Journal article
SU‐FF‐T‐429: Treatment Planning Modeling and Dose Delivery Advantages of Standard Linac Without Flattening Filter
Medical physics (Lancaster), Vol.34(6), pp.2500-2500
06/2007
DOI: 10.1118/1.2761154
Abstract
Purpose: The objective of this study is to determine the accuracy with which treatment planning systems can model dose distributions generated by conventional linear accelerators without the flattening filter, and the potential benefits. Method and Materials: Data was collected on a Siemens Oncor linear accelerator, where the flattening filter has been removed and energy tuned to match a standard 6 MV x‐ray beam but with dose rates of 1000 MU/min. Data was acquired to model and commission four treatment planning systems (Philips Pinnacle, CMS Xio, Nomos Corvus, and Siemens Konrad). Comparisons included: TPS model parameters w/ and w/o flattening filter, measured and computed %dd and profiles, conventional and IMRT dose distributions both via planning and delivery measurements in phantom. Results: Beam energy spectrum characteristics show only a modest softening in the beam since beam tuning matched the filtered 6 MV. Differences are seen in the off‐axis fluence and off‐axis energy softening: the fluence is reduced linearly away from the central axis and the energy spectrum is only slightly reduced by comparison. Dose profiles and %dd were accurately modeled to within 2% and 2mm for all field sizes 2–40 cm. When applied to IMRT treatment plans, the model produced equivalent dose distributions for head‐and‐neck, CNS, and prostate plans; the number of monitor units was slightly increased (∼15%) but the number of segments was identical. Delivery times at 1000 MU/min were shorter (20% reduction), and the IMRT plans delivered had a 30–50% reduction in the number of pixels showing dose‐differences beyond 5%. Conclusion: Treatment planning systems are not only capable of modeling the dose distributions produced without flattening filters, they perform superior than with the filter present, and can reduce common dosimetric errors observed in IMRT phantom studies.
Research sponsored by Siemens Medical Solutions corporation.
Details
- Title: Subtitle
- SU‐FF‐T‐429: Treatment Planning Modeling and Dose Delivery Advantages of Standard Linac Without Flattening Filter
- Creators
- J Bayouth - 2West Pennsylvania Hospital, Pittsburgh, PAH Shukla - 2West Pennsylvania Hospital, Pittsburgh, PAD Pavord - 2West Pennsylvania Hospital, Pittsburgh, PAE Nixon - 2West Pennsylvania Hospital, Pittsburgh, PAR Siochi - 2West Pennsylvania Hospital, Pittsburgh, PA
- Resource Type
- Journal article
- Publication Details
- Medical physics (Lancaster), Vol.34(6), pp.2500-2500
- DOI
- 10.1118/1.2761154
- ISSN
- 0094-2405
- eISSN
- 2473-4209
- Number of pages
- 1
- Date published
- 06/2007
- Academic Unit
- Radiation Oncology
- Record Identifier
- 9984047757902771
Metrics
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