- Title
- Comparison of prostate set-up accuracy and margins with off-line bony anatomy corrections and online implanted fiducial-based corrections
- Creator
- Greer, P. B.; Dahl, K.; Ebert, M. A.; Wratten, C.; White, M.; Denham, J. W.
- Relation
- Journal of Medical Imaging and Radiation Oncology Vol. 52, Issue 5, p. 511-516
- Publisher Link
- http://dx.doi.org/10.1111/j.1440-1673.2008.02005.x
- Publisher
- Elsevier
- Resource Type
- journal article
- Date
- 2008
- Description
- The aim of the study was to determine prostate set-up accuracy and set-up margins with off-line bony anatomy-based imaging protocols, compared with online implanted fiducial marker-based imaging with daily corrections. Eleven patients were treated with implanted prostate fiducial markers and online set-up corrections. Pretreatment orthogonal electronic portal images were acquired to determine couch shifts and verification images were acquired during treatment to measure residual set-up error. The prostate set-up errors that would result from skin marker set-up, off-line bony anatomy-based protocols and online fiducial marker-based corrections were determined. Set-up margins were calculated for each set-up technique using the percentage of encompassed isocentres and a margin recipe. The prostate systematic set-up errors in the medial–lateral, superior–inferior and anterior–posterior directions for skin marker set-up were 2.2, 3.6 and 4.5 mm (1 standard deviation). For our bony anatomy-based off-line protocol the prostate systematic set-up errors were 1.6, 2.5 and 4.4 mm. For the online fiducial based set-up the results were 0.5, 1.4 and 1.4 mm. A prostate systematic error of 10.2 mm was uncorrected by the off-line bone protocol in one patient. Set-up margins calculated to encompass 98% of prostate set-up shifts were 11–14 mm with bone off-line set-up and 4–7 mm with online fiducial markers. Margins from the van Herk margin recipe were generally 1–2 mm smaller. Bony anatomy-based set-up protocols improve the group prostate set-up error compared with skin marks; however, large prostate systematic errors can remain undetected or systematic errors increased for individual patients. The margin required for set-up errors was found to be 10–15 mm unless implanted fiducial markers are available for treatment guidance.
- Subject
- quality assurance; physics; radiation oncology imaging
- Identifier
- http://hdl.handle.net/1959.13/43509
- Identifier
- uon:5608
- Identifier
- ISSN:1754-9477
- Rights
- The definitive version is available at www.blackwell-synergy.com
- Language
- eng
- Full Text
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