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SU‐E‐T‐401: The Development of Intensity and Energy Modulated Electron Radiotherapy; An Alternative to Photon Volumetric Modulated Arc Therapy
Author(s) -
Alexander A,
Soisson E,
Sarfehnia A,
Hijal T,
Deblois F,
Seuntjens J
Publication year - 2011
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 - 10.1118/1.3612355
Subject(s) - radiation treatment planning , lumpectomy , radiation therapy , nuclear medicine , dosimetry , medicine , collimator , breast cancer , medical physics , physics , cancer , radiology , mastectomy , optics
Purpose: This work explains the development of an advanced treatment planning system for the generation of intensity and energy modulated electron radiotherapy (MERT) plans. The quality of MERT plans for the treatment of tumour bed boost in breast cancer is compared to direct electrons (DE) and volumetric modulated photon arc therapy (MAT). Method and Materials: The MERT treatment planning and delivery system at McGill University consists of MMCTP, an inverse optimization toolkit and the few leaf electron collimator. The stepwise planning process consists of: 1) generating a series of field openings, 2) Monte Carlo dose calculation for each field, 3) planning constraints, 4) iterative direct‐aperture optimization. For evaluation purposes, fourteen patients with breast cancer treated by lumpectomy and requiring post‐operative whole breast radiotherapy with tumour bed boost were planned using conventional DE, MAT and MERT. The planning goal was to deliver 10 Gy to at least 95% of the target volume. Dosimetry parameters for all techniques were compared. Results: Target coverage and homogeneity was best for MERT (D98=9.77 Gy, D2=11.03 Gy) followed by MAT (D98=9.56 Gy, D2=11.07 Gy) and DE (D98=9.81 Gy, D2=11.52 Gy). Relative to the DE plans, the MERT plans predicted a reduction of 35% in mean breast dose (p<0.05), 54% in mean lung dose (p<0.05) and 46% in mean body dose (p<0.05). Relative to the MAT plans, the MERT plans predicted a reduction of 24%, 36% and 39% in mean breast dose, heart dose and body dose respectively (p<0.05). Conclusions: MERT was a considerable improvement in dosimetry over DE. In some cases, there was a dosimetric advantage in using MERT over MAT for increased target conformity and low‐dose sparing of healthy tissue. Based on the favorable comparisons shown in this work it is reasonable to suggest that MERT could play a more significant role in breast radiotherapy.