Derivation of mean dose tolerances for new fractionation schemes and treatment modalities

Avoiding toxicities in radiotherapy requires the knowledge of tolerable organ doses. For new, experimental fractionation schemes (e.g. hypofractionation) these are typically derived from traditional schedules using the biologically effective dose (BED) model. In this report we investigate the difficulties of establishing mean dose tolerances that arise since the mean BED depends on the entire spatial dose distribution, rather than on the dose level alone. A formula has been derived to establish mean physical dose constraints such that they are mean BED equivalent to a reference treatment scheme. This formula constitutes a modified BED equation where the influence of the spatial dose distribution is summarized in a single parameter, the dose shape factor. To quantify effects we analyzed 24 liver cancer patients for whom both proton and photon IMRT treatment plans were available. The results show that the standard BED equation - neglecting the spatial dose distribution - can overestimate mean dose tolerances for hypofractionated treatments by up to 20%. The shape difference between photon and proton dose distributions can cause 30-40% differences in mean physical dose for plans having identical mean BEDs. Converting hypofractionated, 5/15-fraction proton doses to mean BED equivalent photon doses in traditional 35-fraction regimens resulted in up to 10 Gy higher doses than applying the standard BED formula. The dose shape effect should be accounted for to avoid overestimation of mean dose tolerances, particularly when estimating constraints for hypofractionated regimens. Additionally, tolerances established for one treatment modality cannot necessarily be applied to other modalities with drastically different dose distributions, such as proton therapy. Last, protons may only allow marginal (5-10%) dose escalation if a fraction-size adjusted organ mean dose is constraining instead of a physical dose.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.RST/Reactor Physics and Nuclear Material

Automated Data Annotation for 6-DoF AI-Based Navigation Algorithm Development

Accurately estimating the six degree of freedom (6-DoF) pose of objects in images is essential for a variety of applications such as robotics, autonomous driving, and autonomous, AI, and vision-based navigation for unmanned aircraft systems (UAS). Developing such algorithms requires large datasets; however, generating those is tedious as it requires annotating the 6-DoF relative pose of each object of interest present in the image w.r.t. to the camera. Therefore, this work presents a novel approach that automates the data acquisition and annotation process and thus minimizes the annotation effort to the duration of the recording. To maximize the quality of the resulting annotations, we employ an optimization-based approach for determining the extrinsic calibration parameters of the camera. Our approach can handle multiple objects in the scene, automatically providing ground-truth labeling for each object and taking into account occlusion effects between different objects. Moreover, our approach can not only be used to generate data for 6-DoF pose estimation and corresponding 3D-models but can be also extended to automatic dataset generation for object detection, instance segmentation, or volume estimation for any kind of object

Comparable three months' outcome of total arterial revascularization versus conventional coronary surgery:Copenhagen Arterial Revascularization Randomized Patency and Outcome trial

ObjectiveThe in-hospital safety of total arterial revascularization for coronary artery bypass surgery seems to be comparable to conventional revascularization, but randomized trials evaluating this are few and data on complications in the postoperative months are sparse.MethodsIn a randomized single-center trial, 331 patients underwent total arterial revascularization using single or bilateral internal thoracic and radial arteries versus conventional revascularization using the left internal thoracic artery and saphenous vein grafts. We report the results from 3 months' follow-up.ResultsThe mean age of patients was 59 ± 8 years, and 39 were women (12%). The median EuroSCORE was 2 (interquartile range 1–4). The arterial group comprised 161 patients, and the conventional group comprised 170 patients. The mean number of bypasses in the arterial group was 2.9 ± 0.9 versus 3.2 ± 0.9 in the conventional group (P = .004). Three months' follow-up for the arterial versus conventional groups showed the following: deaths: 1 (0.6%) versus 0; stroke: 3 (1.9%) versus 3 (1.8%); myocardial infarction: 6 (3.7%) versus 4 (2.4%); sternal wound reoperation: 4 (2.5%) versus 0 (P = .054); arm and leg wound complications requiring hospitalization: 3 (1.9%) versus 6 (3.5%) (P = .50), respectively.ConclusionThese results confirm previous reports that total arterial revascularization can be performed with low in-hospital morbidity and mortality. Further, in the 3 postoperative months, total arterial revascularization did not lead to more complications or admissions than conventional surgery. Arterial grafting was performed with significantly fewer bypasses, but no differences in anginal status were seen after 3 months. A tendency toward more sternal complications after arterial grafting was observed, but clinical outcomes were comparable to conventional grafting