Time-of-Flight Fluorescence Imaging for Surgical Depth Localization

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Solution Overview

Problem

Current surgical techniques face challenges in visualizing and distinguishing between normal and abnormal tissues, particularly malignant tumors, during procedures due to poor visibility and contrast, leading to potential damage to surrounding tissues.

Innovation Solution

The use of optical time-of-flight imaging and fluorescence depth estimation methods, combining pulsed structured light illumination with time-of-flight camera acquisition, to accurately determine the depth and shape of fluorescent-tagged targets within tissues, such as tumors, while calibrating for varying tissue optical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If fluorescence-based imaging is used to detect tumors, then abnormal tissue visibility is improved, but depth localization accuracy deteriorates due to tissue scattering and absorption

Engineering Contradiction:

Improvefluorescence signal intensityVSAvoiddepth localization accuracy

Core Design Contradiction:

Illumination intensityVSMeasurement precision

Solution Approach 1:

The patent combines time-of-flight depth imaging with fluorescence imaging into a single integrated system. The time-of-flight camera captures both depth information and fluorescence signals simultaneously, merging two imaging modalities to overcome their individual limitations. This allows the system to achieve both good depth localization accuracy and fluorescence detection sensitivity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces the time dimension to resolve the depth-fluorescence trade-off. By using time-resolved detection where different depths correspond to different arrival times of photons, the system adds temporal information as an additional dimension that enables accurate depth localization independent of fluorescence intensity variations caused by tissue scattering and absorption.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of operation

If surgeons rely on visible tissue discrimination, then surgical simplicity is maintained, but tissue differentiation accuracy deteriorates due to poor contrast between normal and malignant tissues

Engineering Contradiction:

Improvesurgical simplicityVSAvoidtissue differentiation accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent utilizes fluorescence emission at different wavelengths to create optical contrast between normal and malignant tissues. By detecting fluorescence signals at specific wavelength bands, the system enables surgical guidance based on spectral differences rather than visible color changes, improving tissue differentiation accuracy while maintaining ease of operation through automated detection.

Inventive Principle:

Principle #32Color changes

3Device complexity

If conventional imaging methods are used, then device complexity is minimized, but tissue depth information deteriorates due to inability to resolve sub-surface structures

Engineering Contradiction:

Improveimaging system complexityVSAvoidsub-surface depth information

Core Design Contradiction:

Device complexityVSLoss of information

Solution Approach 1:

The patent replaces complex mechanical depth measurement systems with optical time-of-flight measurement. By using the speed of light as a reference and measuring photon arrival times, the system achieves accurate depth resolution without mechanical scanning or moving parts, thereby minimizing device complexity while recovering sub-surface depth information.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This approach enhances the accuracy of depth localization and shape evaluation, allowing for precise identification and removal of abnormal tissues while minimizing damage to nearby structures, providing real-time surgical guidance with improved visualization of fluorophore concentrations.

Implementation Method 1

resolving sub-surface depth of a fluorescent object embedded in tissue using a two-dimensional, time-of-flight light sensor

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Implementation Method 2

It is known that some fluorescent compounds will accumulate in tumors and other abnormal tissues

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Data Source

PatentUS20240000316A1Optical time-of-flight imaging methods and systems for surgical guidance and fluorescence depth estimation in tissue

Publication Date: 2024.01.04 TRUSTEES OF DARTMOUTH COLLEGE THE

AI summary

A system and method for depth-resolved imaging of fluorophore concentrations in tissue uses a pulsed light source stimulus wavelength to illuminate the tissue; and a time-gated electronic camera such as a single-photon avalanche detector camera to observe the tissue in multiple time windows after start of each light pulse. A filter device is between the tissue and the electronic camera with fluorescent imaging and stimulus wavelength settings. an image processor receives reflectance images and fluorescent emissions images from the time-gated camera and processes these images into depth and quantity resolved images of fluorophore concentrations in the tissue. Then image processor derives a fluorescence lifetime signal from the received temporal fluorescence signals and derives from these fluorescence lifetime signals biochemical property images of the tissue.