title: Adaptive prostate IGRT combining online re-optimization and re-positioning: a feasibility study.
abstract: In prostate radiation therapy, inter-fractional organ motion/deformation has posed significant challenges on reliable daily dose delivery. To correct for this issue, off-line re-optimization and online re-positioning have been used clinically. In this paper, we propose an adaptive images guided radiation therapy (AIGRT) scheme that combines these two correction methods in an anatomy-driven fashion. The AIGRT process first tries to find a best plan for the daily target from a plan pool, which consists of the original CT plan and all previous re-optimized plans. If successful, the selected plan is used for daily treatment with translational shifts. Otherwise, the AIGRT invokes the re-optimization process of the CT plan for the anatomy of the day, which is afterward added to the plan pool as a candidate for future fractions. The AIGRT scheme is evaluated by comparisons with daily re-optimization and online re-positioning techniques based on daily target coverage, organs at risk (OAR) sparing and implementation efficiency. Simulated treatment courses for 18 patients with re-optimization alone, re-positioning alone and AIGRT shows that AIGRT offers reliable daily target coverage that is highly comparable to daily re-optimization and significantly improves from re-positioning. AIGRT is also seen to provide improved OAR sparing compared to re-positioning. Apart from dosimetric benefits, AIGRT in addition offers an efficient scheme to integrate re-optimization to current re-positioning-based IGRT workflow.
authors.affiliation: Department of Radiation Oncology, Duke University Medical Centre, Durham, NC, USA. taoran.li@duke.edu
authors.forename: Taoran
authors.initials: T
authors.lastname: Li
authors.forename: Danthai
authors.initials: D
authors.lastname: Thongphiew
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Zhu
authors.forename: W Robert
authors.initials: WR
authors.lastname: Lee
authors.forename: Zeljko
authors.initials: Z
authors.lastname: Vujaskovic
authors.forename: Fang-Fang
authors.initials: FF
authors.lastname: Yin
authors.forename: Q Jackie
authors.initials: QJ
authors.lastname: Wu
mesh_terms: D005240:Feasibility Studies; D006801:Humans; D008297:Male; D058958:Organs at Risk / Q000528:radiation effects; D056888:Patient Positioning / Q000379:methods*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods*; D014057:Tomography, X-Ray Computed