Path: Home > MISC > Page350 > WS 530-2017 || Home > Standard_List > MISC > Page350 > WS 530-2017

WS 530-2017 PDF English

Std ID	Contents [version]	USD	STEP2	[PDF] delivered in	Standard Title (Description)	Status
WS 530-2017	English	799	Add to Cart	4 days [Need to translate]	Specification for testing of quality control in computed radiography systems for mammography	Obsolete

Standard similar to WS 530-2017

GBZ 130 | GBZ/T 250 | GBZ/T 201.1 | WS/T 523 | WS 523 | WS 531 |

Basic data

Standard ID	WS 530-2017 (WS530-2017)
Description (Translated English)	Specification for testing of quality control in computed radiography systems for mammography
Sector / Industry	Health Industry Standard
Classification of Chinese Standard	C57
Word Count Estimation	20,264
Date of Issue	2017-04-10
Date of Implementation	2017-10-01
Regulation (derived from)	State-Health-Communication (2017) 2
Issuing agency(ies)	National Health and Family Planning Commission of the People's Republic of China

WS 530-2017: Specification for testing of quality control in computed radiography systems for mammography

---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 computed radiography systems for mammography ICS 13.280 C 57 WS People's Republic of China Health Industry Standard Computerized mammography system Quality control testing specifications 2017-04-10 released 2017-10-01 Implementation Issued by the National Health and Family Planning Commission of the People's Republic of China

Foreword...II 1 Scope...1 2 Terms and definitions...1 3 Quality control testing requirements...2 4 Testing methods and evaluation of general testing items...3 5 Testing methods and evaluation of special testing items...6 Appendix A (Normative Appendix) Quality Control Testing Items and Technical Requirements...10 Appendix B (informative appendix) Technical requirements for breast CR system IP of different manufacturers...12 Appendix C (Normative Appendix) Calculation of Average Breast Dose...14 Appendix D (informative appendix) Equipment and utensils required for quality control testing...16 References...17

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009. 3.1.1~3.1.7, 3.2, Appendix A and Appendix C of this standard are mandatory, and the rest are recommended. Drafting organizations of this standard. Chinese Center for Disease Control and Prevention, Institute of Radiation Protection and Nuclear Safety Medicine, Beijing Center for Disease Control and Prevention, China National Institute of Metrology. The main drafters of this standard. Yue Baorong, Xu Hui, Wei Kedao, Fan Yaohua, Lou Yun, Zhang Yanli, Wang Jianchao, Huang Zhuo. Specification for quality control and inspection of breast computer X-ray photography system

1 Scope

This standard specifies the requirements and methods for quality control and testing of breast computer X-ray photography (breast CR) systems. This standard applies to the quality control testing of breast CR system. This standard does not apply to mammography screen/film photography system, mammography digital radiography (breast DR) system and mammography digital body lamination Quality control inspection of the camera system.

2 Terms and definitions

The following terms and definitions apply to this document. 2.1 Computed radiography (CR) system CR system Reusable imaging plate is used instead of intensifying screen-film is used as the carrier to be exposed by X-ray, and the potential obtained after exposure with laser scanning imaging plate Image information is collected and amplified by an optical system, and collected by a computer to obtain a digital image display. 2.2 CR system for mammography Breast CR system Computer X-ray photography system dedicated to mammography. 2.3 Imaging plate; IP An X-ray surface detector made of an X-ray storage luminescent material (such as fluorine barium halide). X-rays form an electron void in IP The latent image of the distribution of acupoints, which recombines and emits fluorescence under the excitation of red laser scanning, and its intensity is proportional to the intensity of X-rays. CR system The laser scanning readout device reads the electronic latent image of the IP and displays the digitized image on the display screen of the CR system. 2.4 Detector dose indicator; DDI Provided by the manufacturer of the breast CR system to reflect the specific kerma of the average incident air on the imaging plate during the image acquisition process Instructions can be used to check whether the technical parameters of the breast CR system are appropriate and verify whether the photography technology is correct. 2.5 Threshold contrast details Under the specified measurement conditions, the minimum contrast details of the specified shape and area that can be distinguished from a uniform background condition, in% Said. 2.6 Artifact The image that is clearly visible on the image does not reflect the internal structure of the object, nor can it use noise or system modulation transfer function To explain. 2.7 Average glandular dose; AGD In mammography, the average absorbed dose in the gland tissue of the subject that is uniformly compressed on the breast. 2.8 Region of interest; ROI The pixel area (circle or rectangle) delineated in the image. Use software tools to provide the average pixel value and standard deviation of the area. 2.9 Pre-processed image Unprocessed image The original image has undergone pixel defect correction, gain compensation correction, etc., but this image has not undergone image post-processing. 2.10 Nyquist frequency; fNyquist The spatial frequency determined by the sampling interval a, the relational formula is. fNyquist=1/(2a). 2.11 Specific radiation output According to the radiation output per milliampere second measured from the focal point to a point above the support, the radiation output per milliampere second at 1 m from the focal point is calculated

