U.S. patent application number 15/726399 was filed with the patent office on 2018-02-15 for method of monitoring the status of a wound.
The applicant listed for this patent is Nicholas A. McMurray, James G. Spahn. Invention is credited to Nicholas A. McMurray, James G. Spahn.
Application Number | 20180047162 15/726399 |
Document ID | / |
Family ID | 56555904 |
Filed Date | 2018-02-15 |
United States Patent
Application |
20180047162 |
Kind Code |
A1 |
Spahn; James G. ; et
al. |
February 15, 2018 |
Method of Monitoring the Status of a Wound
Abstract
A system for determining a clinically relevant temperature
differential between a predetermined area of interest on the body
surface of a mammal and a control area on the body surface of said
mammal, said system comprising: a visual and thermal image
capturing device, said image capturing device comprising: a
housing, a means for capturing a digital visual image within said
housing; and a means for capturing a digital thermal image within
said housing; a display apparatus, said display apparatus
comprising means for showing said captured visual image and said
captured thermal image; and a computing apparatus, said computing
apparatus operatively connected to said image capturing device and
to said display apparatus, said computing apparatus comprising: a
means for selecting a control area on the surface of the skin; a
means for determining an temperature of said control area; a means
for selecting an area of clinical interest within said visual
image; a means for calculating plane geometric features of said
selected area of clinical interest; a means for overlaying said
digital image onto said thermal image in a desired orientation on
said display apparatus; and a means for applying a unique pixel
value to a specific predetermined temperature range on said thermal
image.
Inventors: |
Spahn; James G.; (Carmel,
IN) ; McMurray; Nicholas A.; (Indianapolis,
IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Spahn; James G.
McMurray; Nicholas A. |
Carmel
Indianapolis |
IN
IN |
US
US |
|
|
Family ID: |
56555904 |
Appl. No.: |
15/726399 |
Filed: |
October 6, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14876535 |
Oct 6, 2015 |
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15726399 |
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14577571 |
Dec 19, 2014 |
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14876535 |
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13439177 |
Apr 4, 2012 |
9357963 |
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14577571 |
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62060322 |
Oct 6, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06T 2207/10048
20130101; A61B 5/6844 20130101; A61B 2560/0431 20130101; G01J
2005/0077 20130101; G01J 5/0265 20130101; G06T 7/62 20170101; G01J
5/0859 20130101; G06T 2207/30096 20130101; A61B 5/015 20130101;
G06T 2207/30088 20130101; G01J 5/025 20130101; A61B 5/445 20130101;
A61B 5/0077 20130101; A61B 5/7425 20130101; G01J 5/089 20130101;
A61B 5/1072 20130101; G01J 5/0025 20130101; A61B 5/441 20130101;
A61B 5/1075 20130101; A61B 5/0075 20130101; G06T 7/0012 20130101;
A61B 5/01 20130101 |
International
Class: |
G06T 7/00 20060101
G06T007/00; G01J 5/02 20060101 G01J005/02; A61B 5/01 20060101
A61B005/01; G01J 5/08 20060101 G01J005/08; G01J 5/00 20060101
G01J005/00; A61B 5/00 20060101 A61B005/00 |
Claims
1. A system for determining a clinically relevant temperature
differential between a predetermined area of interest on the body
surface of a mammal and a control area on the body surface of said
mammal, said system comprising: a visual and thermal image
capturing device, said image capturing device comprising: a
housing, a means for capturing a digital visual image within said
housing; and a means for capturing a digital thermal image within
said housing; a display apparatus, said display apparatus
comprising means for showing said captured visual image and said
captured thermal image; and a computing apparatus, said computing
apparatus operatively connected to said image capturing device and
to said display apparatus, said computing apparatus comprising: a
means for selecting a control area on the surface of the body; a
means for determining a temperature of said control area; a means
for overlaying said digital image onto said thermal image in a
desired orientation on said display apparatus; and a means for
applying a unique pixel value to a specific predetermined
temperature range on said thermal image.
2. The system of claim 1, wherein the system further comprises a
means for selecting an area of clinical interest within said visual
image.
3. The system of claim 1, wherein the system further comprises a
means for calculating plane geometric features of said selected
area of clinical interest.
4. The system of claim 1, wherein the system further comprises a
means for overlaying said digital image onto said thermal image in
a desired orientation on said display apparatus.
5. A system for determining a clinically relevant temperature
differential between a predetermined area of interest on the body
surface of a mammal and a control area on the body surface of said
mammal, said system comprising: a visual and thermal image
capturing device, said image capturing device comprising: a
housing, a means for capturing a digital visual image within said
housing; and a means for capturing a digital thermal image within
said housing; a display apparatus, said display apparatus
comprising means for showing said captured visual image and said
captured thermal image; and a computing apparatus, said computing
apparatus operatively connected to said image capturing device and
to said display apparatus, said computing apparatus comprising: a
means for selecting a control area on the surface of the body; a
means for determining a temperature of said control area; a means
for selecting an area of clinical interest within said visual
image; a means for calculating plane geometric features of said
selected area of clinical interest; a means for overlaying said
digital image onto said thermal image in a desired orientation on
said display apparatus; and a means for applying a unique pixel
value to a specific predetermined temperature range on said thermal
image.
6. A method of contemporaneously comparing an average temperature
of predetermined area of interest on the body surface of a mammal
and a control area on the body surface of said mammal, said method
comprising the steps of: capturing a physical image of a portion of
the body of a mammal; capturing a thermal image of said body
portion; displaying said physical and said thermal image on a
screen; selecting a control area on the surface of the skin;
determining an temperature of said control area; selecting an area
of clinical interest within said visual image; calculating plane
geometric features of said selected area of clinical interest;
overlaying said digital image onto said thermal image in a desired
orientation on said display apparatus; and applying a unique pixel
value to a specific predetermined temperature range on said thermal
image.
7. The method of claim 6, wherein the method further comprise
selecting an area of clinical interest within said visual
image.
8. The method of claim 6, wherein the method further comprise
calculating plane geometric features of said selected area of
clinical interest.
9. The method of claim 6, wherein the method further comprise
overlaying said digital image onto said thermal image in a desired
orientation on said display apparatus
10. A method of contemporaneously comparing an average temperature
of predetermined area of interest on the body surface of a mammal
and a control area on the body surface of said mammal, said method
comprising the steps of: capturing a physical image of a portion of
the body of a mammal; capturing a thermal image of said body
portion; displaying said physical and said thermal image on a
screen; selecting a control area on the surface of the body;
determining an temperature of said control area; selecting an area
of clinical interest within said visual image; calculating plane
geometric features of said selected area of clinical interest;
overlaying said digital image onto said thermal image in a desired
orientation on said display apparatus; and applying a unique pixel
value to a specific predetermined temperature range on said thermal
image.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present continuation-in-part application claims priority
to provisional U.S. patent application No. 62/060,322, filed on
Oct. 6, 2014; pending non-provisional U.S. patent application Ser.
No. 13/439,177, filed on Apr. 4, 2012; and pending to
non-provisional U.S. patent application Ser. No. 14/577,571, filed
on Dec. 19, 2014.
BACKGROUND
1. Field of the Invention
[0002] The present invention relates generally to methods of using
non-invasive technologies in medical care. More specifically, the
present invention relates to novel thermal imaging methods and the
use of the same in the medical field.
2. Description of the Prior Art
[0003] Over the last century, clinicians, which term includes
herein certified and licensed medical doctors of all specialties,
osteopathic doctors of all specialties, podiatrists, dental doctors
of all specialties, chiropractors, veterinarians of all
specialties, nurses, and medical imaging technicians, have become
dependent on the use of medical devices that assist them in their
delivery of patient-centered care. The common function of these
devices is to assist and not replace the clinical judgment of the
clinician. This fulfills the dictum that best practice is clinical
judgment assisted by scientific data and information.
[0004] Entering into the era of computer science and sophisticated
electronics, clinicians have the opportunity to be supported by
data and information in a statistically significant and timely
fashion. These advancements have allowed more extensive and useful
collection of meaningful data that can be acquired, analyzed, and
applied in conjunction with the knowledge and expertise of the
clinician.
[0005] Medical long-wave infrared (LIR) thermography has been known
to be beneficial in the evaluation of thermal heat intensity and
gradiency relating to abnormalities of the skin and underlying
tissue (SUT). Although this technology has expanded to other areas
of medical evaluation, the scope of this patent application is
limited to the skin and underlying tissue abnormalities. These
abnormalities include the formation of deep tissue injury (DTI) and
subsequent necrosis caused by mechanical stress, infection,
auto-immune condition, and vascular flow problems. DTI caused by
mechanical stress (pressure, shear and frictional forces) can be
separated into three categories. The first category is a high
magnitude/short duration mechanical stress represented by traumatic
and surgical wound and/or areas of interest. The second category is
low magnitude/long duration mechanical stress represented by
pressure ulcer development, which is also a factor in the
development of ischemic and neuropathic wound and/or areas of
interests. The third category is a combination of categories one
and two represented by pressure ulcer formation in the bariatric
patient.
[0006] The pathophysiologic conditions that occur with DTI and
subsequent necrosis of the affected tissue are ischemia, cell
distortion, impaired lymphatic drainage, impaired interstitial
fluid flow, and reperfusion injury: Category one is dominated by
cell distortion and even destruction. Category two is dominated by
ischemia. Category three is a combination of cell distortion and
ischemia.
[0007] Hypoxia causes aerobic metabolism to convert to anaerobic
metabolism. This occurrence causes lactic acidosis followed by cell
destruction, release of enzymes and lytic reactions. The release of
these substances causes additional cell injury and destruction, and
initiation of the inflammatory response.
[0008] It is very important to recognize that ischemic-reperfusion
injury is associated with all of the above mechanical stress
induced underlying tissue injuries. This condition is caused by a
hypoxia induced enzymatic change and the respiratory burst
associated with phagocytosis when oxygen returns after an ischemic
event. The result of ischemic-reperfusion injury is the formation
of oxygen free radicals (hydroxyl, superoxide, and hydrogen
peroxide) that cause damage to healthy and already injured cells
leading to extension of the original injury
[0009] Underlying tissue injury and subsequent necrosis can also be
caused by vascular disorders. Hypoxia can be caused by an arterial
occlusion or by venous hypertension. Lymphatic flow or node
obstruction can also create vascular induced injury by creating
fibrous restriction to venous drainage and subsequent cellular
stasis in the capillary system. These disorders are also
accentuated by reperfusion injury and oxygen free radical
formation.
[0010] Infection of the skin (impetigo), underlying tissue
(cellulitis), deep tissue (fasciitis), bone (osteomyelitis) and
cartilage (chondritis) causes injury and necrosis of the affected
tissue. Cells can be injured or destroyed by the microorganism
directly, by toxins released by the microorganism and/or the
subsequent immune and inflammatory response. These disorders are
also accentuated by reperfusion injury and oxygen free radical
formation.
