skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Accuracy and Consistency of Respiratory Gating in Abdominal Cancer Patients

Abstract

Purpose: To evaluate respiratory gating accuracy and intrafractional consistency for abdominal cancer patients treated with respiratory gated treatment on a regular linear accelerator system. Methods and Materials: Twelve abdominal patients implanted with fiducials were treated with amplitude-based respiratory-gated radiation therapy. On the basis of daily orthogonal fluoroscopy, the operator readjusted the couch position and gating window such that the fiducial was within a setup margin (fiducial-planning target volume [f-PTV]) when RPM indicated “beam-ON.” Fifty-five pre- and post-treatment fluoroscopic movie pairs with synchronized respiratory gating signal were recorded. Fiducial motion traces were extracted from the fluoroscopic movies using a template matching algorithm and correlated with f-PTV by registering the digitally reconstructed radiographs with the fluoroscopic movies. Treatment was determined to be “accurate” if 50% of the fiducial area stayed within f-PTV while beam-ON. For movie pairs that lost gating accuracy, a MATLAB program was used to assess whether the gating window was optimized, the external-internal correlation (EIC) changed, or the patient moved between movies. A series of safety margins from 0.5 mm to 3 mm was added to f-PTV for reassessing gating accuracy. Results: A decrease in gating accuracy was observed in 44% of movie pairs from daily fluoroscopic movies ofmore » 12 abdominal patients. Three main causes for inaccurate gating were identified as change of global EIC over time (∼43%), suboptimal gating setup (∼37%), and imperfect EIC within movie (∼13%). Conclusions: Inconsistent respiratory gating accuracy may occur within 1 treatment session even with a daily adjusted gating window. To improve or maintain gating accuracy during treatment, we suggest using at least a 2.5-mm safety margin to account for gating and setup uncertainties.« less

Authors:
; ;  [1];  [1]
  1. Department of Radiation Oncology, Washington University School of Medicine, St Louis, Missouri (United States)
Publication Date:
OSTI Identifier:
22224392
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 85; Journal Issue: 3; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; ACCURACY; ALGORITHMS; CORRELATIONS; FLUOROSCOPY; IMAGES; LINEAR ACCELERATORS; NEOPLASMS; PATIENTS; RADIOTHERAPY; SAFETY MARGINS

Citation Formats

Ge, Jiajia, Santanam, Lakshmi, Yang, Deshan, and Parikh, Parag J., E-mail: pparikh@radonc.wustl.edu. Accuracy and Consistency of Respiratory Gating in Abdominal Cancer Patients. United States: N. p., 2013. Web. doi:10.1016/J.IJROBP.2012.05.006.
Ge, Jiajia, Santanam, Lakshmi, Yang, Deshan, & Parikh, Parag J., E-mail: pparikh@radonc.wustl.edu. Accuracy and Consistency of Respiratory Gating in Abdominal Cancer Patients. United States. doi:10.1016/J.IJROBP.2012.05.006.
Ge, Jiajia, Santanam, Lakshmi, Yang, Deshan, and Parikh, Parag J., E-mail: pparikh@radonc.wustl.edu. Fri . "Accuracy and Consistency of Respiratory Gating in Abdominal Cancer Patients". United States. doi:10.1016/J.IJROBP.2012.05.006.
@article{osti_22224392,
title = {Accuracy and Consistency of Respiratory Gating in Abdominal Cancer Patients},
author = {Ge, Jiajia and Santanam, Lakshmi and Yang, Deshan and Parikh, Parag J., E-mail: pparikh@radonc.wustl.edu},
abstractNote = {Purpose: To evaluate respiratory gating accuracy and intrafractional consistency for abdominal cancer patients treated with respiratory gated treatment on a regular linear accelerator system. Methods and Materials: Twelve abdominal patients implanted with fiducials were treated with amplitude-based respiratory-gated radiation therapy. On the basis of daily orthogonal fluoroscopy, the operator readjusted the couch position and gating window such that the fiducial was within a setup margin (fiducial-planning target volume [f-PTV]) when RPM indicated “beam-ON.” Fifty-five pre- and post-treatment fluoroscopic movie pairs with synchronized respiratory gating signal were recorded. Fiducial motion traces were extracted from the fluoroscopic movies using a template matching algorithm and correlated with f-PTV by registering the digitally reconstructed radiographs with the fluoroscopic movies. Treatment was determined to be “accurate” if 50% of the fiducial area stayed within f-PTV while beam-ON. For movie pairs that lost gating accuracy, a MATLAB program was used to assess whether the gating window was optimized, the external-internal correlation (EIC) changed, or the patient moved between movies. A series of safety margins from 0.5 mm to 3 mm was added to f-PTV for reassessing gating accuracy. Results: A decrease in gating accuracy was observed in 44% of movie pairs from daily fluoroscopic movies of 12 abdominal patients. Three main causes for inaccurate gating were identified as change of global EIC over time (∼43%), suboptimal gating setup (∼37%), and imperfect EIC within movie (∼13%). Conclusions: Inconsistent respiratory gating accuracy may occur within 1 treatment session even with a daily adjusted gating window. To improve or maintain gating accuracy during treatment, we suggest using at least a 2.5-mm safety margin to account for gating and setup uncertainties.},
doi = {10.1016/J.IJROBP.2012.05.006},
journal = {International Journal of Radiation Oncology, Biology and Physics},
number = 3,
volume = 85,
place = {United States},
year = {Fri Mar 01 00:00:00 EST 2013},
month = {Fri Mar 01 00:00:00 EST 2013}
}