Ray-tracing methods for realistic interactive ultrasound simulation
Inventors
MATTAUSCH, Oliver • GOKSEL, Orcun • MAKHINYA, Maxim
Assignees
Eidgenoessische Technische Hoschschule Zurich (ethz) • VIRTAMED AG
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Publication Number
US-10565900-B2
Publication Date
2020-02-18
Expiration Date
Abstract
Stochastic ray-tracing methods such as Monte-Carlo ray-tracing may be adapted to provide more efficient and more realistic ultrasound imaging systems and methods. Many random ray paths that are perturbed according to a probability distribution may be generated until they converge to the correct solution. New surface thickness and roughness models enable to reproduce complex ultrasound interactions such as multiple reflections and refractions. The contribution of each ray path may be further weighted to better simulate a beamformed ultrasound signal. Tracing many individual rays per transducer element is easily parallelizable on modern GPU computing architectures.
Core Innovation
The patent describes a computer-implemented method for rendering a simulated ultrasound image from a 3D anatomical model using a processor. For an incoming ray that hits a geometric surface, the method identifies at a geometric intersection point P_T0 at least one variable surface thickness parameter and/or one variable roughness parameter as properties of an underlying anatomy object tissue, and these properties characterize the geometric surface as a partially diffuse surface.
The method calculates multiple ray-tracing paths from multiple intersection points P_T, with the multiple paths distributed as a function of the variable surface thickness parameter and/or the variable surface roughness parameter. The ray-tracing is performed using a stochastic ray-tracing method, and the ultrasound image is rendered by combining one or more contributions from the calculated multiple ray-tracing paths.
Each calculated ray-tracing path is further attenuated as a function of an attenuation parameter α characterizing the underlying anatomy object tissue and of a penetrated distance l in the tissue. The simulated ultrasound image is produced by combining attenuated contributions from multiple stochastic ray paths, with tissue interface behavior represented as partially diffuse through variable surface thickness and/or variable roughness.
Claims Coverage
The document provides two independent claims (clm-00001 and clm-00018), both covering a processor-implemented stochastic ray-tracing rendering method for a simulated ultrasound image from a 3D anatomical model. Each independent claim includes a core sequence: identifying variable surface properties at a ray-surface intersection as partially diffuse, calculating multiple stochastic ray-tracing paths distributed according to a variable surface parameter, and rendering by combining path contributions with attenuation using α and penetrated distance l.
Partially diffuse tissue surface characterization with variable parameters
Identifying, for an incoming ray hitting a geometric surface on a 3D anatomical model at a geometric intersection point P_T0, at least one variable surface thickness parameter and/or one variable roughness parameter, or at least one variable surface parameter, as properties of an underlying anatomy object tissue to characterize the surface as a partially diffuse surface.
Stochastic ray-tracing with multiple distributed ray paths
Calculating multiple ray-tracing paths from multiple intersection points P_T distributed as a function of the variable surface thickness parameter and/or the variable surface roughness parameter, or distributed as a function of the variable surface parameter, with a stochastic ray-tracing method.
Combined rendering with attenuation by tissue parameter and penetrated distance
Rendering the ultrasound image by combining one or more contributions from the calculated multiple ray-tracing paths, each calculated ray-tracing path being further attenuated as a function of an attenuation parameter α characterizing the underlying anatomy object tissue and of a penetrated distance l in the tissue.
Across the independent claims, the inventive coverage focuses on treating at least one tissue interface as partially diffuse using variable surface thickness and/or variable roughness parameters, propagating multiple stochastic ray-tracing paths distributed according to those variable surface parameters, and rendering the simulated ultrasound image by combining contributions that are attenuated based on α and penetrated distance l.
Stated Advantages
Improved perceived realism versus deterministic binary ray tracing, as indicated by experimental results in the provided description.
Improved performance versus recursion-dependent deterministic schemes, as indicated by performance comparisons in the provided description.
Documented Applications
Interactive ultrasound simulation and rendering of simulated ultrasound image content.
Use in ultrasound image simulation including simulated RF/B-mode ultrasound signals, as described in the provided summary.
Pregnancy ultrasound simulation, as indicated by the listed key entities in the provided description.
Embryo model, as indicated by the listed key entities in the provided description.
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