Christer Andre Jensen1, Ana María Acosta Roa2, Marie Johansen3, Jo-Åsmund Lund4, Jomar Frengen5. 1. Department of Oncology, Ålesund Hospital, Ålesund, Norway. Electronic address: christer.jensen@helse-mr.no. 2. Department of Oncology, Ålesund Hospital, Ålesund, Norway. Electronic address: anaaco@ous-hf.no. 3. Department of Oncology, Ålesund Hospital, Ålesund, Norway. Electronic address: Marie.Johansen@helse-mr.no. 4. Department of Medicine and Healthcare, Ålesund Hospital, Ålesund, Norway; Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway. Electronic address: Jo-Asmund.Lund@helse-mr.no. 5. Cancer Clinic, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway. Electronic address: Jomar.Frengen@stolav.no.
Abstract
PURPOSE: The aim of our study was to evaluate and compare the robustness of treatment plans produced using the volumetric modulated arc-therapy (VMAT) and the standard three-dimensional conformal radiotherapy (3DCRT) techniques by estimating perturbed doses induced by localization offsets for deep inspiration breath-hold (DIBH) in locally advanced breast cancer radiation therapy. METHODS: Twenty patients with left breast carcinoma requiring radiation therapy were analysed in this planning study. Robust VMAT plans regarding minimum CTV doses and standard 3DCRT plans were produced, and perturbed doses were calculated in accordance with localization values from the weekly offline imaging protocol. Offsets from 5 weeks were summed to a perturbed overall treatment plan. Dose criteria for evaluation were coverage and homogeneity of the target, as well as doses to organs at risk. RESULTS: VMAT plans resulted in significantly better target coverage compared to 3DCRT, as well as lowered doses to heart and left anterior descending artery, while the perturbed doses were less variable for VMAT than 3DCRT plans. Homogeneity was significantly improved in VMAT plans. The statistical analysis taking all organs into account found that VMAT plans were more robust than 3DCRT to localization offsets (p = .001). The overall mean setup-deviation for the DIBH-patients was less than 2 mm in all directions. CONCLUSIONS: VMAT plans were more robust on average than conventional 3DCRT plans for DIBH when localization errors were taken into consideration. The combination of robust VMAT planning and DIBH generally improves the homogeneity and target doses.
PURPOSE: The aim of our study was to evaluate and compare the robustness of treatment plans produced using the volumetric modulated arc-therapy (VMAT) and the standard three-dimensional conformal radiotherapy (3DCRT) techniques by estimating perturbed doses induced by localization offsets for deep inspiration breath-hold (DIBH) in locally advanced breast cancer radiation therapy. METHODS: Twenty patients with left breast carcinoma requiring radiation therapy were analysed in this planning study. Robust VMAT plans regarding minimum CTV doses and standard 3DCRT plans were produced, and perturbed doses were calculated in accordance with localization values from the weekly offline imaging protocol. Offsets from 5 weeks were summed to a perturbed overall treatment plan. Dose criteria for evaluation were coverage and homogeneity of the target, as well as doses to organs at risk. RESULTS: VMAT plans resulted in significantly better target coverage compared to 3DCRT, as well as lowered doses to heart and left anterior descending artery, while the perturbed doses were less variable for VMAT than 3DCRT plans. Homogeneity was significantly improved in VMAT plans. The statistical analysis taking all organs into account found that VMAT plans were more robust than 3DCRT to localization offsets (p = .001). The overall mean setup-deviation for the DIBH-patients was less than 2 mm in all directions. CONCLUSIONS: VMAT plans were more robust on average than conventional 3DCRT plans for DIBH when localization errors were taken into consideration. The combination of robust VMAT planning and DIBH generally improves the homogeneity and target doses.
Authors: Henrik Svensson; Dan Lundstedt; Maria Hällje; Magnus Gustafsson; Roumiana Chakarova; Per Karlsson Journal: Phys Imaging Radiat Oncol Date: 2019-08-30