80525-02 IMSure Physics Data Guide
Contents
1. Photon Wedge Data O TMR Tissue maximum Ratios From smallest to largest fields size with a 0 field size extrapo lated from available data See the IMSure technical note avail able from the Standard Imaging website titled Obtaining and extrapolating data for IMSure calculations TMR must be normalized to the dax value and should encom pass all clinically relevant depths If the largest field size for the wedge is rectangular e g 40 x 20 then the table should contain a field size of 26 67 equivalent square of 40 x 20 An additional field of 40 cm should be added at the end of the table duplicating the 40 x 20 measurements as this is required for the model A typical table would look like this FIELD SIZE 3 00 4 00 6 00 10 00 15 00 20 00 2667 40 00 0 00 0 360 0382 0 403 0 428 0 465 0503 0 559 0 559 0 10 0 393 0 415 0 438 0 462 0 497 0 535 0 589 0 589 0 20 0 444 O464 0484 0 507 0 641 0 579 O630 0 630 0 30 0 507 0 525 0544 0564 0595 0630 0 679 0 679 0 40 0 578 0 595 0 611 0 629 0 657 0689 0 732 0 732 0 50 0 654 0 668 0683 O698 0 723 0 750 O787 0 787 0 60 0 724 0 735 0747 0760 0 781 0 803 0835 0 835 0 70 0 793 0 803 0 812 0 822 0840 0 857 0 883 0 883 0 80 0 852 0859 O866 0 875 0 889 0 901 0 921 0 921 0 90 0 898 0 903 0 908 0 915 0 926 0 934 0 951 0 951 1 00 0 930 0 934 0 938 0 942 0 950 0 957 0 968 0 968 1 102. See the csv files in the Machine Data folder in the Sample Data directory for an example on how to set up the file correctly csv file formatted files can be created in various programs but Standard Imaging suggests utilizing Microsoft Excel for this task IMPORTANT Data must be set up exactly as shown or it will not import into the IMSure physics module See pg 15 of user manual Version number must say version in first column and can be any number in 2nd column Data place data in columns under appropriate field size e g 0 911 is the Sc value for the field size 0 cm Table type Must say Table in first column and Scatter in the second column FieldSize First column must say FieldSize no space increasing to the right in cm 0 3 4 5 0 956 0 966 0 2 Electrons a b PDD Should be measured down the central axis with the phantom surface at calibration phantom distance PDD should be normalized to reference depth IMSure QA has no requirements for the actual depths measured but in typical use measurements to the practical range for each energy are preferred rule of thumb 2 cm depth for each MeV of energy IMSure QA will not extrapolate PDD and will not compute dose or MU for points that lie outside of the PDD table See the csv files in the Machine Data folder in the Sample Data directory for an example on how to set up the file correctly csv file formatted files can be created in variou
3. 2nd in cm Radius Depth Must say Radius Depth backslash in first column and then depths increase to the right in mm with radius increasing down in mm OF for Cyberknife The Cyberknife planning system can export as text files the OF tables that were originally input from ma chine data The format for the IMSure csv files for Cyberknife OF was designed to be very similar to those in order to make it easy to create the correct file structure An OF table should contain the measured output factors for each collimator size and a variety of SAD distances All output factors are relative to the 60 mm collimator and are normalized to that value The value of the 60 mm collimator OF is 1 00 by definition See the csv files in the Machine Data folder in the Sample Data directory for an example on how to set up the file correctly csv file formatted files can be created in various programs but Standard Imaging suggests utilizing Microsoft Excel for this task IMPORTANT Data must be set up exactly as shown or it will not import into the IMSure physics module See pg 15 of user manual Data place data in columns under appropriate field sze with SAD increasing e g 0 801 is the OF value for a 7 5 cm cone at 600 mm SAD First Column first cell must say IMSure Data Import File Version number must say version number in first column and can be any number in 2nd Table type Must say Table in first column and OF
