Respiratory gating of sliding window IMRT Conference Paper


Authors: Yorke, E.; Mageras, G.; LoSasso, T.; Mostafavi, H.; Ling, C.
Editor: Enderle, J. D.
Title: Respiratory gating of sliding window IMRT
Conference Title: 22nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Abstract: Breathing motion may limit sites of applicability for intensity modulated radiation therapy (IMRT). Respiratory gating reduces motion by activating the beam during a chosen phase of respiration. We investigated the effect of gating on the dose distribution of sliding window dynamic multileaf collimator (DMLC) fields. A Varian 2100C beam was gated by the Varian Real-time Position Management System that tracks moving infrared reflective markers with a wall-mounted camera. A rotating eccentric wheel simulated marker breathing motion. Dose distributions from normal (ungated) and gated DMLC were compared using film dosimetry and also by calculating dose distributions from the leaf motion log files. Fields included prostate (15 MV) and H&N (6 MV) treatment fields and special test fields. Kodak V films under polystyrene phantom were exposed separately for gated and ungated operation. Additional ungated fields were filmed as controls. Log files for gated and ungated deliveries were copied to a program written in-house which uses the clinical treatment planning system to calculate the dose distribution delivered by the recorded leaf motion. The films were digitized, optical densities converted to dose, and matched pairs of films were registered. The largest differences (≈5% or ∼1 mm) occurred in high dose gradient regions and were consistent with uncertainties in aligning pairs of films. Gated vs. ungated dose distributions calculated from the log files agreed to better than 0.5%. These preliminary results show no deleterious effects of gating on DMLC dose distributions.
Keywords: intensity modulated radiation therapy; radiotherapy; dosimetry; respiration; respiratory mechanics; infrared radiation; dose distribution; respiratory system; optical collimators; respiratory gating; cameras; polystyrenes; computer control; density (optical); dynamic multileaf collimator fields; varian real time position management system
Journal Title IEEE Engineering in Medicine and Biology Society. Annual International Conference. Proceedings
Volume: 3
Conference Dates: 2000 Jul 23-28
Conference Location: Chicago, IL
ISBN: 1094-687X
Publisher: IEEE  
Location: Chicago, IL
Date Published: 2000-01-01
Start Page: 2118
End Page: 2121
Language: English
PROVIDER: scopus
DOI: 10.1109/IEMBS.2000.900547
DOI/URL:
Notes: Annu Int Conf IEEE Eng Med Biol Proc -- Conference code: 58180 -- Cited By :2 -- Export Date: 18 November 2015 -- CODEN: CEMBA -- 23 July 2000 through 28 July 2000 -- Source: Scopus
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MSK Authors
  1. Gikas S Mageras
    252 Mageras
  2. Ellen D Yorke
    314 Yorke
  3. C Clifton Ling
    313 Ling
  4. Thomas J LoSasso
    86 LoSasso