[0011] Auto-immune morbidities of the skeletal joints (rheumatoid
arthritis), skin and underlying tissue (tendonitis, myelitis,
dermatitis) and blood vessels (vasculitis) cause similar
dysfunction and necrosis of the tissue being affected by the
hypersensitivity reactions on the targeted cells and the subsequent
inflammatory response. Again, these conditions are accentuated by
reperfusion and oxygen free radical formation.
[0012] The common event that addresses all of the above skin and
underlying tissue injuries is the inflammatory response. This
response has two stages. The first stage is vascular and the second
is cellular. The initial vascular response is vasoconstriction that
will last a short time. The constriction causes decrease blood flow
to the area of injury. The decrease in blood flow causes vascular
"pooling" of blood (passive congestion) in the proximal arterial
vasculature in the region of injury and intravascular cellular
stasis occurs along with coagulation.
[0013] The second vascular response is extensive vasodilation of
the blood vessels in the area of necrosis. This dilation along with
the "pooled" proximal blood causes increased blood flow with high
perfusion pressure into the area of injury. This high pressure flow
can cause damage to endothelial cells. Leakage of plasma, protein,
and intravascular cells causes more cellular stasis in the
capillaries (micro-thrombotic event) and hemorrhage into the area
of injury. When the perivascular collagen is injured, intravascular
and extravascular coagulation occurs. The rupture of the mast cells
causes release of histamine that increases the vascular dilation
and the size of the junctions between the endothelial cells. This
is the beginning of the cellular phase. More serum and cells
(mainly neutrophils) enter into the area of the mixture of injured
and destroyed cells by the mechanism of marginalization, emigration
(diapedesis) and the chemotaxic recruitment (chemotaxic gradiency).
Stalling of the inflammatory stage can cause the area of necrosis
(ring of ischemia) to remain in the inflammatory stage long past
the anticipated time of 2-4 days. This continuation of the
inflammatory stage leads to delayed resolution of the ischemic
necrotic event.
[0014] The proliferation stage starts before the inflammatory stage
recedes. In this stage angiogenesis occurs along with formation of
granulation and collagen deposition. Contraction occurs, and peaks,
at 5-15 days post injury.
[0015] Re-epithelialization occurs by various processes depending
on the depth of injury. Partial thickness wound and/or area of
interests can resurface within a few days. Full thickness wound
and/or area of interests need granulation tissue to form the base
for re-epithelialization to occur. The full thickness wound and/or
area of interest does not heal by regeneration due to the need for
scar tissue to repair the wound and/or area, of interest. The
repaired scarred wound and/or area of interest has less vascularity
and tensile strength of normal regional uninjured skin and
underlying tissue. The final stage is remodeling. In this stage the
collagen changes from type III to a stronger type I and is
rearranged into an organized tissue.
[0016] All stages of wound and/or area of interest healing require
adequate vascularization to prevent ischemia, deliver nutrients,
and remove metabolic waste. Following the vascular flow and
metabolic activity of a necrotic area is currently monitored by
patient assessment and clinical findings of swelling, pain,
redness, increased temperature, and loss of function.
[0017] Medical devices are now available to assist the clinician in
defining the presence, type, and status of the skin and underlying
tissue injury. The LIR thermal and digital imaging device is a
non-contact and non-radiating device that can be utilized bedside.
The combination of imagers allows both visible and invisible
radiation from the body to be evaluated. (See FIG. 1) This allows
both the anatomical and physiologic status of the skin and
underlying tissue to be evaluated for injuries or disorders that
are not yet clinically recognizable. By visualizing the IR thermal
intensity, the clinician can evaluate the gradiency of the
long-wave radiation emitted from the body region being imaged. The
ability to visualize the thermal gradiency allows the clinician to
evaluate the metabolic activity and blood flow of the region being
imaged. The normal underlying tissue can be used as a control for
that specific imaging procedure.
[0018] Having a real time control allows an area of interest (AOI)
to be recognized. The AOI can be of greater intensity (hotter) or
less intensity (cooler) than the normal underlying tissue of that
region of the body. The AOI can then be evaluated by the clinician
for the degree of metabolism, blood flow, necrosis, inflammation
and the presence of infection by comparing the warmer or cooler
thermal intensity of the AOI or wound and/or area of interest base
and peri-AOI or wound and/or area of interest area to the normal
underlying tissue of the location being imaged. Serial imaging also
can assist the clinician in the ability to recognize improvement or
regression of the AOI or wound and/or area of interest over
time.
[0019] The use of an LIR thermal and digital visual imager can be a
useful adjunct tool for clinicians with appropriate training to be
able to recognize physiologic and anatomical changes in an AOI
before it presents clinically and also the status of the AOI/wound
and/or area of interest in a trending format. By combining the
knowledge obtained from the images with a comprehensive assessment,
skin and underlying tissue evaluation, and an AOI or wound and/or
area of interest evaluation will assist the clinician in analyzing
the etiology, improvement or deterioration, and the presence of
infection affecting the AOI or wound and/or area of interest.
[0020] The foundational scientific principles behind LIR
thermography technology are energy, heat, temperature, and
metabolism.
[0021] Energy is not a stand-alone concept. Energy can be passed
from one system to another, and can change from one form to
another, but can never be lost. This is the First Law of
Thermodynamics. Energy is an attribute of matter and
electromagnetic radiation. It is observed and/or measured only
indirectly through effects on matter that acquires, loses or
possesses it and it comes in many forms such as mechanical,
chemical, electrical, radiation (light), and thermal.
[0022] The present application focuses on thermal and chemical
energy. Thermal energy is the sum of all of the microscopic scale
randomized kinetic energy within a body, which is mostly kinetic
energy. Chemical energy is the energy of electrons in the force
field created by two or more nuclei; mostly potential energy.
[0023] Energy is transferred by the process of heat. Heat is a
process in which thermal energy enters or leaves a body as the
result of a temperature difference. Heat is therefore the transfer
of energy due to a difference in temperature; heat is a process and
only exists when it is flowing. When there is a temperature
difference between two objects or two areas within the same object,
heat transfer occurs. Heat energy transfers from the warmer areas
to the cooler areas until thermal equilibrium is reached. This is
the Second Law of Thermodynamics. There are four modes of heat
transfer: evaporation, radiation, conduction and convection.
[0024] Molecules are the workhorses and are both vehicles for
storing and transporting energy and the means of converting it from
one form to another. When the formation, breaking, or rearrangement
of the chemical bonds within the molecules is accompanied by the
uptake or release of energy it is usually in the form of heat. Work
is completely convertible to heat and defined as a transfer due to
a difference in temperature, however work is the transfer of energy
by any process other than heat. In other words, performance of work
involves a transformation of energy.
[0025] Temperature measures the average randomized motion of
molecules (kinetic energy) in a body. Temperature is an intensive
property by which thermal energy manifests itself. It is measured
by observing its effect on some temperature dependent variable on
matter (i.e. ice/steam points of water). Scales are needed to
express temperature numerically and are marked off in uniform
increments (degrees).
[0026] As a body loses or gains heat, its temperature changes in
direct proportion to the amount of thermal energy transferred from
a high temperature object to a lower temperature object. Skin
temperature rises and falls with the temperature of the
surroundings. This is the temperature that is referred to in
reference to the skins ability to lose heat its surroundings.
[0027] The temperature of the deep tissues of the body (core
temperatures) remains constant (within .+-.1.degree.
F./.+-.0.6.degree. C.) unless the person develops a febrile
illness. No single temperature can be considered normal.
Temperature measurements on people who had no illness have shown a
range of normal temperatures. The average core temperature is
generally considered to be between 98.0.degree. F. and 98.6.degree.
F. measured orally or 99.0.degree. F. and 99.6.degree. F. measured
rectally. The body can temporarily tolerate a temperature as high
as 101.degree. F. to 104.degree. F. (38.6.degree. C. to 40.degree.
C.) and as low as 96.degree. F. (35.5.degree. C.) or lower.
[0028] Metabolism simply means all of the chemical reactions in all
of the cells of the body. Metabolism creates thermal energy. The
metabolic rate is expressed in terms to the rate of heat release
during the chemical reactions. Essentially all the energy expended
by the body is eventually converted into heat.
[0029] Since heat flows from hot to cold temperature and the body
needs to maintain a core temperature of 37.0.degree.
C..+-.0.75.degree. C., the heat is conserved or dissipated to the
surroundings. The core heat is moved to the body surface by blood
flow. Decreased flow to the body surface helps conserve heat, while
increased flow promotes dissipation. Conduction of the core heat to
the body surface is fast, but inadequate alone to maintain the core
temperature. Heat dissipation from the body surface (3 mm
microclimate) also occurs due to the conduction, convection and
evaporation.
[0030] Heat production is the principal by-product of metabolism.
The rate of heat production is called the metabolic rate of the
body. The important factors that affect the metabolic rate are:
[0031] Basal Rate of Metabolism (ROM) of all cells of the body.
[0032] Extra ROM caused by muscle activity including shivering.
[0033] Extra ROM caused by the effect of thyroxine and other
hormones to a less extent (i.e.: growth hormone, testosterone).
[0034] Extra ROM caused by the effect of epinephrine,
norepinephrine, and sympathetic stimulation on the cells. [0035]
Extra ROM caused by increased chemical activity in the cells
themselves, especially when the cell temperature increases.
[0036] Most of the heat produced in the body is generated in the
deep organs (liver, brain, heart and the skeletal muscles during
exercise). The heat is then transferred to the skin where the heat
is lost to the air and other structures. The rate that heat is lost
is determined by how fast heat can be conducted from where it is
produced in the body core to the skin.
[0037] The skin, underlying tissues and especially adipose tissue
are the heat insulators for the body. The adipose tissue is
important since it conducts heat only 33% as effective as other
tissue and specifically 52% as effective as muscle. Conduction rate
of heat in human tissue is 18 kcal/cm/m2k. The skin and underlying
tissue insulator system allows the core temperature to be
maintained yet allowing the temperature of the skin to approach the
temperature of the surroundings.
[0038] Blood flows to the skin from the body core in the following
manner. Blood vessels penetrate the adipose tissue and enter a
vascular network immediately below the skin. This is where the
venous plexus comes into play. The venous plexus is especially
important because it is supplied by inflow from the skin
capillaries and in certain exposed areas of the body
(hands-feet-ears) by the highly muscular arterio-venous
anastomosis. Blood flow can vary in the venous plexus from barely
above zero to 30% of the total cardiac output. There is an
approximate eightfold increase in heat conductance between the
fully vasoconstricted state and the fully vasodilated state. The
skin is an effective controlled heat radiator system and the
controlled flow of blood to the skin is the body's most effective
mechanism of heat transfer from the core to the surface.