4. 948 0 948 0 983 6 00 0 962 0 962 0 987 7 00 0 973 0 973 0 990 8 00 0 983 0 983 0 993 9 00 0 992 0 992 0 997 10 00 1 000 1 000 1 000 12 00 1 015 1 015 1 007 15 00 1 033 1 033 1 017 17 00 1 043 1 043 1 023 20 00 1 057 1 057 1 030 25 00 1 073 1 073 1 040 30 00 1 085 1 085 1 046 35 00 1 093 1 093 1 050 40 00 1 099 1 099 1 053 IMSure QA Machine Data continued Sc Head Scatter Factors O Sc is measured for each field size at isocenter SAD with an appropriate buildup cap of at least dax effective radius over the measurement chamber Sc is normalized to the calibration field size 10x10 Clean data at every cm below 10x10 will provide the best results for the 3 source model although measurements below 3 cm tend to be suspect due to the difficulty of accurately measuring fields this small A zero field size head scatter factor needs to be extrapolated for the model See the IMSure technical note available from the Standard Imaging website titled Obtaining and extrapolating data for IMSure calculations A typical Sc table will look like this FS Imported Computed Factor Factor 0 00 0 888 0 909 200 0 922 0 930 300 0 938 0 943 4 00 0 953 0 955 5 00 0 965 0 968 600 0 975 0 976 7 00 0993 0 984 8 00 0 990 0 990 900 0 995 0 995 10 00 1 000 1 000 1200 1 008 1 007 15 00 1 016 1 017 17 00 1 020 1 021 20 00 1 026 1 027 25 00 1 032 1 033 30 00 1 037 1 037 3 00 1 04 1 039 40 00 1044 1 04
5. CK in the second column SADIFS 5 he 10 12 5 15 500 0 625 0 76 0 838 0 888 0 92 550 0 631 0 791 0 647 0 894 0 925 600 0 637 0 801 0 856 0 901 0 929 650 0 643 0 612 0 665 0 908 0 933 700 0 649 0 823 0 874 0 915 0 938 750 0 655 0 834 0 883 0 921 0 942 ann need N QAE n aa n anA n aac SAD FS Must say SAD FS backslash in first column and then collimator sizes increase to the right in cm with SAD increasing down in mm IMSure QA Software IMSure QA Machine Data continued SSS Table B Rules for Machine Data Consistency 1 The Maximum Field size for the TMR data must be greater than or equal to the Maximum Field size for that Wedge 2 For open fields the Minimum Field size for the TMR data must be equal to 0 0 cm 3 For non open fields the Minimum Field size for the TMR data must be less than or equal to the Minimum Field size for that Wedge 4 A Field size must exist in the TMR data that matches the Minimum Field size for that Wedge 14 The TMR Field Size set must include the Calibration Field Size 15 The Output Factor Field Sizes must include the Calibration Field Size 16 The Collimator Scatter Factor Field Sizes must include the Calibra tion Field Size 17 The output factors for all fields must be normalized to the value at the Calibration Field Size i e the output factor at FS CFS will equal 1 000 The values for the TMR depths must increase monotonically 6 The values for the TMR Field Siz
6. be very similar to those in order to make it easy to create the correct file structure C An OCR table should be created for each collimator size and should contain data out to the maximum radius used clinically at several clinically used depths normalized to the central axis See the csv files in the Machine Data folder in the Sample Data directory for an example on how to set up the file correctly csv file formatted files can be created in various programs but Standard Imaging suggests utilizing Microsoft Excel for this task IMPORTANT Data must be set up exactly as shown or it will not import into the IMSure physics module See pg 15 of user manual Data place data in columns under appropriate field sze with depths increasing e g 0 994 is the OCR value at 5 cm depth and 0 2 mm off axis First Column first cell must say IMSure Data Import File Version number must say version number in first column and can be any number in 2nd IMSure Data Import File Version 2 Table type Must say Table in Table OCR CK first column and OCR CK in the FS 5 second column Radius Depth 15 50 100 150 Cone Size Must say FS in first 0 1 1 1 1 column and then the cone size 7 0 1 0 997 0 997 0 997 0 997 0 2 0 993 0 994 0 994 0 994 0 3 0 989 0 991 0 991 0 991 0 4 0 966 0 986 0 986 0 987 0 5 0 983 0 954 0 964 0 954 0 6 0 972 0 975 0 975 0 974 0 7 0 962 0 966 0 965 0 965 na n G62 n Ga N GAR n G64 in the
7. larg est possible square fields and normalized to the 10x10 field size A zero field size output factor does not need to be extrapolated for the wedge An additional wedge factor for the 10x10 field size relative to open field is needed Variation of the wedge factors with field size are accounted for in the output factor and collimator scatter tables of each wedge Enhanced Dynamic Wedge The Enhanced Dynamic Wedge model is algorithmically based and no additional data is needed IMSure QA Software IMSure QA Machine Data continued Electron Data e PDD Percent Depth Dose tables o Should be measured down the central axis with the phantom surface at calibration phantom distance PDD should be normal ized to reference depth IMSure QA has no requirements for the actual depths measured but in typical use measurements to the practical range for each energy are preferred rule of thumb 1 2 cm depth for each MeV of energy IMSure QA will not extrapo late PDD and will not compute dose or MU for points that lie outside of the PDD table e OCR Off center Ratios also knows as Off axis ratios o Should be measured with the phantom surface at calibration phantom distance and at several depths OCR must be normal ized to the central axis value for each depth o In many clinical situations electron dose will always be speci fied at the central axis In this case where the off axis distances would not be used the
