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YY/T 0890-2013: Electronic portal imaging device using in radiotherapy - Functional performance characteristics and test methods
YY/T 0890-2013
Electronic portal imaging device using in radiotherapy.Functional performance characteristics and test methods
ICS 11.040.60
C43
People's Republic of China pharmaceutical industry standards
Radiotherapy electronic portal imaging device
Performance and test methods
Issued on. 2013-10-21
2014-10-01 implementation
China Food and Drug Administration released
Foreword
This standard was drafted in accordance with GB/T 1.1-2009 given rules.
Please note that some of the content of this standard may involve patents. The standard release mechanism does not assume the responsibility to identify these patents.
This standard was proposed by the China Food and Drug Administration.
This standard by the National Standardization Technical Committee appliances medical radiotherapy, nuclear medicine science equipment at the Technical Committee and the radiation dose
(SAC/TC10/SC3) centralized.
This standard was drafted. Beijing Medical Device Testing, Elekta North Institute (Beijing) Co., Ltd. medical equipment.
The main drafters of this standard. Feng Jian, Wang Peichen, Wanghui Liang, Jiao spring camp.
Radiotherapy electronic portal imaging device
Performance and test methods
1 Scope
This standard specifies performance requirements and test methods for electronic portal imaging device.
This standard applies to medical radiotherapy accelerator electron beam radiation as electronic portal imaging device of the radiation source.
2 Normative references
The following documents for the application of this document is essential. For dated references, only the edition are not applicable to the present
file. For undated references, the latest edition (including any amendments) applies to this document.
GB/T 17857 Medical imaging academic language (radiotherapy, nuclear medicine and radiation dosimetry equipment)
GB/T 18987 radiotherapy device coordinates, movement and scale
3 Definitions
GB/T 17857 and defined by the following terms and definitions apply to this document.
3.1
Electronic imaging apparatus electronicimagingdevice; EID
By one or more radiation detectors and associated electronic components, in order to make digital images of radiation in the form of the patient's anatomy
Observation equipment on the viewing screen.
NOTE. See 3.2.
3.2
Electronic portal imaging device electronicportalimagingdevice; EPID
It consists of a two-dimensional radiation detector and associated electronic components, placed perpendicular to the axis of the radiation beam to medical electron accelerator radiation beam
As the radiation source, enabling the patient's anatomy observation device in the form of a digital radiation image is carried out on a viewing screen.
Note. electronic portal imaging device main function is to use an alternative method of imaging film to verify patient positioning.
3.3
Low contrast resolution lowcontrastresolution
Under specified measurement conditions can be distinguished from a homogeneous background conditions out of a predetermined shape and area of low contrast details thereof,
The unit is%.
3.4
Spatial resolution spatialresolution
Under specified measurement conditions, with eyesight specified minimum resolvable spatial frequency wire line group graphics image of the group, the unit is lp/mm.
4 Requirements
4.1 General requirements
If the argument electronic imaging devices, and/or conditions may not apply or can not meet the requirements of this chapter, shall be described in detail with this random file
These exceptions and describes the parameters for the electronic imaging device, and/or conditions.
4.2 mechanical support structure
Random file the following parameters should be given the support structure of an electronic imaging device.
a) an image detector.
1) distance to the plane of the detectors and other centers, this distance or range (if applicable);
2) the center of the detector and X-radiation beam range of longitudinal movement (Y-direction) between the shaft;
3) the center of the detector and X-radiation beam range of lateral movement (X-direction) between the shaft;
b) in the source given gantry angle to the detector and a predetermined distance between the center of the image detector and X radiation beam axis projection bias
Difference (measured in normal treatment distance), in mm.
4.3 Imaging Performance Requirements
4.3.1 detector pixel size and spacing
Random files should be given an electronic portal imaging device detector area and the pixel pitch; detector area should be given in units of cm2,
Mm pixel pitch should be given in units, the pixel size can also be expressed.
