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 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. Then, | + | 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 | + | The geometry is constructed by voxelizing the volume. There are four navigation algorithms used to create the voxel geometry: G4SmartVoxel, G4VNestedParameterisation, G4RegularNavigation and G4Replica. In this tutorial we investigate the different geometry implementations. |
- | Then, the densities are converted to material type according to | + | |
+ | The material 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 type 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 inside the patient. The output of the example is a text file with dose deposited in several voxels. | A simple monenergetic electron beam is simulated inside the patient. The output of the example is a text file with dose deposited in several voxels. | ||
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http://www.hep.ucl.ac.uk/pbt/RadiotherapyWorkbook/skins/common/images/DICOM/dicom.png | http://www.hep.ucl.ac.uk/pbt/RadiotherapyWorkbook/skins/common/images/DICOM/dicom.png | ||
- | This is one of the DICOM files that | + | This is one of the DICOM files that is used in the tutorial. |
== <span style="color:#000080"> Setting up the environment </span> == | == <span style="color:#000080"> Setting up the environment </span> == |