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Various reconstruction   algorithms for Tomosnythesis            WEIHUA ZHOU, LINLIN CONG                    11/07/2011DEP...
Current Technology of Breast Cancer Detection Early detection of breast cancer is viewed as the best  hope to decrease br...
X-ray Attenuation Model                                    I                                          Reconstructed Volume...
Current Tomosynthesis Imaging Geometry  X-Ray tube                                               Compression paddleReconst...
Reconstruction Algorithms of Digital Breast                Tomosynthesis  Reconstruct 3D object volume based on acquired 2...
Reconstruction Algorithm:                                SAA (Shift-And-Add)                                          X-ra...
Reconstruction Algorithm:                                BP (Back-Projection)                                             ...
Reconstruction Algorithm:                FBP (Filtered Back Projection) Take BP as the foundation Apply high-freq and lo...
Reconstruction Algorithm:       MLEM (Maximum Likelihood Expectation Maximization) Originally invented by Lange and Fessl...
Reconstruction Algorithm:             SART (Simultaneous Algebraic Reconstruction Technique)    Originated from ART and w...
Image Reconstruction with Breast Phantom  Breast Biopsy Training Phantom   Low Dosage Middle Projection• Standard breast b...
In-plane slice images of FBP and MLEM
Image Reconstruction with Breast Phantom     (a) BP              (b) FBP            (c) MLEM              (d) SARTReconstr...
Comparisons of Reconstruction Methods MITS and FBP are fast-speed reconstruction methods with deblurring algorithms to re...
AcknowledgementsAppreciate our collaborators at   The University of North Carolina at Chapel Hill (UNC),   North Carolin...
Thank you
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  1. 1. Various reconstruction algorithms for Tomosnythesis WEIHUA ZHOU, LINLIN CONG 11/07/2011DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING SOUTHERN ILLINOIS UNIVERSITY CARBONDALE
  2. 2. Current Technology of Breast Cancer Detection Early detection of breast cancer is viewed as the best hope to decrease breast cancer mortality. Mammography  The most commonly accomplished screening tool for early detection Supplemental tools  Breast Ultrasound  Breast CT  Breast MRI  Biopsy
  3. 3. X-ray Attenuation Model I Reconstructed Volume  x T Ie Voxel j T Projection Image Pixel iI : incident intensity T : transmitted intensity : attenuation coefficientx : the length of the path where x-ray passes through the voxel
  4. 4. Current Tomosynthesis Imaging Geometry X-Ray tube Compression paddleReconstructed Breastplanes Digital detector X-ray tube rotates along an arc path above the breast Series of low dosage images are acquired at different angles
  5. 5. Reconstruction Algorithms of Digital Breast Tomosynthesis Reconstruct 3D object volume based on acquired 2D projection images Categories  Mathematic reconstruction methods (SAA / BP)  Filter-based reconstruction methods (FBP / MITS)  Statistical reconstruction methods (MLEM, MOSC, etc)  Algebraic reconstruction methods (ART, SART, etc)
  6. 6. Reconstruction Algorithm: SAA (Shift-And-Add) X-ray tubes (1) Compression paddle Plane I OZ Pi DetectorNote: O is the center of the reconstructed plane I. The shift amount of any pixel on Plane I will be equal tothe shift amount of O.
  7. 7. Reconstruction Algorithm: BP (Back-Projection) X-ray tubes Compression paddle Plane I A O Z Pi DetectorNote: O is the center of the reconstructed plane I. The shift amount of any pixel A on Plane I varies with itslocation.
  8. 8. Reconstruction Algorithm: FBP (Filtered Back Projection) Take BP as the foundation Apply high-freq and low-freq filters to enhance signals and suppress the noise Filters Ramp Filter Hamming Filter Gaussian Filter
  9. 9. Reconstruction Algorithm: MLEM (Maximum Likelihood Expectation Maximization) Originally invented by Lange and Fessler ML: maximize the likelihood of getting the projection T from the incident X-ray intensity I and attenuation coefficient μ. EM: one of the methods to solve ML problem. Iterative equation*:  i li , j  I i e  l .u ( n )  i  Ti  (n)    (j n 1)   j    j   j  (n) (n) (n) j     i    l ,u (n) i  l i, j  l,  (n)  i I i e   * Wu, T., et al, “Tomographic mammography using a limited number of low-dose cone-beam projection images,” Med. Phys. 30, 365-380 (2003).
  10. 10. Reconstruction Algorithm: SART (Simultaneous Algebraic Reconstruction Technique)  Originated from ART and was invented by Henderson  Iteratively solves the attenuation equations  Iterative equation *:  Di   j l ij  n    i lij  j  j lij       (n) (n) (n)  ( n 1)     i l i , j j j j j* Zhang, Y., et al.,“A comparative study of limited-angle cone-beam reconstruction methods for breast tomosynthesis,” Med. Phys. 33(10), 3781-3795 (2006).
  11. 11. Image Reconstruction with Breast Phantom Breast Biopsy Training Phantom Low Dosage Middle Projection• Standard breast biopsy training phantom with solid masses and two micro-calcification clusters.• 25 projection images at a total exposure of 100 mAs (4mAs/projection) were obtained. View angle 48 degrees.
  12. 12. In-plane slice images of FBP and MLEM
  13. 13. Image Reconstruction with Breast Phantom (a) BP (b) FBP (c) MLEM (d) SARTReconstructed ROIs of a mass (z=45 mm above the detector). (a) BP (b) FBP (c) MLEM (d) SARTReconstructed ROIs of a micro-cluster / micro-calcification (z=45 mm above thedetector).
  14. 14. Comparisons of Reconstruction Methods MITS and FBP are fast-speed reconstruction methods with deblurring algorithms to remove out-of-plane blur MLEM and SART are iterative methods based on ray- tracing computation; they can provide good image quality, but need a long running time
  15. 15. AcknowledgementsAppreciate our collaborators at The University of North Carolina at Chapel Hill (UNC), North Carolina State University (NCSU), Southern Illinois University (SIU).o The related work is supported by U.S. National Institutes of Health (NIH/NCI R01 CA134598-01A1).
  16. 16. Thank you

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