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Publication Number
US-10269112-B2
Publication Date
2019-04-23
Expiration Date
Abstract
Through the measurement and interpretation of the pixels of grayscale digital thermographic images of abnormalities of the skin and its subcutaneous tissue, early intervention and treatment of abnormalities of the skin and its subcutaneous tissue are possible, thereby assisting clinicians in making significant impacts on prevention and treatment.
Core Innovation
The invention provides grayscale digital thermographic imaging for objectively detecting abnormalities in and beneath a mammalian body surface. It uses long-wave infrared thermal imaging having wavelengths in the long-wave infrared range of 7 to 14 microns to passively read radiant energy emissions from a target on an outer surface. Abnormalities are detected by comparing relative differences in temperature between two body surface areas, using acquired thermal images comprising pixels.
The thermal images are mapped to a standardized unsigned 8-bit grayscale representation using a default pixel intensity range defined between a default lower thermal intensity limit and a default upper thermal intensity limit. The mapping is further constrained by a default thermal image resolution determined by an algorithm that includes the default upper thermal intensity limit, the default lower thermal intensity limit and a predetermined fixed number of different pixel values. The method also enables visual enhancement by adding positive or negative pixel offsets for brightness adjustment while maintaining the underlying stored raw data.
For analysis, the invention generates a respective histogram of the pixel values within each of the two long-wave infrared thermal images and detects abnormalities in one area relative to the other by comparing the histograms. It also supports quantitative image-analysis features such as calculating thermal intensity ratios based on temperature-related pixel values, calculating region areas using pixel counting of highlighted pixels, and generating profile-line plots across a wound with comparison to an unaffected reference line, including computed metrics derived from the profile line such as area above or below the reference, rise or drop, slopes or derivatives, and percentage of pixels above or below.
To improve reproducibility and scaling, the imaging device is arranged relative to a mammal at a standardized separation distance using converging Class I laser beams that intersect at a predetermined distance from the target. This supports consistent length and width and area measurements from the grayscale digital thermographic images and enables longitudinal wound trending by repeated imaging with quantitative comparison.
Claims Coverage
The independent claim covers objective abnormality detection on and beneath a mammalian body surface by comparing relative temperature differences between two outer surface areas using long-wave infrared thermal images. It incorporates multiple inventive features including a default thermal imaging configuration with constrained pixel-value mapping and resolution and histogram-based comparison for detection.
Histogram-based abnormality detection by comparing pixel-value distributions
Generating a respective histogram of the pixel values within each of said first and second long-wave infrared thermal images, and detecting abnormalities in one of the first and second body surface areas relative to the other by comparing the histograms.
Default pixel intensity range mapping covering physiological thermal intensity
The imaging device having a default configuration in which long-wave infrared thermal images acquired using the imaging device have a default pixel intensity range defined as a default thermal span between a default lower thermal intensity limit and a default upper thermal intensity limit, wherein thermal intensity variations within long-wave infrared thermal images acquired using the imaging device in the default configuration are limited to a range of thermal intensity variations that substantially covers the physiological thermal intensity range of the mammalian body.
Default thermal image resolution based on fixed number of pixel values and thermal limits
A default thermal image resolution determined by an algorithm that includes the default upper thermal intensity limit, the default lower thermal intensity limit and a predetermined fixed number of different pixel values and is contained in a program on a computer readable medium.
Default quantized pixel-value assignment using predetermined fixed number
Assigning each pixel of the acquired first long-wave infrared thermal image to a respective one of the predetermined fixed number of different pixel values according to the default thermal image resolution; assigning each pixel of the acquired second long-wave infrared thermal image to a respective one of the predetermined fixed number of different pixel values according to the default thermal image resolution.
Quantized fixed pixel values count (255) for resolution
Characterized by using a predetermined fixed number of different pixel values equal to 255.
Affected area versus unaffected control area for average pixel comparison
Defining an affected area of interest on a first body surface and an unaffected control area on a second body surface, then calculating average pixel values for first and second long-wave infrared thermal images using pixels from the respective affected and control areas.
Temporal comparison using stored raw mapped pixel values across subsequent dates
Acquiring long-wave infrared thermal images of a first body surface area on two subsequent dates, storing predetermined fixed numbers of pixel values from each image as raw data, and using the stored raw data to compare images across the dates to objectively evaluate status changes.
Pixel-level thermal intensity gradient calculation relative to reference average
Calculating the thermal intensity gradient of each pixel in a first long-wave infrared thermal image relative to the average pixel value of a second long-wave infrared thermal image and visualizing the calculated gradient for each pixel.
The claim set centers on objectively detecting abnormalities by histogram comparison of default-mapped long-wave infrared thermal image pixels, with a structured default pixel intensity range and a default thermal image resolution based on predetermined fixed pixel values. Dependent claims expand the covered approach by specifying a fixed pixel-value count, selecting affected versus unaffected regions for average pixel computation, enabling temporal status-change evaluation from stored mapped pixel-value raw data, and adding pixel-level thermal intensity gradient visualization.
Stated Advantages
Enables objective detection of abnormalities in one body surface area relative to another by comparing temperature differences.
Provides histogram-based comparison of pixel-value distributions for detecting abnormalities.
Supports standardized thermal image mapping and resolution constrained by default thermal limits and a predetermined fixed number of pixel values.
Enables temporal comparisons to objectively evaluate status changes using stored raw mapped pixel values across subsequent dates.
Documented Applications
Objective detection of abnormalities in and beneath a mammalian body surface using long-wave infrared thermographic imaging, including evaluation of wound-related regions via comparisons to an unaffected reference line.
Longitudinal wound trending by repeated imaging and quantitative comparison.
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