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Direct aperture optimization for FLEC-based MERT and its application in mixed beam radiotherapy
Andrew Alexander1, Emilie Soisson, Marc-André Renaud
1Medical Physics Unit, McGill University, Montreal, Quebec H3G 1A4, Canada. andrew.alexander@mail.mcgill.ca
Medical Physics
|August 17, 2012
Summary
This study developed a direct aperture optimization (DAO) method for modulated electron radiotherapy (MERT) using the McGill few leaf electron collimator (FLEC). Combining MERT with photon fields improved treatment plan quality for sarcoma patients.
Area of Science:
- Medical Physics
- Radiation Oncology
- Radiotherapy Planning
Background:
- Modulated electron radiotherapy (MERT) shows promise but lacks commercial applicators and planning software.
- The McGill few leaf electron collimator (FLEC) is a device for MERT delivery.
Purpose of the Study:
- Investigate an optimization process for MERT treatment planning using the FLEC device.
- Examine the combination of MERT with photon fields for mixed beam radiotherapy.
Main Methods:
- Developed a FLEC direct aperture optimization (DAO) method for iterative aperture and weight optimization.
- Evaluated DAO performance against previous FLEC techniques and commercial photon algorithms.
- Applied DAO to a sarcoma treatment case and assessed mixed beam therapy with photon fields.
Main Results:
- DAO-generated MERT plans were competitive in sparing organs at risk (OAR) but less conformal to the target volume compared to alternatives.
- Incorporating photon fields enhanced the MERT plan's OAR sparing and target conformality.
Conclusions:
- The DAO approach enables deliverable FLEC-based MERT plans with a limited number of fields.
- Combining MERT with photon optimization offers flexibility and improves overall plan quality by leveraging the strengths of each modality.
