MegaQA Program: User Manual Brian King 23-May
Contents
1. Test Central axis Central axis Beam Profile Beam Profile Beam Profile Beam Profile Beam Profile Beam Profile Beam Profile Beam Profile Beam Profile Beam Profile EDW EDW EDW EDW Relative Response Relative Response Relative Response Relative Response Relative Response Relative Response Relative Response Relative Response Dose Response Dose Response Dose Response Asymmetric Jaws Asymmetric Jaws Asymmetric Jaws Asymmetric Jaws Parameter IP Central axis pixels CP Central axis pixels IP Field Width mm CP Field Width mm IP Maximum difference from baseline CP Maximum Difference from baseline IP Standard Deviation from baseline CP Standard Deviation from baseline IP Profile Flatness CP Profile Flatness IP Profile Symmetry CP Profile Symmetry IP Maximum Difference from baseline CP Maximum Difference from baseline IP Standard Deviation from baseline CP Standard Deviation from baseline IP Maximum Difference from baseline CP Maximum Difference from baseline IP Standard Deviation from baseline CP Standard Deviation from baseline IP Profile Flatness CP Profile Flatness IP Profile Symmetry CP Profile Symmetry Central axis dose current Central axis dose baseline Dose Change from baseline Jaw 1 Position mm Jaw 2 Position mm Jaw Gap mm Junction Dose2. The MegaQA software will read either standard dicom images or text files output from Varian s Portal Dosimetry software in DXF format As the normalization of the two file types is different all files to be analysed must be in only a single file format No mixing and matching of file formats is supported In either case the files to be analysed must be exported from the record and verify system assuming that a verification plan was set up as recommended In the case of files exported in DXF format the images are scaled to CU units and an off axis profile is included in the images If the scaling factor or off axis profile are changed this will affect the results of the test Images exported in dicom format do not have this issue MegaQA Directories The output Excel workbook for all machines must be located in a single directory the output directory Each machine should have a defined data directory where images acquired for that particular machine will be stored The images acquired during each test session must be stored in individual subdirectories Establishing baselines After the verification plan has been setup in the treatment database baselines for each test must be established This entails simply running the verification plan and acquiring images for each test that is to be performed The images should be stored in a subdirectory of the data directory for the given machine Software Configuration When sta
3. Test or Partial Test mode by selecting the appropriate option under the Mode menu In Full Test mode before the data can be saved in the output sheet all tests that can be performed using the acquired images must be performed In Partial Test mode the data can be saved in the output sheet as long as a single test has been performed The default mode is Full Test but the software will store the selection for future use Mode View Modify About Test Date Machine Hunter Mont Physicist SDD cm File Configuration Figure 2 The main MegaQA window Machine Configuration Each machine to be tested must be configured using the MegaQA software There are several things that must be configured for each machine e Data directory This is the root directory where all data files for the machine will be stored The images acquired during each test session should be stored in individual subdirectories beneath the specified data directory Each session s images must as a minimum be stored in their own individual directory e Baseline directory This is the directory where the baseline images are stored e Baseline files Specify which files in the baseline directory correspond to which images e SDD offset Specify the offset between the Epid detector plane and the nominal Epid position in cm This is necessary to accommodate different imager position calibration schemes that may b
4. be set to the same position 105 cm source detector distance is assumed here All images are acquired with a gantry angle of 0 degrees The 18 MV measurements must have an extra 2 cm of Perspex added to the top of the imager for build up Table 4 Field details for setup of MegaQA treatment plan Field ID Energy MU _ Collimator X1 X2 Y1 Y2 Other 6X Whole 6 100 0O 195 19 5 14 5 14 5 6X 20x20 6 100 0O 10 10 10 10 6X EDW 6 100 0O 10 10 10 10 EDW60IN 6X 6 40 0 10 0 10 10 AsymX2 6X 6 40 0 0 10 10 10 AsymX 1 6X 6 40 0 10 10 10 0 AsymY2 6X 6 40 0 10 10 0 10 AsymY 1 6X 6 40 90 10 0 10 10 AsymY 1X2 6X 6 40 90 0 10 10 10 AsymY 2X1 6X10 90 6 100 90 5 5 5 5 6X 10_270 6 100 270 5 5 5 5 18X Whole 18 100 O 19 5 19 5 14 5 14 5 buildup 18X 20x20 18 100 O 10 10 10 10 buildup 18XEDW 18 100 O 10 10 10 10 buildup EDW600UT 18X 10x10 18 100 0O 5 5 5 5 buildup Appendix B The MegaQA File Selection Window An example of the MegaQA file selection window is shown in Figure 10 There are two main sections The Data Directory section where the directory containing the relevant files is selected and the Data Files section where the files in the data directory are matched against the required images for later analysis A valid data directory must be selected using the Select button before the Data Files section is activated When a valid directory is selected all files with the appropriate extension in the directory
