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Title: A method for robust segmentation of arbitrarily shaped radiopaque structures in cone-beam CT projections

Abstract

Purpose: Implanted markers are commonly used in radiotherapy for x-ray based target localization. The projected marker position in a series of cone-beam CT (CBCT) projections can be used to estimate the three dimensional (3D) target trajectory during the CBCT acquisition. This has important applications in tumor motion management such as motion inclusive, gating, and tumor tracking strategies. However, for irregularly shaped markers, reliable segmentation is challenged by large variations in the marker shape with projection angle. The purpose of this study was to develop a semiautomated method for robust and reliable segmentation of arbitrarily shaped radiopaque markers in CBCT projections. Methods: The segmentation method involved the following three steps: (1) Threshold based segmentation of the marker in three to six selected projections with large angular separation, good marker contrast, and uniform background; (2) construction of a 3D marker model by coalignment and backprojection of the threshold-based segmentations; and (3) construction of marker templates at all imaging angles by projection of the 3D model and use of these templates for template-based segmentation. The versatility of the segmentation method was demonstrated by segmentation of the following structures in the projections from two clinical CBCT scans: (1) Three linear fiducial markers (Visicoil) implantedmore » in or near a lung tumor and (2) an artificial cardiac valve in a lung cancer patient. Results: Automatic marker segmentation was obtained in more than 99.9% of the cases. The segmentation failed in a few cases where the marker was either close to a structure of similar appearance or hidden behind a dense structure (data cable). Conclusions: A robust template-based method for segmentation of arbitrarily shaped radiopaque markers in CBCT projections was developed.« less

Authors:
; ; ; ; ; ;  [1]
  1. Department of Oncology, Aarhus University Hospital, Nr Brogade 44, 8000 Aarhus C (Denmark)
Publication Date:
OSTI Identifier:
22096978
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 38; Journal Issue: 4; Other Information: (c) 2011 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; 60 APPLIED LIFE SCIENCES; COMPUTERIZED TOMOGRAPHY; IMAGE PROCESSING; IMAGES; LUNGS; NEOPLASMS; PATIENTS; RADIOTHERAPY; VALVES; X RADIATION

Citation Formats

Poulsen, Per Rugaard, Fledelius, Walther, Keall, Paul J., Weiss, Elisabeth, Jun, Lu, Brackbill, Emily, Hugo, Geoffrey D., Department of Radiation Oncology, Stanford University, Stanford, California 94305, and Virginia Commonwealth University, Richmond, Virginia 23284. A method for robust segmentation of arbitrarily shaped radiopaque structures in cone-beam CT projections. United States: N. p., 2011. Web. doi:10.1118/1.3555295.
Poulsen, Per Rugaard, Fledelius, Walther, Keall, Paul J., Weiss, Elisabeth, Jun, Lu, Brackbill, Emily, Hugo, Geoffrey D., Department of Radiation Oncology, Stanford University, Stanford, California 94305, & Virginia Commonwealth University, Richmond, Virginia 23284. A method for robust segmentation of arbitrarily shaped radiopaque structures in cone-beam CT projections. United States. doi:10.1118/1.3555295.
Poulsen, Per Rugaard, Fledelius, Walther, Keall, Paul J., Weiss, Elisabeth, Jun, Lu, Brackbill, Emily, Hugo, Geoffrey D., Department of Radiation Oncology, Stanford University, Stanford, California 94305, and Virginia Commonwealth University, Richmond, Virginia 23284. Fri . "A method for robust segmentation of arbitrarily shaped radiopaque structures in cone-beam CT projections". United States. doi:10.1118/1.3555295.
@article{osti_22096978,
title = {A method for robust segmentation of arbitrarily shaped radiopaque structures in cone-beam CT projections},
author = {Poulsen, Per Rugaard and Fledelius, Walther and Keall, Paul J. and Weiss, Elisabeth and Jun, Lu and Brackbill, Emily and Hugo, Geoffrey D. and Department of Radiation Oncology, Stanford University, Stanford, California 94305 and Virginia Commonwealth University, Richmond, Virginia 23284},
abstractNote = {Purpose: Implanted markers are commonly used in radiotherapy for x-ray based target localization. The projected marker position in a series of cone-beam CT (CBCT) projections can be used to estimate the three dimensional (3D) target trajectory during the CBCT acquisition. This has important applications in tumor motion management such as motion inclusive, gating, and tumor tracking strategies. However, for irregularly shaped markers, reliable segmentation is challenged by large variations in the marker shape with projection angle. The purpose of this study was to develop a semiautomated method for robust and reliable segmentation of arbitrarily shaped radiopaque markers in CBCT projections. Methods: The segmentation method involved the following three steps: (1) Threshold based segmentation of the marker in three to six selected projections with large angular separation, good marker contrast, and uniform background; (2) construction of a 3D marker model by coalignment and backprojection of the threshold-based segmentations; and (3) construction of marker templates at all imaging angles by projection of the 3D model and use of these templates for template-based segmentation. The versatility of the segmentation method was demonstrated by segmentation of the following structures in the projections from two clinical CBCT scans: (1) Three linear fiducial markers (Visicoil) implanted in or near a lung tumor and (2) an artificial cardiac valve in a lung cancer patient. Results: Automatic marker segmentation was obtained in more than 99.9% of the cases. The segmentation failed in a few cases where the marker was either close to a structure of similar appearance or hidden behind a dense structure (data cable). Conclusions: A robust template-based method for segmentation of arbitrarily shaped radiopaque markers in CBCT projections was developed.},
doi = {10.1118/1.3555295},
journal = {Medical Physics},
issn = {0094-2405},
number = 4,
volume = 38,
place = {United States},
year = {2011},
month = {4}
}