Software-controlled, highly automated intrafraction prostate motion correction with intrafraction stereographic targeting: System description and clinical results

Theodore Mutanga, HCJ de Boer, V (Vinayakrishnan) Rajan, Maarten Dirkx, Marjolein Os, Luca Incrocci, Ben Heijmen

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Purpose: A new system for software-controlled, highly automated correction of intrafraction prostate motion," intrafraction stereographic targeting" (iSGT), is described and evaluated. Methods: At our institute, daily prostate positioning is routinely performed at the start of treatment beam using stereographic targeting (SGT). iSGT was implemented by extension of the SGT software to facilitate fast and accurate intrafraction motion corrections with minimal user interaction. iSGT entails megavoltage (MV) image acquisitions with the first segment of selected IMRT beams, automatic registration of implanted markers, followed by remote couch repositioning to correct for intrafract Results: SDs of systematic (Sigma) and random (sigma) displacements relative to the planning CT measured directly after initial SGT setup correction were < 0.5 and < 0.8 mm, respectively. Without iSGT corrections, effective Sigma and sigma for the 11-min treatments would increase to Sigma(eff) < 1.1 mm and sigma(eff) < 1.2 mm. With the iSGT procedure with an action level of 4 mm, effective positioning errors were reduced to Sigma(eff) < 0.8 mm and sigma(eff) < 1.0 mm, with 23.1% of all fractions Conclusions: Without increasing imaging dose, iSGT successfully reduces intrafraction prostate motion with minimal workload and increase in fraction time. An action level of 2 mm is recommended. (C) 2012 American Association of Physicists in Medicine. [DOI: 10.1118/1.3684953]
Original languageUndefined/Unknown
Pages (from-to)1314-1321
Number of pages8
JournalMedical Physics
Issue number3
Publication statusPublished - 2012

Research programs

  • EMC MM-03-32-04

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