[0039] Heat exchange is based on the scientific principle that heat
flows from warmer to cooler temperatures. Temperature is thought of
as heat intensity of an object. The methods of heat exchange are:
radiation (60%), loss of heat in the form of LIR waves (thermal
energy), conduction to a solid object (3%), transfer of heat
between objects in direct contact and loss of heat by conduction to
air (15%) caused by the transfer of heat, caused by the kinetic
energy of molecular motion. Much of this motion can be transferred
to the air if it is cooler than the surface. This process is
self-limited unless the air moves away from the body. If that
happens, there is a loss of heat by convection. Convection is
caused by air currents. A small amount of convection always occurs
due to warmer air rising. The process of convection is enhanced by
any process that moves air more rapidly across the body surface
(forced convection). This includes fans, air flow beds and air
warming blankets.
[0040] Convection can also be caused by a loss of heat by
evaporation which is a necessary mechanism at very high air
temperatures. Heat (thermal energy) can be lost by radiation and
conduction to the surroundings as long as the skin is hotter than
the surroundings. When the surrounding temperature is higher than
the skin temperature, the body gains heat by both radiation and
conduction. Under these hot surrounding conditions the only way the
body can release heat is by evaporation. Evaporation occurs when
the water molecule absorbs enough heat to change to gas. Due to the
fact water molecules absorb a large amount of heat in order to
change into a gas, large amounts of body heat can be removed from
the body.
[0041] Insensible heat loss dissipates the body's heat and is not
subject to body temperature control (water loss through the lungs,
mouth and skin). This accounts for 10% heat loss produced by the
body's basal heat production. Sensible heat loss by evaporation
occurs when the body temperature rises and sweating occurs.
Sweating increases the amount of water to the skins surface for
vaporization. Sensible heat loss can exceed insensible heat loss by
30 times. The sweating is caused by electrical or excess heat
stimulation of the anterior hypothalamus pre-optic area.
[0042] The role of the hypothalamus (anterior pre-optic area) in
the regulation of the body's temperatures occurs due to nervous
feedback mechanisms that determine when the body temperature is
either too hot or too cold.
[0043] The role of temperature receptors in the skin and deep body
tissues relate to cold and warm sensors in the skin. Cold sensors
outnumber warm sensors 10 to 1. The deep tissue receptors occur
mainly in the spinal cord, abdominal viscera and both in and around
the great veins. The deep receptors mainly detect cold rather than
warmth. These receptors function to prevent low body temperature.
These receptors contribute to body thermoregulation through the
bilateral posterior hypothalamus area. This is where the signals
from the pre-optic area and the skin and deep tissue sensors are
combined to control the heat producing and heat conserving
reactions of the body.
[0044] "Temperature Decreasing Mechanisms" include: [0045]
Vasodilation of all blood vessels, but with intense dilation of
skin blood vessels that can increase the rate of heat transfer to
the skin eight fold. [0046] Sweating can remove 10 times the basal
rate of body heat with an additional increase in body temperature.
[0047] Decrease in heat production by inhibiting shivering and
chemical thermogenesis.
[0048] "Temperature Increasing Mechanisms" include: [0049] Skin
vasoconstriction throughout the body. [0050] Increase in heat
production by increasing metabolic activity, which may include:
Shivering (4 to 5 times increase) or Chemical Thermogenesis i.e.
burning fat, which may cause adults to have a 10-15% increase in
temperature and infants 100% increase in temperature.
[0051] LIR thermography evaluates the infra-red thermal intensity.
The microbolometer is a 320.times.240 pixel array sensor that can
acquire the long-wave infrared wavelength (7-14 micron) (NOT
near-infrared thermography) and convert the thermal intensity into
electrical resistance. The resistance is measured and processed
into digital values between 1-254. A digital value represents the
long-wave infrared thermal intensity for each of the 76,800 pixels.
A grayscale tone is then assigned to the 1-254 thermal intensity
digital values. This allows a grayscale image to be developed.
[0052] Using LIR thermography is a beneficial device to monitor
metabolism and blood flow in a non-invasive test that can be
performed bedside with minimal patient and ambient surrounding
preparation. The ability to accurately measure the LIR thermal
intensity of the human body is made possible because of the skins
emissivity (0.98.+-. is 0.01), which is independent of
pigmentation, absorptivity (0.98.+-.0.01) reflectivity (0.02) and
transmitability (0.000). The human skin mimics the "BlackBody"
radiation concept. A perfect blackbody only exists in theory and is
an object that absorbs and reemits all of its energy. Human skin is
nearly a perfect blackbody as it has an emissivity of 0.98,
regardless of actual skin color. These same properties allow
temperature degrees to be assigned to the pixel digital value. This
is accomplished by calibration utilizing a "BlackBody" simulator
and an algorithm to account for the above factors plus ambient
temperatures. A multi-color palate can be developed by clustering
pixel values. There are no industry standards how this should be
done so many color presentations are being used by various
manufacturers. The use of gray tone values is standardized,
consistent and reproducible. Black is usually considered cold and
white is usually considered hot by the industry.
[0053] An LIR camera has the ability to detect and display the LIR
wavelength in the electromagnetic spectrum. The basis for infrared
imaging technology is that any object whose temperature is above
0.degree. K radiates infrared energy. Even very cold objects
radiate some infrared energy. Even though the object might be
absorbing thermal energy to warm itself, it will still emit some
infrared energy that is detectable by sensors. The amount of
radiated energy is a function of the object's temperature and its
relative efficiency of thermal radiation, known as emissivity.
[0054] Emissivity is a measure of a surface's efficiency in
transferring infrared energy. It is the ratio of thermal energy
emitted by a surface to the energy emitted by a perfect blackbody
at the same temperature.
[0055] LIR thermography is a beneficial device to monitor
metabolism, and blood flow, and profusion of the skin and
underlying tissue in a non-invasive test that can be performed
bedside with minimal patient and ambient surrounding preparation.
It uses the scientific principles of energy, heat, temperature and
metabolism. Through measurement and interpretation of thermal
energy, it produces images that will assist clinicians to make a
significant impact on wound and/or area of interest care
(prevention, early intervention and treatment) through
detection.
SUMMARY
[0056] Accurate and repeatable measurement of size is essential for
documenting progression or regression of the wound and/or area of
interest. The long accepted gold standard of length times width
wound and/or area of interest measurement has been shown to have
significant errors between when used to compare the results of one
observer to another. The first part of the present invention
provides a system and method of tracing the wound and/or area of
interest edge on a visual image to provide clinicians with both
measurements of area and perimeter but the area and perimeter
measurement have been shown to be more accurate than length times
width with the perimeter measurement being the most accurate.
Another aspect of the present invention discloses a system and
method for using long wave infrared thermography to analyze
physiological aspects such as perfusion and metabolic activity as
measured by the effect of a body surface temperature. In another
aspect of the present invention there is disclosed a new
combination of digital and long wave infrared thermography cameras
to simultaneously capture a visual and infrared image of a wound
and/or area of interest and surrounding body surface.
[0057] Once captured the visual image is used to document the
appearance of a wound and/or area of interest, trace the wound
and/or area of interests edge, and determine the area and perimeter
of the wound and/or area of interest. The long wave infrared
thermographic camera however is used to provide insight into the
physiological functions of a wound and/or area of interest and
surrounding body surface. The present invention provides means for
a trace visual images wound and/or area of interest to be overlaid
onto the congruent thermal wound and/or area of interest shown by
the long wave infrared thermographic camera.
[0058] The present invention uses long wave infrared thermography
as a temperature measurement technique for the visualization and
quantification of thermal energy emitted by the human body surface.
When using long wave infrared thermography, thermal energy is
represented through a unique conversion of gray scale pixel values
to temperature values. The gray scale pixel value is a spectrum of
absolute white to absolute black where pixel value of one (absolute
black) is usually (but not necessarily) the coolest and a pixel
value of 254 (absolute white) is usually (but not necessarily) the
warmest.
[0059] Advantageously the system and methods of the present
invention do not provide absolute measurements of temperatures.
Instead the system and method of the present invention allows
clinicians to measure and record the temperature of a wound and/or
area of interest area of interest and compare that to known
unaffected areas on the patient. Thus the effects of extrinsic and
intrinsic variables that affect absolute temperature on a given day
and make absolute measurements unreliable for clinical purposes
especially when taken across different days or by different
clinicians are avoided. Some of these intrinsic variables include
the normal cycle of thermal production, age, chromatic morbidities,
body region, medications, core temperature and others. Extrinsic
variables including ambient temperature, humidity, air convection,
climate adaption of the tissue, configuration of the body surface,
sub straight temperature of the infrared core.
[0060] When assessing temperature data from multiple points in
time, it is essential that the intrinsic and extrinsic variables
described above are minimized. To accomplish this, selection of an
unaffected area on a body surface can be used as a control relative
to an affected area or likely affected area such as a wound and/or
area of interest area of interest. Because the control is exposed
to the same intrinsic and extrinsic variables as the affected area,
a comparison of the two makes them independent of such variables.
Since the temperature data can vary between body regions, it is
preferable that the selection of the control area occur on or near
the same body surface of the area of interest. If unable to obtain
the above, compare to same area on the contralateral side of the
body or an available part of the body of the contralateral side is
not available. This new reference area should be reproducible for a
particular patent.
[0061] In combinations with other clinical information clinicians
are provided with relative quantitative data and relative
qualitative data. Measurements of relative temperature differential
can allow clinicians to accurately and reliably evaluate wound
and/or area of interest by comparing the same over time through
ratio analyses, graphs, and algorithms to unaffected areas thus
eliminating the variables that might affect the accuracy of such
measurements at a single point in time.
[0062] Thus, the present invention comprises, in one exemplary
embodiment, a system for determining a clinically relevant
temperature differential between a predetermined area of interest
on the body surface of a mammal and a control area on the body
surface of said mammal, said system comprising: a visual and
thermal image capturing device, said image capturing device
comprising: a housing, a means for capturing a digital visual image
within said housing; and a means for capturing a digital thermal
image within said housing; a display apparatus, said display
apparatus comprising means for showing said captured visual image
and said captured thermal image; and a computing apparatus, said
computing apparatus operatively connected to said image capturing
device and to said display apparatus, said computing apparatus
comprising: a means for selecting a control area on the surface of
the skin; a means for determining an temperature of said control
area; a means for selecting an area of clinical interest within
said visual image; a means for calculating plane geometric features
of said selected area of clinical interest; a means for overlaying
said digital image onto said thermal image in a desired orientation
on said display apparatus; and a means for applying a unique pixel
value to a specific predetermined temperature range on said thermal
image.
[0063] In another exemplary embodiment, the present invention
comprises a method of contemporaneously comparing an average
temperature of predetermined area of interest on the body surface
of a mammal and a control area on the body surface of said mammal,
said method comprising the steps of: capturing a physical image of
a portion of the body of a mammal; capturing a thermal image of
said body portion; displaying said physical and said thermal image
on a screen; selecting a control area on the surface of the skin;
determining an temperature of said control area; selecting an area
of clinical interest within said visual image; calculating plane
geometric features of said selected area of clinical interest;
overlaying said digital image onto said thermal image in a desired
orientation on said display apparatus; and applying a unique pixel
value to a specific predetermined temperature range on said thermal
image.
