The presence of a 1.5 T magnetic field has an impact on the dose distribution when the air content changes of within a few percent in these selected rectal cancer patients. The authors consider this influence of the transverse magnetic field on the dose distribution in IMRT for rectal cancer patients clinically acceptable.
This article investigates the possibilities for creating behavioural models of military decision making in a data-driven manner. As not much data from actual operations is available, and data cannot easily be created in the military context, most approaches use simulators to learn behaviour. A simulator is however not always available or is difficult to create. This study focusses on the creation of behavioural models from data that was collected during a field exercise. As data in general is limited, noisy and erroneous, this makes the creation of realistic models challenging. Besides using the traditional approach of hand-crafting a model based on data, we investigate the emerging research area of imitation learning. One of its techniques, reward engineering, is applied to learn the behaviour of soldiers in an urban warfare operation. Basic, but realistic, soldier behaviour is learned, which lays the groundwork for more elaborate models in the future.
Purpose: The purpose of this planning study is to investigate the influence of the ERE on the day‐to‐day dose distribution in rectal cancer patients, where changes in gas‐pockets frequently occur. Methods: Daily CT scans of 5 patients treated neo‐adjuvant with 5×5Gy for rectal cancer were used. We optimized two plans on the planning CT (Monaco, 1 mm3 dosegrid), a conventional 7‐field 6MV IMRT plan (Dconv) and a plan in the presence of a 1.5T field (Dmrl). We recalculated the plans on all repeat‐CT scans and evaluated under/over‐dosage of the daily CTVs. Changes of more than 1% were considered significant. In the bowel area, we investigated the relative dose changes due to the ERE, where the contribution of the ERE was separated from other effects such as attenuation. Results: Both plans were comparable and compliant with ICRU 62 for all patients. For 2 fractions in one patient under‐dosage in the CTV was significant, due to a disappearing gas‐pocket. Here the V95 was 96.82 and 97.36% in in Dmrl compared to 98.85 and 98.66% in Dconv, respectively. For 3 fractions in another patient appearing gas‐pockets resulted in significant over‐dosage of the CTV. In these fractions the V107 was 1.88–2.68% in Dmrl compared to 0.33–1.27% in Dconv. In the bowel area the dose changes attributable to the ERE were approximately ± 5% in 1cc, at low dose levels. Conclusion: We were able to calculate acceptable treatment plans with and without a magnetic field. The ERE was present in the Dmrl, but the volumetric effect within the CTV was limited. Outside the CTV relative dose differences were similar, but on small volumes at lower, less relevant dose levels. This suggests that there is no clinical relevant ERE on dose distributions in rectal cancer patients on a 1.5T MR‐Linac.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.