Optical Probe Spatial Slope Correction for Deep Tissue Measurement
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Solution Overview
Problem
Current Near-Infrared Spectroscopy (NIRS) methods, particularly the spatially resolved method, lack an effective correction method for the influence of superficial tissues, leading to inaccuracies in measuring deep layer tissue properties such as muscle tissue oxygen concentration and hemoglobin concentration.
Innovation Solution
An optical measuring apparatus and method that includes a light emitting and receiving system with distinct positions to account for different light transmission distances through superficial and deep layers, using spatial slope computation and stored computation parameters to correct for superficial tissue influence, allowing for accurate measurement of deep layer light absorption and hemoglobin concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the continuous light method or spatially resolved method is used for NIRS measurement, then the apparatus simplicity, portability, and real-time performance are improved, but the measurement precision deteriorates due to the large influence of superficial tissue on deep layer tissue measurement
Solution Approach 1:
The invention segments the light receiving process into multiple distance groups, where light receivers are positioned at different distances from the light emitter. By grouping receivers at specific distance intervals (e.g., first distance group at d1, second distance group at d2), the system can separately analyze light transmission through different tissue depths, thereby isolating the deep layer tissue signal from superficial tissue interference while maintaining apparatus simplicity.
Solution Approach 2:
The invention introduces a spatial dimension (distance from light emitter) to the measurement system by positioning light receivers at multiple predetermined distances. This creates a distance-resolved measurement capability that transforms the single-point measurement into a multi-distance profile, enabling the system to differentiate between superficial and deep layer tissue contributions based on their different light transmission characteristics at various distances.
2Measurement precision
If a correction method for superficial tissue influence is applied in the continuous light method, then the measurement precision of deep layer tissue is improved, but the device complexity increases
Solution Approach 1:
The invention performs preliminary action by pre-calculating and storing reference data that represents the light transmission characteristics of superficial tissue at different distances and wavelengths. During actual measurement, the system retrieves these pre-computed reference values and uses them to correct the measured signal, eliminating the need for complex real-time calculations and reducing device complexity while maintaining high measurement precision.
Solution Approach 2:
The invention introduces an intermediary computational layer that processes the relationship between measured light intensity, distance, and tissue properties. By using pre-stored reference data as an intermediary, the system mediates between the raw measurement and the final corrected result, simplifying the correction process while improving accuracy without requiring complex real-time computational resources.
3Measurement precision
If multiple light receiving positions at different distances are used to correct superficial tissue influence, then the measurement precision of deep layer tissue is improved, but the device complexity increases
Solution Approach 1:
The invention applies local quality by assigning different functional roles to light receivers at different distances. Receivers at shorter distances primarily capture information about superficial tissue, while receivers at longer distances capture information about deep layer tissue. By optimizing the positioning and grouping of receivers at specific distances, each receiver contributes locally to different aspects of the measurement, enabling effective correction while maintaining a relatively simple device 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
Enables accurate measurement of deep layer light absorption and hemoglobin concentrations by correcting for superficial tissue effects, improving the quantitative performance and reducing errors in muscle tissue oxygen concentration and oxygen saturation measurements.
Implementation Method 1
a light emitting means for irradiating with light a layered structure which is an object of measurement, the layered structure including plural layers, the plural layers including at least a superficial layer and a deep layer
Implementation Method 2
a light receiving means for receiving, at a position at a first predetermined distance from the light emitting means, light emitted from the light emitting means and transmitted through the superficial layer and the deep layer
Data Source
AI summary
The present invention provides an optical measuring apparatus and an optical measuring method for being able to correct the influence of a superficial tissue to be able to accurately measure a degree of light absorption of a deep layer tissue such as a human body and fruits, and a storage medium that stores an optical measuring program. The optical measuring apparatus includes a probe, and the probe includes one light emitting diode and two photodiodes. In a configuration of the optical measuring apparatus, one of the photodiodes receives light which is emitted from the light emitting diode and transmitted through a superficial layer and a deep layer of a tissue, and the other photodiode receives light having a deep layer transmission distance different from that of the light received by one of the photodiodes. The light received by the other photodiode is also transmitted through the superficial layer and deep layer of the tissue. Based on intensity of the light received by each photodiode, a control unit computes a propagation constant in a medium through which the light propagates. An arithmetic expression is selected in accordance with an input fat thickness of the tissue, and an absorption coefficient of the light from a muscle tissue using the arithmetic expression based on the fat thickness and a spatial slope. A hemoglobin concentration and an oxygen saturation are obtained based on the obtained absorption coefficient of the light.