arXiv subjects

Brian Miller

Publications and source records attributed to Brian Miller.

4 recordsLinked to original sources

arXiv2023

A 2D antiscatter grid and scatter sampling based CBCT method for online dose calculations during CBCT guided radiation therapy of pelvis

Online dose calculations before radiation treatment have applications in dose delivery verification, plan adaptation, and treatment planning. We propose a novel CBCT imaging pipeline to enhance accuracy. Our approach aims to improve HU accuracy in CBCT images for more precise dose calculations. A quantitative CBCT pipeline was implemented, combining data correction strategies and scatter rejection, achieving high CT number accuracy. We evaluated the pipeline's effect using pelvis anatomy phantoms and found that dosimetric errors in quantitative CBCT-based dose calculations were minimal. In contrast, clinical CBCT and high-performance ASG CBCT-based plans showed significant errors. The proposed quantitative CBCT pipeline offers comparable dose calculation accuracy to the gold-standard planning CT, eliminating the need for density overrides and enabling precise dose delivery monitoring or online plan adaptations in radiation therapy.

physics.med-ph↗

arXiv2023

Robotic Defect Inspection with Visual and Tactile Perception for Large-scale Components

In manufacturing processes, surface inspection is a key requirement for quality assessment and damage localization. Due to this, automated surface anomaly detection has become a promising area of research in various industrial inspection systems. A particular challenge in industries with large-scale components, like aircraft and heavy machinery, is inspecting large parts with very small defect dimensions. Moreover, these parts can be of curved shapes. To address this challenge, we present a 2-stage multi-modal inspection pipeline with visual and tactile sensing. Our approach combines the best of both visual and tactile sensing by identifying and localizing defects using a global view (vision) and using the localized area for tactile scanning for identifying remaining defects. To benchmark our approach, we propose a novel real-world dataset with multiple metallic defect types per image, collected in the production environments on real aerospace manufacturing parts, as well as online robot experiments in two environments. Our approach is able to identify 85% defects using Stage I and identify 100% defects after Stage II. The dataset is publicly available at https://zenodo.org/record/8327713

cs.RO↗

arXiv2020

Evaluation of scatter rejection and correction performance of 2D antiscatter grids in cone beam computed tomography

Purpose: We have been investigating 2D antiscatter grids (2D ASG) to reduce scatter fluence and improve image quality in cone beam computed tomography (CBCT). In this work, two different aspects of 2D ASGs, their scatter rejection and correction capability, were investigated in CBCT experiments. To correct residual scatter transmitted through the 2D ASG, it was used as a scatter measurement device with a novel method: grid-based scatter sampling. Methods: Three focused 2D ASG prototypes with grid ratios of 8, 12, and 16 were developed for linac-mounted CBCT geometry. In the first phase, 2D ASGs were used as a scatter rejection device, and the effect of grid ratio on CT number accuracy and contrast-to-noise ratio (CNR) evaluated in CBCT images. In the second phase, the grid-based scatter sampling method was implemented. The percent change in CT numbers was measured by changing the phantom size from head to pelvis configuration.Results: When 2D ASG was used as a scatter rejection device, CT number variation due to change in phantom dimensions was reduced from 23% to 2 - 6%. A grid ratio of 16 yielded the lowest CT number variation. All three 2D ASGs yielded improvement in CNR, up to a factor of two in pelvis-sized phantoms. When 2D ASG prototypes were used for both scatter rejection and correction, CT number variations were reduced further, to 1.3 - 2.6%. Conclusions: When 2D ASG was used solely as a scatter rejection device, substantial improvement in CT number accuracy could be achieved by increasing the grid ratio. 2D ASGs could also provide significant CNR improvement even at lower grid ratios. When 2D ASG was used in conjunction with the grid-based scatter sampling method, it provided further improvement in CT number accuracy, irrespective of the grid ratio, while preserving 2D ASG's capacity to improve CNR.

physics.med-ph↗

arXiv2019

Microgrid Resilience: A holistic approach for assessing threats, identifying vulnerabilities, and designing corresponding mitigation strategies

Microgrids are being increasing deployed to improve the operational flexibility, resilience, coordinated-energy management capabilities, self-adequacy, and increased reliability of power systems. This strong market growth is also driven by advances in power electronics, improved control systems, and the rapidly falling price and increased adoption of distributed energy generation technologies, like solar photovoltaics and storage. In the event of grid outages, microgrids can provide a backup source of power; providing resilience to the critical loads; however, this requires that the microgrid itself is resilient to physical and cyber threats. Building highly resilient microgrids requires a methodological assessment of potential threats, identification of vulnerabilities, and design of mitigation strategies. This paper provides a comprehensive review of threats, vulnerabilities, and mitigation strategies and develops a definition for microgrid resilience. The paper also develops a methodology for designing resilient microgrids by considering how microgrid designers and site owners evaluate threats, vulnerabilities, and consequences and choose the microgrid features required to address these threats under different situations.

eess.SY↗