Dual-Slope Near-Infrared Spectroscopy for Deep Tissue Sensitivity
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Solution Overview
Problem
Existing near-infrared spectroscopy methods struggle to effectively separate signals from the region of interest from noise contributed by superficial tissues, due to strong scattering in biological tissue, leading to confounded measurements.
Innovation Solution
The use of a pair of sources and a pair of detectors, arranged to reshape the region of greatest sensitivity, allows for the derivation of parameters indicative of matched slopes, such as phase or mean time-of-flight, to enhance sensitivity to deeper tissue regions and spatially confine the region-of-sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional near-infrared spectroscopy methods are used to inspect internal structures, then the measurement can be performed non-invasively, but the signal from superficial tissues dominates and confounds the measurement of deeper regions
Solution Approach 1:
The patent segments the detected signal into contributions from different tissue depths by using multiple source-detector separations. Each separation probes different depths, allowing the signal to be divided into superficial and deep tissue components that can be separately analyzed and combined to isolate the deep tissue signal.
Solution Approach 2:
The patent adds the dimension of source-detector separation distance as an additional parameter for signal discrimination. By measuring at multiple separations (adding a spatial dimension to the measurement), the system can distinguish between superficial and deep tissue signals that would be indistinguishable at a single separation.
2Measurement precision
If multiple source-detector separations are used to improve depth sensitivity, then sensitivity to deeper tissue regions increases, but the complexity of the measurement system and data processing increases
Solution Approach 1:
The patent applies local quality by using different source-detector separations to probe different local regions (depths) of the tissue. Each separation is optimized for its specific depth range, with shorter separations for superficial layers and longer separations for deeper regions, allowing tailored measurement of each layer's properties.
3Measurement precision
If sophisticated forward models and inversion procedures are used to separate signals, then the separation of useful signal from noise can be achieved, but the computational intensity and processing time increase significantly
Solution Approach 1:
The patent performs preliminary action by collecting data at multiple source-detector separations before any complex processing is attempted. This preliminary multi-distance measurement provides the necessary information to directly calculate depth-resolved signals using analytical solutions, avoiding the need for subsequent computationally intensive inversion procedures.
4Device complexity
If a single source-detector separation is used, then the measurement system is simple, but the sensitivity to deeper tissue regions is insufficient
Solution Approach 1:
The patent applies dynamics by making the effective probing depth dynamic and adjustable through selection of source-detector separation. The system can adaptively choose appropriate separations based on the depth of interest, allowing the measurement depth to be dynamically adjusted without changing the physical probe structure.
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 reduces sensitivity to superficial layers and increases sensitivity to deeper portions of the medium, providing a robust method for diffuse optical imaging of deep tissue without the need for complex inversion procedures.
Implementation Method 1
radiation is selected so that it can penetrate the skin... wavelengths slightly longer than that of visible light... near infrared
Implementation Method 2
strong scattering experienced by near-infrared radiation in biological tissue... banana-shaped cross-section
Implementation Method 3
frequency-domain near-infrared spectroscopy... intensity-modulated or pulsed near-infrared radiation... phase of the near-infrared radiation
Data Source
AI summary
An apparatus for earning out near-infrared spectroscopy using intensity-modulated near-infrared radiation or pulsed near-infrared radiation includes sources and detectors. For each source, there exists first and second distances. The first distance is a distance between the source and a first detector. The second distance is a distance between the source and the second detector. For each source, the difference between these two distances is the same. Additionally, wherein, for each source, the detector at a shorter distance is the same detector that is at a longer distance for the other source. A processor derives, from signals received by the detectors, a parameter indicative of two matched slopes. Tins parameter is either phase of the intensity-modulated near-infrared radiation or mean time-of-flight data for the pulsed near-infrared radiation. The processor then provides output data based on an average of the matched slopes. This promotes reduced sensitivity to superficial layers and enhanced sensitivity to deeper portions of a medium that is under investigation.