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Title: MO-FG-BRA-03: A Novel Method for Characterizing Gating Response Time in Radiation Therapy

Abstract

Purpose: Low temporal latency between a gating ON/OFF signal and the LINAC beam ON/OFF during respiratory gating is critical for patient safety. Current film based methods to assess gating response have poor temporal resolution and are highly qualitative. We describe a novel method to precisely measure gating lag times at high temporal resolutions and use it to characterize the temporal response of several gating systems. Methods: A respiratory gating simulator with an oscillating platform was modified to include a linear potentiometer for position measurement. A photon diode was placed at linear accelerator isocenter for beam output measurement. The output signals of the potentiometer and diode were recorded simultaneously at 2500 Hz (0.4 millisecond (ms) sampling interval) with an analogue-to-digital converter (ADC). The techniques was used on three commercial respiratory gating systems. The ON and OFF of the beam signal were located and compared to the expected gating window for both phase and position based gating and the temporal lag times extracted using a polynomial fit method. Results: A Varian RPM system with a monoscopic IR camera was measured to have mean beam ON and OFF lag times of 98.2 ms and 89.6 ms, respectively. A Varian RPM system with amore » stereoscopic IR camera was measured to have mean beam ON and OFF lag times of 86.0 ms and 44.0 ms, respectively. A Calypso magnetic fiducial tracking system was measured to have mean beam ON and OFF lag times of 209.0 ms and 60.0 ms, respectively. Conclusions: A novel method allowed for quantitative determination of gating timing accuracy for several clinically used gating systems. All gating systems met the 100 ms TG-142 criteria for mean beam OFF times. For beam ON response, the Calypso system exceeded the recommended response time.« less

Authors:
; ; ;  [1];  [2];  [1];  [3]
  1. The University of Chicago, Chicago, IL (United States)
  2. University Illinois at Chicago, Orland Park, IL (United States)
  3. (United States)
Publication Date:
OSTI Identifier:
22653866
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; BEAMS; LINEAR ACCELERATORS; RADIOTHERAPY; SIGNALS

Citation Formats

Wiersma, R, McCabe, B, Belcher, A, Jenson, P, Smith, B, Aydogan, B, and University Illinois at Chicago, Orland Park, IL. MO-FG-BRA-03: A Novel Method for Characterizing Gating Response Time in Radiation Therapy. United States: N. p., 2016. Web. doi:10.1118/1.4957296.
Wiersma, R, McCabe, B, Belcher, A, Jenson, P, Smith, B, Aydogan, B, & University Illinois at Chicago, Orland Park, IL. MO-FG-BRA-03: A Novel Method for Characterizing Gating Response Time in Radiation Therapy. United States. doi:10.1118/1.4957296.
Wiersma, R, McCabe, B, Belcher, A, Jenson, P, Smith, B, Aydogan, B, and University Illinois at Chicago, Orland Park, IL. Wed . "MO-FG-BRA-03: A Novel Method for Characterizing Gating Response Time in Radiation Therapy". United States. doi:10.1118/1.4957296.
@article{osti_22653866,
title = {MO-FG-BRA-03: A Novel Method for Characterizing Gating Response Time in Radiation Therapy},
author = {Wiersma, R and McCabe, B and Belcher, A and Jenson, P and Smith, B and Aydogan, B and University Illinois at Chicago, Orland Park, IL},
abstractNote = {Purpose: Low temporal latency between a gating ON/OFF signal and the LINAC beam ON/OFF during respiratory gating is critical for patient safety. Current film based methods to assess gating response have poor temporal resolution and are highly qualitative. We describe a novel method to precisely measure gating lag times at high temporal resolutions and use it to characterize the temporal response of several gating systems. Methods: A respiratory gating simulator with an oscillating platform was modified to include a linear potentiometer for position measurement. A photon diode was placed at linear accelerator isocenter for beam output measurement. The output signals of the potentiometer and diode were recorded simultaneously at 2500 Hz (0.4 millisecond (ms) sampling interval) with an analogue-to-digital converter (ADC). The techniques was used on three commercial respiratory gating systems. The ON and OFF of the beam signal were located and compared to the expected gating window for both phase and position based gating and the temporal lag times extracted using a polynomial fit method. Results: A Varian RPM system with a monoscopic IR camera was measured to have mean beam ON and OFF lag times of 98.2 ms and 89.6 ms, respectively. A Varian RPM system with a stereoscopic IR camera was measured to have mean beam ON and OFF lag times of 86.0 ms and 44.0 ms, respectively. A Calypso magnetic fiducial tracking system was measured to have mean beam ON and OFF lag times of 209.0 ms and 60.0 ms, respectively. Conclusions: A novel method allowed for quantitative determination of gating timing accuracy for several clinically used gating systems. All gating systems met the 100 ms TG-142 criteria for mean beam OFF times. For beam ON response, the Calypso system exceeded the recommended response time.},
doi = {10.1118/1.4957296},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}