3 Quality control testing requirements

3.1 General requirements 3.1.1 The breast CR system should be checked for acceptance after the new installation and overhaul, and the status and stability should be checked regularly during use. Breast The CR system should be checked annually. The cycle of stability testing is shown in Table A.1 in Appendix A. 3.1.2 The quality control test items shall cover the items specified in this standard, and the tested equipment that does not have the function or cannot meet the test conditions It should be stated in the test report. 3.1.3 The quality control test items of the breast CR system are divided into two parts. general test items and special test items. General inspection items See Chapter 4 for the test method, and the evaluation should meet the requirements of Table A.1 in Appendix A. Refer to Chapter 5 for the testing methods of special testing items, and the evaluation should comply with the attached Record A in Table A.2 requirements. The test result is equal to or better than the index value specified in this standard as qualified. 3.1.4 The basic content of the test report should include. basic information and equipment information of the inspected unit, test items and test methods, and necessary inspections. Test conditions, test results and corresponding standard requirements. 3.1.5 Mammography examination should use breast dedicated IP. 3.1.6 Appendix B Table B.1 ~ Table B.4 gives the detection setting conditions and technical requirements of the breast CR system of different manufacturers. 3.1.7 See Appendix C for the calculation method of average breast dose. 3.1.8 Refer to Table D.1 in Appendix D for equipment and utensils required for quality control and testing of breast CR system. 3.2 Requirements for testing equipment and phantom 3.2.1 Special instruments suitable for quality control and testing of mammography systems should be used, including digital high voltage (kV) testers, Dosimeters, etc. 3.2.2 Testing instruments should be verified or calibrated in accordance with relevant regulations, and the results should be traceable. 3.2.3 For air ionization chamber detectors, some testing items require the detector to be supported on a support platform at a certain height (unified in this standard) It is specified as 10cm). For some semiconductor detectors with lead lining at the bottom, the detector can be directly placed on the support table for measurement. 3.2.4 The polymethyl methacrylate (PMMA) phantom used must be a uniform phantom with a thickness error within ±1mm, semicircular The radius of the shaped phantom should not be less than 10cm, and the size of the rectangular phantom should not be less than 10cm×12cm. 3.2.5 The standard aluminum absorbing sheet used for detecting the half-value layer should be at least 8cm×8cm in rectangular size, the purity of aluminum should not be less than 99.9%, and the thickness The size error should be within 1%.

