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Independent Verification of VMAT Treatment Plans Using a DICOM-RT Framework


R Reynolds

R Reynolds*, S Stojadinovic, A Pompos, X Gu, R Foster, T Solberg, UT Southwestern Medical Center, Dallas, TX

SU-E-T-575 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: To compare volumetric modulated arc therapy (VMAT) treatment plans calculated with Eclipse 10 (RapidArc, Varian Medical Systems) and Pinnacle 9.2 (SmartArc, Philips Healthcare) to those computed with an independent verification system utilizing a DICOM-RT framework Mobius3D (M3D 1.1, Mobius Medical Systems, LP).

Methods: Mobius3D (M3D) utilizes standardized machine data, supplemented by custom scaled measured depth dose curves, output factors and off-axis ratios, to create institution specific beam models as an independent dose validation check. A randomly selected set of clinical radiotherapy plans generated by two treatment planning systems (TPS) consisting of 26 RapidArc prostate plans and 29 SmartArc head and neck plans were exported to M3D. The requisite DICOM-RT files sent to M3D included CT images, contoured structure sets, RT plan and RT dose. This data was used to recalculate 3D dose distributions using a collapsed cone algorithm in M3D. Dose distributions were compared to those calculated by the TPS 3D dose using a 3D gamma analysis with 3% global dose difference and 3 mm isodose point distance criteria. Additionally, TPS's and M3D's target coverage and regions of interests sparing were compared by calculating the mean dose percent difference for each structure. DVH from each system were also compared.

Results: On average, M3D plans showed excellent 3D gamma passing rates agreement of (99.1%±1.1%) and (95.7%±2.2%) relative to RapidArc and SmartArc plans, respectively. Similarly, the M3D recalculated and RapidArc and SmartArc calculated mean target dose percent differences demonstrated small differences of (-0.3%±1.2%) and (-1.2%±0.9%), respectively.

Conclusion: Mobius3D enables a paradigm shift in clinical quality assurance practice by moving beyond single point dose and MU verification to a full 3D treatment plan QA check. The VMAT results obtained utilizing fast and fully automated M3D software showed that M3D is suitable for an independent check of RapidArc and SmartArc plans.

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