Computed tomography
From UCL HEP PBT Wiki
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== <span style="color:#000080"> Introduction </span> == | == <span style="color:#000080"> Introduction </span> == | ||
| - | This tutorial is based on the GEANT4 DICOM example originally developed by Louis Archambault, Luc Beaulieu and Vincent Hubert-Tremblay. In this example a list of DICOM files (.dcm) are converted to ASCII files (.g4dcm) and binary (.g4bin) that can be read by GEANT4. Each of these files corresponds to a Z slice. Then, the .g4dcm (.g4bin) files are merged into one | + | This tutorial is based on the GEANT4 DICOM example originally developed by Louis Archambault, Luc Beaulieu and Vincent Hubert-Tremblay. In this example a list of DICOM files (.dcm) are converted to ASCII files (.g4dcm) and binary files (.g4bin) that can be read by GEANT4. Each of these files corresponds to a Z Computed tomography (CT) slice. Then, the .g4dcm (.g4bin) files are merged into one volume. |
| - | The geometry is constructed by voxelizing | + | The geometry is constructed by voxelizing this volume. There are four navigation algorithms used to create the voxel geometry: '''G4RegularNavigation''', '''G4VNestedParameterisation''', '''G4SmartVoxel'''/'''G4VoxelNavigation''' and '''G4PVReplica'''. |
| - | The material is constructed by converting the pixel values (Hounsfield numbers) from the DICOM images to densities using | + | The material for this volume is constructed by converting the pixel values (Hounsfield numbers) from the DICOM images to densities using the [http://www.hep.ucl.ac.uk/pbt/RadiotherapyWorkbook/skins/common/images/DICOM/CT2Density.dat Hounsfield scale]. Then, the densities are converted to material types according to this [http://www.hep.ucl.ac.uk/pbt/RadiotherapyWorkbook/skins/common/images/DICOM/Materials.txt table]. |
| - | the [http://www.hep.ucl.ac.uk/pbt/RadiotherapyWorkbook/skins/common/images/DICOM/CT2Density.dat Hounsfield scale]. Then, the densities are converted to material types according to this [http://www.hep.ucl.ac.uk/pbt/RadiotherapyWorkbook/skins/common/images/DICOM/Materials.txt table]. | + | |
A simple monenergetic electron beam is simulated using '''G4ParticleGun''' class. The output of the tutorial is a text file with dose deposition in several voxels. The dose is scored using classes '''G4MutiFunctionalDetector''', '''G4VPrimitiveScorer''', '''G4PSDoseDeposit3D''' and '''G4THitsMap'''. | A simple monenergetic electron beam is simulated using '''G4ParticleGun''' class. The output of the tutorial is a text file with dose deposition in several voxels. The dose is scored using classes '''G4MutiFunctionalDetector''', '''G4VPrimitiveScorer''', '''G4PSDoseDeposit3D''' and '''G4THitsMap'''. | ||