4 Testing methods and evaluation of general testing items

4.1 Alignment of the lateral radiation field on the chest wall 4.1.1 Adjust the alignment of the light field with the edge of the support table on the chest wall side (if it is not possible to align, adjust to the position closest to the edge of the support table within the chest wall Set), the light field size is at least 10cm×15cm, and the light field/irradiation field consistency inspection tool (such as inspection board, inspection ruler or IP, etc.) is placed on On the breast support table, 5cm beyond the edge of the chest wall side support table, record the position of the chest wall side support table edge on the inspection tool. 4.1.2 Expose according to the conditions required by the testing tool or common clinical conditions, and record the radiation field markers left by the radiation on the testing tool position. 4.1.3 Measure the distance between the chest wall side irradiation field and the edge of the chest wall side support table. 4.2 Consistency of light field and irradiation field 4.2.1 Adjust the alignment of the light field with the edge of the support platform on the chest wall side (if it is not possible to align, adjust to the position within the chest wall side closest to the edge of the support platform Set), the size of the light field is at least 10cm×15cm, and the light field/irradiation field is tested with a consistent tool (such as a test board, a test ruler or a film cassette, etc.) Place it on the breast support table and record the scale positions of the light fields on the inspection tool on the other three sides except the chest wall. 4.2.2 Expose according to the conditions required by the testing tool or common clinical conditions, and record the radiation field markers left by the radiation on the testing tool position. 4.2.3 Calculate the deviation of the light field on the other three sides except the chest wall and the corresponding edge of the irradiation field. 4.3 Deviation of tube voltage indication 4.3.1 Non-invasive methods should be used, such as a digital high voltage (kV) tester for mammography. 4.3.2 Measure in the state of large focus and small focus respectively. The target/filter selected for exposure, the presence or absence of a compressor and additional filter should be in accordance with the tester The instrument verification or calibration is the same. 4.3.3 For each focus state, select at least 3 commonly used clinical kV values (25 kV～32kV) for measurement, and the selected kV value should be able to cover Usually used for mammography. 4.3.4 Place the detector of the dedicated digital high voltage (kV) tester on the X-ray beam axis 4cm inside the chest wall of the support table, with the light field larger than the measured Measure the probe area. In order to protect IP, lead protective equipment can be added under the kV detector and cover the breast support table. 4.3.5 When kV is selected, perform automatic exposure or manual exposure (30mAs～50mAs), read the reading of the measuring instrument, and calculate The deviation of a kV measurement value from the nominal value. 4.4 Half-value layer 4.4.1 Place the dosimeter detector on the X-ray beam axis 4cm inwardly from the chest wall of the breast support. The effective point of the detector thickness is located on the breast 10cm above the room support table (if there is no effective thickness mark, the thickness center of the detector shall prevail). 4.4.2 Adjust the compressor to about one-half between the focus and the detector. 4.4.3 Set the tube voltage to 28kV, the appropriate tube current time product (30mAs～50mAs), and carry out exposure without aluminum sheet, record Record the reading of the dosimeter. 4.4.4 Place a 0.1mm thick aluminum sheet on the compressor or on the special support for the half-value layer. The aluminum sheet should completely cover the light field. Perform exposure under the same conditions and record the dosimeter reading. Add aluminum sheet until the indicated value of the dosimeter drops to two points of the value without aluminum sheet One below. 4.4.5 For the dose of X-ray attenuation rate around 50%, according to the value of the aluminum sheet thickness corresponding to the respective dose, according to formula (1) Find the half-value layer (HVL). 