Monte Carlo Tissue Oximetry for Fast Oxygen Saturation Sensing
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Solution Overview
Problem
Existing oximeters face challenges in improving measurement accuracy, reducing measurement time, lowering cost, and reducing size and power consumption, particularly in non-ideal conditions, and there is a need for accurate oxygen saturation measurements in clinical settings like surgery where tissue viability is critical.
Innovation Solution
A tissue oximetry device uses a large number of simulated reflectance curves to determine tissue optical properties, including emitting light, detecting reflections, and fitting data points to stored curves to calculate oxygen saturation, utilizing a processor to analyze reflectance data and generate accurate oxygen saturation values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing oximetry methods are used, then measurement capability is provided, but measurement accuracy is insufficient in non-ideal conditions
Solution Approach 1:
The patent transforms the measurement approach by changing from direct measurement to indirect measurement through parameter transformation. Reflectance data is converted to optical properties (absorption and scattering coefficients) which are then compared against a database of simulated curves with known oxygen saturation values. This parameter transformation enables accurate measurements in non-ideal conditions where direct measurement fails.
Solution Approach 2:
The patent performs preliminary action by pre-calculating and storing a comprehensive database of simulated reflectance curves covering a wide range of optical properties and oxygen saturation values before actual measurement. This pre-computed database allows the device to quickly find the best match during measurement without requiring complex real-time calculations, improving both accuracy and speed.
2Measurement precision
If complex measurement algorithms are used to improve accuracy, then measurement precision improves, but measurement time increases
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing a comprehensive database of simulated reflectance curves covering a wide range of optical properties and oxygen saturation values before actual measurement. This pre-computed database allows the device to quickly find the best match during measurement without requiring complex real-time calculations, improving both accuracy and speed.
Solution Approach 2:
The patent creates simplified copies of complex tissue optical behavior through simulated reflectance curves that replicate the relationship between optical properties, oxygen saturation, and reflectance. These simulated curves serve as reference models that can be quickly compared against actual measurements, avoiding the need for complex iterative calculations during real-time measurement.
3Measurement precision
If more processing power is used to analyze reflectance data, then measurement accuracy improves, but device complexity and power consumption increase
Solution Approach 1:
The patent creates simplified copies of complex tissue optical behavior through simulated reflectance curves that replicate the relationship between optical properties, oxygen saturation, and reflectance. These simulated curves serve as reference models that can be quickly compared against actual measurements, avoiding the need for complex iterative calculations during real-time measurement.
Solution Approach 2:
The patent uses periodic action by implementing an iterative fitting process that cycles through comparing measured reflectance data against multiple simulated curves with different oxygen saturation values. The process periodically refines the estimate by selecting curves that best match the measured data, converging on the accurate oxygen saturation value through repeated comparison cycles.
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 device provides rapid and accurate oxygen saturation measurements without requiring a pulse, suitable for various medical and veterinary applications, including plastic surgery, by employing a weighted average and iterative fitting methods to minimize errors.
Implementation Method 1
emitting light from a set of light sources into tissue; detecting the light by a plurality of detectors subsequent to reflection of the light from the tissue
Implementation Method 2
generating reflectance data points for the tissue based on detecting the light by the plurality of detectors
Implementation Method 3
Light absorption differs significantly for oxygenated and deoxygenated hemoglobins at certain wavelengths of light. Tissue oximeters can measure oxygen levels in human tissue by exploiting these light-absorption differences
Data Source
AI summary
A method for determining oxygen saturation includes emitting light from sources into tissue; detecting the light by detectors subsequent to reflection; and generating reflectance data based on detecting the light. The method includes determining a first subset of simulated reflectance curves from a set of simulated reflectance curves stored in a tissue oximetry device for a coarse grid; and fitting the reflectance data points to the first subset of simulated reflectance curves to determine a closest fitting one of the simulated reflectance curves. The method includes determining a second subset of simulated reflectance curves for a fine grid based on the closest fitting one of the simulated reflectance curves; determining a peak of absorption and reflection coefficients from the fine grid; and determining an absorption and a reflectance coefficient for the reflectance data points by performing a weighted average of the absorption coefficients and reflection coefficients from the peak.