title: Three-dimensional dosimetry of TomoTherapy by MRI-based polymer gel technique.
abstract: Verification of the dose calculation model and the software used for treatment planning is an important step for accurate radiation delivery in radiation therapy. Using BANG3 polymer gel dosimeter with a 3 Tesla magnetic resonance imaging (MRI) scanner, we examined the accuracy of TomoTherapy treatment planning and radiation delivery. We evaluated one prostate treatment case and found the calculated three-dimensional (3D) dose distributions agree with the measured 3D dose distributions with an exception in the regions where the dose was much smaller (25% or less) than the maximum dose (2.5 Gy). The analysis using the gamma-index (3% dose difference and 3 mm distance-to-agreement) for a volume of 12 cm × 11 cm × 9 cm containing the planning target volume showed that the gamma values were smaller than unity for 53% of the voxels. Our measurement protocol and analysis tools can be easily applied to the evaluation of other newer complex radiation delivery techniques, such as intensity-modulated arc therapy, with a reasonably low financial investment.
authors.affiliation: Department of Therapeutic Radiology, University of Minnesota, Minneapolis, MN, USA. watan016@umn.edu
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Watanabe
authors.forename: N
authors.initials: N
authors.lastname: Gopishankar
mesh_terms: D000465:Algorithms; D005782:Gels / Q000737:chemistry; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D011108:Polymers / Q000737:chemistry*; D011874:Radiometry / Q000379:methods*; D011878:Radiotherapy / Q000379:methods*; D011879:Radiotherapy Dosage
chemical_list: D005782:Gels; D011108:Polymers