of a point 3m away from the periphery. 3.5 Indication of the radiation beam axis
For radiation fields symmetrical to the isocenter, the equipment must be equipped with elements that indicate the position of the radiation beam axis at the patient's incident surface, such as front pointers, decibels, etc.
3.5.1 Position and indication of the radiation beam axis on the patient entrance surface Within the full angle range of the gantry and beam limiting system, the maximum deviation between the actual position of the radiation beam axis on the patient entrance surface and the indicated point shall be: a. For x-radiation, within the NTD ± 25 cm or the equipment working range (whichever is smaller), it shall not exceed ± 2 mm b. For electron radiation, within the NTD ± 25 cm or the equipment working range, whichever is smaller), it shall not exceed ± 4 mm. 3.5.2 Position indication of the radiation beam axis on the patient exit surface For all elements indicating the patient's X-radiation exit point (such as the rear pointer, etc.), within the NTD ± 50 cm or the equipment working range, whichever is smaller), the maximum deviation between the actual position of the radiation beam axis on the patient exit surface and the indicated point shall not exceed ± 3 mM. 3.6 Isocenter
3.6.1 The deviation of the radiation beam axis from the isocenter point For each nominal energy level of X-ray and electro-radiation and all radiation fields, the deviation of the radiation beam axis from the isocenter point shall not exceed ±2 mm within the full angular range of the gantry and beam limiting system. 3.6.2 Indication of isocenter
The maximum deviation of the isocenter indication point of the isocenter device from the isocenter position determined by 3.6.1 shall not exceed ±2 mm
3.7 Distance indication along the radiation beam axis
3.7.1 Indication of the distance to the isocenter
The equipment must be equipped with an indication device (such as a mechanical front pointer, optical distance ruler) to indicate the distance to a reference point along the radiation beam axis. For isocentric equipment, the reference point must be the isocenter point. For non-isocentric equipment, the reference point must be at the normal treatment distance on the radiation beam axis. GB 15213-94
At NTD ± 25 cm or at the extreme position of the working range of the indicating device (whichever is smaller), the maximum deviation between the indicated distance along the radiation beam axis to the reference point and the actual distance shall not exceed ± 5 mm. At the isocenter, this deviation shall not exceed ± 2 mm. This condition must be met for isocenter equipment within the entire angular range of the rack. 3.7.2 Indication of the distance to the radiation source
For isocenter equipment with a variable distance from the radiation source to the rack rotation axis (1) (as shown in Figure 1) and non-isocenter equipment, an indicating device (such as a mechanical front pointer, optical distance ruler) must be provided to indicate the distance along the radiation beam axis to the radiation source. Within VTD ± 25 cm or within the working range of the indicating device (whichever is smaller), the maximum deviation between the indicated distance from the indicating point to the radiation source and the actual distance shall not exceed ± 5 mm. 3.B Zero Position of Rotational Scales
For rotating gantries (and other gantries in use), the scales of axes (1), (2), (5) and (6) must be zero when: all axes of rotation except (3) and (7) are coplanar, the beam axis is vertically downward, the longitudinal axis of the treatment bed is parallel to axis (1) or (2), and the bed support is away from the gantries (as shown in Figure 1). When the beam axis is vertically downward, the scales of axes (1) and (2) are zero, and the scale of axis (3) must be zero. When the two sides of the optical system are parallel and perpendicular to the gantry rotation axis, respectively, and the thin end of the wedge filter points toward the gantries, the scale of axis (4) must be zero.
