[807] | 1 | $Id: README,v 1.6 2005/11/27 13:13:59 mpiergen Exp $ |
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| 2 | ------------------------------------------------------------------- |
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| 3 | |
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| 4 | |
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| 5 | ========================================================= |
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| 6 | Geant4 - Medical Linac example |
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| 7 | ========================================================= |
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| 8 | |
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| 9 | README |
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| 10 | --------------------- |
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| 11 | |
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| 12 | |
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| 13 | ------------------------------------------------------------------------ |
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| 14 | ----> Introduction. |
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| 15 | |
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| 16 | Medical_Linac is an example of application of Geant4 in a medical physics |
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| 17 | envinronment. It simulates energy deposit in a Phantom filled with water |
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| 18 | for a typical linac used for intensity modulated radiation therapy. |
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| 19 | The experimental set-up is very similar to one used in clinical practice. |
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| 20 | |
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| 21 | ------------------------------------------------------------------------ |
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| 22 | ----> 1.Experimental set-up. |
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| 23 | |
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| 24 | The elements simulated are: |
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| 25 | |
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| 26 | 1-The point source of electrons (the distribution of the electron energy |
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| 27 | and the electron radial intensity was assumed Gaussian in shape) |
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| 28 | (the beam is along the z axis) |
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| 29 | 2-The primary collimator |
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| 30 | 3-The target |
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| 31 | 4-The vacuum window |
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| 32 | 5-The flattening filter |
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| 33 | 6-The ion chamber |
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| 34 | 7-The mirror |
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| 35 | 8-The light field reticle |
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| 36 | 9-The secondary movable collimators (jaws) |
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| 37 | 10-The Multi Leaf Collimator |
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| 38 | 11-The phantom (filled with water) |
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| 39 | |
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| 40 | The objects (2) and (3) are in a box filled with vacuum. |
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| 41 | The world volume is filled with air. |
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| 42 | The distance between the upper surface of the target and the upper surface |
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| 43 | of the phantom (SSD) is 100 cm. |
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| 44 | The particles exiting from the target with an angle>25deg are killed. |
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| 45 | |
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| 46 | ------------------------------------------------------------------------ |
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| 47 | ----> 2.Setting up the environment variables |
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| 48 | |
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| 49 | compiler = gcc-3.2.3 |
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| 50 | |
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| 51 | setenv G4SYSTEM Linux-g++ |
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| 52 | |
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| 53 | setenv G4INSTALL points to the installation directory of GEANT4; |
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| 54 | |
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| 55 | setenv G4LIB point to the compiled libraries of GEANT4; |
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| 56 | |
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| 57 | setenv G4WORKDIR points to the work directory; |
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| 58 | |
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| 59 | setenv CLHEP_BASE_DIR points to the installation directory of CHLEP; |
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| 60 | |
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| 61 | setenv G4LEDATA points to the low energy electromagnetic libraries - G4EMLOW2.3 |
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| 62 | |
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| 63 | setup for analysis: AIDA 3.2.1, PI 1.3.3 |
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| 64 | |
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| 65 | Users can download the analysis tools from: |
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| 66 | |
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| 67 | http://aida.freehep.org/ |
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| 68 | http://www.cern.ch/PI |
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| 69 | |
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| 70 | #------------------------------------------ |
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| 71 | |
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| 72 | - Setup for Visualization |
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| 73 | |
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| 74 | IMPORTANT: be sure that your Geant4 installation has been done |
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| 75 | with the proper visualization drivers; for details please see the |
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| 76 | file geant4/source/visualization/README. |
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| 77 | |
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| 78 | To use the visualization drivers set the following variables in |
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| 79 | your local environment: |
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| 80 | |
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| 81 | setenv G4VIS_USE_OPENGLX 1 # OpenGL visualization |
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| 82 | setenv G4VIS_USE_DAWNFILE 1 # DAWN file |
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| 83 | setenv G4VIS_USE_VRMLFILE 1 # VRML file |
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| 84 | setenv G4VRMLFILE_VIEWER vrmlview # If installed |
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| 85 | |
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| 86 | ------------------------------------------------------------------------ |
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| 87 | ----> 3.How to run the example. |
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| 88 | |
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| 89 | - batch mode: |
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| 90 | |
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| 91 | OpenGL visualization: |
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| 92 | $G4WORDIR/bin/Linux-g++/MedLinac vis.mac |
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| 93 | |
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| 94 | or DAWN file: |
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| 95 | $G4WORDIR/bin/Linux-g++/MedLinac dawnvis.mac |
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| 96 | |
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| 97 | or VRML file: |
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| 98 | $G4WORDIR/bin/Linux-g++/MedLinac vrmlvis.mac |
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| 99 | |
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| 100 | or without visualization: |
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| 101 | $G4WORDIR/bin/Linux-g++/MedLinac macro.mac |
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| 102 | |
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| 103 | - Interative mode: |
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| 104 | 3) $G4WORDIR/bin/Linux-g++/MedLinac |
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| 105 | |
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| 106 | -->possible different configurations for interactive mode: |
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| 107 | |
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| 108 | The user can select the cut of the physics processes: |
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| 109 | /PhysicsList/cut 0.2 mm |
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| 110 | |