5. in more detail See documentation of the EImage function for more information on how to use the Extended Image window A zoomed in profile through the junction is also shown in a separate window Clicking the Return button in the results window signifies completion of the test for the current jaw configuration and the next one will be processed When all configurations have been tested the test button turns green Saving Results When all of the desired tests have been completed the results can be saved in the Excel output sheet This is accomplished by clicking the Save Results button When this is clicked a window will open that will accept any optional comments that the user may want to add The comments will be included in the output Excel worksheet with the test results The test results are output to four separate sheets contained in the output workbook The test results can then be tracked over time for each machine To select a new machine for testing click the Unlock button next to the machine drop down menu This will reset all of the completed tests and remove all of the calculated results from memory To start a new test at any time click the File Configuration button and select a new set of files to analyse Appendix A MegaQA Treatment Fields Table 4 gives the necessary details for configuring a treatment plan to acquire the images necessary for performing the MegaQA analysis In all cases the EPID must
6. tests can be performed This test uses the two images of 10 cm fields with collimator positions of 90 and 270 degrees It finds the centre pixel of these images as defined by the full width half maximum of in plane and cross plane profiles All other tests shift the images such that the centre pixel will be consistent with those in the baseline images The Find Central Axis test produces a results window that shows the calculated central axis pixel Clicking the Return button in the results window completes the test causing the Find Central Axis button to turn green and all other available tests to be enabled Tests that require files that were not configured in the File Selection window will not be enabled Beam Profile Tests These tests use the 20 cm square field images They are used to verify the consistency of the accelerator beam profile over time The images are normalized to 1 at the central axis The images are compared to the baseline 20 cm images and the symmetry and flatness of profiles through the centre pixel are calculated Specifications for all of these parameters are read from the Excel output sheet When the test is complete a results window will appear showing the status of each parameter as shown in Figure 8 Additionally an image comparison window will appear which will allow visual inspection of the images as shown in Figure 9 For more details on the Image Comparison window see the documentation for t
7. will be loaded into the drop down menu options in the file selection table The user can manually select any file in the directory to match with any of the images that MegaQA is expecting The user also has the option of selecting a blank entry to signify that no file matches a particular image Blank entries will affect which MegaQA tests are available File Selection Current r Data Directory GAQA Forms Monthly QAMegaQA images Hunter_EPID 201 0 09 30 Data Files Show Labels Rename Files 6 My 18 MV 10 x 10 90 degree coll 6x 10 90 dxf 18x 10 dxf 10 x 10 270 degree coll 6x 10 270 dxf NIA 20 x 20 6x 20 dxf 18x 20 dxf Enhanced Dynamic Wedge 6x edw dxf 18x edw dxf Whole Detector 6x whole dxt 18x whole dxt Asymmetric Fields X1 6x x1 dxf NAA Asymmetric Fields X2 6x x2 dxf NIA Asymmetric Fields Y1 NIA Asymmetric Fields 2 NIA Asymmetric Fields Y1 x2 6x y1x2 dxf N A Asymmetric Fields Y2 xX1 6x y2x1 dxf N A Save amp Exit Exit No Save Figure 10 An example file selection screen SSESeseeseseseeegeg See aR ER EEEE If the Show Labels button is clicked the available entries in the drop down menus will display the field label stored in each file instead of the file name For dicom files this information is found in the RTImageLabel dicom tag while for DXF files this information is found in the FieldId field of the header Duplicate e
