Journal article
Characteristics and limitations of a secondary dose check software for VMAT plan calculation
Journal of applied clinical medical physics, Vol.22(3), pp.216-223
03/05/2021
DOI: 10.1002/acm2.13206
PMCID: PMC7984465
PMID: 33666339
Abstract
Purpose
To assess the implementation, accuracy, and validity of the dosimetric leaf gap correction (DLGC) in Mobius3D VMAT plan calculations.
Methods
The optimal Mobius3D DLGC was determined for both a TrueBeam with a Millennium multi-leaf collimator and a TrueBeamSTx with a high-definition multi-leaf collimator. By analyzing a broad series of seven VMAT plans and comparing the calculated to the measured dose delivered to a cylindrical phantom, optimal DLGC values were determined by minimizing the dose difference for both the collection of all plans, as well as for each plan individually. The effects of plan removal from the optimization of the collective DLGC value, as well as plan-specific DLGC values, were explored to determine the impact of plan suite design on the final DLGC determination.
Results
Optimal collective DLGC values across all energies were between −0.71 and 0.89 mm for the TrueBeam, and between 0.35 and 1.85 mm for the TrueBeamSTx. The dose differences ranged between −6.1% and 2.6% across all plans when the optimal collective DLGC values were used. On a per-plan basis, the plan-specific optimal DLGC values ranged from −4.36 to 2.35 mm for the TrueBeam, and between −1.83 and 2.62 mm for the TrueBeamSTx. Comparing the plan-specific optimal DLGC to the average absolute leaf position from the central axis for each plan, a negative correlation was observed.
Conclusions
The optimal DLGC determination depends on the plans investigated, making it essential for users to utilize a suite of test plans that encompasses the full range of expected clinical plans when determining the optimal DLGC value. Validation of the secondary dose calculation should always be based on measurements, and not a comparison with the primary TPS. Varying disagreement with measurements across plans for a single DLGC value indicates potential limitations in the Mobius3D MLC model.
Details
- Title: Subtitle
- Characteristics and limitations of a secondary dose check software for VMAT plan calculation
- Creators
- Andrew J. Shepard - University of Wisconsin–MadisonSean P. Frigo - University of Wisconsin–Madison
- Resource Type
- Journal article
- Publication Details
- Journal of applied clinical medical physics, Vol.22(3), pp.216-223
- DOI
- 10.1002/acm2.13206
- PMID
- 33666339
- PMCID
- PMC7984465
- NLM abbreviation
- J Appl Clin Med Phys
- ISSN
- 1526-9914
- eISSN
- 1526-9914
- Publisher
- John Wiley and Sons Inc
- Language
- English
- Date published
- 03/05/2021
- Academic Unit
- Radiation Oncology
- Record Identifier
- 9984312989702771
Metrics
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