Lone Hoffmann1, Markus Alber2, Maria Fuglsang Jensen3, Marianne Ingerslev Holt3, Ditte Sloth Møller4. 1. Department of Medical Physics, Aarhus University Hospital, Denmark. Electronic address: Lone.Hoffmann@aarhus.rm.dk. 2. Department of Radiation Oncology, Heidelberg University Hospital, Germany. 3. Department of Oncology, Aarhus University Hospital, Denmark. 4. Department of Medical Physics, Aarhus University Hospital, Denmark.
Abstract
BACKGROUND AND PURPOSE: Large anatomical changes during radiotherapy are seen for a large proportion of lung cancer patients. We investigate the applicability of a decision support protocol for photon therapy in a proton therapy setting. MATERIAL AND METHODS: Twenty-three consecutive NSCLC patients treated with adaptive photon therapy were retrospectively planned using IMPT. The adaptive protocol was based on geometrical measures of target positioning and large anatomical changes as shown on daily CBCT scans. Two surveillance CT-scans were acquired during the treatment course. The consequences of anatomical changes were evaluated by recalculating the proton plans on the surveillance scans. The CTV receiving 95% of the prescribed dose was analysed. RESULTS: Fourteen (61%) patients needed adaptations when treated with protons, given that 95% of the CTV must be covered by 95% of the dose. In comparison, no patients needed adaptation when treated with photons using this criterion. The adaptive protocol was found to identify patients with large target under-dosage for proton therapy (six patients). Additionally, target under-dosage was observed for eight patients with non-rigid changes up to 15mm in the positioning of the bones. CONCLUSIONS: Proton therapy for loco-regional lung cancer demands daily imaging and therapy adaptation for a high proportion of patients.
BACKGROUND AND PURPOSE: Large anatomical changes during radiotherapy are seen for a large proportion of lung cancerpatients. We investigate the applicability of a decision support protocol for photon therapy in a proton therapy setting. MATERIAL AND METHODS: Twenty-three consecutive NSCLCpatients treated with adaptive photon therapy were retrospectively planned using IMPT. The adaptive protocol was based on geometrical measures of target positioning and large anatomical changes as shown on daily CBCT scans. Two surveillance CT-scans were acquired during the treatment course. The consequences of anatomical changes were evaluated by recalculating the proton plans on the surveillance scans. The CTV receiving 95% of the prescribed dose was analysed. RESULTS: Fourteen (61%) patients needed adaptations when treated with protons, given that 95% of the CTV must be covered by 95% of the dose. In comparison, no patients needed adaptation when treated with photons using this criterion. The adaptive protocol was found to identify patients with large target under-dosage for proton therapy (six patients). Additionally, target under-dosage was observed for eight patients with non-rigid changes up to 15mm in the positioning of the bones. CONCLUSIONS: Proton therapy for loco-regional lung cancer demands daily imaging and therapy adaptation for a high proportion of patients.
Authors: Jianzhong Cao; Xiaodong Zhang; Bo Jiang; Jiayun Chen; Xiaochun Wang; Li Wang; Narayan Sahoo; X Ronald Zhu; Rong Ye; Pierre Blanchard; Adam S Garden; C David Fuller; G Brandon Gunn; Steven J Frank Journal: Radiother Oncol Date: 2021-04-08 Impact factor: 6.901
Authors: Carri K Glide-Hurst; Percy Lee; Adam D Yock; Jeffrey R Olsen; Minsong Cao; Farzan Siddiqui; William Parker; Anthony Doemer; Yi Rong; Amar U Kishan; Stanley H Benedict; X Allen Li; Beth A Erickson; Jason W Sohn; Ying Xiao; Evan Wuthrick Journal: Int J Radiat Oncol Biol Phys Date: 2020-10-24 Impact factor: 7.038