4.4.6 Select other target/filter combinations used clinically and repeat the above steps to calculate the half value of all target/filter combinations in the device Floor. Note. The HVL measuring instrument can also be used to directly measure the half-value layer. It should be carried out in the light field completely covering the dosimeter detector and without additional aluminum sheet measuring. For different targets/filters, the device readings should be calibrated according to the manufacturer's instructions. 4.5 Repeatability of output 4.5.1 Remove the breast compressor and place the dosimeter detector on the X-ray beam axis 4cm inward from the chest wall of the breast support table. The effective point of thickness is located 10cm above the breast support (if there is no effective point of thickness mark, the thickness center of the detector shall prevail). 4.5.2 Set the tube voltage to 28kV, the commonly used clinical target/filter, the appropriate tube current time product (such as 40mAs～80mAs), and repeat the exposure Light 5 times, record the air kerma kinetic energy value of each exposure, and calculate the coefficient of variation CV of radiation output according to formula (2) to express the output Repeatability. 4.6.2 Set the exposure conditions the same as 4.5.2, repeat the exposure 5 times, record the air kerma value of each exposure, and calculate the 5 exposures The average air kerma value of light. 4.6.3 Use formula (3) to calculate the distance from the focus to the detector 4.6.4 Divide the dose at 1m by the current time product set during exposure, that is, the specific radiation output, in microgray per milliamp second (ΜGy/mAs). 4.7 Repeatability of automatic exposure control 4.7.1 Place a 4cm thick PMMA phantom on the breast support table, covering the commonly used clinical AEC area, the phantom edge and breast support table chest Align the wall side. 4.7.2 Press the compressor on the phantom, set the common clinical tube voltage (such as 28kV) and target/filter, select the automatic exposure control (AEC) bar Pieces are exposed. If the parameters cannot be set individually, select the fully automatic exposure conditions. 4.7.3 Repeat the exposure 5 times, record the milliampere second value in time after each exposure, and calculate the average milliampere second value for 5 times. 4.7.4 Calculate the deviation (E) between the recorded milliampere second (RmAs) and the average milliampere second (mmAs) value according to formula (4). Will be the largest The deviation value is compared with the standard specified value. 4.8 Average breast dose 4.8.1 Place the PMMA phantom with a thickness of 4 cm on the breast support table, with the edge of the phantom aligned with the chest wall of the breast support table. 4.8.2 Adjust the compressor to the bottom 0.5cm away from the top of PMMA. Select AEC exposure conditions for exposure, when recording tube voltage and tube current Exposure parameters such as interval product and target/filter. Note. According to the composition of the phantom, the X-ray absorption of 4cm thick PMMA is equivalent to 4.5cm thick average human breast. In order to obtain clinical AEC of 4.5cm thick breast For exposure conditions, the compressor can be adjusted to 4.5cm away from the supporting table for AEC exposure. In this method, there may be a gap and zero compression force between the compressor and PMMA, If the system requires the exposure to be under pressure, you can put 0.5cm thick foam on the 4cm PMMA phantom (or other non-significant influence on X-ray absorption) Material) and press the compressor on the foam surface to keep the height of the compressor at 4.5cm and cause the pressure, the system can be exposed normally. 4.8.3 Remove the PMMA phantom and place the dosimeter detector on the X-ray beam axis 4cm inward from the chest wall of the breast support. The detector is thick The effective point of degree is the same as the position of the phantom surface (4cm above the breast support) (if there is no effective point mark of thickness, the thickness center of the detector is taken as quasi). 4.8.4 Select the exposure parameters in 4.8.2 for manual exposure (if the manual exposure parameter selection is not completely consistent with AEC, then select The closest exposure parameter), record the kerma value of the incident air. 4.8.5 Calculate the average breast dose according to formula (C.1).

