Virtual Light Source Illumination Model for Medical Volume Rendering

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Solution Overview

Problem

Current volume rendering methods for medical images, such as those used in cardiac imaging, struggle to provide a straightforward and accurate visualization of tissue thickness, often resulting in artificial-looking images that are sensitive to noise and lack a clear, intuitive representation of tissue thickness variations.

Innovation Solution

A novel illumination model is introduced that uses a virtual light source positioned within the tissue of interest, simulating how light interacts with the tissue through absorption and scattering effects, producing a photo-realistic image that intuitively represents tissue thickness by varying color and intensity based on light absorption, which is less sensitive to noise and provides a more accurate representation of wall thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a texture-based thickness mapping method is used, then tissue thickness can be visualized, but the rendered image appears artificial and less intuitive

Engineering Contradiction:

Improvetissue thickness visualization accuracyVSAvoidimage realism

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the artificial texture-mapping approach with a physically-based illumination model that simulates light transport through tissue. Instead of projecting thickness values as textures onto surfaces, the system uses volumetric rendering with absorption and scattering models to naturally visualize thickness variations, producing photo-realistic images that maintain diagnostic accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the rendering parameters from surface-based texture coordinates to volumetric optical properties (absorption coefficient, scattering coefficient, light path length). By integrating these optical parameters along light paths through the tissue volume, the system achieves both accurate thickness representation and natural appearance.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If conventional volume rendering is used, then the process is straightforward, but tissue thickness visualization is not intuitive without additional processing

Engineering Contradiction:

Improverendering process simplicityVSAvoidtissue thickness information

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The patent performs preliminary calculation of optical parameters (absorption, scattering, light path length) for each voxel before the actual rendering process. This pre-computation of physical optical properties allows the subsequent rendering to naturally reveal thickness information through light attenuation, eliminating the need for separate thickness calculation and texture mapping steps.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If a virtual light source inside the tissue is used, then photo-realistic images with intuitive thickness representation are produced, but the computational model becomes more complex

Engineering Contradiction:

Improvetissue thickness representation accuracyVSAvoidillumination model complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces optical parameters (absorption coefficient, scattering coefficient, light path length) as intermediaries between the virtual light source and the final image. These intermediaries simplify the computational model by providing physically-based transfer functions that naturally encode thickness information, avoiding the need for complex geometric calculations or multiple rendering passes.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The proposed method delivers high-quality, photo-realistic images that effectively convey tissue thickness and variations, offering a more accurate and intuitive visualization compared to traditional texture-based or shading-based approaches, while being insensitive to noise in the image data.

Implementation Method 1

simulating how light interacts with the tissue through absorption and scattering effects

Methodology Applied

Scientific EffectAbsorption: Absorption (EM radiation)

Implementation Method 2

simulating how light interacts with the tissue through absorption and scattering effects

Methodology Applied

Scientific EffectScattering: Scattering

Data Source

PatentUS9330485B2Volume rendering of medical images

Publication Date: 2016.05.03 TOSHIBA MEDICAL SYST CORP

AI summary

Certain embodiments provide a photo-realistic rendering apparatus and method. An illumination model is used that includes placing a synthetic or virtual light source adjacent a region of tissue of interest in order to visualize the thickness of the tissue by modeling how light from the virtual light source interacts with the tissue of interest, through effects including absorption and scattering, as light emitted from the light source travels through the tissue of interest to a view point of view plane. It is simulated how some light is absorbed making tissue regions that are thicker darker (since more of the light is absorbed and the intensity reduces) and more red (since tissue tends to absorb blue and green wavelengths more strongly than red wavelengths and this chromatic effect is incorporated in the illumination model). A 2D image can thus be provided in which the color and intensity of light propagating through the tissue provides visual feedback on the tissue thickness.