# US 8,787,620 B2 · Automated crystal identification achieved via watershed segmentation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,620 B2 - Document ID: US8787620B2 - Status: Granted - Kind: B2 - Application number: 13/955,029 - Filed: 2013-07-31 - Published: 2013-11-28 - Granted: 2014-07-22 - Earliest claimed: 2010-06-15 - Assignees: Koninklijke Philps N.V. - Applicants: Koninklijke Philips N.V. - Inventors: Thomas Laurence; Sharon X. Wang; Jerome J. Griesmer; Thomas Blaffert; Zhiqiang Hu; Steffen Renisch - Web page: https://patentgrep.com/patent/US8787620B2 ## CPC - G01T 1/1647: {Processing of scintigraphic data (not related to a particular imaging system G01T1/2992)} - G01T: MEASUREMENT OF NUCLEAR OR X-RADIATION (radiation analysis of materials, mass spectrometry G01N23/00; tubes for determining the presence, intensity, density or energy of radiation or particles H01J47/00) ## Abstract A nuclear imaging system includes a crystal identification system which receives a flood image which includes a plurality of peaks, each peak responsive to radiation detected by a corresponding scintillator crystal. A crystal identification processor partitions the flood image into a plurality of candidate regions with a watershed segmentator implementing a watershed algorithm. The candidate regions are linked in an adjacency graph, and then classified as background or relevant, where relevant regions contain a peak within the watershed lines. The regions are then assigned to a crystal according to an objective function and an assignability score. A calibration processor maps the peaks to a rectangular grid. ## Claims ### Claim 1 A method for crystal identification in nuclear imaging systems, comprising: generating a flood image which includes a plurality of peaks, each peak responsive to received radiation and corresponding to a scintillator crystal; identifying candidate regions in the flood image with a watershed segmentator implementing a watershed transform; assigning crystal for each candidate region; and, aligning the identified candidate regions of the flood image according to a rectangular grid. ### Claim 2 (depends on 1) The method according to claim 1, wherein the identifying step includes: generating watershed lines according to minima within the flood image to form candidate regions; and generating an adjacency graph with an adjacency graph generator to link the candidate regions within the flood image. ### Claim 3 (depends on 1) The method according to claim 1, wherein the assigning step includes: assigning candidate regions with an intensity below a defined threshold as a background region. ### Claim 4 (depends on 3) The method according to claim 3, wherein the assigning step includes: assigning non-background candidate regions to individual crystals. ### Claim 5 (depends on 3) The method according to claim 3, wherein the assigning step includes: calculating an assignability score for each region; selecting the highest assignability scored region; assigning the selected region to a grid location with crystal coordinates; and assigning adjacent regions according to a selected objective function. ### Claim 6 (depends on 5) The method according to claim 5, wherein the assigning step includes: for regions with low assignability score, selecting a combination of crystal coordinates according to the objective function. ### Claim 7 (depends on 3) The method according to claim 3, wherein the assigning step includes: renumbering the crystal coordinates. ### Claim 8 (depends on 1) A non-transitory computer readable medium carrying software for controlling one or more processors to perform the method of claim 1. ### Claim 9 A crystal identification system, comprising: an image memory which receives a flood image which includes a plurality of peaks, each peak responsive to radiation detected by a corresponding scintillator crystal; a crystal identification processor configured to: identify candidate regions with an identification processor implementing a watershed transform; assign a crystal for each candidate region; align the candidate regions according to a rectangular grid for the flood image. ### Claim 10 (depends on 9) The crystal identification system according to claim 9, wherein the crystal identification processor is further programmed to identify the candidate regions by: generating watershed lines with a watershed segmentator according to minima within the flood image; and generating an adjacency graph with an adjacency graph generator to link the candidate regions within the flood image. ### Claim 11 (depends on 9) The crystal identification system according to claim 9, wherein the crystal identification processor is further programmed to assign the candidate regions by: assigning candidate regions having an intensity below a defined threshold as a background region. ### Claim 12 (depends on 11) The crystal identification system according to claim 11, wherein the crystal identification processor is further programmed to assign the candidate regions by: assigning non-background candidate regions to individual crystals. ### Claim 13 (depends on 12) The crystal identification system according to claim 12, wherein the crystal identification processor is further programmed to assign the candidate regions by: calculating an assignability score for each region; selecting the highest assignability scored region; assigning the selected region to a grid location with crystal coordinates; and assigning adjacent regions according to a selected objective function. ### Claim 14 (depends on 13) The crystal identification system according to claim 13, wherein the crystal identification processor is further programmed to assign the candidate regions by: renumbering the crystal coordinates. ### Claim 15 (depends on 12) The crystal identification system according to claim 12, wherein the crystal identification processor is further programmed to assign the candidate regions by: for regions with a low assignability score, selecting an optimal combination according to the objective function. ### Claim 16 An apparatus for crystal identification in nuclear imaging systems with a crystal identification processor configured to: generate a flood image; generating watershed lines along local intensity minima within the flood image to create candidate regions; partition the flood image into a plurality of candidate regions; identify maxima within each candidate region; assign the candidate regions to corresponding crystals; and assign the identified maxima to a crystal having crystal coordinates. ### Claim 17 (depends on 16) The apparatus according to claim 16, the crystal identification processor further configured to: segment the flood image into candidate regions using a watershed algorithm; generate an adjacency graph to link candidate regions); locate a peak within each candidate region; label each peak with x/y coordinates according to an assignability score and a defined optimality objective function; map the adjacency graph to a rectangular template with a calibration processor; and display the mapped adjacency graph to a user via a graphical user interface.