8. step by step instructions for exporting this data from Eclipse This data then is zipped and sent to Standard Imaging via e mail It is easily converted to IMSure format and setup into an IMSure physics file which is then sent to you for commissioning Your data will be returned to you formatted into a physics imsure file see pg 12 of user manual This file contains all of your data pre formatted for use with IMSure Place the physics imsure file into the directory of your choice and then in IMSure preferences Folder preferences see pg 6 of user manual set the Machine folder to the same directory Clicking on the Physics tab after setting this param eter will display the physics data NOTE You will need to change the Machine Name s in the phys ics file to match the name your TPS uses for your machine Setting up your data yourself Use the sample csv files that can be found in the Machine Data directory in the Sample Data folder see pg 9 of user manual as a guide in setting up your data The structure of these csv files is very specific and will not import into IMSure if they are not correct The structure for each is as follows 1 Photons a From smallest to largest field size A zero field TMR must be added to the open field table by the user in order to use the 3 source model See the IMSure QA Physics Technical Note regarding extrapolation of 0 field size data However the model is relatively insensitive to that extr
9. the IMSure physics module See pg 15 of user manual Version number must say version in first column and can be any number in 2nd column Data place data in columns under appropriate field size e g 0 861 is the OF value for the field size 0 cm Table type Must say Table in first column and OF in the second column FieldSize First column must say FieldSize no space increasing to the right in cm 0 3 4 5 361 0 916 0 937 0 95 0 Sc Table Head Scatter Collimator Scatter Sc is very important to the 3 source model Sc for the square field sizes is required to 1 compute the phantom scatter from the output factor and 2 verify that the three source model head scatter coefficients are modeled correctly Sc is not necessary for wedged fields as this is automatically calculated from the formula Sc wedged Sc p wedged Sp open Sc is measured for each field size at isocenter SAD with an appropriate buildup cap of at least dax effective radius over the measurement chamber Sc is normalized to the calibration field size 10x10 A zero field size Sc is needed for the open field non wedged data to use the 3 source model and may be extrapolated from the small field size data See the IMSure QA Physics Technical Note regarding extrapolation of 0 field size data Because of the nature of the model clean Sc data ranging down to at least 3x3 measured for every FS between 3 and 12 will give the best results
10. 0 951 0 954 0957 0 961 0 965 0 970 0980 0 980 1 20 0 967 0969 0 971 0 975 0 977 0980 0 988 0 988 1 30 0 979 0 981 0 983 0 985 0 986 0 988 0 994 0 994 1 40 0 987 0 989 0 991 0 992 0 993 0994 0 997 0 997 1 50 0 994 0995 0996 0 997 0 997 0 997 0 999 0 999 1 60 1 000 1000 1000 1000 1000 1 000 1 000 1 000 1 70 1 002 1002 1002 1 001 1 002 1 000 1 001 1 001 orca pmo OCR Off center Ratios also known as Off axis ratios O O Only the largest field size is needed e g 40 cm Ideally OCR is measured at 100 cm SSD and at multiple depths including dyn 9 dmax 9CM 10cm 15cm 20cm 30cm OCR data must be normalized to the central axis OCR data for wedges should be set up with the thick edge of the wedge oriented to the positive right axis of the off axis distance i e OCR s greater than one should be to the negative left axis and OCR s less than one should be to the positive right axis OF Output Factors O The algorithms in IMSure require that output factors be mea sured or re calculated to a setup geometry of 100 cm SSD and duax depth For output factors measured at a different setup IMSure will automatically re calculate the output factors to the required setup geometry as long as the geometry is specified in the setup and TMR tables have been previously imported see pg 13 of user manual O The output factors should be measured for the smallest to
