Dosimetric impact of intrafraction prostate rotation and accuracy of gating, multi-leaf collimator tracking and couch tracking to manage rotation: An end-to-end validation using volumetric film measurements

AbstractBackground and purpose Both gating tracking can mitigate the deteriorating dosimetric impact of intrafraction translation during prostate stereotactic body radiotherapy (SBRT). However, their ability to manage rotation has not yet been thoroughly investigated. The accuracy gating, MLC couch was Materials methods Treatment plans for end-to-end tests SBRT with focal boosting were generated a dynamic anthropomorphic pelvis phantom. phantom applied internal lateral (up 25°) coupled vertical longitudinal radiochromic film stack that used dose measurements. Dose delivered each plan while motion according three typical traces without compensation (i), (ii), (iii) or (iv). Measured doses four strategies compared planned in terms γ-index analysis, target coverage organs at risk (OAR) sparing. Results Intrafraction reduced 3%(global)/2mm passing rate (γPR) volume by median (range) –33.2% (−68.6%, −4.1%) when no applied. use improved γPR 13.2% (−0.4%, 32.9%) 6.0% (−0.8%, 27.7%) 11.1% (1.2%, 22.9%) tracking. techniques most cases. Gating showed better OAR sparing than Conclusions Compensation investigated experimentally first time. All accuracy, but residual motion-related errors remained due lack correction.