4.3.2 Detectors
Random files should be given an electronic portal imaging device the size of the detector field of view, should be given in units of cm. Not by motion detection
Is to the maximum observed a rectangular field of view (measuring distance at normal therapeutic) in size in each axis to represent.
If the detector plane to the distance of such centers is variable, field of view should be set at a distance of measurements, including maximum and minimum distance.
4.3.3 shows the number of pixels
Random files should be given an electronic portal imaging detector means the number of pixels visible. The maximum image size you can use the number of pixels displayed.
The maximum number of rectangular field of pixels of the image size should be at a time without moving the probe can be observed is given.
4.3.4 Detector frame time
Random files should be given corresponding to the maximum frame rate (frames/s) Minimum time frame. Detectors should be less than the minimum frame time 0.5s; corresponding
The maximum frame rate should be not less than 2/s.
4.3.5 SNR and dynamic range imaging apparatus
4.3.5.1 random file shall be given with respect to the amount of signal to noise ratio, expressed as a percentage or in decibels. Shall be given the dynamic decibels
range.
4.3.5.2 1cGy dose of SNR should be not less than 5000%.
4.3.6 imaging device delay
Incentive should be measured after the elimination of image retention. After completion of the exposure ratio of the first frame and the second frame signals should not exceed 5%, or the fifth frame
The ratio of the first frame signal shall be not more than 0.3%.
4.3.7 linear imaging device
The manufacturer shall give appropriate for the treatment of (for example, dosimetry applications) non-linearity within the dynamic range of the image.
In the above range, the manufacturer should be measured based on the maximum percentage of deviation of the video signal of a linear relationship between the amount of radiation and the detector signal
Linear number.
4.3.8 spatial resolution imaging device
For a given set of imaging conditions (energy, dose monitoring counting detector frames) when located on a surface with a contrast EID
Modulation transfer function test card phantom imaging, the manufacturer shall be given in a random file Distinguished highest spatial frequency function
(MTF). When using the measuring card contrast test, contrast test card should be relative to the X-axis or Y-axis detector was certain angle
Place the angle is determined by the use of specific performance test phantom (see note below). Should also describe the use of test phantoms geometric knot
Structure and radiation from X to EID surface distance.
NOTE. Because of the EID some (particularly those of the electronic element using amorphous silicon) structure reason, spatial resolution may be based on the contrast with respect to the probe card testing
XY axis direction detector varies (see GB/T 18987, coordinate system X-radiation imaging apparatus), the MTF measurement should contrast test card
Parallel with the test phantoms specified by the manufacturer under the direction of.
For a given X-radiation energy, dose, dose rate, when the card is EID contrast test surface, the maximum frequency can be resolved under
Not less than the spatial resolution of the imaging device 0.6lp/mm.
4.3.9 Low contrast resolution
Random file manufacturer shall be given low contrast resolution. It should not be less than the value specified by the manufacturer.
4.3.10 image distortion
Random file manufacturer shall specify the image distortion. It should not be less than the value specified by the manufacturer.
5 Test methods
5.1 Test conditions
Desired image acquisition parameters are interrelated and should be placed together are given. If the design of electronic imaging devices allow for these parameters
Associate of adjustments for the following four parameters are combined to achieve a variety of typical repeat settings. Dose measurements should be given for use
Count (MU), energy, radiation field size and source-to-detector distance and other parameters.
Unless otherwise provided in the mold body manufacturer, using the normal treatment distance test.
Before all tests should be completed calibration.
Quantitative measurements of image quality, the test of this chapter may require software tools and test phantoms combination.
Other electronic imaging test is usually specified by the manufacturer shall contain the following.
a) In the image correction or calibration (such as offset, gain and bad pixel correction) should be made after the image acquisition tests to verify that the
Achieve acceptable contrast and spatial resolution. X-radiation energy should be used at each file, such as high-contrast phantom
Aluminum LasVegas phantom or a simulation mannequin for imaging.
b) generally electronic imaging device manufacturer should also recommend on electronic imaging device calibration frequency of certain parameters such as.