BRIEF DESCRIPTION OF THE DRAWINGS
[0064] The present invention will be understood more fully from the
detailed description given hereinafter and from the accompanying
drawings of the preferred embodiment of the present invention,
which, however, should not be taken to limit the invention, but are
for explanation and understanding only.
[0065] In the drawings:
[0066] FIG. 1A shows: A visual and thermal image capturing device
according to the present invention.
[0067] FIG. 1B shows: Left side view of the device open and closed
of FIG. 1A.
[0068] FIG. 1C shows: Top view of the device open and closed of
FIG. 1A.
[0069] FIG. 1D shows: front view of the device open and closed of
FIG. 1A.
[0070] FIG. 1E shows: right side view of the device open and closed
of FIG. 1A.
[0071] FIG. 1F shows: bottom side view of the device open and
closed of FIG. 1A.
[0072] FIG. 1G shows: back side view of the device open and closed
of FIG. 1A.
[0073] FIG. 1H shows: Side by side thermal and visual images
captured by the device of FIGS. 1A and 1B.
[0074] FIG. 2 shows: A computer display of a wound trace on a
visual image of the body surface.
[0075] FIG. 3 shows: A computer display of a wound trace overlaid
on a thermal image of the body surface.
[0076] FIG. 4 shows: A computer display of a wound trace placed on
a thermal image of the body surface.
[0077] FIG. 5 shows: A non-relative "gray scale" for use with the
present invention.
[0078] FIG. 6 shows: A non-relative "color scale for use with the
present invention.
[0079] FIG. 7 shows: An exemplary "hot" thermal image for use with
the present invention.
[0080] FIG. 8A shows: An exemplary "cold" thermal image for use
with the present invention.
[0081] FIG. 8B shows: An exemplary "cold" thermal image for use
with the present invention.
[0082] FIG. 9 shows: A "profile" line for use with the present
invention.
[0083] FIG. 10A shows: A profile line plot showing body surface and
underlying tissue anomaly before and after resolution for use with
the present invention.
[0084] FIG. 10B shows: A profile line plot showing body surface and
underlying tissue anomaly before and after resolution for use with
the present invention.
[0085] FIG. 11 shows: A larger view of the profile line shown in
FIG. 9.
[0086] FIG. 12 shows: A graphical representation of the data used
to calculate the center point of a traced area.
[0087] FIG. 13 shows: A graphical representation of orienting an
unaffected reference area based on head direction and the center
point of the traced area.
[0088] FIG. 14 shows: An alternative representation of orienting an
unaffected reference area based on head direction and the center
point of the traced area.
[0089] FIG. 15 shows: A graph and calculation for automatically
calculating an unaffected reference area.
[0090] FIG. 16 shows: A photograph of a wound trace on a visual
image of the body surface.
[0091] FIG. 17 shows: A photograph of a wound trace placed on a
thermal image of the body surface.
[0092] FIG. 18 shows: A photograph of a graphical method of
calculating the center point of a traced area.
[0093] FIG. 19 shows: A photograph of a graphical method before
choosing proper head direction.
[0094] FIG. 20 shows: A photograph of the graphical method of FIG.
19 after proper head direction has determined.
[0095] FIG. 21 shows: A photograph of an unaffected reference area
displayed by the present invention.
[0096] FIG. 22 shows: A photograph of a traced area, head
direction, and unaffected reference area on a first day of
study.
[0097] FIG. 23 shows: A photograph of the automatic unaffected
reference area of FIG. 22 on a second day of study; based on traced
area, head direction, and unaffected reference area from first day
of study.
[0098] FIG. 24 shows: A photograph of the automatic unaffected
reference area of FIG. 22 on a third day of study; based on traced
area, head direction, and unaffected reference area from first day
of study.
[0099] FIG. 25 shows: A non-relative "gray" scale as may be used
with the present invention.
[0100] FIG. 26 shows: A non-relative "color" scale as may be used
with the present invention.
[0101] FIG. 27 shows: A gray scale image before applying a
non-relative color scale.
[0102] FIG. 28 shows: A non-relative color scale based on the image
in FIG. 27.
[0103] FIG. 29 shows: A relative color scale may be used with the
present invention.
[0104] FIG. 30 shows: A relative color scale image comparing the
area of interest to an unaffected reference area.
[0105] FIG. 31 shows: An exemplary graphical representation of a
wound site comprising a wound base and periwound.
[0106] FIG. 32 shows: A computer display of wound trace on a visual
image of the body surface.
[0107] FIG. 33 shows: A photograph of a wound trace overlaid cm a
thermal image of the body surface.
[0108] FIG. 34 shows: A close up view of FIG. 33.
[0109] FIG. 35 shows: A photograph of a wound trace placed on a
thermal image as in FIG. 33.
[0110] FIG. 36 shows: A photograph of the display of FIG. 35 with a
non-relative color scale.
[0111] FIG. 37 shows: A photograph of the wound of FIG. 33 with an
unaffected reference area selected.
[0112] FIG. 38 shows: A photograph of an overlaid wound trace and
unaffected reference area on a thermal image with a relative color
scale.
[0113] FIG. 39 shows: A photograph of an overlaid wound trace,
unaffected reference area, and area of interest trace on a thermal
image with a relative color scale.
[0114] FIG. 40 shows: A photograph of the relative color wound bend
of FIG. 38 combined with a non-relative gray scale image.
[0115] FIG. 41 shows: A photograph of the relative color periwound
of FIG. 38 combined with a non-relative gray scale image.
[0116] FIG. 42 shows: A photograph of the relative color wound site
of FIG. 38 combined with a non-relative gray scale image.
[0117] FIG. 43A shows: A plot of relative temperature histogram
data from the wound bed, periwound, wound site, and unaffected
reference area.
[0118] FIG. 43B shows: A plot of relative temperature histogram
data from the wound bed, periwound, wound site, and unaffected
reference area.
[0119] FIG. 43C shows: A plot of relative temperature histogram
data from the wound bend, periwound, wound site, and unaffected
reference area.
[0120] FIG. 43D shows: A plot of relative temperature histogram
data from the wound bend, periwound, wound site, and unaffected
reference area.
[0121] FIG. 44 shows: An exemplary algorithm for calculating the
wound trace, overlaid wound trace, periwound trace, wound site
trace, general (area of interest) trace and unaffected reference
area in the manner of the present invention.
[0122] FIG. 45 shows: A photograph of a wound trace in profile
line.
[0123] FIG. 46 shows: A plot of the profile line of FIG. 45.
[0124] FIG. 47 shows: A plot of temperature gradiency of a wound
bend.
[0125] FIG. 48 shows: A plot of the temperature gradiency of a
periwound.
[0126] FIG. 49 shows: A plot of the temperature gradiency of the
wound bed based on the unaffected reference area.
[0127] FIG. 50 shows: A plot of the wound bed area.
[0128] FIG. 51 shows: A plot of the wound bed perimeter.
[0129] FIG. 52 shows: A plot of wound bed temperature gradiency
compared to an unaffected area.
[0130] FIG. 53 shows: A plot periwound temperature gradiency
compared to a gradiency of an unaffected area.
[0131] FIG. 54 shows: A schematic of pixel values applied to a
thermal image of a wound.
[0132] FIG. 55A shows: Photographs comparing non-relative thermal
images to relative thermal images.
[0133] FIG. 55B shows: Photographs comparing non-relative thermal
images to relative thermal images.
[0134] FIG. 55C shows: Photographs comparing non-relative thermal
images to relative thermal images.
[0135] FIG. 56 shows: Trace of visual wound edge.
[0136] FIG. 57 shows: Traced wound edge on thermal.
[0137] FIG. 58 shows: Center point of wound based on overlaid
trace.
[0138] FIG. 59 shows: Head direction of wound selected based on
visual or thermal image.
[0139] FIG. 60 shows: Head direction of wound selected based on
visual or thermal image.
[0140] FIG. 61 shows: Reference area for software selected on
thermal image.
[0141] FIG. 62 shows: Distance from vertex to reference area on
first day.
[0142] FIG. 63 shows: Distance from vertex to reference area on
second day.
[0143] FIG. 64 shows: Distance from vertex to reference area on
third day.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0144] The present invention will be discussed hereinafter in
detail in terms of the preferred embodiment according to the
present invention with reference to the accompanying drawings. In
the following description, numerous specific details are set forth
in order to provide a thorough understanding of the present
invention. It will be obvious, however, to those skilled in the art
that the present invention may be practiced without these specific
details. In other instance, well-known structures are not shown in
detail in order to avoid unnecessary obscuring of the present
invention.
[0145] The following detailed description is merely exemplary in
nature and is not intended to limit the described embodiments or
the application and uses of the described embodiments. As used
herein, the word "exemplary" or "illustrative" means "serving as an
example, instance, or illustration." Any implementation described
herein as "exemplary" or "illustrative" is not necessarily to be
construed as preferred or advantageous over other
implementations.
[0146] All of the implementations described below are exemplary
implementations provided to enable persons skilled in the art to
make or use the embodiments of the disclosure and are not intended
to limit the scope of the disclosure, which is defined by the
claims. In the present description, the terms "upper", "lower",
"left", "rear", "right", "front", "vertical", "horizontal", and
derivatives thereof shall relate to the invention as oriented in
FIG. 1.
[0147] Furthermore, there is no intention to be bound by any
expressed or implied theory presented in the preceding technical
field, background, brief summary or the following detailed
description. It is also to be understood that the specific devices
and processes illustrated in the attached drawings, and described
in the following specification, are simply exemplary embodiments of
the inventive concepts defined in the appended claims. Hence,
specific dimensions and other physical characteristics relating to
the embodiments disclosed herein are not to be considered as
limiting, unless the claims expressly state otherwise.
[0148] Accurate and repeatable measurement of size is essential for
documenting progression or regression of the wound and/or area of
interest. The long accepted standard of wound and/or area of
interest measurement is to multiply the length of the wound and/or
area of interest by its width. However, this method has been shown
to have significant errors when used to compare the results of one
observer to another. The present invention provides a system and
method of tracing the wound and/or area of interest edge on a
visual image to provide clinicians with both measurements of wound
and/or area of interest area and perimeter. The present invention
further comprises a system and method for using long wave infrared
thermography to analyze physiological aspects such as perfusion and
metabolic activity as measured by the effect of a body surface
temperature. In another aspect of the present invention there is
disclosed a new combination of digital and long wave infrared
thermography cameras to simultaneously capture a visual and
infrared image of a wound and/or area of interest and surrounding
body surface.
