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SU‐E‐T‐602: Dynamic Electron Arc Radiotherapy (DEAR): A Planning Study
Author(s) -
Rodrigues A,
Yin F,
Wu Q
Publication year - 2013
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4815030
Subject(s) - penumbra , imaging phantom , nuclear medicine , isocenter , physics , optics , dosimetry , homogeneity (statistics) , cold spot , radiation treatment planning , cathode ray , radiation therapy , electron , mathematics , nuclear physics , medicine , statistics , ischemia , astrobiology , cardiology
Purpose: Electron beam therapy is under‐utilized in radiation treatment of cancer and has remained practically unchanged for decades. We propose a new technique, Dynamic Electron Arc Radiotherapy (DEAR) with synchronized couch motion. In DEAR, gantry rotation, dose rate, and intensities are modulated to create desirable dose distributions free of hot and/or cold spots, with high homogeneity, and narrow penumbra. This study demonstrates the potential of DEAR in improving dose distributions. Methods: Dose distributions for single‐field and two‐field were compared to DEAR with equal and optimized beam weights on a 32 cm diameter cylindrical phantom. Plans were designed to irradiate equivalent field size on the phantom surface, with the target dimension extending from 315° –45° in radial angle and target depth at 1 cm (6 MeV) or 2 cm (9 MeV). Penumbra (20–80%), dose homogeneity, and dose area histogram (DAH) were evaluated at target depths. Plans were calculated with the eMC algorithm in Eclipse v10. Results: In‐plane (longitudinal direction) penumbra was comparable across all plans as expected. Cross‐plane (along curved surface) penumbra was 5.0, 1.5, and 2.0 cm (6 MeV) and 5.6, 1.7, and 2.1 (9 MeV), for single‐field, two‐field, and DEAR, respectively. While the two‐field penumbra was better, it exhibited a hot spot 60% higher than the target mean at the beam junction covering approximately 20% of the target. DEAR plans displayed homogenous dose distributions with variations of less than ±1.5%. DAH of the single‐field failed to achieve optimal coverage, while the two‐field displayed a high‐dose tail (>100%). 90% of the target receives at least 95% (two‐field) and 88% (DEAR) of the target dose. Conclusion: Preliminary findings show that DEAR can produce homogenous dose distributions over large and curved targets without hot and/or cold spots while maintaining narrow penumbra. Future work includes planning for various target shapes and desired dose distributions.