When the table surface is horizontal, the scales of axes (7) and (8) must be zero. The maximum deviation between the zero scale position of each scale and the specified zero position: the frame rotation axis (1)
radiation head transverse rotation axis (2)
radiation head longitudinal rotation axis <3)
beam limiting system axis (4)
shall not exceed ±0.5°
shall not exceed ±0.1°;
shall not exceed ±0.1°
shall not exceed ±0.5°;
treatment bed isocentric rotation axis (5) shall not exceed ±0.5°; bed surface white rotation axis (6)
bed surface longitudinal rotation axis (7)
bed surface transverse rotation axis (8)
3. 9 The overlap of the front and rear radiation fields shall not exceed ±0.5\
shall not exceed ±0.5°;
shall not exceed ±0.5°
At the isocenter, the maximum deviation between the main axes of the front and rear radiation fields shall not exceed ±2m. 3.10 Movement of the treatment bed
When the treatment bed surface is at the nominal height of the isocenter, the longitudinal axis of the bed surface is collinear with the rotation axis of the frame, and the axis (5) and axis (6) are at zero position, and the longitudinal distance between the bed surface and the frame is the maximum, the linear motion scale of the treatment bed must be zero. -3. 10. 1 Vertical movement of the treatment bed
Under the following two load conditions:
a. The bed surface load is 30kg, evenly distributed within a range of 1m on the bed surface, and the center of gravity of the load acts on the isocenter; b. The bed surface load is 135kg, evenly distributed within a range of 2m on the bed surface, and the center of gravity of the load acts on the isocenter. If the treatment couch is extended to its maximum extent (Figure 1, direction 11) and the distance from the extension end to the isocenter is less than 1 m, the 135 kg load is evenly distributed over twice the distance from the extension end to the isocenter. When the treatment couch is raised or lowered near the normal treatment distance, the maximum horizontal displacement of the couch shall not exceed 2 mm when the height changes by 20 cm in direction (9) (as shown in Figure 1).
3. 10.2 Isocenter rotation of the treatment couch
Under the load conditions of 3.10.1, the maximum displacement of the rotation axis (5) (as shown in Figure 1) of the isocenter rotation of the treatment couch relative to the isocenter shall not exceed ±2 mm.
3.10.3 Parallelism of the rotation axis of the treatment bed
When the treatment bed surface is loaded with 135kg and evenly distributed within a 2m length range (same as 3.10.1) and the center of gravity acts on the isocenter, the maximum angle between the isocenter rotation axis (5) of the treatment bed (as shown in Figure 1) and the rotation axis (6) of the treatment bed surface (as shown in Figure 1) should not be less than 0.5°.
3.10.4 Rigidity of the treatment bed
3.10.4.1 Longitudinal rigidity of the treatment bed
The treatment bed is subjected to the following two load conditions (the center of gravity of the load acts on the isocenter): 1. The bed surface is retracted, and the 30kg load is evenly distributed within a 1m length range; 2. The bed surface is extended, and the 135kg load is evenly distributed within a 2m length range. The load distribution is the same as in 3.10.1.
The height change of the treatment bed surface near the isocenter under two loads shall not exceed 5mm. 3.10.4.2 Lateral stiffness of the treatment bed
When the load of 135 kg is evenly distributed within the 2 m length of the treatment bed (see 3.10.1) and the center of gravity acts on the isocenter, within the entire height range of the vertical lifting of the treatment bed (direction 9, as shown in Figure 1): a. The lateral inclination angle of the treatment bed surface relative to the horizontal plane shall not exceed 0.5° b. When the treatment bed surface makes the maximum lateral displacement (direction 10, as shown in Figure 1), the height change of the treatment bed surface near the isocenter shall not exceed 5mm.
4 Test method
4.1 Standard test conditions
Unless otherwise required, when testing the performance of medical electron accelerators according to this standard, the standard test conditions given in 4.1 to 4.5 must be followed.
4.1.1 Angular positions
Unless otherwise specified, the following angles are 0° (as shown in Figures 1 to 3): a. lateral rotation of the radiation head, axis (2),
b. longitudinal rotation of the radiation head, axis (3);
c. rotation of the beam limiting system, axis (4).
If the test conditions in this standard require that the test must be carried out when the frame rotation axis (1) or the beam limiting system axis (4) is at 90°, the test can also be carried out at the 270° position.
4.1.2 Materials and Position of Phantoms
Unless otherwise specified, the phantom shall be a water phantom. If the phantom is made of other materials, appropriate corrections shall be made. For any test requiring the use of a phantom: The phantom surface shall be perpendicular to the radiation beam axis. The phantom shall extend at least 5 cm beyond the edge of the radiation beam, unless it can be demonstrated that a small phantom will not significantly affect the test results. The phantom depth shall be at least 10 cm greater than the depth of the test point. 4.1.3 Position of Test Points
Unless otherwise specified, the test position shall be (whichever is most suitable): 1 cm on the radiation beam axis
b. In the plane perpendicular to the radiation beam axis at the standard test depth within the phantom. Unless otherwise specified, for tests of electron accelerator X-radiation at the isocenter, the test plane shall include the isocenter and the phantom surface shall be located 10 cm from the isocenter in the direction from the isocenter to the radiation source. Unless otherwise specified, for the tests of electron radiation from isocentric accelerators and electron radiation from non-isocentric electron accelerators and X-radiation, the phantom surface is located at the normal treatment distance (see Figure 8). 4.1.4 Radiation detectors
The radiation detectors used in the tests are required to: a. determine the absorbed dose from the readings of the radiation detectors after correction for the spatial variation of the radiation energy spectrum; b. have sufficient spatial resolution in areas of high dose gradients, such as at the edge of the radiation field. 4.1.5 Standard test depth
4.1.5.1 X-radiation beams
The standard test depth of X-radiation beams is 10 cm. 4.1.5.2 Electron beams
The standard test depth of electron beams is half of the specified penetration value for a 10 cm × 10 cm radiation field. 4.1.6 Radiation field
During the test, the radiation field size should be selected from the radiation field that is closest to the commonly used situation. The size of the radiation field refers to the size at the normal treatment distance.
