Investigation into the feasibility of using PRESAGE™/optical-CT dosimetry for the verification of gating treatments
- 26 March 2010
- journal article
- Published by IOP Publishing in Physics in Medicine & Biology
- Vol. 55 (8), 2187-2201
- https://doi.org/10.1088/0031-9155/55/8/005
Abstract
This work presents an investigation into the use of PRESAGE dosimeters with an optical-CT scanner as a 3D dosimetry system for quantitative verification of respiratory-gated treatments. The CIRS dynamic thorax phantom was modified to incorporate a moving PRESAGE dosimeter-simulating respiration motion in the lungs. A simple AP/PA lung treatment plan was delivered three times to the phantom containing a different but geometrically identical PRESAGE insert each time. Each delivery represented a treatment scenario: static, motion (free-breathing) and gated. The dose distributions, in the three dosimeters, were digitized by the optical-CT scanner. Improved optical-CT readout yielded an increased signal-to-noise ratio by a factor of 3 and decreased reconstruction artifacts compared with prior work. Independent measurements of dose distributions were obtained in the central plane using EBT film. Dose distributions were normalized to a point corresponding to the 100% isodose region prior to the measurement of dose profiles and gamma maps. These measurements were used to quantify the agreement between measured and ECLIPSE(R) dose distributions. Average gamma pass rates between PRESAGE and EBT were >99% (criteria 3% dose difference and 1.2 mm distance-to-agreement) for all three treatments. Gamma pass rates between PRESAGE and ECLIPSE(R) 3D dose distributions showed excellent agreement for the gated treatment (100% pass rate), but poor for the motion scenario (85% pass rate). This work demonstrates the feasibility of using PRESAGE/optical-CT 3D dosimetry to verify gating-enabled radiation treatments. The capability of the Varian gating system to compensate for motion in this treatment scenario was demonstrated.Keywords
This publication has 41 references indexed in Scilit:
- Phantom for moving organ dosimetry with gelJournal of Physics: Conference Series, 2009
- Historical overview of the development of gel dosimetry: Another personal perspectiveJournal of Physics: Conference Series, 2009
- Verification of dynamic radiotherapy: the potential for 3D dosimetry under respiratory-like motion using polymer gelPhysics in Medicine & Biology, 2008
- Effects of phantom volume and shape on the accuracy of MRI BANG gel dosimetry using BANG3TMThe British Journal of Radiology, 2008
- Characterization of a parallel-beam CCD optical-CT apparatus for 3D radiation dosimetryPhysics in Medicine & Biology, 2007
- A review on the clinical implementation of respiratory-gated radiation therapyBiomedical Imaging and Intervention Journal, 2007
- IMRT verification using a radiochromic/optical-CT dosimetry systemJournal of Physics: Conference Series, 2006
- Dosimetric verification of breathing adapted radiotherapy using polymer gelJournal of Physics: Conference Series, 2006
- Focusing optics of a parallel beam CCD optical tomography apparatus for 3D radiation gel dosimetryPhysics in Medicine & Biology, 2006
- Compensation for respiratory motion by gated radiotherapy: an experimental studyPhysics in Medicine & Biology, 2005