医学影像重建原理PPT课件.ppt

《医学影像重建原理PPT课件.ppt》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、醫學影像重建原理.1.DYNAVISION3.Imagecalibration+2Dslicecalculation4.3Dimagegeneration+3DimagedisplayWorkflow2.Imagetransfer5.InroomdatadisplayPixelSmallestpictureelementintheimagereconstructedfromdigitaldata,displayedonamatrix.VoxelSmallestvolumeunit,pictureelement.

2、Cube-shapedvolumeelementwhichisassociatedwithadigitizedpointinavolume.BitDepthNumberofdifferentcolors(orgrayshades)availableinadatasetfordisplayingeachvoxelvalue(HU).Abitcanhaveeitherthevalue1or0.Thusanimagewith“bitdepth”1hasalimitedpalettewithonlytwocolors,bl

3、ackandwhite.Thebitdepth2resultsin4colors(grayshades)etc.ThecurrentlyusedCTmachinesuse12bitsdepth,whichresultsin4096grayshades.BitDepthOpacityAtransparencyvaluecanbeallocatedtoeachvoxelinadataset.Valuesrangefrom0.0to1.0anddeterminewhetheravoxelshouldbedisplayed

4、astransparent(lowopacity)orasopaque(highopacity).0.11.0HistogramGraphicalrepresentationinwhichtheXaxiscorrespondstothevoxelvalue(CT=Grayscalevalue).TheYaxisrepresentsthenumberofvoxelswithacertainvoxelvalue.100HU-100001000RayTracingEachpixelofthescreenimageisge

5、neratedbya(simulated)lightraywhichissentfrominfinitythroughthevolumetobedisplayed.Theresultingcolordependsonthealgorithminusewhilevisitingthepenetratedvoxel(e.g.meangrayvalue,weightingbyopacity,maximumgrayvalue(MIP)).RenderingAllvoxelsinadatasetservefordisplay

6、inga3Dimage.Renderingreferstoaprocess,e.g.rotation,projectionetc.,whichisrequiredsothattheimagecanbedisplayedas3Dimageonthescreen.OptimizingFineadjustmentofcolorsandtransparencyvaluestobeabletodifferentiatetissuewithsimilarvoxelvalues.Postprocessing-CTMulti-Pl

7、anarReconstructionMPRShadedSurfaceDisplaySSDMaximumIntensityProjectionMIPMinimumIntensityProjectionVolumeRenderingTechniqueVRTEachvoxelisselectedaccordingtotheselectedthresholdvalue.Thevisible(i.enothidden)surfaceofallselectedvoxelsisdisplayed;allothervoxelsar

8、etreatedastransparent.Thecomputerprojectsalightsourcesothattheimagesreceiveathree-dimensionalappearance.Only10%ofthedatasetareused!ShadedSurfaceDisplaySSDThevisible(i.enothidden)su