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Use of a multileaf collimator as a dynamic missing-tissue compensator
1Stanford University Hospital, Department of Radiation Oncology, California 94305, USA.
Medical Physics
|July 1, 1996
Summary
Dynamic multileaf collimators (D-MLC) can create missing-tissue compensators, mimicking physical filters. This study shows D-MLC compensation is comparable to conventional methods for radiation therapy.
Area of Science:
- Medical Physics
- Radiation Oncology
Background:
- Conventional physical compensators are used in radiation therapy to shape dose distributions.
- Dynamic multileaf collimators (D-MLC) offer potential for novel treatment delivery techniques.
Purpose of the Study:
- To investigate the feasibility of using a D-MLC to create missing-tissue compensators.
- To develop and validate a method for calculating monitor units (MU) for D-MLC compensated fields.
Main Methods:
- A D-MLC was used to deliver sequences of shaped subfields, mimicking physical compensators.
- A Moiré camera measured tissue deficits in an anatomical phantom.
- Dose distributions were measured using film for uncompensated, conventionally compensated, and D-MLC compensated fields.
Main Results:
- A method for calculating MU for dynamic compensating filters was developed.
- D-MLC-based compensation was found to be comparable to conventional physical compensating filters.
- Isodose distributions demonstrated effective dose modulation with the D-MLC approach.
Conclusions:
- Dynamic multileaf collimators provide a feasible method for producing missing-tissue compensators in radiation therapy.
- D-MLC compensation offers a comparable alternative to traditional physical compensating filters.
- This technique expands upon existing methods for compensating filter MU calculations.