1) gain, and
2) offset.
c) shall describe the conformance test between EID center of the image and the radiation beam axis.
5.2 mechanical support structure
5.2.1 Checking the file, check the portal means mechanical range of motion, shall comply with the requirements given random file.
5.2.2 The accelerator rack is adjusted to 0 °, the treatment head is adjusted to 0 °, remove the deck, open the light field, so crosshairs projected image detector
The maximum and minimum distance from the surface at a position, and so on from the center of the detector.
Mark the image detector surface projection of crosshairs.
Recovery image detectors, and once again make the image detector stretch, measuring reticle projection center mark and the radiation field deviation. Shall comply with random
Requirements documents.
Accelerator rack 90 °, 180 ° and 270 °, repeat the above steps.
5.3 Electronic portal imaging
5.3.1 detector pixel size and spacing
Checking the file should meet the requirements of 4.3.1.
5.3.2 Detectors
Checking the file should meet the requirements of 4.3.2.
5.3.3 shows the number of pixels
Checking the file should meet the requirements of 4.3.3.
5.3.4 Detector frame time
Checking the file should meet the requirements of 4.3.4.
5.3.5 SNR and dynamic range imaging apparatus
The method of detection according to the manufacturer shall comply with the requirements given random file.
5.3.6 imaging device delay
The method of detection according to the manufacturer shall comply with the requirements of 4.3.6.
5.3.7 linear imaging device
5.3.7.1 copper or aluminum ladder ladder method
5.3.7.1.1 motif
Copper or aluminum ladder ladder structure, the absorption maximum thickness of the high-energy photons should be more than 30cm of water, corresponding to the thickness of each ladder gradation
The difference should be equal. Ladder series should not be less than five.
5.3.7.1.2 Test Method
Set motif in the beam, the central copper or aluminum ladder ladder should be near the center of the field position. Phantom image receiving surface as close as possible. Obtain
image.
Adjust window width and position, so that as many ladder display. Were measured gray value of each ladder, the gray value of the ladder line thickness
Properties fitting.
5.3.7.2 MU law
1/2, to 1MU irradiation will reduce the adjusted maximum radiation field of radiation field size 1/3 to 1MU exposure, then the radiation field
Size reduced by 1/3, to give 1MU irradiation to obtain an image. Were measured gray scale value of each stepped image, the total irradiation corresponding gray value
MU number of linear fit.
If EPID system allows more MU followed by irradiation, irradiation may be a corresponding increase in the number of field to get more detailed gradation ladder.
5.3.8 spatial resolution imaging device
Set on the phantom line in the center of the beam. Phantom as close to the image receiving surface. Get image.
Analysis Method 1. Adjust the window width and position to get the most clear display, observe the number of pairs can be resolved.
Analysis Method 2. adjustment to the minimum window width, window level adjustment, so that the maximum number of lines can be distinguished clearly show the mold section, viewed in FIG.
Black and white image, with or without interruption, select a group of completely uninterrupted, as the highest resolution.
5.3.9 Low contrast resolution
5.3.9.1 motif
Excavation low contrast phantom is 0.5mm ~ 15mm diameter hole, the hole depth material on a certain thickness of aluminum or copper
The thickness is proportionally
5.3.9.2 Test Method
Set low contrast phantom in the beam center. Phantom as close to the image receiving surface. Get image.
Analysis Method 1. Adjust the window width and position to get the most clear display, number of holes can be observed resolved.
Analysis Method 2. adjustment to the minimum window width, window level adjustment, making it possible to distinguish clearly show the hole gradually edge observation hole, seamless
Hole gap of effective resolution, choose the smallest gap completely set, as the highest of the low contrast resolution.
5.3.10 image distortion
5.3.10.1 motif
Measuring image distortion motif should contain four display can locate point whose geometrical position should form a square or rectangular, wherein a
Side should not be less than the maximum field of view detector size 1/2.
5.3.10.2 Test Method
Set phantom image distortion in the beam, a rectangular or square in the center center of the field into posi...