8. AGA Forms Monthly QAMegaQA images Hunter_EPID 201 0 09 16 Baseline Data Files Show Labels 6 My 18 MV 10 x 10 90 degree coll 6X_10_90_corrected dxf Y 18x_10 dxt 10 x 10 270 degree coll NIA YV NA 20 x 20 6x_20_corrected dxf Y 18x_20 dxf Enhanced Dynamic Wedge 6x_EDW_corrected dxf Y 18x_EDW dxf Whole Detector 6x_VWWHOLE_corrected dxt Y 18x_VVHOLE dxt Asymmetric Fields X1 NIA vy NA vv b v vv v Asymmetric Fields X2 NA NIA Asymmetric Fields 1 NIA NIA Asymmetric Fields Y2 NA N A Asymmetric Fields 1 X2 NA NA Asymmetric Fields 2 1 NA NA SESE SEES E SE Enter offset between detector surface and active layer cm Figure 6 Specifying the detector offset MegaQA Test Analysis To analyse the acquired images enter the date that the images were acquired the physicist name and source detector distance in the appropriate boxes Then select the machine where the images were acquired from the Machine drop down menu and click the File Configuration button At this point the software will read the selected Excel workbook to try to extract information about the data directory and baseline files If this information is not present the software will ask the user to provide it see the Machine Configuration section Next the software will ask the user to specify where the images to be analysed are stored This is done with the standard MegaQA fil
9. MegaQA Program User Manual Brian King 23 May 2011 Overview The MegaQA program is a system for performing routine accelerator photon quality assurance tasks using the amorphous silicon electronic portal imaging device EPID attached to most accelerators Quality assurance is performed by acquiring a series of EPID images and comparing them to initially established baselines Software has been written in the Matlab programming language to quickly and accurately analyse the images The initial program and software was instituted at the Calvary Mater Newcastle hospital by Peter Greer in 2006 The analysis software was streamlined and updated in 2010 by Brian King The tests that are performed as part of the MegaQA program are listed in Table 1 For more details see the section MegaQA Test Analysis Table 1 Tests included in the MegaQA program Test Image Field Collimator Energy Central axis 10x10 cm 90 270 6 MV Beam profile 20x20 cm 0 6 MV 18 MV EDW EDW 0 6 MV 18 MV Relative 30x40 cm 0 6 MV response 18 MV Dose response 10x10 cm 90 6 MV 18 MV Asymmetric Various asymmetric 0 90 6 MV jaws All tests are optional with the exception of the central axis test as the other tests use the output of the central axis test in order to align the images The results of each test are stored in a machine specific Excel workbook at the completion of the test This allows for analysis of long term trends in the results Initial Setup Befo
10. e selection window An example is shown in Figure 7 Select the appropriate directory and ensure that all required files have been properly selected See the Asymmetric jaws test section for the proper field naming scheme in the asymmetric jaws test If the file selection process is cancelled the data analysis will stop When the files have been configured properly the Save amp Exit button should be clicked This will cause the file selection window to close the File Configuration button on the main MegaQA window to turn green and the Find Central Axis test to be enabled File Selection Current Data Directory GAGA Forms Monthly QAMegaQA images Hunter_EPID 201 0 09 30 Data Files 6 MV 18 My 10 x 10 90 degree coll 6x 10 90 dxf 18x 10 dxf 10 x 10 270 degree coll 6x 10 270 dxt NIA 20 x 20 6x 20 dxf 18x 20 dxf Enhanced Dynamic Wedge 6x edw dxf 18x edw dxf 18x whole dxt NIA N A NIA N A NIA N A Save amp Exit Exit No Save Figure 7 Selecting files to analyse with the File Selection window whole Detector 6x whole dxt Asymmetric Fields X1 6x x1 dxf Asymmetric Fields X2 Bx x2 dxf Asymmetric Fields 1 Asymmetric Fields 2 Asymmetric Fields 1 X2 6x y1x2 dxf Asymmetric Fields 2 1 6x y2x1 dxf MAURAN TD a a Find Central Axis Test The Find Central Axis test must be completed before any other
11. e selection window The files in the specified baseline directory must be matched to the appropriate energy and field configurations using the Data Files drop down menus Only files in the appropriate file format dcm or dxf will be shown The software will attempt to automatically determine the proper configuration based on the file names and labels within the file The selections can be changed if required See appendix C for the file naming scheme that MegaQA prefers The selections that are given as N A are not required for the baseline files and can not be changed If the detector offset has not been set a window will appear as in Figure 6 Cancelling any of these windows will stop the file configuration process and the analysis will stop Once all of this information has been defined the information will be saved in the output sheet and the actual test process will begin This is explained in detail in the next section Select Root Data Directory Select the root directory that contains all of the MegaQA data for this machine Note You will still be able to select any directory for data files Selected Directory Figure 3 Prompting for root data directory Select Baseline Directory Select the directory that contains all of the baseline data for this machine Selected Directory Figure 4 Prompting for baseline data directory File Selection Baseline Data Directory G