5 Testing methods and evaluation of special testing items

5.1 IP dark noise 5.1.1 Select the IP processing conditions recommended by the manufacturer, see Table B.1 in Appendix B. 5.1.2 Perform an erasing process on the selected IP before testing. 5.1.3 Choose 3~5 IPs to put into the reader, scan and read, adjust the window width and window position, and obtain soft copy images respectively. 5.1.4 Read the DDI value of each IP, its value should be within the value range specified by the manufacturer, see Table B.2.in Appendix B. 5.2 IP response linear 5.2.1 Select the IP processing conditions recommended by the manufacturer, see Table B.1 in Appendix B. 5.2.2 Place the dosimeter detector on the X-ray beam axis 4cm inward from the chest wall of the breast support table, and place the 4cm thick PMMA phantom On the top of the detector of the dosimeter and completely covering the detector, the edge of the phantom is aligned with the chest wall of the breast support table. 5.2.3 Set 28kV, select 4~6 mAs values between 10mAs～100mAs for manual exposure. Record each exposure parameter (KV, mAs, and target/filter, etc.), and the IP incident air kerma value after each exposure. 5.2.4 Remove the dosimeter detector, use a single piece of IP, and place the IP on the breast support table to ensure that the IP incident surface and the dosimeter detection The effective point of the thickness of the detector is consistent. 5.2.5 According to the exposure conditions in 5.2.3, complete multiple exposures in sequence and read the IP, and keep the same delay time for reading after each exposure. 5.2.6 Obtain the preprocessed image after each exposure, record the DDI value, and select about 4cm2 in the center of each preprocessed image For small areas of interest, measure the average pixel value. 5.2.7 Perform straight-line fitting with reference to the information provided by the manufacturer, and calculate the square R2 of the linear correlation coefficient. Note. PV is the pixel value, K is the IP incident dose, a, b, and c are all coefficients formed after fitting the formula. 5.3 IP response uniformity 5.3.1 Select the IP processing conditions recommended by the manufacturer, see Table B.1 in Appendix B. 5.3.2 Place a 4cm thick PMMA phantom on the breast support table, with the edge of the phantom aligned with the chest wall of the breast support table. 5.3.3 Set 28kV, select common clinical conditions (mAs, target/filter combination, presence or absence of grid and compressor) to manually expose IP Light, or choose AEC for automatic exposure of IP. 5.3.4 Obtain the preprocessed image after exposure, and select about 4cm2 in the area covered by the PMMA image in the preprocessed image according to Figure 1. Measure the average pixel value of the area of interest. 5.3.5 According to the fitting formula result of the IP linear response measurement in 5.2, linearize the measured average pixel value (PV). a) For a linear response system, the linearization processing formula is K=(PV-b)/a; b) For systems with nonlinear response (such as logarithmic correlation), the linearization formula is K=exp[(PV-b)/a]; c) For systems with nonlinear response (such as power correlation), the linearization formula is K= [(PV-c)/a](1/b). Note. PV is the pixel value, K is the average pixel value after linearization, and a, b, and c are all coefficients formed after the fitting formula. 5.3.6 It is required that the average pixel value after linearization in the three ROIs has the deviation of any two results within ±10%. 5.4.1 Using preprocessed images generated when evaluating IP response uniformity, see 5.3. 5.4.2 Adjust the window width and window level to display the image to the clearest state considered by the observer, and observe whether there are non-uniform areas, blurred areas or Other abnormal images that affect clinical diagnosis. 5.4.3 If there are suspicious artifacts mentioned in 5.4.2, rotate or translate the image, if the suspicious artifacts do not move along, it may be the display system Artifacts rather than image receiver artifacts. 5.5 IP response consistency 5.5.1 Select the IP processing conditions recommended by the manufacturer, see Table B.1 in Appendix B. 5.5.2 Place a 4cm thick PMMA phantom on the breast support table, and the edge of the phantom is aligned with the chest wall of the breast support table. 5.5.3 Choose three IPs of the same size/model, fixed tube voltage (such as 28kV), use automatic exposure control mode for exposure, no automatic The equipment in exposure control mode can be used in common clinical conditions. Ensure the same exposure conditions for each piece of IP, and maintain the same delay after each exposure Read it later and obtain three softcopy images. 5.5.4 Record the DDI value of each image. The DDI deviation of multiple IPs should meet the requirements of Appendix B, Table B.3. 5.6 Completeness of IP erasure 5.6.1 Select the IP processing conditions recommended by the manufacturer, see Table B.1 in Appendix B. 5.6.2 Place the 4cm thick PMMA phantom longitudinally on one side of the breast support, covering half of the IP, as shown in the white area on the left in Figure 2. 5.6.3 Select common clinical conditions for manual exposure (such as 28kV, 30mAs～50mAs), and read the IP. 5.6.4 Place the 4cm thick PMMA phantom horizontally in the center of the breast support table, and place the 0.1mm thick aluminum sheet in the upper center of the PMMA phantom Place. Use the same IP and use the same exposure conditions as in 5.6.3 to expose the IP again to obtain a soft copy image. Double exposure time Should be as short as possible (within 3min). 5.6.5 Obtain the second exposure image, and measure the average pixel value of zone 1, zone 2 and zone 3 according to the figure below. 5.6.6 Use the method described in 5.3.5 to linearize the average pixel value. Figure 2 Schematic diagram of IP erasure completeness measurement 5.6.7 Bring the linearized measurement results into formula (5) to calculate the ghost factor, which should be ≤0.3. 5.7 High contrast resolution 5.7.1 Place two high-contrast resolution cards (maximum number of line pairs not less than 10 lp/mm) on the breast support in horizontal and vertical directions, respectively On the stage, the high-contrast resolution card is as close as possible to the image receiver. 5.7.2 Place a 4cm thick PMMA phantom on the breast support table and press the high-contrast resolution card. The edge of the phantom and the breast wall side of the breast support Aligned. 5.7.3 Perform exposure according to the test steps and methods provided by the manufacturer. If the manufacturer does not provide conditions, select AEC mode for exposure Light. 5.7.4 Print and watch 1.1 on mammography film, or read the image on a high-resolution monitor, adjust the window width and position to display the image Optimization, observe the number of distinguishable pairs of pairs. 5.7.5 During the acceptance test, compare the results of the horizontally and vertically placed line-pair cards with the values specified by the manufacturer. If you can't get the factory It is compared with the Nyquist frequency (fNyquist). Establish the baseline value, compare with the baseline during status and stability testing Value to compare. 5.8 Contrast detail threshold 5.8.1 Select the contrast detail phantom for mammography. Place the contrast detail phantom on the breast support table, on the edge of the phantom Align with the breast wall side of the breast support. 5.8.2 Exposure is carried out according to the conditions given in the phantom manual. 5.8.3 Read the image on the high-resolution display, adjust the window width and position to optimize the image display, observe the exposure image, and determine the different details. For the smallest detail that can be observed at the diameter of the joint, refer to the phantom manufacturer's instructions to obtain the minimum resolvable contrast of the diameter. 5.8.4 For cases where the clinical exposure conditions do n...