R Sayah1, T Felefly2, L Zouein3, J El Barouky4, N Khater5, N Farah6, C Roukoz2, C El Khoury2, F Azoury2, D Nehme Nasr2, E Nasr2. 1. Department of Radiation Oncology, Hôtel-Dieu de France University Hospital, Saint Joseph University, Beirut, Lebanon. Electronic address: rima.sayah@hdf.usj.edu.lb. 2. Department of Radiation Oncology, Hôtel-Dieu de France University Hospital, Saint Joseph University, Beirut, Lebanon; Department of Radiation Oncology, School of Medicine, Saint Joseph University, Beirut, Lebanon. 3. Physics Department, Faculty of Sciences, Saint Joseph University, Beirut, Lebanon. 4. Department of Radiation Oncology, Hôtel-Dieu de France University Hospital, Saint Joseph University, Beirut, Lebanon; Physics Department, Faculty of Sciences, Saint Joseph University, Beirut, Lebanon. 5. Department of Radiation Oncology, Saint Louis University, Saint Louis, MO, USA. 6. Department of Radiation Oncology, Hôtel-Dieu de France University Hospital, Saint Joseph University, Beirut, Lebanon.
Abstract
PURPOSE: This work aims to evaluate the dosimetric consequences of replacing the Anisotropic Analytical Algorithm (AAA) by Acuros XB (AXB), dose-to-water (Dw) or dose-to-medium (Dm), for RapidArc plans of nasopharyngeal carcinomas (NPC). MATERIALS AND METHODS: Seventeen NPC plans created with AAA (v15.6) were recalculated with AXB (v15.6) Dw and Dm. The dose-volume parameters to the planning target volumes (PTV) and relevant organs at risk (OAR) were compared. The high dose PTV was divided into bone, air and tissue components and the comparison was performed for each of them. RESULTS: AXB Dw revealed no significant differences in the PTVs compared to AAA. Lower values were observed to spinal cord, brainstem, oral cavity and parotids (0.5% to 2.3%), and higher values to cochleas (up to 5.4%) and mandible (up to 6.7%). AXB Dm predicted lower values than AAA for all PTVs and OARs (2.0% to 6.1%). For the bone PTV subvolume, AXB Dw and Dm predicted respectively higher (2.4%) and lower (2.2% to 3.4%) values. No significant differences were noted in air. AXB predicted lower values than AAA in soft tissues (0.4% to 1.6%). The largest difference was found to the mandible V60Gy parameter, with median differences of 6.7% for AXB Dw and -6.0% for AXB Dm. CONCLUSION: Significant dose differences are expected when switching from AAA to AXB in NPC cases. The dose prescriptions and the tolerance limits for some OARs, especially those of high density, may need to be adjusted depending on the selected dose calculation algorithm and reporting mode.
PURPOSE: This work aims to evaluate the dosimetric consequences of replacing the Anisotropic Analytical Algorithm (AAA) by Acuros XB (AXB), dose-to-water (Dw) or dose-to-medium (Dm), for RapidArc plans of nasopharyngeal carcinomas (NPC). MATERIALS AND METHODS: Seventeen NPC plans created with AAA (v15.6) were recalculated with AXB (v15.6) Dw and Dm. The dose-volume parameters to the planning target volumes (PTV) and relevant organs at risk (OAR) were compared. The high dose PTV was divided into bone, air and tissue components and the comparison was performed for each of them. RESULTS:AXB Dw revealed no significant differences in the PTVs compared to AAA. Lower values were observed to spinal cord, brainstem, oral cavity and parotids (0.5% to 2.3%), and higher values to cochleas (up to 5.4%) and mandible (up to 6.7%). AXBDm predicted lower values than AAA for all PTVs and OARs (2.0% to 6.1%). For the bone PTV subvolume, AXB Dw and Dm predicted respectively higher (2.4%) and lower (2.2% to 3.4%) values. No significant differences were noted in air. AXB predicted lower values than AAA in soft tissues (0.4% to 1.6%). The largest difference was found to the mandible V60Gy parameter, with median differences of 6.7% for AXB Dw and -6.0% for AXBDm. CONCLUSION: Significant dose differences are expected when switching from AAA to AXB in NPC cases. The dose prescriptions and the tolerance limits for some OARs, especially those of high density, may need to be adjusted depending on the selected dose calculation algorithm and reporting mode.
Authors: Vladimir Feygelman; Kujtim Latifi; Mark Bowers; Kevin Greco; Eduardo G Moros; Max Isacson; Agnes Angerud; Jimmy Caudell Journal: J Appl Clin Med Phys Date: 2022-02-25 Impact factor: 2.243