11. A www STANDARDIMAGING amp coM IMSure QA Software Machine and Physics Data Guide STANDARD IMAGING INC TEL 800 261 4446 3120 Deming Way TEL 608 831 0025 Middleton WI 53562 1461 FAX 608 831 2202 May 2008 2008 Standard Imaging Inc www standardimaging com DOC 80525 02 i Wa STANDARDIMAGING 4 IMSure QA Machine Data Most data required for IMSure QA is similar to that normally acquired in the commissioning process of a linear accelerator With all data readily avail able an entire dual energy machine can be set up in as little as a half hour The items needed for machine data configuration are listed below Items like machine names configuration tray factors and calibration speci fications can be entered directly in the Physics Module Tabular data such as TMR PDD OCR OF and Sc must be imported from CSV format files as specified at the end of this guide Some consistency rules apply to the imported data as listed in Table B Other machine parameters such as jaw distances rotation configurations and average MLC leaf leakages are needed as defined in Table A Jaw distances are common for all available machines and can be noted from our sample data or from Table C on page 4 Leaf leakages are also fairly uniform from machine to machine and this parameter may also be used to make small corrections in final IMSure QA IMRT results As many photon and electron energies along with their respective wedges a
12. Rs should be measured with the thick end of the wedge oriented to the positive right axis of the off axis distance i e OCRs greater than one should be to the negative left axis and OCRs less than one should be to the positive right axis See the csv files in the Machine Data folder in the Sample Data directory for an example on how to set up the file correctly csv file formatted files can be created in various programs but Standard Imaging suggests utilizing Microsoft Excel for this task NOTE Data must be set up exactly as shown or it will not import into the IMSure physics module See pg 15 of user manual Version number must say version in Data place data in columns under appropriate distance from CAX with first column and can be any number depths increasing e g 0 046329 is the OCR value for the distance 32 2 in 2nd column cm from CAX 2 4 depth Table type Must say Table in first column and OCR in the second column Depth and then depths increase to the right in cm B2 2 31 9 31 6 31 3 31 0 046329 0 046804 0 047329 0 047979 0 048828 0 051624 0 052585 0 055346 0 054269 0 055139 0 066252 0 069034 0 070208 0 071641 0 072813 0 11197 0 114347 0 116433 0 116519 0 121079 Distance Must say Distance in first column with negative values starting at left cm IMSure QA Software IMSure QA Machine Data continued SSS C d IMSure QA Software OF Table Output Factors Fro
13. apolated data Wedged fields only need the smallest to largest field size TMR should be normalized to the d of the energy TMR data must include reference depth IMSure QA does not extrapolate TMR depth so values to clinically reasonable depths must be taken or extrapolated by the user For non square wedged fields there should be two entries for the largest field size one at the equivalent square of the non square field and one at the largest opening size for the individual jaws For example in the case of a 40 x 20 field there would be an entry for a field size of 26 7 equivalent square and one for 40 cm both containing the same data See the csv files in the Machine Data folder in the Sample Data directory for an example on how to set up the file correctly csv file formatted files can be created in various programs but Standard Imaging suggests utilizing Microsoft Excel for this task NOTE Data must be set up exactly as shown or it will not import into the IMSure physics module See pg 15 of user manual Version number must say version Data place data in columns under appropriate field sze with depths number in first column and can be increasing e g 0 383486 is the TMR value for the 0 field size 0 depth any number in 2nd column and 0 502067 is the TMR value for the 0 field size 0 2 depth Table type Must say Table in first column and TMR in the second column Depths First column must say Depth and
14. bles that were originally input from machine data The format for the IMSure csv files for Cyberknife TMR was designed to be very similar to those in order to make it easy to create the correct file structure The TMR table should contain data for each collimator size and all clinical depths and must be normalized to the dax value See the csv files in the Machine Data folder in the Sample Data directory for an example on how to set up the file correctly csv file formatted files can be created in various programs but Standard Imaging suggests utilizing Microsoft Excel for this task IMPORTANT Data must be set up exactly as shown or it will not import into the IMSure physics module See pg 15 of user manual Data place data in columns under appropriate field sze with depths increasing e g 0 666 is the TMR value for the 5 cm cone 2mm depth First Column first cell must say IMSure Data Import File Version number must say version number in first column and can be any number in 2nd 0 57 0 541 o Depth FieldSize backslash and 0 599 0 572 OF no space in first column and 0 639 0 611 abe then cone sizes increase to the 0 766 0 712 0 685 OE right in cm with depths increasing down in mm nanan nore n oco nc OCR for Cyberknife The Cyberknife planning system can export as text files the OCR tables that were originally input from machine data The format for the IMSure csv files for Cyberknife OCR was designed to
