医学影像分析与实作.ppt

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displayed by assigning a gray or color scale that depends on the number of counts in each element.,3,.,Digital Image,The Image arrays are square matrices that have dimensions range from 32*32 up to 1024*1024,In nuclear medicine:,32*32,64*64,128*128,256*256,512*512,1024*1024,Byte mode&word mode,4,.,Image formation,Frame Mode,List Mode,Dual Isotope Imaging,5,.,Frame mode,X-Y coordinate,Byte mode:,256 gray scale,1 byte=8 bits,Word mode:,65535 gray scale,2 byte=1 word,6,.,List mode,2 byte data series,Event addresses,Time flag,List mode can be formatted any frame size,List mode need more memory,7,.,Sampling,Sampling size:,pixel size(mm)=field of view(mm)/#of pixels,What should the pixel size be?,1.The spatial resolution of imaging system,2.The smallest object of interest in the image,3.The time it takes to perform any processing steps.,4.The amount of storage and archival space available,.,8,.,Information Density,What information can we expect to perceive at a given count density?,this depends on the size of the smallest region in the image you are trying to perceive and its apparent contrast to the surrounding background.,How to define the image information density?,n k,2,/C,2,d,2,n:estimate the count density,k:the signal to noise ratio(35),C:image constrast,d:image diameter,Image constrast=(object count density-background count density)/background count density,9,.,Image Acquisition,Static studies,Whole-Body Imaging,Dynamic studies,Gated Acquisition,SPECT Acquisition,10,.,Data Acquisition Method,Frame Mode,List Mode,11,.,Frame mode Acquisition,Picture elements,64*64,128*128,256*256,Pixel:Picture element,Square mosaic:,Image matrix,Image array,pixel array,12,.,Resolution,Spatial Resolution,Temporal Resolution,Energy Resolution,13,.,Spatial Resolution,Each pixel in the image matrix has one-to-one correspondence with a given location in the plane of NaI crystal,Ex:Gamma camera FOV=40cm diameter,For 64*64 S.R=400/64=6.25mm/pixel,For 128*128 S.R=400/128=3.13mm/pixel,14,.,Statistical Noise,15,.,Increase Spatial resolution,Zooming,Hardware,Software,Zoom can,(1)decrease Background count,(2)increase resolution,The spatial resolution of computer image is ultimately limit by resolution of gamma camera,16,.,Byte mode V.S.Word mode,1 Byte=2,8,bits=256 (0-255),1 Word=2,16,bits=65536 (0-65535),1 Word=2 Bytes,17,.,Byte mode V.S.Word mode,Byte mode Acquisition:a pixel deep is 1 byte,Word mode Acquisition:a pixel deep is 2 byte,What Kind of the acquisition mode we should used?,In low count studies =Byte mode,In High count studies=Word mode,18,.,Byte mode V.S.Word mode,Byte mode,優點,:less memory,缺點,:1.dead time,2.truncation error,Word mode,優點,:1.No dead time,2.No truncation,缺點,:more memory,Overflow:,Dead time:,Truncation:,19,.,臨床診斷上使用的應用軟體,影像增強,(Image enhancement),量化分析,(Qualitative Image analysis,ECT,影像重建,(ECT image reconstruction),20,.,Image Enhancement,Image smoothing filters,P7,21,.,Image Enhancement,Nine-point smooth(mask),w1w2w3,w4w5w6,w7w8w9,1 1 1,1 1 1,1 1 1,22,.,Image Enhancement,23,.,Image Enhancement,24,.,Image Enhancement,Medium smooth,Half way mask=replace average(weight),50%count value (mask),50%count value (Keep),25,.,26,.,27,.,Image Enhancement,Edge-enhancement filter,(sharpen mask),Mask:(2N+1)*(2N+1),28,.,29,.,Image Enhancement,Point processing operations,Background subtraction,Gray scales,Color translation table,Frame processing operation,ex:Parathyroid scan study,30,.,Parathyroid subtractuin,31,.,Image Enhancement,-1 -1 -1,-1 8 -1,-1 -1 -1,32,.,影像量化分析,ROI(region of interesting)create,Histogram create,Analysis ROI and Histogram,Clinical mathematic,33,.,Point processing operation,Background subtraction(pixel-by-pixel),34,.,Point processing operation,Interpolated background subtraction(weight),Wa=Xb/Xa,Wb=Xa/Xb,Wc=Yd/Yc,Wd=Yc/Yd,Xa:Q,距,A,點距離,Xb:Q,距,B,點距離,Yc:Q,距,C,點距離,Yd:Q,距,D,點距離,35,.,Gray scales and color table,Gray scale(dynamic range),the number of shades of gray between these two extremes,Type:,Linear,exponential,logarithmic,36,.,Gray and color table,37,.,Gray scales and color display,38,.,Gray scales and color display,39,.,Lung perfusion/ventilation ratio,40,.,Tl201 myocardial perfusion study,41,.,Creating ROIs,Automatic edge detection methods:,42,.,Create ROI,Method:,Circular ROI,Rectangular ROI,Irregular ROI,Automatic ROI,43,.,Curve Generation and Analysis,The starting point for analyzing the flow pattern quantitatively is the construction of an activity-versus-time curve.,Method,Eye-balling,The move average method,The weighted moving-average method,44,.,The Moving Average method,45,.,The Moving Average method,46,.,Data smoothing by curve Fitting,47,.,Clinical Mathematic in Nuclear Medicine,Nuclear Cardiology,Multiple-gate equilibrium,First pass blood-pool,Static myocardial perfusion study,Renal function,GFR,Kidney radio,ERPF,Diuretic renography(Lasix),Captopril renography,Other,48,.,Example for Ventricular Ejection Fraction,49,.,Multiple gate mode,50,.,Ejection Fraction,51,.,Ejection Fraction,52,.,Ejection Fraction,53,.,Ejection Fraction,54,.,Ejection fraction,55,.,Gastric empty time study,56,.,Example for renal function,57,.,Analysis tools,For renal image ratio:,1.Arithmetic method,2.Geometric method,For functional image:,1.ROI(region of interesting),2.Histogram(Time activity curve,TAC),3.Curve fitting,58,.,Arithmetic v.s.Geometric,ROI information(RINFO),Renal image ratio,59,.,Image ratio,Arithmetic method:,anterior view:right kidney count(Ra),left kidney count(La),posterior view:right kidney count(Rp),left kidney count(Lp),mean:(Ra+Rp)/2=Rm,(La+Lp)/2=Lm,Ratio:Kr=Rm/(Rm+Lm),Kl=Lm/(Rm+Lm),60,.,Image ratio,Geometric method:,anterior view:right kidney count(Ra),left kidney count(La),posterior view:right kidney count(Rp),left kidney count(Lp),mean:,Ratio:Kr=Rm/(Rm+Lm),Kl=Lm/(Rm+Lm),61,.,Gates method,62,.,Start,Create ROI,Create Background ROI,Frame grouping,Create TAC(time activity curve),Choice integral area,Final report,End,Procedure Flow Chart,63,.,GFR renal function study,64,.,Conclusion,核子醫學造影檢查,造影過程,電腦資料分析,未來發展趨勢,Trace Kinetics model,Mathematic Tools,New Procedure,More powerful Image process tool,65,.,THE END,66,.,practice,請依下列數據繪出活性時間曲線,並做,curve smooth.(,三點平均,),Time(sec)count Time(sec)count,20 250 160 1500,40 375 180 1350,60 500 200 930,80 700 220 740,100 850 240 600,120 1160 260 340,140 1580 280 120,計算,120180sec,內的累積計數為若干,?,67,.,