Detailed evaluation of Mobius3D dose calculation accuracy for volumetric-modulated arc therapy |
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| Affiliation: | 1. Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, South Korea;2. Department of Radiation Oncology, Ewha Womans University College of Medicine, Seoul, South Korea;1. Department of Radiation Oncology, University Hospital Jena, Bachstraße 18, 07743, Jena, Germany;2. Department of Radiation Oncology, Helios Hospital Erfurt, Nordhäuser Straße 74, 99089, Erfurt, Germany;3. Department of Radiation Oncology, University Hospital Leipzig, Stephanstraße 9a, 04103, Leipzig, Germany;4. Department of Radiation Oncology, Otto-von-Guericke University Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany;5. Department of Radiation Oncology, University Hospital Halle, Ernst-Grube-Straße 40, 06120 Halle, Saale, Germany;6. Department of Radiation Oncology, SRH Hospital Gera, Straße des Friedens 122, 07548, Gera, Germany;7. Department of Radiation Oncology, SRH Central Hospital Suhl, Albert-Schweitzer-Straße 2, 98527, Suhl, Germany;8. Department of Radiation Oncology, Hospital of Chemnitz, Bürgerstraße 2, 09113, Chemnitz, Germany;9. MVZ Center for Radiation Oncology Halle GmbH, Niemeyerstraße 24, 06110 Halle, Saale, Germany;10. Department of Radiation Oncology, Community Hospital Dresden-Friedrichstadt, Friedrichstraße 41, 01067, Dresden, Germany;11. Department of Radiosurgery and High Precision Robotic Treatments, Cyberknife Center Mitteldeutschland, Nordhäuserstraße 74, 99089 Erfurt, Germany;2. Department of Oncology, Western University, London, Ontario, Canada;3. Department of Medical Biophysics, Western University, London, Ontario, Canada;1. Department of Radiation Oncology, Graduate School of Medicine, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan;2. Department of Radiology, Juntendo University Hospital, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431, Japan;1. Department of Radiology, University of Texas Health San Antonio, San Antonio 78229, USA;2. Cancer Therapy and Research Center, 7979 Wurzbach Rd, 78229 San Antonio, USA;3. Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA;4. Department of Radiation Oncology, University of North Carolina, Chapel Hill, NC 27514, USA;1. University of Florence, Italy;2. Medical Physics Unit, Azienda USL Toscana Centro, Florence, Italy |
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| Abstract: | PurposeTo perform a detailed evaluation of dose calculation accuracy and clinical feasibility of Mobius3D. Of particular importance, multileaf collimator (MLC) modeling accuracy in the Mobius3D dose calculation algorithm was investigated.MethodsMobius3D was fully commissioned by following the vendor-suggested procedures, including dosimetric leaf gap (DLG) optimization. The DLG optimization determined an optimal DLG correction factor which minimized the average difference between calculated and measured doses for 13 patient volumetric-modulated arc therapy (VMAT) plans. Two sets of step-and-shoot plans were created to examine MLC and off-axis open fields modeling accuracy of the Mobius3D dose calculation algorithm: MLC test set and off-axis open field test set. The test plans were delivered to MapCHECK for the MLC tests and an ionization chamber for the off-axis open field test, and these measured doses were compared to Mobius3D-calculated doses.ResultsThe mean difference between the calculated and measured doses across the 13 VMAT plans was 0.6% with an optimal DLG correction factor of 1.0. The mean percentage of pixels passing gamma from a 3%/1 mm gamma analysis for the MLC test set was 43.5% across the MLC tests. For the off-axis open field tests, the Mobius3D-calculated dose for 1.5 cm square field was −4.6% lower than the chamber-measured dose.ConclusionsIt was demonstrated that Mobius3D has dose calculation uncertainties for small fields and MLC tongue-and-groove design is not adequately taken into consideration in Mobius3D. Careful consideration of DLG correction factor, which affects the resulting dose distributions, is required when commissioning Mobius3D for patient-specific QA. |
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| Keywords: | Mobius3D Patient-specific quality assurance Multileaf collimator modeling Accuracy evaluation |
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