15. ccelerator Heads Jaw Distances in cm Distances for Primary collimator and Flattening Filter Geometry used in 3 source model Fixed non editable Linac MLC Type Zx Elekta 80 43 4 Siemens Varian 52 Varian 80 Varian 120 The IMSure QA model assumes that MLC leaves are in the X direction The Elekta system can be accommodated by specifying the jaw distances as above with the Lower Jaw specified as closer to the source than the Upper Jaw An additional offsetting correction must be made in the Jaw Naming convention where the expected X jaw and Y jaw names are exchanged IMSure QA Software
16. cing the Gantry Jaw Naming May differ between manufacturers Two alphanu Conventions meric characters allowed Jaw limits Machine dependent may include over travel Specified for both upper and lower jaws Allowed Field Size May differ for Open and wedged data May be Limits specified in rectangular form as for most hard wedges Jaw Transmission for future use Factors Source to Jaw See table C Distances Allowed EDW wedge Any of 10 15 20 25 30 45 and 60 degrees may angles be chosen Source to MLC See table C distances Allowed Wedge Refers to the thin end toe of wedge Directions Measurements and parameters Calibration In cGy MU at Calibration Depth and at Calibration Dose Rate Phantom distance Tray Factor Tray Field Open Field less than 1 000 Photons Only IMSure QA Software IMSure QA Machine Data continued Mean Dose Leaf Leakage Photon Only Mean Fluence Map Leaf Leakage Photon Only Dosimetric Leaf The distance from the light field edge of an MLC Offset Photon Only leaf to the radiation field edge EDW data Derived from STT User must choose STT en Photon Only ergy Wedge Factor At calibration field size usually 10x10 De Photon Only fined as the ratio of the measured values of the wedged field at reference depth over the similar open field Used in 3 source model Typically between 1 and 3 Used in 3 source model Typically between 1 and 3 Used in map c
17. data See the IMSure technical note avail able from the Standard Imaging website titled Obtaining and extrapolating data for IMSure calculations o TMR must be normalized to the dax value and should encom pass all clinically relevant depths e OCR Off center Ratios also known as Off axis ratios o Only the largest field size is needed e g 40 cm o Ideally OCR is measured at 100 cm SSD and at multiple depths including diay 9 Aya 9CM 10cm 15cm 20cm 30cm o OCR data must be normalized to the central axis e OF Output Factors o The algorithms in IMSure require that output factors be mea sured or re calculated to an SAD setup geometry and d depth For output factors measured at a different depth IMSure will automatically re calculate the output factors to the required setup geometry as long as the geometry is specified in the setup and TMR tables have been previously imported see pg 13 of user manual o The output factors should be measured for the smallest to largest possible square fields and normalized to the 10x10 field size A zero field size output factor needs to be extrapolated for the model See the IMSure technical note available from the Standard Imaging website titled Obtaining and extrapolating data for IMSure calculations A typical OF table will look like this FS OF OF ref PSF 0 00 0 847 0 847 0 953 2 00 0 887 0 887 0 963 3 00 0 908 0 908 0 968 4 00 0 928 0 928 0 974 5 00 0
18. es must increase monotonically 5 7 The values for the Output Factor Field Sizes must increase mono tonically 8 The values for the Collimator Scatter Factor Field Sizes must in crease monotonically 18 The Collimator Scatter factors must be normalized to the value at the Calibration Field Size i e the output factor at FS CFS will equal 1 000 19 The TMR value for the Calibration Field Size and at the Reference depth must equal 1 20 For open fields the Min Jaw position for either upper or lower jaws 9 The values for the Off axis Ratio Depths must increase monotoni cally 10 The values for the Off axis Ratio Distances must increase monotoni may not be less than Maximum Field Size 2 21 Foropen fields the Max Jaw position for either upper or lower jaws may not be greater than Maximum Field Size 2 cally 22 PDD must contain the reference depth and the value at that point 11 The minimum value for the Off axis Ratio Distances must be equal must equal 1 000 to or less than Maximum Field Size 2 23 PDD depths must increase monotonically 24 OCR must have at least one point 1 000 at d on CAX 25 Cone Factor must contain at least one point 1 000 for FS sqrt ConeX ConeY 12 The maximum value for the Off axis Ratio Distances must be equal to or greater than Maximum Field Size 2 13 The TMR depths must include the Reference Depth Table C Known Geometry Values for Various Linear A
