title: An experimental investigation into the effect of periodic motion on proton dosimetry using polymer gel dosimeters and a programmable motion platform.
abstract: Organ motion in proton therapy affects treatment dose distribution during both double-scattering (DS) and uniform-scanning (US) deliveries. We investigated the dosimetric impact of target motion using three-dimensional polymer gel dosimeters and a programmable motion platform. A simple one-beam treatment plan with 16 cm range and 6 cm modulation was generated from the treatment planning system (TPS) in both the DS and US modes. One gel dosimeter was irradiated with a stationary DS beam. Two other gel dosimeters were irradiated with the DS and US beams while they moved in the same sinusoidal motion profile using a programmable motion platform. The dose distribution of the stationary DS delivery agreed with the TPS plan. Dosimetric comparisons between DS motion delivery and the MATLAB-based motion model showed insignificant differences. Dose-volume histograms of a cylindrical target volume inside the gel dosimeters showed target coverage degradation caused by motion. A three-dimensional gamma index calculation (3% and 3 mm) confirmed different dosimetric impacts from DS and US with the same target motion. This polymer-gel-dosimeter-based study confirmed the dosimetric impact of intrafraction target motion and its interplay with temporal delivery of different energy layers in US proton treatments.
authors.affiliation: University of Florida Proton Therapy Institute, Jacksonville, FL 32206, USA. zsu@floridaproton.org
authors.forename: Zhong
authors.initials: Z
authors.lastname: Su
authors.forename: Olena
authors.initials: O
authors.lastname: Lopatiuk-Tirpak
authors.forename: Omar
authors.initials: O
authors.lastname: Zeidan
authors.forename: S I
authors.initials: SI
authors.lastname: Sruprisan
authors.forename: Sanford L
authors.initials: SL
authors.lastname: Meeks
authors.forename: Roelf
authors.initials: R
authors.lastname: Slopsema
authors.forename: Stella
authors.initials: S
authors.lastname: Flampouri
authors.forename: Zuofeng
authors.initials: Z
authors.lastname: Li
mesh_terms: D000465:Algorithms; D002138:Calibration; D004867:Equipment Design; D005782:Gels; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008175:Lung Neoplasms / Q000473:pathology; D009038:Motion; D011108:Polymers / Q000737:chemistry*; D061766:Proton Therapy; D011874:Radiometry / Q000379:methods*; D011878:Radiotherapy / Q000379:methods; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D005782:Gels; D011108:Polymers