[0149] Using the system and methods of the present invention, a
visual image is captured and used to document the appearance of a
wound and/or area of interest, trace the wound and/or area of
interests edge, and determine the area and perimeter of the wound
and/or area of interest. Simultaneously, a long wave infrared
thermographic camera is used to provide insight into the
physiological functions of a wound and/or area of interest and
surrounding body surface. The present invention thus includes means
for a trace around an area of interest on a visual image of a wound
and/or area of interest to be overlaid onto the congruent thermal
wound and/or area of interest shown by the long wave infrared
thermographic camera.
[0150] The present invention further comprises using long wave
infrared thermography as a temperature measurement technique for
the visualization and quantification of thermal energy emitted by
the human body surface. When using long wave infrared thermography,
thermal energy is represented through a unique conversion of gray
scale pixel values to temperature values. The gray scale pixel
value is a spectrum of absolute white to absolute black where pixel
value of one (absolute black) is the coolest and a pixel value of
254 (absolute white) is the warmest. Since the imaging device of
the present invention is calibrated to within a range of 22 to 42
degrees Celsius, it is able to detect temperature differentials
within 0.08 degrees Celsius.
[0151] Advantageously, the system and methods of the present
invention do not provide absolute measurements of temperatures.
Instead, the system and method of the present invention allows
clinicians to measure and record the temperature of a wound and/or
area of interest area of interest and compare that to known
unaffected areas on the patient. Thus, the effects of intrinsic and
intrinsic variables that affect absolute temperature on a given day
and make absolute measurements unreliable for clinical purposes
especially when taken across different days or by different
clinicians are avoided. Some of these intrinsic variables include
the normal cycle of thermal production, age, chromatic morbidities,
body region, medications, core temperature and others. Extrinsic
variables including ambient temperature, humidity, air convection,
climate adaption of the tissue, configuration of the body surface,
sub straight temperature of the infrared core.
[0152] When assessing temperature data from multiple points in
time, it is essential that the intrinsic and extrinsic variables
described above are minimized. To accomplish this, selection of an
unaffected area on a body surface can be used as a control relative
to an affected area or likely affected area such as a wound and/or
area of interest area of interest. Because the control is exposed
to the same intrinsic and extrinsic variables as the affected area,
a comparison of the two makes them independent of such variables.
Since the temperature data can vary between body regions however it
is important that the selection of the control area occur on or
near the same body surface of the area of interest.
[0153] In combinations with other clinical information, clinicians
are provided with relative quantitative data and relative
qualitative data as shown in FIG. 55. Measurements of relative
temperature differential can allow clinicians to accurately and
reliably evaluate wound and/or area of interest areas of interest
by comparing the same over time through ratio analyses, graphs, and
algorithms to unaffected areas thus eliminating the variables that
might affect the accuracy of such measurements at a single point in
time.
[0154] In the present invention, thermal images taken of the body
surface are constructed by passively reading emitted radiant energy
formed by the underlying tissue and the skin tissue by detecting
wavelengths in the long-wave infrared range (LIR) of 7-14 microns,
and then in real time converting these values into pixels within a
digital image. The value assigned to the pixel indicates the
thermal intensities of a particular area of the skin when imaged.
Thermal images are presented in digital 8-bit grayscale with pixel
values ranging from 0-254. Generally, the unaffected skin thermal
intensity will be a uniform gray color within a range of +/-3 to 6
pixel values, which is equal to 0.25 to 0.5 degrees centigrade.
Abnormally hot areas of the skin will be represented by patches of
increasingly white pixels, while abnormally cold areas will be
represented by increasingly dark patches of pixels.
[0155] These same techniques work with images of varying color
resolutions.
[0156] These images are preferably stored in a data bank along with
information about the data that can be retrieved by a clinician for
future review and analysis.
[0157] The use of LIR (7-14 microns) imaging along with visual
digital imaging allows both physiologic (long-wave infrared and
visual) and anatomic assessment of skin and underlying tissue
abnormalities and or existing open wound and/or area of interests.
The gradiency of the thermal intensity, not the absolute amount of
intensity, is the important component of the long-wave thermal
image analysis that will allow the clinician to evaluate
pathophysiologic events. This capability is beneficial to the
clinician in the prevention, early intervention and treatment
assessments of a developing existing condition caused by, but not
exclusively, wound and/or area of interests, infection, trauma,
ischemic events and autoimmune activity.
[0158] As stated previously herein, utilizing absolute temperature
values (P, C0, and Kelvin) as the numerical values of LIR thermal
heat intensity is complicated due to the need to have a controlled
environment. This is required since the value of the absolute
temperature scales is affected by ambient temperature, convection
of air, and humidity. These variables would need to be measured and
documented continuously if temperature values were used. Also the
emissivity, absorptivity, reflexivity and transmitability of the
skin and underlying tissue can be affected by skin moisture,
scabbing, slough and/or eschar formation in an open wound and/or
area of interest.
[0159] The thermal imager of the present invention utilizes raw
data captured by a microbolometer. This data is utilized in
determining pixel values relating to the intensity of the thermal
energy from the long-wave infrared electromagnetic radiation
spectrum being emitted by the human body. The pixel gradient
intensities are represented for visualization by the grayscale
presentation.
[0160] The pixel values in the grayscale thermal images also vary
with the varying conditions mentioned above and hence the
algorithms proposed in this application use the average pixel value
of the unaffected skin region for that patient on the day the image
was taken as a reference point for all the calculations.
[0161] There is a difference in the LIR thermal intensity regions
of the human body. LIR images have a defined pixel intensity range
that is based on the specific usage of an LIR image. In the arena
of skin and underlying tissue LIR thermal gradiency, the range is
within homeostasis requirements to sustain life. The visualization
of pixel intensities is accomplished by the use of a standardized
8-bit grayscale. Black defines cold, gray tones define cool and/or
warm and white defines hot. When the imager is used for capturing
extremely hot or extremely cold regions that fall outside the
thermal range of the imager, the pixel values reach the saturation
point, and it becomes extremely difficult for the human eye to
differentiate variations in the pixel values.
[0162] Visual and thermal imagers used in the imaging apparatus of
the present invention don't have the exact same field of view.
Hence, the digital visual and thermal images cannot be overlaid
automatically. To help the user with positioning the overlay image,
the present invention comprises image alignment line feature by
which a user can draw a line tracing the edges of an area of
interest of a body part seen in a visual image. A transparent image
is created showing the area traced on the visual image which is
then overlaid on top of a thermal image. When creating the
transparent overlay image, the lines along with the trace will be
included. Since the edges of the human body are clearly
distinguishable in a thermal image, having an alignment line,
described herein below, along with the trace, provides visual aid
in deciding the proper positioning of the overlay.
[0163] Once the trace has been placed around the area of interest
on the visual image, for each coordinate along the trace, by adding
the X and Y shift, the corresponding X and Y coordinates on the
thermal image can be obtained. A transparent image is created and a
trace is drawn using the new X and Y coordinate and is overlaid on
top of the thermal image as shown in the figure below, allowing the
user to position it if needed before dropping the trace on the
digital image.
[0164] When the user confirms the position where the trace needs to
be dropped in the thermal image, the overlay image is removed and
the trace is placed on the thermal image itself as shown in FIG.
3.
[0165] Long wave infrared thermography captures thermal images that
can provide insight into the physiological functions of the wound
and/or area of interest and the surrounding body surface. They
provide more in-depth information than an image captured using a
regular digital camera. The method of the present invention
comprises software means that allow the user to trace an area of
interest and obtain several measurements including for example
temperature gradiency within the wound and/or area of interest
which is helpful in tracking the progression or regression of the
area of interest.
[0166] Thus, the system and methods of the present invention allow
a user to analyze a pair of thermal and visual images to obtain an
in-depth understanding of the status of an area of interest on a
patient. Using the present system and methods a trace is drawn
around an area of interest on a visual image representing. The area
and perimeter for the traced area are calculated and displayed as
results. The traced area on the visual image is then overlaid on a
thermal image.
[0167] The thermal core, however, of a camera according to the
present invention is likely to produce an image with barrel
distortion. In barrel distortion, image magnification decreases
with distance from the optical axis. The apparent effect is that of
an image which has been morphed around a sphere or a barrel. In
order to correct for barrel distortion, several different methods
may be used. However in the present invention, it's preferable to
use the lens distort algorithm available in MATLAB. The algorithm
takes as input the original distorted image as well as additional
parameters and generates as output a barrel distortion corrected
image. The method of accomplishing this is shown in Appendix 1.
Those of skill in the art will appreciate that the color scale has
a degree of predetermined "grouping" to enhance visual clarity.
[0168] The barrel distortion corrected image is then adjusted for
Keystone correction. In order to make sure that both cameras are
pointing at the same field of view, the thermal camera is installed
at an angle which produces a Keystone effect on the images. The
Keystone effect algorithm developed in MATLAB takes the input image
that needs to be corrected and the amount of blank space and
generates the corrected images as output.
[0169] Thus, when the images are opened, the system of the present
invention incorporates software means for correcting the images for
barrel (and Keystone) distortion before the images are displayed on
a screen for the user. The distortion correction software is
applied each time the images are opened, but the original image
data is never altered. In the preferred embodiment of the present
invention, the only data stored in the database is the original
images. The parameters used for the distortion correction are
specific to each calibrated image capture device.
[0170] The image capture device of the present invention may
further incorporates means for live video stream image capture from
the thermal camera. Visual and thermal captured images may be
displayed and stored (in grey scale, another color scale, or in a
specific pixel value scale) simultaneously. The image is captured
or stored in a database in their original format, i.e. without
distortion correction. Distortion correction is not applied until
the image is uploaded and pulled from the database for review.
[0171] A trace has been drawn around an area of interest on the
visual image for later study. For each coordinate along the trace,
by adding the X and Y shift, the corresponding X and Y coordinates
on the thermal image can be obtained. A transparent image is
created, and a trace is drawn using the new X and Y coordinates and
is overlaid on top of the thermal image allowing the user to
position it if needed before dropping the trace onto the thermal
image. The user confirms the position where the trace needs to be
dropped on the thermal image overlay. The overlay image is then
removed and the trace is drawn on the thermal image itself.
[0172] To help the user with positioning the overlay image, an
image alignment line feature is incorporated into the system of the
present invention to allow the user to draw a line tracing the
edges of the body part on the visual image. When creating the
transparent overlay image, the line along with the trace is
included. Since the edges of the human body are clearly
distinguishable in a thermal image, having an alignment line along
with a trace provides visual aid in deciding the proper positioning
of the overlay. Once a trace has been drawn on the thermal image an
unaffected reference point can be selected. To help with the
process of selecting an unaffected reference point, a gray scale or
iron scale thermal mosaic is applied to the thermal image. Grey
scales (or other color scales, such as "iron") are used for
"unbundled" raw data. "Bundled" data uses a single reference point
rather than a reference area.
