2-D Dose-CT Mapping in GEANT4

geant4.web.cern.ch

2-D Dose-CT Mapping in GEANT4

PurposeWe designed and developed 2-D 2 D Dose-CTMapping software using Geant4 and ImageJ– To convert CT image to a format that can beprocessed in Geant4– To display dose mapping on CT image usingImageJ


MaterialsMonte Carlo Simulation Toolkit– Geant4(ver.4.8.1p01)2-D D Dose-CT Viewer– ImageJ(ver.1.37b)a public domain Java image processing programruns, either as an online applet or as a downloadableapplication, on any computer with a Java 1.1 or later virtualmachine.available for Windows, Mac OS, Mac OS X and Linux.designed with an open architecture that provides extensibilityvia Java plugins.Custom acquisition, analysis and processing plugins can bedeveloped using ImageJ's built in editor and Java compiler.User-writtenplugins make it possible to perform almost anyimage processing or analysis.


Methods in Monte Carlo simulationTarget (Detector) construction– Load DICOM-CT CT images– Convert pixel to voxel– Set voxels– Convert CT value to “physical density” and“element composition”Beam data (X-ray Spectra)– X-ray spectrum used for radiation diagnosis (X-ray tube) Birch formula– X-ray spectrum used for radiotherapy (Linac)Load x-ray xspectrum data


Methods in 2-D 2 D Dose-CT MappingCT data– Load DICOM-CT CT imagesDose data– Load the data with energy deposition, voxellocation (x, y, z), and voxel density.– Calculate Dose with energy deposition and itsdensity– Create Dose images with color map2-D D dose map– Superimpose Dose image onto CT image


Process flow in Monte Carlo simulation


Pre-Process Process in Monte Carlo simulationSort DICOM images by slice locationCreate “Data.dat” with names of DICOM images,the number of DICOM images, and compress ratio.


Process flow in Monte Carlo simulation(Detector construction)Convert pixel to voxel Pixel spacing (x,y(x,y)Slice thickness


Process flow in Monte Carlo simulation(Detector construction)Set VoxelsSlice location


Process flow in Monte Carlo simulation(Detector construction)Physical density (Ref. W Schneider et al, Phys. Med. Biol. 45 (2000) )2.000000– CT value1600 default: 10g/cm 3 AgPhysical density (g/cm 3 )1.5000001.0000000.500000Air & lungSoft tissueSkeletal tissue0.000000-1000 -800 -600 -400 -200 0 200 400 600 800 1000 1200 1400 1600CT value (HU)


Process flow in Monte Carlo simulation(Beam data)Ratio of the number of photonsX-ray spectrum used for diagnosis (X-ray tube)10.80.60.40.20– Tube voltage (TV, kV)– Inherent filter (IF, mmAl), Added filter (AF, mmAl, mmCu)– Target angle (TA, degree)TV: 60kV, TA: 12deg., IF: 1.1mmAl,AF: NONETV: 90kV, TA: 12deg., IF: 1.1mmAl,AF: NONETV: 90kV, TA: 12deg., IF: 5mmAl,AF: NONE0 20 40 60 80 100 120 140 160Photon energy (keV)Birch formula


Process flow in Monte Carlo simulation(Beam Focus and Field)Source– The area of startingpoint– Shape: squarePhotonSourceField– The are ofdestination pointShape: squareField


Process flow in Monte Carlo simulation(Beam Direction)Direction– 0 degree – 360 degree


Process flow in 2-D 2 D Dose-CT MappingWith our Plugin


Process flow in 2-D 2 D Dose-CT Mapping(CT data)Load CT images– Convert 16-bit to 8-bit 8gray scaleLoad CT imagesConvert 16-bitto 8bit gray scalePhantom (Tough Water)


Process flow in 2-D 2 D Dose-CT Mapping(Dose data)Load output datax y zenergydepositphysicaldensityWith our PluginDose =Energy depositPhysical densityCompress: 2The number of slices: 46


Process flow in 2-D 2 D Dose-CT Mapping(Dose mapping on CT image)CT imagesDose images2-D D Dose-CT images


Process flow in 2-D 2 D Dose-CT Mapping(2-D D dose map)AxialCoronalSagittal


Process flow in 2-D 2 D Dose-CT Mapping(Difference between high-energy and low-energy)4MV X-rayX40KV X-rayX


Future workTo optimize radiation therapy verificationtool– The enormous amount of time necessary tocalculate dose by CT imagesRemove extra voxel ex) Air outside body– Dose Analysis ToolDose Volume Histogrametc…– Irregular Shape Field– Dynamic Wedge– Dynamic Multi-Leaf Collimator

More magazines by this user
Similar magazines