Unless otherwise specified, the maximum radiation field refers to the most square radiation field. 4.1.7 Adjustments during the test
During the test, only the following two types of adjustments are allowed: a. Adjustments made using the control methods normally used by the operator, b. Adjustments during positive belt operation,
Axis (1) to axis (8); direction (9) to direction (13) in the following text; see the provisions of Figures 1, 2 and 3. 4.2 Dose monitoring system
4.2.1 Repeatability
Gantry axis (1)
0° or 90°
0° or 90°
Beam system axis (4)www.bzxz.net
Radiation field
10×10
10×10
Repeatability Test conditions
Absorbed dose rate
Maximum value
Minimum value
Radiation type
X radiation
Electron radiation
Nominal energy
According to Table 1, 10 irradiations are carried out continuously under each set of conditions. A dose of 2 Gy is preset at the normal treatment distance each time. During the measurement, the probe must be placed in the phantom or with appropriate construction materials (this requirement applies to all R-value measurements, omitted below). The test results must comply with the provisions of 3.1. 1.
4.2.2 Linearity
Table 2 Linear test conditions for dose monitoring system Angle
Gantry axis (1)
Beam limiting system axis (4)
Radiation field
10×10
Absorbed dose rate
Radiation type
X-radiation
Electron radiation
Note: If the absorbed dose varies continuously, take an absorbed dose rate value at equal intervals from 20% of the maximum value to the measured value. Nominal energy
According to the test conditions specified in Table 2, for each absorbed dose rate (set the number of levels to j. If the absorbed dose rate is continuously adjustable, 4 different absorbed dose rate values are taken at equal intervals from 20% to the maximum absorbed dose rate, which is equivalent to =4), select n different absorbed dose preset values (1=5 are specified) at approximately equal intervals within the absorbed dose range greater than 1 Gy, and irradiate n times for measurement at each absorbed dose rate and each absorbed dose preset value (n=5 is specified). GB15213-94
Let D represent the absorbed dose measurement result of the irradiation at the th absorbed dose preset value and the 1st absorbed dose rate, and D, be the average value of the absorbed dose measurement results of n irradiations at the th absorbed dose preset value and the th absorbed dose rate. Then:
D. is the average value of the D, values of the absorbed dose rates at the th absorbed dose preset. Then we have:
Use the least square fitting method to find the following linear relationship for each D. data: D, =aU+b
Wherein; D, is the calculated value of absorbed dose obtained by the least square method, a is the proportional factor;
b is the intercept of the straight line and the ordinate axis;
is the preset value of absorbed dose (see Figure 9). (4)
-（5)
（6）
Compare the deviation between the measured average value D. and the value D. calculated by the least square fitting method, expressed as a percentage. The maximum deviation (D,-D.)m.×100
% must comply with the provisions of Article 3.1.2. U
4.2.3 Relationship with the angular position of the device Table 3 Test conditions for the relationship between the dose monitoring system and the angular position of the device Angle
Gantry axis (1)
0 or 180°
0°180°
90° or 270°
90° or 270°
Beam limiting system axis (4)
Radiation field
10 ×10
10×10
10×10
10×10
10×10
Absorbed dose rate
Radiation type
X-radiation
Electronic radiation
X-radiation
Electronic radiation
X-radiation
Electronic radiation
Nominal energy
GB 1521394
Fix the detector with appropriate balanced thickness on the treatment head, keep the equipment still, and conduct 5 tests under each group of conditions to calculate the R value. In each test, irradiate an absorbed dose of about 2Gy at the normal treatment distance. The test results must meet the requirements of Article 3.1.3. 4.2.4 Relationship of random gantry rotation
Table 4 Test conditions of the relationship of dose monitoring system with random gantry rotation Gantry angle range
Axis (1)
Through 45\sector
Beam limiting system angle
Axis (1)
Radiation field
10×10
Dose rate
Radiation type
X-radiation
Electronic radiation
Nominal energy
A detector with appropriate balanced thickness is fixed on the treatment head. According to Table 4, 4 tests are carried out under each group of conditions to determine the table value. In each test, the gantry rotates through a range of about 45, and an absorbed dose of about 2Gy is irradiated at the normal treatment distance. If possible, two irradiations should be completed in clockwise rotation and the other two in counterclockwise rotation. The test results must meet the requirements of Article 3.1.4. 4-2.5 Relationship with radiation field
Table 5 Test conditions for the relationship between dose monitoring system and radiation field Angle
Gantry axis (1)
Beam limiting system axis (4)
20×5\
Note, 1) If less than 20 cm, take the most appropriate value. Absorbent Maximum
Radiation type
X-radiation
Electron radiation
Nominal energy
According to Table 5, 5 tests are carried out under each set of conditions to determine the R value. Each radiation irradiates a dose of about 2 Gy at the normal treatment distance.
