A method for optimizing LINAC treatment geometry for volumetric modulated arc therapy of multiple brain metastases
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231 (United States)
Purpose: Volumetric modulated arc therapy (VMAT) is a rotational delivery technique in which MLC shapes, dose rate, and gantry rotation speed are optimized to produce conformal dose distributions. The aim of this work is to develop a beam projection method for deriving the optimal table and collimator angles for multilesion treatment planning. Methods: The method consists of four steps. The first step is to define the vector of beam-eye-view (BEV)-Y-axis in the treatment planning CT coordinates. The second step is to project each target onto the BEV-Y-axis vector. In the third step, the best table and collimator angle are found with a brute-force optimization technique that minimizes MLC leaf sharing between lesions. The fourth step is to generate an optimized VMAT plan with appropriate table/collimator angles and evaluate the plan quality. Results: The authors tested the method on three example cases with targets of various locations in the brain and sizes ranging from 1.18 to 17.86 cm{sup 3}. Applying the optimized geometric parameter to generate VMAT plan, a reduction of the 12 Gy volume was more than 6.1% for all cases; the plan homogeneity (D{sub 2%}-D{sub 95%}) was improved from 5.88{+-}1.21 to 5.21{+-}0.93 Gy vs a VMAT plan with the manufacturer recommended table and collimator angles. Conclusions: The authors conclude that the use of the projection method minimizes the sharing of MLC leaves between lesions and improves the plan quality for multilesion VMAT delivery.
- OSTI ID:
- 22096748
- Journal Information:
- Medical Physics, Journal Name: Medical Physics Journal Issue: 8 Vol. 37; ISSN 0094-2405; ISSN MPHYA6
- Country of Publication:
- United States
- Language:
- English
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