A preliminary study on the effect of modulated photon radiotherapy (XMRT) optimization for prostate cancer treatment planning

Philip McGeachy, Jose Eduardo Villarreal-Barajas, Yuriy Zinchenko, Pooyan Shirvani, Rao Khan

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

This preliminary work compared a new optimization technique, modulated photon radiotherapy (XMRT), with IMRT in a treatment planning study for a cohort of eight prostate cancer patients. XMRT differs from IMRT in that it allows the typically fixed beam energy to vary such that the optimizer finds a dose distribution by simultaneously optimizing photon beamlet fluence and energy. Plans were comprised of a seven-coplanar beam arrangement, with IMRT restricted to 6 MV while XMRT used both 6 and 18 MV beams. Both IMRT and XMRT optimization were based on a linear programming model with partial-volume constraints implemented via the conditional variable at risk (cVaR) approach. XMRT and IMRT provided similar coverage to 95% of the target (PTV) with the prescribed dose (78 Gy), however XMRT improved the target dose homogeneity. XMRT was able to reduce the dose to a large volume (p <0.05) of the rectum, bladder, and femoral heads, particularly in the low-dose region (≤ 40 Gy). Further, XMRT provided an improvement in the high dose-region of the bladder with a lower near maximum dose, D2%, Bladder, and reduced volume receiving at least 80 Gy, V80, Bladder (p <0.05). Overall, a significant (p<0.05) decrease in certain healthy organ dosimetric parameters was observed using XMRT. This preliminary study provides an impetus for further use of XMRT in a larger cohort clinical evaluation.

Original languageEnglish
Title of host publicationWorld Congress on Medical Physics and Biomedical Engineering, 2015
EditorsDavid A. Jaffray
PublisherSpringer Verlag
Pages417-420
Number of pages4
ISBN (Print)9783319193878
DOIs
StatePublished - Jan 1 2015
EventWorld Congress on Medical Physics and Biomedical Engineering, 2015 - Toronto, Canada
Duration: Jun 7 2015Jun 12 2015

Publication series

NameIFMBE Proceedings
Volume51
ISSN (Print)1680-0737

Conference

ConferenceWorld Congress on Medical Physics and Biomedical Engineering, 2015
Country/TerritoryCanada
CityToronto
Period06/7/1506/12/15

Keywords

  • IMRT
  • Mixedenergy
  • Optimization
  • Prostate cancer
  • Treatment planning

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