[0173] An area of interest needs to be traced before the unaffected
reference point can be selected. The mean or average pixel value of
the traced area is used as a reference. For the thermal images
captured using the devices disclosed in the present invention, a
pixel value difference of preferably about 12 represents a one
degree Celsius change in temperature. All of the pixels whose pixel
values fall within the range of a mean of plus or minus six are
considered suitable to be selected as a reference point. A
different color is used for representing each degree change in
temperature. White is generally used to represent hot, and black
generally represents cold in the preferred embodiment. However,
those with skill in the art will appreciate that any colors may be
chosen. Similarly for the R G B scale it is preferred to use red to
represent hot and green or blue to represent pixels that are colder
than the reference area.
[0174] To select an unaffected reference point a user of the system
of the present invention should check whether a thermal trace
exists. If yes, check to see whether pixels fall inside the trace
and use the pixel values of all those pixels to calculate the
average pixel value, decide on the color codes that represent each
temperature interval, for example 15 different shades are chosen
for the color scale, then use the base color that falls within the
color scale to highlight all pixels within a pixel mean value of
between plus and minus six. Appendix 2 shows the logic used to
color the rest of the pixels.
[0175] After reviewing the images by drawing traces and obtaining
measurements out of these traces, a particular session with regard
to a particular patient may be saved. The system of the present
invention can generate visual or graphical or tabular results based
on the images obtained and the calculations made. FIGS. 32-43 show
various representations of the steps of the methods described
above.
[0176] FIG. 44 shows an exemplary logic model for the visual
overlay trace and the wound and/or area of interest sight trace
aspects of the present invention. In FIG. 46 shows a profile line
plot according to the method of the present invention. FIG. 45
shows a visual representation on a patient of the profile line plot
shown in FIG. 46.
[0177] FIGS. 47 through 53 show various graphical representations
of the calculations that can be performed by the system in methods
of the present invention.
[0178] The periwound is defined as the skin and all underlying
tissue surrounding contiguously with the area that is recognized as
the wound and/or area of interest base. Abnormalities of this
tissue can be clinically or non-clinically recognizable. The
periwound should be considered a deep tissue injury prone area.
Accordingly, the periwound is an ideal area of interest for a trace
on the visual image of a wound and/or area of interest.
[0179] The periwound is the tissue surrounding the wound and/or
area of interest itself. This tissue provides an access corridor
for blood, etc. to the wound and/or area of interest, for healing
and progress. Complications to this ideal function come because
periwound tissue can be adversely affected by infection prolonged
inflammation; poor blood supply; poor metabolic activity. It is
important to clean the area of the wound and/or area of interest
and monitor the status of the wound and/or area of interest and
periwound including the skin and underlying tissue. Even using the
infrared thermographic images sometimes it is difficult to trace
the edges of a periwound as the periwound region does not have an
abrupt change in thermal intensity due to infrared radiation versus
visual. Instead, it slowly fades into the unaffected portion of the
skin.
[0180] To assist clinicians in choosing the periwound accurately,
the following technique was developed: [0181] 1. Trace the area of
interest or the visual image; [0182] 2. Overlay the trace from
visual image onto the thermal image. The overlaid trace can now be
treated as the wound and/or area of interest base; [0183] 3. Allow
the user to specify the distance in centimeters, generally 1 to 5
centimeters, between the wound and/or area of interest base edge
and the periwound edge; [0184] 4. Using the coordinates of the
wound and/or area of interest base and the distance information a
new set of coordinates can be calculated that represent the corners
of the periwound.
[0185] To highlight the abnormal area of interest in a visual
image: [0186] 1. Start tracing the area of interest by clicking on
the image; see the X and Y coordinates of the click points. [0187]
2. Use the mouse, or other input device to draw lines connecting
the adjacent points on the computer screen. [0188] 3. When the user
double clicks the mouse join the last point of the first point
which finishes up the trace. [0189] 4. Using each click point as a
coordinate determine which pixels fall inside the polygon area
representing the trace. The trace now represents the wound and/or
area of interest base region as shown on the figure below.
[0190] Once the wound and/or area of interest base area has been
traced, the user is given an option to provide the distance between
the wound and/or area of interest base and the periwound regions.
The user can specify the distance in centimeters or any other
convenient set of measuring units. By knowing the distance at which
the image was captured, we can convert the distance in centimeters
to distance in pixels. For example, we know that for a thermal
image captured at 18 inches, there would be approximately 40 pixels
in an inch. So, if the user says the distance between the periwound
base and the periwound traces is 1 centimeter, we can calculate the
corresponding number of pixels between the two traces.
[0191] The wound and/or area of interest base can be considered as
a polygon where each coordinate corresponds to a corner. The new
coordinates of the periwound can be calculated by offsetting the
polygon for a distance equal to the distance (in pixels) between
the two traces. The Clipper Library was used for performing polygon
offsetting. This library is based on Vatti's clipping algorithm.
FIG. 4 shows the periwound trace obtained by offsetting the wound
and/or area of interest base polygon by 1 centimeter in all
directions.
[0192] Since the polygon is offset by the same amount in all
directions, there are chances that a portion of the periwound trace
may fall outside the desired area (for example the trace may
coincide with the background or other portions of the body that do
not comprise the periwound. As a work around for this problem the
user can either manually resize the periwound trace by altering the
position of one or more of the coordinates, or choose to exclude a
certain portion of the trace that falls outside the desired
area.
[0193] Wound and/or area of interest base and periwound together
are considered as the wound and/or area of interest sight. The
status of these traces can be monitored on a daily basis in
comparison to previous measurements to assess whether the wound
and/or area of interest is getting better or getting worse.
[0194] The periwound is defined as the area of skin surrounding a
wound and/or area of interest. The periwound can be traced on the
thermal image produced by the systems and methods of the present
invention then overlaid on the visual image. The area and perimeter
of the periwound can then be calculated relative to the visual
image.
[0195] The system checks to ensure that the periwound trace does
not overlap or fall outside the trace representing the base wound
and/or area of interest. Periwound calculations include only the
pixels that fall inside the outer thermal trace but not inside the
wound and/or area of interest bed trace. The combination of the two
is the wound site, as shown in FIG. 31.
[0196] A control unaffected area is chosen which allows for a true
relative temperature comparison between an unaffected area and
areas of interest. Relative temperature gradients above about 1.5
to 2 degrees Celsius are known to indicate significant
physiological aberrations. Possible causes for these aberrations
may include hyperthermia caused by inflammation or infection or
hypothermia caused by poor perfusion and/or tissue necrosis. The
present invention allows means to display the visual and
thermographic recorded data concurrently in a quantitative and
organized sequential format while storing the objective data for
future reference.
[0197] Combining the above technique with suggested usage of
unaffected skin and underlying tissue in the proximity of an
abnormality of a skin/underlying tissue location as a real time
control helps to minimize the variability and time consuming
requirements in utilizing temperature scales.
[0198] Choosing a controlled unaffected reference area ("CUA")
allows for a minimization of intrinsic and extrinsic variables for
the accurate determination of the relative temperature gradiency
between the wound and/or area of interest base, periwound, or
entire wound and/or area of interest sight in reference to the CUA.
Relative temperature gradients greater than 0.5 degrees Celsius are
known to indicate significant physiological aberrations. Possible
causes for hyperthermia include inflammation, infection. Possible
causes for hypothermia include poor perfusion, tissue necrosis,
poor metabolic activity; inflammation. Using the systems and
methods of the present invention visual and thermal recorded data
are displayed in human readable form in a quantitative and
organized sequential format. This thermal data allows for the
objective assessment of relative parodies and disparities between
the wound and/or area of interest base, periwound, and entire wound
and/or area of interest sight. This data, combined with other
information provided by the systems and methods of the present
invention allows a clinician to save and record quantitative
measurements from both an anatomical and physiological perspective
that may otherwise go unseen.
[0199] As stated previously, an unaffective reference area needs to
be chosen such that the temperature variation ("gradiency") across
the area is less than 1.5 degrees Celsius. In order to aid with the
selection of reference area, features like a "profile line" and
"color mosaic" provided in the software can be used.
[0200] The portion of the plot shown in FIG. 10 where the various
in temperature is less than 1.5 degrees Celsius represent the
suitable position for selecting the unaffected reference area. The
plot is user interactive, so the user can click on the chart to
highlight the point on the image and vice versa.
[0201] A profile line is another tool provided by the systems and
methods of the present invention that can be used to aid the user
in selecting the unaffected reference point. Profile line plots
show the variation in the pixel values across the line drawn at the
top of the wound and/or area of interest. Since the thermal
intensity is directly related to the gray scale pixel values in an
image, these plots can be used to monitor how the thermal intensity
is varying across the areas of interest.
[0202] Profile lines can be plotted by simply drawing a line across
an area of interest. FIG. 9 shows an example of the profile line
generated by drawing a line starting from the center of the wound
and/or area of interest base to a point that represents unaffected
skin. As seen in the plot, there is a huge drop in the pixel
value/thermal intensity across the wound and/or area of interest
base region and the value starts increasing as the line is moving
away from the wound and/or area of interest base and entering the
areas with normal skin tissue.
[0203] FIG. 11 shows an unaffected reference area chosen using the
profile line plot. The area of interest can be traced as seen on
the visual image and then overlaid onto the thermal image. The
results of the wound and/or area of interest trace along with the
information about head direction and unaffected reference area can
then be used to predict the suitable position for placing the
reference point on the images captured at future times.
[0204] Automating the process of selecting a reference point based
on the information provided makes the reference point selection
more consistent and eliminates variation between users evaluating
patients on different dates. An algorithm used in the present
invention for selecting a reference point comprises of the
following steps: [0205] 1. Selecting a direction of the head on a
visual image; [0206] 2. Overlaying an external wound and/or area of
interest trace drawn on the visual image onto a thermal image or
performing a thermal wound and/or area of interest trace on the
thermal image; [0207] 3. And manually selecting a reference area on
the thermal image.
[0208] Referring now to FIG. 12 there is shown a visual
representation useful in performing the calculations for selecting
a reference point. The method of selecting a reference point
includes calculating the distance between the center point of the
external wound and/or area of interest trace and the manually
selected reference area. Since the wound and/or area of interest
trace is a polygon, to find the center of the polygon one must
first find the minimum and maximum x coordinates along the
horizontal axis and the minimum and maximum y values along the
vertical axis. The distance between the center of the wound and/or
area of interest trace polygon (x1, y1) and the center of the
reference area (x2, y2, as shown in FIG. 12, can be calculated
using a standard distance formula where the distance equals the
square root of (x2-x1) squared plus (y2-y1) squared. Next the angle
formed between the selected head direction relative to the line
joining the center point of the overlaid external wound and/or area
of interest trace from the thermal image to the manually selected
reference area is calculated. With reference to FIG. 13, in order
to calculate angle B, angles H and A need to be calculated. H is
the head direction angle, and A is the angle made by the line
joining the center of the wound and/or area of interest trace and
the center of the reference point which can be calculated as
follows: If x1, y1 represent to the center of the wound and/or area
of interest trace and x2, y2 represent to the center of the
reference point, then the slope of the line can be calculated using
traditional geometry as the slope equals y2-y1 divided by x2-x1.
