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Feasibility of delivering grid therapy using a multileaf collimator
Jonathan K Ha1, Guowei Zhang, Shahid A Naqvi
1Radiation Oncology, University of Maryland, Baltimore, Maryland 21201, USA.
Medical Physics
|February 21, 2006
Summary
Multileaf collimators (MLCs) can create grids for radiation therapy, matching or exceeding the performance of traditional blocks. This method offers comparable dosimetric properties for grid therapy, though treatment times may increase.
Area of Science:
- Medical Physics
- Radiation Oncology
Background:
- Grid therapy is a technique used in radiation oncology to improve dose distribution.
- Traditional grid collimators are often made of dense materials like Cerrobend.
Purpose of the Study:
- To evaluate the feasibility of using multileaf collimators (MLCs) for creating grid patterns in radiation therapy.
- To compare the dosimetric properties of MLC-generated grids with those of conventional Cerrobend grid collimators.
Main Methods:
- MLCs were used to create grid fields with 10 mm x 10 mm and 5 mm x 5 mm openings.
- Film dosimetry in a solid water phantom measured dose at various depths.
- Monte Carlo simulations quantified dose transmission through MLCs.
Main Results:
- MLC grids achieved valley-to-peak dose ratios of approximately 11% (10 mm) and 19% (5 mm) at dmax.
- These ratios were comparable or superior to Cerrobend grids (15% and 20%).
- Monte Carlo simulations indicated a 7% reduction in valley-to-peak dose ratio due to MLC transmission.
Conclusions:
- MLCs are a feasible alternative for generating grids in radiation therapy.
- MLC-based grids offer comparable or better dosimetric performance than Cerrobend grids.
- While effective, MLC grid therapy may require longer treatment delivery times.