19. m smallest to largest possible square fields only normalized to 10x10 FS The models in MSure require output factors measured at d It is common practice to measure output factors at deeper depths e g 5 cm to remove the electron contamination from the measurements IMSure can automatically back adjust these measurements to dyax aS long as there is TMR data already input into the physics module see pg 13 of user manual For Open field data a zero FS extrapolation is needed See the IMSure QA Physics Technical Note regarding extrapolation of 0 field size data For wedged data Sc p should be normalized to 10x10 and should range from smallest to largest field sizes An additional wedge factor for the 10x10 field size relative to open field is needed Variation of the wedge factors with field size are accounted for in the output factor and collimator scatter tables of each wedge The output factors in combination with the Collimator Scat ter Factors are used to compute the phantom scatter as Sp OF Sc OF is specified independently for wedged fields so that FS dependent wedge factors may be accommodated See the csv files in the Machine Data folder in the Sample Data directory for an example on how to set up the file correctly csv file formatted files can be created in various programs but Standard Imaging suggests utilizing Microsoft Excel for this task NOTE Data must be set up exactly as shown or it will not import into
20. nd cones can be entered i e both upper and lower wedges even old fashioned split wedges and half beam blocks Table A Machine Names Configurations Parameters and Data used in IMSure QA Name RTP or DICOM RT convention Nominal Gap Typically 5 cm describes the distance from the bottom of the cone to patient surface at 100 SSD Beam Energy Nominal in MV photon MeV electron Calibration Depth at which the calibrated does rate is set Reference Depth in cm Calibration Field Size In cm typically 10 cm Photons Only Calibration Cone Size Choose from drop down list of available cones Electrons Only Calibration Phantom In cm typically 100 cm Distance Diode Calibration Calibration factor for diodes used with this en Factor ergy MLC Type Choose your MLC configuration from drop down list Wedge Name Common Wedge name for hard wedges e g 15 Photons Only deg A default wedge named Open Field must be present for all Photon energies Wedge Angle The numerical value for the wedge angle Must Photons Only match the value used in the imported RTP or DICOM RT convention Common Cone name for electron cones e g A10 Cone Size The numeric value of the cone that describes it s dimension in both the X and Y directions in cm Machine Geometry IMSure QA defaults to the IEC 1217 Conven tion Base Gantry IEC 1217 Convention describes 0 degrees as the Rotation Gan
21. ollimator size with measured data at multiple depths including d g 15 mm 50 mm 100 mm 150 mm 200 mm and 250 mm normalized to the central axis e OF Output factors o Output factors at different collimator sizes for differing SADs typically from 500mm to 1100mm IMSure QA Machine Data continued Setting up your data for IMSure There are two choices for getting your data into IMSure 1 Send your data to Standard Imaging for conversion and setup 2 Convert your data yourself There are advantages to each Having Standard Imaging convert your data of course means less work up front and we include the conversion of up to 3 different machine s data with your purchase On the other hand doing the conversion yourself gives you the peace of mind that the data was converted correctly and might mean less commission ing of the data before use Sending your data to Standard Imaging for conversion Make sure you have all of the required data In most cases this data is available from the scanning system that you use Most scanning system s software offers multiple export functions The data needs to be output in ASCII format and ideally output as Excel spreadsheets IMPORTANT For Eclipse users only The Eclipse system saves all of the raw beam data that is imported for beam model ing If you use the Eclipse system contact Standard Imaging and ask for the IMSure Eclipse export instructions This docu ment includes
