Computed tomography
From UCL HEP PBT Wiki
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This tutorial will based on the DICOM GEANT4 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 unique volume and used by GEANT4 to construct the patient geometry and materials. | This tutorial will based on the DICOM GEANT4 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 unique volume and used by GEANT4 to construct the patient geometry and materials. | ||
| - | The geometry is constructed by voxelizing the volume. There are four navigation algorithms used to create the voxel geometry: ''' | + | The geometry is constructed by voxelizing the 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 is constructed by converting the pixel values (Hounsfield numbers) from the DICOM images to densities using | ||
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* Using '''G4RegularNavigation''' | * Using '''G4RegularNavigation''' | ||
| - | + | It is a special algorithm to navigate in a regular voxelised geometry. It includes an option to skip frontiers between voxels when they have the same material i.e. "replacing group of voxels with a smaller number of larger voxels". The '''G4RegularNavigation''' class is the default setup for this tutorial. To run with the default settings simply run macro run.mac. | |
<pre style="color: #800000; background-color: #dcdcdc"> | <pre style="color: #800000; background-color: #dcdcdc"> | ||
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</pre> | </pre> | ||
| - | * Usinging '''G4VoxelNavigation''' | + | * Usinging '''G4SmartVoxel'''/'''G4VoxelNavigation''' |
Using smart voxels required a huge amount of memory. At /home/username/DICOMFolder/DICOM_source/src/DicomRegularDetectorConstruction.cc set | Using smart voxels required a huge amount of memory. At /home/username/DICOMFolder/DICOM_source/src/DicomRegularDetectorConstruction.cc set | ||