12. e used If the imager position is calibrated such that the nominal position corresponds to the position of the imager detector layer this offset is 0 e The minimum and maximum allowed values for each individual test All of this information is stored in the machine Excel workbook The test specifications are stored in the sheet called Tolerances and must be set directly from within Excel All other configuration information is stored in the sheet called File Details The information on the File Details sheet can be set directly from within Excel if desired or if missing will be prompted for automatically by the MegaQA software when the File Configuration button is clicked The automatic process is recommended and is explained below When a machine is selected in the Machine drop down menu and the File Configuration button is clicked to start the test the appropriate Excel workbook is opened and the information in the File Details sheet is read Each piece of missing information will be prompted for If the data directory is not specified in the File Details sheet a window will appear as in Figure 3 If the baseline data directory is not specified in the File Details sheet a window will appear as in Figure 4 If the baseline files have not been set a window will appear as in Figure 5 This window is the standard MegaQA file selection window See appendix B for detailed information on the fil
13. e user The preferred naming scheme is given in Table 5 The matching is case insensitive Table 5 File naming convention used by MegaQA Collimator Preferred Energy Field size MV cm 10x10 10x10 20x20 EDW 30x40 X1 X2 Y1 Y2 Y1X2 6 Y2X1 18 10x10 18 20x20 18 EDW 18 30x40 NNNNDNDDDDADA AD deg 90 270 0 0 0 oO ooo name 6x 10 90 6x 10 270 6x 20 6x EDW 6x Whole 6x x1 6x x2 6x yl 6x y2 6x y1x2 6x y2x1 18x 10 18x 20 18x EDW 18x Whole Other options 6x 10_90 6x_10_90 6x 10_270 6x_10_270 6x 20x20 6x_20 6x EDW 6x_EDW 6x Whole 6x_Whole 6x AsymX1 6x AsyX1 6x_x1_ 6x AsymX2 6x AsyX2 6x_x2_ 6x AsymY1 6x AsyY1 6x_yl_ 6x AsymY2 6x AsyY2 6x_y2_ 6X AsymY 1X2 6x AsyY1X2 6x_y1x2 6X AsymY2X1 6x AsyY2X1 6x_y2x1 18x 10x10 18x 10_10 18x_10 18x 20x20 18x_20 18x EDW 18x_EDW 18x Whole 18x_Whole
14. he ImageCompare function Clicking the Return button in the results window signifies completion of the test and the test button turns green 6 MV profile results Property units Value Min Spec Max Spec Status IP Field Width mm 198 9765 195 205 PASS cP Field Width mm 200 5206 195 PASS IP Maximum Difference 0 4182932 N A PASS cP Maximum Difference 0 3690391 N A PASS IP Standard Deviation 0 1025637 NA PASS cp Standard Deviation 0 06939693 N A PASS P Profile Flatness 104 7992 NIA PASS ICF Profile Flatness 9 102 7711 N A PASS IP Profile Symmetry 102 2959 N A PASS ICP Profile Symmetry 100 2235 N A PASS i Fi Profile Comparison a AA9Dd 2R0 Baseline Contours Mesh C rones Data Table Statistics Comparison Gamma bs Difference Baseline Baseline Reto Current Current Figure 9 The image comparison window for the 6MV beam profile test Enhanced Dynamic Wedge Test These tests use the enhanced dynamic wedge images They are used to verify the consistency of wedge fields over time The images are normalized to 1 at the central axis The images are compared to the baseline dynamic wedge images Specifications for the parameters are read from the Excel output sheet When the test is complete a results window will appear showing the status of each parameter similar to that produced by the beam profile te
15. ntries will have a 1 2 etc appended This functionality can be useful if the file names are not descriptive as may be the case when the images are exported from the record and verify database The Show Labels button is actually a toggle button that allows the display to be changed back and forth between showing the file names and the field labels The text on the button changes to indicate the effect of clicking the button The Rename Files button provides a simple way of renaming all of the files with the appropriate extension in the directory such that the file names will match the field labels stored within the file This can be useful if the file names are not descriptive as may be the case when the images are exported from the record and verify database Appendix C MegaQA data file namin scheme The MegaQA files can have any desired names The only requirement is that all files from a single session must be stored in the same directory However there is a preferred naming scheme that simplifies the act of selecting the appropriate files If this naming scheme is followed the proper files will be automatically selected by the MegaQA program when a data directory is selected NOTE The file names and field labels must both follow the naming scheme in order for automatic file selection to work properly Any fields where the software can not unambiguously determine the proper file must be manually selected by th