22. om at calibration phantom distance and the chamber at calibration reference depth A series of cutout apertures should be made for each cone in 10 20 increments down to 40 60 for the smallest aperture For example a 6x6 cone might have IMSure QA Machine Data continued SSS 3x3 4x4 and 5x5 cutouts and 6x6 by default A 20x20 cone might range have 10 12 5 15 17 5 and 20 cm cutouts By defi nition CF unblocked field 1 000 Typical ranges of CF will be from 0 900 to 1 100 but can go as low as 0 700 for very small cutouts See the csv files in the Machine Data folder in the Sample Data directory for an example on how to set up the file correctly csv file formatted files can be created in various programs but Standard Imaging suggests utilizing Microsoft Excel for this task IMPORTANT Data must be set up exactly as shown or it will not import into the IMSure physics module See pg 15 of user manual Version number must say version in first column and can be any number in 2nd column Data place data in columns under appropriate field size value e g 0 866 is the CF value for a field size of 2 66 cm Table type Must say Table in first column and CF in the second column FieldSize First column must say FieldSize no space increasing to the right in cm 66 3 54 4 5 0 951 1 019 1 005 3 Cyberknife a TMR for Cyberknife The Cyberknife planning system can export as text files the TMR ta
23. omparisons The ratio of the dose at the reference depth for the indicated cone versus the dose at reference depth for the reference cone Output Factor Electron Only Virtual Source to Surface Distance can be mea sured and used reliably over short ranges for extended distance use VSSD Electron Only Tabular Input Data Tables below must be read in from CSV comma delimited files set up in proprietary IMSure QA format TMR Photons See discussion below PDD Electrons OCR Photons and Electrons oF Photons gt oF Eeron 7 Head Scatter Sc Photons All tabular data can be read into IMSure QA from a comma delimited file see format below or the Sample Data CD ROM for samples The CSV file format was chosen because it is easily manipulated in Excel spreadsheets IMSure QA Software What data is needed The physics data required for setting up IMSure is similar to the data that is acquired during commissioning a linear accelerator Therefore most people will already have the necessary information All data needs to be setup in a proprietary csv comma delimited format that can easily be created with Microsoft Excel Examples of these files can be found in the Sample Data folder that installs in the IMSure 3 1 directory see pg 9 of user manual Photon Open field data e TMR Tissue Maximum Ratios o From smallest to largest fields size with a 0 field size extrapo lated from available
24. s programs but Standard Imaging suggests utilizing Microsoft Excel for this task IMPORTANT Data must be set up exactly as shown or it will not import into the IMSure physics module See pg 15 of user manual Version number must say version in first column and can be any number in 2nd column Data place data in columns under appropriate depth value e g 76 8 is the PDD value for a depth of 0 cm Table type Must say Table in first column and PDD in the second column FieldSize First column must say Depth increasing to the right in cm 0 0 1 0 2 0 3 0 6 8 76 15 79 5 81 75 OCR Should be measured with the phantom surface at calibra tion phantom distance and at several depths OCR must be normalized to the central axis value for each depth In many clinical situations electron dose will always be specified at the central axis In this case where the off axis distances would not be used the user may choose to use the default single point OAR which is specified as 1 000 at the reference depth and central axis IMSure QA will only allow the user to enter off axis distances that are contained in this table and in this case the user will only be able to enter x and y calculation points as 0 0 The file format for electron OCR is identical to photon see pg 6 of this manual CF Table cone factor Cone Factor tables for electrons should be measured for each cone and energy with the surface of the phant
25. then depths increase to the right in cm 0 0 1 0 2 0 3 0 4 0 3 5 6 5 0 439316 0 445336 0 5 0 514515 0 442989 0 49346 0 507523 0 552104 0 566567 0 502067 0 547643 0 566706 0 60521 0 616619 0 566825 0 612639 0 635908 0 674349 0 665666 0 632549 0 679037 0 704112 0 743467 0 753754 0 69835 0 742227 0 764293 0 802605 0 611612 0 765465 0 606419 0 624473 0 661725 0 66967 NAITAASS N A581555 NARRA N A957972 N AN PaNs b OCR table Only the largest field size for open and wedged Ideally the OCR data is measured at 100 SSD at multiple depths Correction for depth dependent divergence is made by IMSure QA No correction is made for the minor variances due to the true divergent depth at off axis positions but as the depth to the specification calculation point is defined as the depth down the central axis no correction is required Field Size Must say FieldSize no space in first column and then field sizes increase to the For open fields a diagonal scan if available may provide more reliable results Half beam scans may be used but must be mirror imaged before import IMSure QA does not distinguish between radial and transverse scans but averaged scans of transverse and radial setup are also acceptable For wedged data only scans in wedged direction are needed and only for the largest field size OCR data should include ref erence depth and must be normalized to the central axis value at each depth and independent of PDD Wedge OC
