Marlies Pasler1, Johannes Lutterbach2, Mari Björnsgard2, Ursula Reichmann2, Susanne Bartelt2, Dietmar Georg3. 1. Lake Constance Radiation Oncology Center Singen, Friedrichshafen, Germany. Electronic address: pasler@strahlentherapie-fn.de. 2. Lake Constance Radiation Oncology Center Singen, Friedrichshafen, Germany. 3. Department of Radiooncology, Medical University Vienna/AKH Wien, Vienna, Austria; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University Vienna, Vienna, Austria.
Abstract
PURPOSE: To investigate the plan quality of two different volumetric modulated arc therapy (VMAT) techniques for lymph node-positive left-sided breast cancer. METHODS: Two VMAT plans were generated for 10 lymph node-positive left-sided breast cancer patients: one plan using one single segment of a full rotation, typically an arc segment of 230° (1s-VMAT); and a second plan consisting of 2 small tangential arc segments of about 50° (2s-VMAT). For plan comparison, various dose and dose volume metrics (Dmean, D98%, D2% for target volumes, D2%, Dmean and Vx% for organs at risk (OAR)) were evaluated. RESULTS: Both techniques fulfilled both clinical target dose and OAR goals. 1s-VMAT achieved a slightly better homogeneity and better target coverage (D2%= 54.2 ± 0.7 Gy, D98%= 30.3 ± 1.8 Gy) compared to 2s-VMAT (D2%= 55.0 ± 1.1 Gy, D98%= 29.9 ± 1.7 Gy). For geometrical reasons, OAR sparing was noticeable but not significant better using 2s-VMAT, particularly heart and contralateral breast. The heart received a mean dose of 4.4 ± 0.8 Gy using 1s-VMAT and 3.3 ± 1.0 Gy using 2s-VMAT; the contralateral breast received 1.5 ± 0.3 Gy and 0.9 ± 0.3 Gy, respectively. CONCLUSIONS: A VMAT technique based on two small tangential arc segments enables improved OAR sparing; the differences between the two techniques in target coverage and homogeneity are minor. Patient age and -anatomy must be considered for each individual case when deciding which technique to be used.
PURPOSE: To investigate the plan quality of two different volumetric modulated arc therapy (VMAT) techniques for lymph node-positive left-sided breast cancer. METHODS: Two VMAT plans were generated for 10 lymph node-positive left-sided breast cancerpatients: one plan using one single segment of a full rotation, typically an arc segment of 230° (1s-VMAT); and a second plan consisting of 2 small tangential arc segments of about 50° (2s-VMAT). For plan comparison, various dose and dose volume metrics (Dmean, D98%, D2% for target volumes, D2%, Dmean and Vx% for organs at risk (OAR)) were evaluated. RESULTS: Both techniques fulfilled both clinical target dose and OAR goals. 1s-VMAT achieved a slightly better homogeneity and better target coverage (D2%= 54.2 ± 0.7 Gy, D98%= 30.3 ± 1.8 Gy) compared to 2s-VMAT (D2%= 55.0 ± 1.1 Gy, D98%= 29.9 ± 1.7 Gy). For geometrical reasons, OAR sparing was noticeable but not significant better using 2s-VMAT, particularly heart and contralateral breast. The heart received a mean dose of 4.4 ± 0.8 Gy using 1s-VMAT and 3.3 ± 1.0 Gy using 2s-VMAT; the contralateral breast received 1.5 ± 0.3 Gy and 0.9 ± 0.3 Gy, respectively. CONCLUSIONS: A VMAT technique based on two small tangential arc segments enables improved OAR sparing; the differences between the two techniques in target coverage and homogeneity are minor. Patient age and -anatomy must be considered for each individual case when deciding which technique to be used.
Authors: Sara Poeta; Younes Jourani; Alex De Caluwé; Robbe Van den Begin; Dirk Van Gestel; Nick Reynaert Journal: Radiat Oncol Date: 2021-04-20 Impact factor: 3.481
Authors: Cameron Stanton; Linda J Bell; Andrew Le; Brooke Griffiths; Kenny Wu; Jessica Adams; Leigh Ambrose; Denise Andree-Evarts; Brian Porter; Regina Bromley; Kirsten van Gysen; Marita Morgia; Gillian Lamoury; Thomas Eade; Jeremy T Booth; Susan Carroll Journal: J Med Radiat Sci Date: 2021-08-12