核医学影像中的数据处理PPT.ppt

extension 2: circular orbit + arbitrary small deviations old new translations rotations 1mm -3mm 1.5mm -1.5mm 1.5mm -1mm 1o -2o 1.5o -1.5o 3.5o -2.5o 1mm 1.2 1.4 1.6 1.8 2mm Outline Data organization Correction methods Rebinning Image reconstruction Image registration and fusion DICOM and PACS Rebinning Convert 3D data to 2D SSRB and MSRB SSRB- Single-slice rebinning Detection: center slice Simple Fast Resolution loss MSRB- Multi-slice rebinning Distribute along all intermediate slices De-blurring along z-axis Fourier rebinning Outline Data organization Correction methods Rebinning Image reconstruction Image registration and fusion DICOM and PACS Image reconstruction Analytical FBP BPF FDK 3D RP … Iterative ART MLEM OSEM OSLS MAP … Analytical algorithms For example, FBP (Filtered Back-projection) Treat the unknown image as continuous Point-by-point reconstruction Regular grid points are commonly chosen Treat projection process as line integral theoretically 解析重建-FBP FBP back projection (BP) = summation of projections filtered back projection (FBP) FDK Feldkamp、Davis、Kress FDK 3D RP—Re-projection Steps of 3D RP Extract 2D sinograms Reconstruct each with 2D FBP and stack to form 3D image Forward project to calculate missing LORs Extract 2D projection data of all oblique slices Take 2D Fourier transform Back project data through 3D image matrix Repeat for all angles and oblique slices What is iterative reconstruction Discrete measurements, discrete image Optimization Attractions of iterative methods Either consistent or inconsistent is OK Complex geometry Physical effects and detection processes can be modeled Non-negativity Great reducing streaking artifacts Better contrast recovery …… Dual energy window methods Multiple energy window methods Scatter Correction Analytical simulation Scatter Correction A B Single Scatter - Model based correction Calculate the contribution for an arbitrary scatter point using the Klein-Nishina equation Before Scatter correcti