Purpose: To study the dosimetric properties of electron arc beams delivered by photon-beam multi-leaf collimators (pMLC) in electron modulated arc therapy (EMAT) for postmastectomy chest wall treatments. Methods: Using the Monte Carlo method, we simulated a 2100EX Varian linear accelerator and verified the beam models in a water tank. Dosimetric characterizations were performed on cylindrical water phantoms of elliptical bases with various field sizes, arc ranges and source-to-surface distances (SSDs) for 6, 9 and 12 MeV beam energy. Results: The arc beam has a higher bremsstrahlung dose than the static beam at the isocenter due to crossfire, but choosing a field size greater than 5 cm effectively reduces the bremsstrahlung dose. The depths of the 90% maximum dose located at 1.7, 2.8 and 4.1 cm for 6, 9 and 12 MeV, respectively, are similar to those of the static beams and independent of the field size and arc range. Conclusion: Based on the study, we recommend using the 5 cm field width for electron arc beams considering both bremsstrahlung dose at the isocenter and the arc profile penumbra. To ensure sufficient PTV edge coverage, we recommend a field length extension of at least 4 cm from PTV's edge for all beam energies and an arc extension of around 7°, 5°, and 5° for beam energies 6, 9, and 12 MeV, respectively. These dosimetric characterizations are the basis of pMLC-delivered EMAT treatment planning for postmastectomy chest wall patients.
- Electron arc therapy (EAT)
- Electron modulated arc therapy (EMAT)
- Monte Carlo (MC)
- Photon MLC (pMLC)
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
- Physics and Astronomy(all)