Since the slope can also be defined as tangent of angle A, angle A
can be calculated as A equals tan superscript negative one times
slope. Once angles H and A are known, angle B. can be calculated as
B=A-H.
[0209] Thus in setting an automated reference area the user must
set the head direction on the visual image; overlay the external
wound and/or area of interest trace and place it onto the thermal
image or perform a thermal wound and/or area of interest trace on
the thermal image; identify the automated reference area feature
then confirm the system determined automated reference area or
manually place the same.
[0210] Based on user's current selection of head direction and the
center point of the overlaid external wound and/or area of interest
trace from the thermal image, the system of the present invention
approximates the location of prior reference areas as shown in FIG.
14.
[0211] Again, as shown in FIG. 14, if "H.sub.new" is a new head
direction angle for the current session, based on the information
from previous sessions the system of the present invention can
determine the relative angle between the head direction line and a
line joining the center of the wound and/or area of interest trace
to the center of the reference point (B). Using the following
formula: Theta=H.sub.new+B, thereby giving the angle of the x
axis.
[0212] For the imaginary line joining the center of the wound
and/or area of interest trace to the center of the automated
reference point, we know the starting point of the line which would
be the coordinates of the center of the wound and/or area of
interest trace, the angle made by the line along the x axis (Theta)
and the length of the line, which is equal to the distance between
the center of the wound and/or area of interest trace and the
center of the pre-selected reference point. Using this information,
the end point, the coordinates of the automated reference point,
can be calculated as shown in FIG. 15.
[0213] User of the present invention is preferably given an option
to either use the automated reference area selection or to manually
select a new area. If the user chooses to use a manual selection
instead, that manual selection now becomes the baseline. The user
does not have to use the automated reference area. The user could
perform a manual selection each time the system and methods of the
present invention are used.
[0214] FIGS. 16 through 24 herein display the various steps
described in the previous paragraphs for determining an automated
reference area.
[0215] "Profile lines" can also be drawn to help with the selection
of an unaffected reference point. Profile lines are freeform lines
drawn across the image. The profile line plots display the
variation in temperature along the line. If the line is flat, it
indicates the temperature gradiency variation is very low and it is
a suitable location for selecting the unaffected reference point.
The user can click on the plot and the corresponding location on
the image is highlighted by the system of the present invention. A
user can then place the unaffected reference point in that location
or choose a different one if the user so desires.
[0216] Even though the thermal images provide more in-depth
definition of area of interest than the digital image, it becomes
harder to differentiate between small variations in temperature as
it is difficult to differentiate between shades of gray. The entire
thermal image is made up of 254 different shades of gray as shown
in FIG. 5.
[0217] To make visual differences between temperature variations
greater the method of the present invention includes incorporating
a unique color for each pixel value to generate a custom color bar
as shown in FIG. 6. The custom color bar shown in FIG. 6 was
developed using MATLAB'S color bar editor.
[0218] To apply the custom color bar to the gray scale thermal
image, the present invention incorporates the following algorithm:
[0219] 1. Generate a matrix that holds the R, G, and B values of
254 different colors representing pixel values ranging from 1 to
254; [0220] 2. Obtaining the pixel value for each pixel in the
image; [0221] 3. Finding the corresponding color for that pixel
value; [0222] 4. Setting the pixel value for that pixel to the new
color; [0223] 5. Applying the new color scale to the entire image;
[0224] 6. Displaying the new image blended with the new color
scale.
[0225] Unmanaged code can be used to make the above-explained
process faster. FIGS. 7 and 8 below show the thermal images before
and after applying the blended custom color scale described
above.
[0226] By looking at either the original gray scale thermal image
or the image with the color scale, unaffected reference area tissue
can be selected at a location that represent unaffected skin with
less temperature variation.
[0227] As the wound and/or area of interest starts healing, the
differences between the pixel value for the unaffected tissue and
the pixel value from the wound and/or area of interest base starts
decreasing and hence the drop scene in the graph of FIG. 10. The
decrease in temperature shown in FIG. 10 indicates that a wound
and/or area of interest is healing and is starting to get closer to
the unaffected skin tissue.
[0228] If the drop in the pixel value starts increasing, when plots
are generated for images taken on a timely basis, then it is an
indication that the wound and/or area of interest is deteriorating
and the clinician needs to turn to strategies to facilitate wound
and/or area of interest healing.
[0229] The thermal mosaic is the colored representation of a gray
scale thermal image. It shows the variation in pixel values using
different colors. Even though thermal images provide more in-depth
definition of area of interest than the digital image, it becomes
harder to differentiate between small variations in temperature as
it is difficult to differentiate between shades of gray. The entire
thermal image is made up of 254 different shades of gray as shown
in FIG. 25.
[0230] However to make the visual representation of the thermal
image clearer, the present invention also provides for a custom
color representation of the thermal image. To accomplish this each
gray scale pixel value is assigned a specific pixel value using the
MATLAB color bar editor as shown in FIG. 26.
[0231] To apply the custom color bar FIG. 26 to a gray scale
thermal image the following steps are performed: [0232] 1.
Generating a matrix is that holds the R, G, and B values of 254
different colors representing the pixel values ranging from 1 to
254; [0233] 2. For each pixel in the image obtaining the pixel
value; [0234] 3. Finding the corresponding color for each pixel and
setting the pixel value for that pixel to the new color; [0235] 4.
Looping the image to apply the new color scale; and [0236] 5.
Displaying the new image with the blended color scale.
[0237] FIGS. 27 and 28 show before and after images respectively
for the blended color scale.
[0238] Using the original gray scale image or the image with the
custom color scale applied, an unaffective reference area can be
chosen which can be used for tracking the progression or regression
of an area of interest.
[0239] Once the reference area has been chosen, another custom
color scale option can be provided where the mean pixel value of an
unaffective reference area is used as a reference and is
represented in a particularly desirable color. For example green.
Using the new color scale all the pixels in the image can be viewed
relative to the selected unaffected reference area. If an area of
interest is warmer than reference it will be assigned a color
closer to the warmer end of the color scale and vice versa. FIG. 29
shows a new custom color scale that takes unaffected reference area
into consideration.
[0240] A method for applying a custom color bar to the gray scale
thermal image comprises choosing an unaffected reference area such
as the temperature variation within the area is less than 1.5
degrees Celsius, finding the average of all the pixel values that
fall within the unaffected reference area called the reference
mean; generating a matrix that holds the R, G, and B values for the
new custom colors; assigning each pixel in the image a pixel value;
and calculating the difference between the current pixel value and
the reference mean. Using the formula difference in pixel value
equals current pixel value minus reference mean. Finding the R G B,
color that corresponds to the difference in pixel value and setting
the pixel value for the pixel to the new color; looping the whole
image to apply the new color scale; and displaying the resulting
image with the blended color scale.
[0241] As shown in FIG. 30, all the portions of the image that have
a temperature equal to the unaffected reference area are presented
with the same color in this case green. Using the above color scale
as a reference, and by comparing the color of an area of interest
with an unaffected reference area, a clinician can get a clear
understanding of how much cooler or warmer an area of interest is
with respect to the reference area.
[0242] By monitoring the images on a scheduled basis and choosing a
reference point consistently between the images a clinician is able
to see a pattern in which the temperatures across the area of
interest are changing. By monitoring changes in colors over time a
clinician is able to visually to interpret whether the wound and/or
area of interest is getting better or worse.
[0243] Thermal mosaic is the colored representation of the thermal
image. It shows the variation in pixel values using different
colors. Gray scale colors are used for the thermal mosaic before
the unaffected reference point is selected, an R G B color scale is
used after the selection is made.
[0244] Once a reference point or reference area is selected, the
color mosaic can be turned on for the whole image and use that as a
visual aid for drawing the periwound trace. In order to generate
the color mosaic, the mean or average pixel value of the unaffected
reference point or mean pixel value of the unaffected reference
area is used as the mean in the algorithm for generating a thermal
mosaic. Since the reference point is just one pixel, there is only
one pixel value. If each time a user engages the system a different
reference point is selected needless variation will be introduced.
Since just one pixel is used as a pixel value, a reference mean is
used instead to generate the color mosaic using the methods
disclosed in Appendix 3 attached hereto.
[0245] The thermal mosaic can be turned on or off for each trace
separately. Using this information, clinicians can calculate using
this system the difference in thermal intensity within the wound
and/or area of interest in degrees Celsius or degrees Fahrenheit;
the percent of pixels that fall within a particular pre-determined
range of the unaffected reference area; the minimum temperature
compared to an unaffected reference point; the maximum temperature
compared to an unaffected reference point; or a mean temperature
compared to an unaffected reference point.
[0246] Long-Wave Infrared Thermography as it Relates to the Human
Body Surface
[0247] Long-Wave Infrared Thermography (LWIT) is a thermal
intensity measurement technique that in this scenario, visualizes
the thermal energy emitted by the human body surface. Thermal
images taken of the skin surface are constructed by the passive
(non-contact and non-ionizing) reading of the emitted radiant
energy formed by the skin and underlying tissue by detecting
wavelengths in the long-wave infrared range of 7-14 microns, and
then in real time converting these values into pixels within a
digital image. The use of LWIT imaging along with visual digital
imaging allows both physiologic and anatomic assessment of skin and
underlying tissue abnormalities and or existing open wounds. The
physiologic principles assessed by LWIT are based on the body heat
produced by cellular metabolism and its distribution by blood to
the rest of the body, and particularly to the overlying skin, for
loss by radiation, conduction and convection. Areas of increased or
decreased blood supply can show an increase or decrease of thermal
energy due to impaired cellular metabolism. (Farid, Winkleman,
Rizkala, & Jones, 2012) This thermal energy is then measured by
LWIT and converted to a thermal image, from which temperature can
be measured.
[0248] The thermal energy of a body surface depends on the presence
or absence of perfusion of the dermal and underlying tissues. Tests
of adequate perfusion are a common part of the patient assessment
process. For example, the assessment of perfusion of a body's
surface using thermography can identify that a blood flow increase
or decrease exists. Other common methods of perfusion evaluation
include skin color, patient condition, capillary refill, Doppler
usage, and invasive dye monitoring.
[0249] The WoundVision Scout can measure hyperperfusion (increased
blood flow) and hypoperfusion (decreased blood flow) of skin and
underlying tissue abnormalities and or existing open wounds
relative to the average level of perfusion of an unaffected,
adjacent body surface (parities and disparities between the good
and the bad). Thus, when comparing a compromised body surface area
to an uncompromised body surface area the clinician may select an
area of adjacent, unaffected tissue to act as a control and
comparator for baseline body surface temperature measurement. This
data can be used to assess and simulate the impact of the parities
and disparities within a selected body surface area or two adjacent
body surface areas (contralateral).
