EDGE-BASED PEAK POSITION SEARCH ALGORITHM FOR PET DETECTORS

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EDGE-BASED PEAK POSITION SEARCH ALGORITHM FOR PET
DETECTORS

• Presenter Kun Di
• Advisor Dr. Chung-E Wang
• Dr. Ted Krovetz

Department of Computer ScienceCalifornia State
University, Sacramento November 22, 2010
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Agenda

• Motivation
• Background
• Methodology
• Edge Detection
• Gradient Information Analysis
• Peaks Detection
• Results
• Summary and Future Work

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Motivation

• The positron emission tomography (PET) scanner
• Gamma Rays
• Array of Scintillation Crystals
• Photomultiplier Tubes (PMTs), Avalanche Photo
  Diodes (APDs)
• Coincidence processing
• Calibration
• Position Profile (Peak Positions)
• Automatic peak detection is desirable because
  manually selecting each peak is time-consuming,
  especially for large crystal arrays (e.g. 20x20).

Pictures (except the right-bottom one) are from
http//en.wikipedia.org/wiki/Positron_emission_tom
ography
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Background

• Previous Effort
• Neural network based algorithm2
• Non-rigid registration to a Fourier-based
  template 3
• PCA-based algorithm 4
• Morphological-based algorithm 56
• Main obstacles
• Distortion
• Peak fusion.

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Edge Detection

• Canny Edge - Continuous Edge
• Gaussian Smooth
• Gradient (magnitude)
• Non-Maximum Suppression
• High and Low Threshold
• Trace Edge

• Gradient

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Gradient Information Analysis

• Gradient Information
• Magnitude
• Direction
• Special Points
• Top, Bottom, Left, right
• Break Points
• Horizontal, Vertical

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Peaks Detection

• Algorithm
• Raw image input
• Generate Gaussian smoothed image
• Edge detection according to gradient magnitude
• Get interested region according to the edges and
  gradient directions of each point on each edge
• Identify peaks according to the number of
  crystals and hit-sum of each interested region
• Manually correct the peaks if necessary
• Save the peaks

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Tools Implementation

• Automatic peaks detection
• Adjustment of settings to achieve better result
• Manual correction
• Sorting peaks
• Saving peak positions to text file for writing
  back to PET system

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Results
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Summary and Future Work

• The tool works pretty good. Distortion problem
  has been solved.
• The result depends upon the quality of edge
  detection.
• Low quality of edge detection may cause peak
  missing in case of highly fused peaks.
• In order to improve the performance, the whole
  image pattern should be considered. Therefore, a
  supplemental algorithm is going to be designed

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Reference

• 1 http//en.wikipedia.org/wiki/Positron_emission
  _tomography
• 2 D. Hu, B. Atkins, M. Lenox, B. Castleberry,
  and S. Siegel, A neural network based algorithm
  for building crystal look-up table of PET block
  detector, in Proc. IEEE Nuclear Science Symp.
  Conf. Rec., Nov. 2006, vol. 4, pp. 24582461.
• 3 A. Chaudhari, A. Joshi, S. Bowen, R. Leahy,
  S. Cherry, and R. Badawi, Crystal identification
  in positron emission tomography using nonrigid
  registration to a Fourier-based template, Phys.
  Med. Biol., vol. 53, no. 18, pp. 50115027, Sep.
  2008.
• 4 J. Breuer and K. Wienhard, "PCA-Based
  Algorithm for Generation of Crystal Lookup Tables
  for PET Block Detecto," IEEE TRANSACTIONS ON
  NUCLEAR SCIENCE, VOL. 56, NO. 3, JUNE 2009, pp.
  602-607.
• 5 Albert Mao, Student Volunteer, Imaging
  Physics Laboratory, Nuclear Medicine Department,
  Clinical Center, National Institutes of Health,
  "Positron Emission Tomograph Detector Module
  Calibration Through Morphological Algorithms and
  Interactive Correction,"
• 6 Z. Hu, C. Kao, W. Liu, Y. Dong, Z. Zhang, Q.
  Xie, C. Chen, "Semi-Automatic Position
  Calibration for a Dual-Head Small Animal PET
  Scanner," 2007 IEEE Nuclear Science Symposium
  Conference Record, pp. 1618-1621.
• 7 P. Després, W. C. Barber, T. Funk, M.
  McClish, K. S. Shah, and B. H. Hasegawa,
  "Modeling and Correction of Spatial Distortion in
  Position-Sensitive Avalanche Photodiodes," IEEE
  TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 54, NO. 1,
  FEBRUARY 2007, pp. 23-29.
• 8 J. Zhang, P. Olcott, and C. Levin, A new
  positioning algorithm for position-sensitive
  avalanche photodiodes, IEEE Trans. Nucl. Sci.,
  vol. 54, no. 3, pp. 433437, Jun. 2007.
• 9 J. Canny, "A computational approach to edge
  detection", IEEE Trans. Pattern Analysis and
  Machine Intelligence, vol 8, pages 679-714, 1986.