26. try pointing down If your system describes O degrees as the Gantry pointing up you would insert 180 to let IMSure QA know that your co ordinate system is set 180 degrees from the IEC standard Gantry Rotation IEC 1217 Convention describes Gantry rotation Direction increasing clockwise CW if facing the Gantry from the foot of the couch 90 degrees will be with the head of the accelerator to the right if facing the gantry from the foot of the couch Base Collimator IEC 1217 Convention describes 0 degrees as Rotation pointing towards the foot of the couch If your system describes 0 degrees as pointing towards the Gantry you would insert 180 to let IMSure QA know that your coordinate system is set 180 degrees from the IEC standard Collimator Rotation IEC 1217 Convention describes Collimator rotation Direction increasing clockwise CW if facing the collimator while lying on the table in standard HFS position 90 degrees would then be facing your right hand in the HFS position Base Table Rotation IEC 1217 Convention describes 0 degrees as the head of the table If your system describes 0 de grees as the foot of the table you would insert 180 to let IMSure QA know that your coordinate system is set 180 degrees from the IEC standard Table Rotation IEC 1217 Convention describes Table Rotation Direction increasing clockwise CW as looking up at the bottom of the table 90 degrees would have the head of the table to the left if fa
27. user may choose to use the default single point OAR which is specified as 1 000 at the reference depth and central axis IMSure QA will only allow the user to enter off axis distances that are contained in this table and in this case the user will only be able to enter x and y calculation points as 0 0 e CF Cutout Factor Table o Should be measured for each cone and energy with the surface of the phantom at calibration phantom distance and the cham ber at calibration reference depth o A series of cutout apertures should be made for each cone in 10 20 increments down to 40 60 for the smallest aperture For example a 6x6 cone might have 3x3 4x4 and 5x5 cutouts and 6x6 by default A 20x20 cone might range have 10 12 5 15 17 5 and 20 cm cutouts By definition CF unblocked field 1 000 Typical ranges of CF will be from 0 900 to 1 100 but can go as low as 0 700 for very small cutouts VSSD Virtual Source to Surface Distance Should be measured for each electron energy and each cone Electron output is affected by jaw and collimator scattering as well as in air scattering and does not follow the inverse square law over large ranges as well as photons do However an effective or virtual SSD can be measured and used reliably over short ranges for extended distance use as are often needed in clinical practice A typical range for clinical use would be from 100 SSD to 115 SSD VSSD can be computed from measured dose at
28. various distances using the method of Khan with a chamber at the reference depth dref in a water or water equivalent phantom beginning at SSDref e g 100 cm and taking several measurements down to a clinically useful extended distance 115 cm or 120 cm SSD IMSure QA Software With these measurements VSSD can be computed by following the algo rithm below 1 Beginning with these measurements for n points first compute a set of points x i Distance i SSDref 1 a y i sqrt Dose SSDref Dose Distance i Tb 2 Compute the average of each set x and y X x1 x2 XN N 2 a y y1 y2 yn n 2p 3 Compute the average area xy x1 y1 x2 y2 xn yn n 70 4 Compute the average of the distance squared XX X1 x1 x2 x2 xn xn n 4 5 Compute the slope m of the best least squares fit for these points m xy x y xx x x 5 6 Finally VSSD 1 m dref 6 VSSD will vary for each energy and each cone and must be measured separately VSSD also vary depending on accelerator and cone construc tion but will typically range between 75 and 98 cm Cyberknife Data e TMR Tissue Maximum Ratio o From smallest to largest collimator size with values from 0 to clinically relevant depths o TMR must be normalized to the d value e OCR Off center Ratios also known as Off axis ratios o Separate tables need to be created for each c
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