The test results must comply with the provisions of Article 3.1.5. 4.2.6 Stability
4.2.6.1 Stability after high-dose irradiation Table 6 Test conditions for stability of dose monitoring system calibration Angle
Gantry axis (1)
Beam limiting system axis (4)
Radiation field
10×10
10×10
Absorbent basis
Radiation type
X-radiation
Electron radiation
Nominal energy
According to Table 6,Use a detector with an appropriate balanced thickness, and irradiate a dose of about 2 Gy at the positive treatment distance. Perform 5 tests under each set of conditions to determine the value. Each irradiation: GB 15213-94
a. Immediately after entering the standby state after at least 30 minutes of standby after starting up, b. Immediately after high-dose irradiation with an absorbed dose of 100 Gy at the normal treatment distance or running at the maximum dose rate for 30 minutes.
During the test, the changes in temperature, air pressure and humidity are corrected according to the random documents. The test results must meet the requirements of Article 3.1.6.1.
4.2.6.2 Daily stability
According to the test conditions in Table 6, the test is performed immediately after entering the standby state after at least 30 minutes of standby after starting up, and irradiate about 2 Gy absorbed dose at the normal treatment distance. The average value is calculated for 5 irradiations. Then, B h continuous cycle operation is performed, each cycle is to irradiate about 4Gy absorbed dose at the typical absorbed dose rate, and then stop for 10 minutes. After 8h continuous cycle operation, irradiate 5 times with 2Gy absorbed dose, and calculate the average value 2. During the test, the changes in temperature, air pressure and humidity are corrected according to the provisions of the random documents. The results must comply with the provisions of Article 3.1.6.2. 4.2.6.3 Weekly stability
The test conditions are the same as Table 6.
According to Table 6, the phantom is fixed on the radiation head, and irradiated 5 times each day under the same test conditions for five consecutive days to determine the R value. Each time, a dose of about 2Gy is irradiated at the normal treatment distance. At least 30 minutes of standby state must be passed before each test. During the test, the changes in temperature, air pressure and humidity are corrected according to the random documents, and the test results must comply with the provisions of Article 3.1.6.3.
4.2.7 Stability of moving beam therapy
Table 7 Test piece for stability of dose monitoring system in moving beam therapy Dose monitoring counts per unit angle of gantry rotation
|Beam limiting system angle
Axis (4)
Radiation field
10×10
10×10
Radiation type
X-radiation
Electron radiation
Nominal energy
According to the conditions of Table 7, the gantry rotates through an angle corresponding to a dose of approximately 4 Gy at the normal treatment distance. If this angle cannot be achieved, it should be as close to 4 Gy as possible. The test results must comply with the provisions of Section 3.1.7. 4.3 Depth absorbed dose characteristics
4.3.1 X-radiation
4.3.1.1 Depth dose curve
Table 8 Test conditions for depth dose characteristics
Gantry axis (1)
0° or 90°
Beam limiting system axis (4)
Radiation field
10×10
Absorbed dose rate
Radiation type
X-ray
Under standard test conditions, use a water phantom to test the depth dose distribution along the radiation beam axis according to the conditions in Table 8. Nominal energy
The maximum dose depth is determined as the dose depth corresponding to the midpoint of the line connecting the two 99% depth dose points on the depth dose curve. Test results
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