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| 111 | The user can select the dimension of the water phantom and the dimension of the phantom's voxels in the detector |
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| 112 | construction: |
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| 113 | /Phantom/dimension 15. cm |
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| 114 | /Phantom/Nvoxels 150/Phantom/maxStep 0.2 mm |
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| 115 | |
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| 116 | and in the definition of the sensitive detector: |
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| 117 | /PhantomSD/dimension 15. cm |
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| 118 | /PhantomSD/Nvoxels 150 |
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| 119 | |
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| 120 | The user can select the max step defined in the detector construction: |
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| 121 | /Phantom/maxStep 0.2 mm |
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| 122 | |
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| 123 | |
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| 124 | The user can select the position of the secondary collimators (the jaws) |
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| 125 | to obtain the desired field at isocenter: |
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| 126 | idle>/Jaws/X1/DistanceFromAxis -20. cm |
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| 127 | idle>/Jaws/X2/DistanceFromAxis 20. cm |
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| 128 | idle>/Jaws/Y1/DistanceFromAxis -20. cm |
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| 129 | idle>/Jaws/Y2/DistanceFromAxis 20. cm |
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| 130 | idle>/Jaws/update |
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| 131 | |
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| 132 | The user can select the position of every single leaf of the Multi-Leaf Collimator, for example: |
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| 133 | Idle> /MLC/leaf_selection a1 |
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| 134 | Idle> /MLC/position 0. cm |
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| 135 | Idle> /MLC/leaf_selection a2 |
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| 136 | Idle> /MLC/position 0. cm |
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| 137 | .. |
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| 138 | .. |
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| 139 | .. |
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| 140 | Idle> /MLC/leaf_selection b39 |
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| 141 | Idle> /MLC/position 0. cm |
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| 142 | Idle> /MLC/leaf_selection b40 |
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| 143 | Idle> /MLC/position 0. cm |
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| 144 | |
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| 145 | The distance selected represent the distance between the leaf tip and the beam axis projected at isocenter. |
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| 146 | |
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| 147 | |
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| 148 | |
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| 149 | The user can select the mean energy ad the standard deviation of the electrons: |
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| 150 | idle>/energy 6.0 MeV |
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| 151 | idle>/sourceType 0.127 MeV |
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| 152 | |
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| 153 | idle>/run/beamOn [NumberOfEvents] ...and then |
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| 154 | idle>exit |
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| 155 | |
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| 156 | ----------------------------------------------------------------------- |
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| 157 | ----> 4. The physics |
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| 158 | |
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| 159 | The electromagnetic physic uses the LowEnergy library, |
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| 160 | specifically provided from GEANT4 to treat low energy processes. |
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| 161 | The default cut in range value is 0.1 mm, a bigger cut is associated to the first collimator. |
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| 162 | |
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| 163 | ------------------------------------------------------------------------ |
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| 164 | ----> 5. Simulation output |
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| 165 | |
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| 166 | The analysis part of Medical_Linac is based on the AIDA interfaces and their |
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| 167 | implementation in Anaphe |
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| 168 | The actual analysis produces some histograms; the histograms are saved at |
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| 169 | the end of the run in the file "medlinac.hbk". |
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| 170 | |
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| 171 | It contains: |
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| 172 | 1) 2Dhistogram with the distribution of energy in the phantom (plane xz) |
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| 173 | 2) 1Dhistogram with the primary particle energy |
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| 174 | |
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| 175 | 3) 2Dhistogram with the distribution of energy )at a depth in the phantom |
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| 176 | of 15 mm (ZThickness = 1. cm ) |
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| 177 | |
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| 178 | 4) 1Dhistogram with the distribution of energy along the z axis |
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| 179 | (Y and X Thickness = 5. mm), from which the user can calculate the PDD |
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| 180 | |
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| 181 | 5) 1Dhistogram with the distribution of energy along the x axis |
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| 182 | (Y and Z Thickness = 5. mm) at a depth in the phantom of 15 mm, |
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| 183 | from which the user can calculate the flatness |
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| 184 | |
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| 185 | 6) 1Dhistogram with the distribution of energy along the x axis |
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| 186 | (Y and Z Thickness = 5. mm) at a depth in the phantom of 50 mm, |
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| 187 | from which the user can calculate the flatness |
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| 188 | |
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| 189 | 7) 1Dhistogram with the distribution of energy along the x axis |
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| 190 | (Y and Z Thickness = 5. mm) at a depth in the phantom of 100 mm, |
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| 191 | from which the user can calculate the flatness |
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| 192 | |
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| 193 | 8) 1Dhistogram with the distribution of energy along the x axis |
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| 194 | (Y and Z Thickness = 5. mm) at a depth in the phantom of 200 mm, |
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| 195 | from which the user can calculate the flatness |
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| 196 | |
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| 197 | Units: the energy deposit is in MeV; |
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| 198 | x, y, z in mm for histograms |
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| 199 | |
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| 200 | To fill histograms from (4) to (8) I suggest you to select NumberOfEvents>500000 |
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| 201 | |
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| 202 | Please note that in a multiple run session, the last run always override the |
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| 203 | hbook file. |
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| 204 | |
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| 205 | To use analisys remember to set G4ANALYSIS_USE. |
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| 206 | |
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| 207 | -------------------------------------------------------------------------- |
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| 208 | |
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| 209 | for comments, advices, doubts and questions: Michela.Piergentili@ge.infn.it |
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| 210 | |
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| 211 | last modified: Michela Piergentili 24/11/2005 |
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| 212 | |
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| 213 | |
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