https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:43535 Wed 21 Sep 2022 11:32:57 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:54435 Tue 27 Feb 2024 13:50:52 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:42887 cut(kinetic) was set at 500, 200, and 10 keV, and differences between 1 and 3 mm voxel were calculated. A planning study with 10 patient stereotactic body radiotherapy (SBRT) spine plans and 10 patient H&N plans was calculated in both Acuros XB (AXB) v15.6.06 and Anisotropic Analytical Algorithm (AAA) v15.6.06. The patient contour was overridden to water as only the penumbral differences between the two different algorithms were under investigation. Results: The dosimetry audit results show that for the SBRT spine case, plans calculated in AXB are colder than what is measured in the spinal cord by 5%-10%. This was also observed for other audit cases where a C-shape target is wrapped around an OAR where the plans were colder by 3%-10%. Plans calculated with Monaco MC were colder than measurements by approximately 7% with the OAR surround by a C-shape target, but these differences were not noted in the SBRT spine case. Results from the clinical patient plans showed that the AXB was on average 7.4% colder than AAA when comparing the minimum dose in the spinal cord OAR. This average difference between AXB and AAA reduced to 4.5% when using the more clinically relevant metric of maximum dose in the spinal cord. For the H&N plans, AXB was cooler on average than AAA in the spinal cord OAR (1.1%), left parotid (1.7%), and right parotid (2.3%). The EGSnrc investigation also noted similar, but smaller differences. The beam penumbra modeled by E_cut(kinetic) = 500 keV was steeper than the beam penumbra modeled by E_cut(kinetic) = 10 keV as the full scatter is not accounted for, which resulted in less dose being calculated in a central OAR region where the penumbra contributes much of the dose. The dose difference when using 2.5 mm voxels of the center of the OAR between 500 and 10 keV was 3%, reducing to 1% between 200 and 10 keV. Conclusions: Lack of full penumbral modeling due to approximations in the algorithms in MC based or LBTE algorithms are a contributing factor as to why these algorithms under-predict the dose to OAR when the treatment volume is wrapped around the OAR. The penumbra modeling approximations also contribute to AXB plans predicting colder doses than AAA in areas that are in the vicinity of beam penumbra. This effect is magnified in regions where there are many beam penumbras, for example in the spinal cord for spine SBRT cases.]]> Tue 06 Sep 2022 13:57:20 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:52206 5% increase in spinal cord dose relative to the original plans. Six plans (from four institutions) passed despite a >10% increase. Conclusions: This novel audit concept evolves beyond testing an institution’s ability to deliver a single test case, to increasing the number of errors caught by institutions themselves, thus increasing quality of radiation therapy and impacting every patient treated. Administered remotely this audit also provides advantages in cost, environmental impact, and logistics.]]> Thu 05 Oct 2023 10:15:47 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:52848 Mon 30 Oct 2023 09:53:46 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:49359 Fri 12 May 2023 12:35:35 AEST ]]>