SCIMITAR: Optimising chest digital tomosynthesis devices using geometric simulations and genetic algorithms

Objective: Digital tomosynthesis (DT) bridges the gap between planar X-rays and computed tomography, offering rapid, low-dose 3D imaging. A mobile chest DT device could transform procedures such as nasogastric tube placement and early cancer detection. Adaptix Ltd. has developed 3D imaging systems using cold-cathode X-ray emitter arrays on flat panel source (FPS) units for veterinary and orthopaedic applications. Designing a chest DT device using multiple FPSs presents new challenges, requiring simulations that can efficiently explore the large design space and rapidly identify optimal configurations. Approach: We developed Scimitar, a geometry-based simulation framework that models X-ray radiation coverage in chest DT systems. It evaluates design viability and performance using irradiation uniformity metrics and integrates a genetic algorithm to optimise key system parameters. Scimitar further facilitates the evaluation of collimator designs, FPS arrangements, engineering constraints, and dynamic adaptation to different patient volumes. Main results: Square collimators generally outperformed circular designs due to better alignment with the cuboid target volume. Across FPS configurations, optimisation consistently yielded maximum source-to-image distances, minimal emitter spacing, and X-ray cone angles near 30deg. A four-panel cross arrangement achieved highest uniformity. Imposing engineering constraints such as increased emitter spacing led to approximately linear reductions in uniformity. Introducing vertical offsets to central panels yielded modest gains, though still underperformed compared to configurations without central panels. Dynamic cone angle adjustment enabled device adaptation to different patient sizes, with the four-panel cross consistently delivering the best results. Significance: Scimitar efficiently optimises chest DT designs under various constraints and assumptions. This work identifies promising configurations, highlights design trade-offs, and demonstrates adaptability across patient sizes. As understanding of system requirements evolve, Scimitar’s adaptability will enable it to remain a valuable tool in guiding the development of clinically effective, low-dose, mobile 3D imaging devices.