16. owing the status of each parameter similar to that produced by the beam profile test Additionally an image comparison window will appear similar to that produced by the beam profile test Clicking the Return button in the results window signifies completion of the test and the test button turns green Asymmetric Jaws Test This test is composed of four identical tests each testing how well asymmetric jaw fields are matched at the centre under different conditions In each test one image is acquired with one collimator eg X1 in an open position and the complementary jaw eg X2 set to the zero position A second image is acquired with the jaw positions reversed These two images are combined together and the signal in the junction area is examined The jaw offset and junction dose increase are computed for each pair of images The jaw combinations are shown in Table 3 Table 3 Asymmetric jaw test configurations The file selection column tells which entry in the File Configuration dialog should be used for each file Collimator Image 1 Image 2 Angle closed jaw file selection closed jaw file selection 0 X1 X1 X2 X2 0 Yl Y1 Y2 Y2 90 Yl Y1 X2 Y1 X2 90 Y2 Y2 X1 Y2 X1 At the end of each stage a results window will be shown as well as an image of the composite image formed by the combination of the two asymmetric images This image is displayed in an Extended Image window and can be manipulated to allow examination
17. re setting up anew MegaQA program ensure that up to date floodfield images have been acquired in integrated image mode for the dose rate that will be used to acquire the images The floodfield image must be acquired with the imager at the same position that will be used during the tests The floodfield image must not be changed in order to consistently compare images to baselines It is recommended that a verification plan be created to reliably and repeatably measure the same set of fields at each session The field details can be found in Appendix A An output Excel workbook must be configured for each accelerator that will be included in the MegaQA program This Excel workbook contains the results of each test as well as machine specific test tolerances and baseline information This Excel workbook has a particular format that must be adhered to A template Excel workbook has been included with this document The tolerances defined for each machine can be found in the output Excel workbook in the sheet called Tolerances Minimum and maximum allowed values for each test can be defined in the appropriate columns of this sheet If no value is specified no check will be performed for that parameter during the MegaQA test A list of the tests and specifications that are checked are given in Table 2 Table 2 List of tests and specifications that are checked by the MegaQA software IP refers to In plane profiles and CP refers to cross plane profiles
18. rting the MegaQA software for the first time the user will be prompted for the location of the output directory as shown in Figure 1 When the directory is selected it will be scanned for Excel workbooks that match the required MegaQA format At least one valid Excel workbook must be present in the specified directory The output directory can be viewed at any later time by accessing the View gt Output Directory menu option from within the MegaQA software It can be changed by accessing the Modify gt Output Directory menu option from within the MegaQA software Changing the output directory will affect the available machines to test and may also affect the baselines and parameter tolerances Select Output Directory Select the directory that contains the Excel data sheets for storing the test results F Selected Directory Save Directory Cancel Figure 1 Configuring the output directory for MegaQA When the output directory has been configured the main MegaQA window will appear as shown in Figure 2 A list of available machines as determined by the Excel workbooks present in the output directory is given in the Machine drop down menu The file format of the test images can be set using either the Mode gt Dicom or Mode gt DXF menu option The default mode is DXF but the software will store the selection for future use The software can also be configured to use either Full
19. st Additionally an image comparison window will appear similar to that produced by the beam profile test Clicking the Return button in the results window signifies completion of the test and the test button turns green Relative Response Test These tests use the whole detector images They are used to verify the stability of all pixels over time The images are normalized to 1 at the central axis The images are compared to the baseline whole detector images and the flatness and symmetry of profiles through the central pixel are computed Specifications for the parameters are read from the Excel output sheet When the test is complete a results window will appear showing the status of each parameter similar to that produced by the beam profile test Additionally an image comparison window will appear similar to that produced by the beam profile test Clicking the Return button in the results window signifies completion of the test and the test button turns green Dose Response Test These tests use the 10 cm collimator 90 images They are used to verify the stability of central axis dose response over time The images are compared to the baseline 10 cm images and the change in the central axis signal compared to the baseline is computed In this test no normalization of the images is performed Specifications for the parameters are read from the Excel output sheet When the test is complete a results window will appear sh
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