[0250] Repeatability and Reliability of Relative LWIT
Assessment
[0251] In some medical applications having a single, absolute value
for temperature measurement is very useful (for example, core
temperature). However, when measuring and comparing an area of
interest a clinician utilizing LWIT should not be as concerned with
a single, absolute temperature value. Instead, the clinician should
place a higher value on the quantitative temperature differences
that exist between an area of interest and an adjacent unaffected
control area. This is because there are many intrinsic and
extrinsic variables that can affect LWIT's ability to capture
absolute thermal energy emissivity with 100% accuracy. Some of the
intrinsic variables include the normal cycle of thermal production,
age, comorbidities, body region, medications, core temperature and
others. Extrinsic variables include the ambient temperature,
humidity, air convection, climate adaptation of the tissue,
configuration of the body surface, substrate temperature of the
microbolometer and others.
[0252] When comparing the thermal intensity data of body surface's
area of interest (underlying tissue abnormalities and or existing
open wounds) from one moment in time to another it is essential
that the above variables be minimized. To do this, an unaffected
control area that's adjacent to the area of interest must be
selected in order for it to be analyzed over time. Since thermal
intensity can vary between body regions, it's imperative that the
selection of the unaffected control area occur on the adjacent
tissue of the area of interest (or similar proximity on the
contralateral body region).
[0253] Let's assume that a clinician wants to assess a patient's
lower extremity wound using LWIT for an increase or decrease in
blood flow, perfusion and metabolic activity. Comparing absolute
temperature measurements of the lower extremity wound from two
different encounters would provide you with incomparable and
unreliable data. This is because there is no way to minimize the
variables that could have an effect on the wound's temperature on
any given day (for example, the room could be warmer on encounter
two).
[0254] However, if an unaffected control area was selected then the
data could be normalized and compared from one moment in time to
another. This is because the control is exposed to the same
intrinsic and extrinsic variables as the wound, thus providing the
clinician with a relative temperature measurement. By utilizing a
control all intrinsic and extrinsic variables can be accounted for
and clinicians can compare "apples to apples".
[0255] Longitudinally comparing an area of interest with an
unaffected control area over time can be done through ratio
analyses and other normalization algorithms that account for the
variables present a given moment in time. As a result, the
clinician is provided with comparable and reliable data over time
to assess blood flow, perfusion and metabolic activity of a skin
and underlying tissue abnormality and or existing open wound
relative to an unaffected control area.
[0256] Clinical Benefit of Relative LWIT Assessment
[0257] With repeatable and reliable relative temperature data
clinicians are able to compare the parities and disparities between
the "good" and the "bad" tissues to enhance their ability to
quantitatively measure and compare an area of interest's
progression or regression. For example, a single snapshot of
relative temperature data could provide valuable clinical insight
such as the revelation of a skin and/or underlying tissue
abnormality not visually present as well as measuring and comparing
(LWIT and visual) an existing open wound over time to help
clinicians to better understand the pathophysiologic principles of
the healing processes.
[0258] To harness this data, a clinician may use the WoundVision
Scout to perform a relative body surface differential analysis to
assess thermal intensity data differentials derived an area of
interest and unaffected control area. To do this: [0259] Step 1:
Identify the area of interest (skin and underlying tissue
abnormality and or existing open wound) and select an unaffected
control area. [0260] Step 2: Extract all thermal intensity data
associated with the area of interest and unaffected control area by
using the WoundVision analysis software for conversion to degrees
Celsius or Fahrenheit. [0261] Step 3: Evaluate the temperature
differential to approximate parities and disparities between the
area of interest and unaffected control area. [0262] Step 4: Apply
this thermal intensity data along with the patient's history and
physical to measure and compare the pathophysiological status of
the area of interest and unaffected control area. Doing so may aid
in clinical decisions regarding the expected impact of past,
current or future decisions and/or treatments that promote healing
or resolution.
EXAMPLE
[0263] Over the last two weeks a patient's pressure ulcer has not
shown any visible signs of wound healing and physical size has
stayed the same. Utilizing long-wave infrared thermography and a
body surface differential analysis reveals that the pressure ulcer
has become increasingly warmer as compared to the adjacent
unaffected control area. A clinician may then use this data, a
history and physical and their clinical expertise to decide that a
change of treatment to combat or prevent possible infection and
further stalling of the wound may be the proper clinical decision.
It should be noted that in scenarios where a body surface
differential analysis shows increased thermal intensities of the
wound, it could just be crossing through the inflammatory phase and
should not always warrant a diagnosis of infection. Since the
inflammatory phase should begin to diminish in 3-4 days, the
patient history and physical become very important.
[0264] Performing a relative body surface differential analysis
provides clinicians with the ability to compare the thermal
intensity data of the area of interest to the unaffected control
area. This may help enable them to more easily and promptly
determine if there exists formation of tissue with similar
structures and comparable functions to that of the unaffected
control area or if there exists formation of tissue that is
structurally and functionally satisfactory but not identical to
that of the unaffected control area. (Li, Chen, & Kirsner,
2007)
Appendix 1
[0265] If selecting unaffected reference point: 1. Check whether
thermal trace exists 2. If yes, check to see which pixels fall
inside the trace and use the pixel values of all those pixels to
calculate the average pixel value (mean). If not stop 3. Decide on
the color codes that represent each temperature interval change. 15
different shades were chosen for the color scale. Gray scale colors
are used before the reference point is selected. 4. Use the base
color that falls in the middle of the color scale to highlight all
the pixels with a pixel value between mean-6 and mean+6. The
following logic was used to color rest of the pixels 5.
TABLE-US-00001 if(PV <(Mean- 6- (6 '''PI))) { Highlight the
pixels using the color'that falls in the bottom of the scale
representing the coldest pixels } else if (PV >=(Mean - 6 - (6
*PI)) & PV <(Mean- 6 - (5 *PI))) { Highlight the pixels
using the color that is second from the bottom of the scale } else
if (PV >=(Mean - 6 - (5 * PI)) & PV <(Mean- 6 - ( 4 *
PI))) { Highlight the pixels using the color that is third from the
bottom of the scale } else if (PV >=(Mean - 6 - ( 4 *PI)) &
PV <(Mean - 6 - (3 * Pl))) { 3 Highlight the pixels using the
color that is fourth from the bottom of the scale } else if(PV
>= (Mean - 6- (3 *PI)) & PV <(Mean -6 - (2 *PI))) {
Highlight the pixels using the color that is fifth from the bottom
of the scale } else if(PV >= (Mean - 6 - (2 *PI)) & PV
<(Mean -6 - (1 *PI))) { Highlight the pixels using the color
that is sixth from the bottom of the scale } else if(PV >=(Mean
- 6- (1 *PI)) & PV <(Mean - 6)) { Highlight the pixels using
the color that is seventh from the bottom of the scale } else ir(PV
>=(Mean - 6) & PV <=(Mean + 6)) { Highlight the pixels
using the base color representing unaffected area. (Center color) }
else if(PV >(Mean + 6) & PV <=(Mean + 6 + (1 * PI))) {
Highlight the pixels using the coJor that is seventh from the top
of the scale } else if(PV >(Mean + 6 + (1 *PI)) & PV <=
(Mean + 6 + (2 * PI))) { Highlight the pixels using the color that
is sixth from the top of the scale } else if(PV > (Mean + 6 + (2
* PI)) & PV <=(Mean + 6 + (3 *PI))) { Highlight the pixels
using the color that is fifth from the top of the scale } else
if(PV >(Mean + 6 + (3 * PI)) & PV <= (Mean + 6 + ( 4
*PI))) { Highlight the pixels using the color that is fourth from
the top of the scale } else if(PV >(Mean + 6 + (4 *PI)) & PV
<=(Mean + 6 + (5 * PI))) { Highlight the pixels using the color
that is third from the top of the scale } else if(PV >(Mean + 6
+ (5 *PI)) & PV <=(Mean + 6 + (6 *PI))) { Highlight the
pixels using the color that is second from the top of the scale }
else if(PV >(Mean + 6 + (6 * PI))) { Highlight the pixels using
the color that falls in the top of the scale representing the
hottest pixels } Where PV - Pixel Value and PI = pixel increment.
PI is set to 13 when the mosaic needs to show 1.degree. C. change
in temperature, PI is set to 9 for 0.75.degree. C. and 6 for
0.5.degree. C. change in temperature.
Appendix 2
[0266] The `lensdistort` algorithm in Matlab takes as input the
original distorted image and the following parameters and generates
as output the barrel distortion corrected image.
`bordertype`--String that controls the treatment of the image
edges. Valid strings are `fit` and `crop`. By default, `bordertype`
is set to `crop`. `interpolation`-String that specifies the
interpolating kernel that the separable re-sampler uses. Valid
strings are `cubic`, `linear` and `nearest`. By default, the
`interpolation` is set to `cubic` `padmethod`--String that controls
how the re-sampler interpolates or assigns values to output
elements that map close to or outside the edge of the input array.
Valid strings are `bound`, circular`, `replicate`, and symmetric'.
By default, the `padmethod` is set to `fill` ` ftype`--Integer
between 1 and 4 that specifies the distortion model to be used. The
models available are 1. `ftype`=1: s=r.*(1./(1+k.*r)); 2.
`ftype`=2: s=r.*(1./(1+k.*(r/'2))); 3. `ftype`=3: s=r.*(1+k.*r); 4.
`ftype`=4: s=r.*(1+k.*(r.A2)); By default, the `ftype` is set to
4.
Appendix 3
[0267] In order to generate the color mosaic the mean (average)
pixel value of the unaffected reference point would be used as the
`Mean` in the algorithm described above for generating thermal
mosaic. Since reference point is just one pixel there is only one
pixel value. If that pixel value is used as the mean it introduces
a lot of variation in the results. Every time a different reference
point is selected, even though very close to the previously
selected location the results varied a lot and were not repeatable
so instead the following method was used
1. Calculate the difference between the selected reference point
pixel value and mean pixel value of the thermal trace (the value
that was used for generating the gray scale thermal mosaic) 2.
increment=Difference calculated from step 1 [0268] Pixel Increment
Pixel Increment is set to 13 when the mosaic needs to show
1.degree. C. change in temperature, 9 for 0.75.degree. C. and 6 for
0.5.degree. C. change in temperature 3.
TABLE-US-00002 [0268] if (increment>O) { Reference_min =(mean +
6 +((increment - 1) *Pixel Increment)) + 1; Reference_max= (mean+ 6
+ ((increment) *Pixel Increment)); } else if (increment= 0) {
Reference_min= (mean- 6); Reference_max= (mean + 6); } else if
(increment< 0) { Reference_min= (mean- 6 + ((increment) *Pixel
Increment)); Reference_max= (mean- 6 + ((increment+ I) *Pixel
Increment)) -1; } where mean= mean pixel value of the thermal
trace;
[0269] 4. Mean (average) pixel value of the unaffected reference
point can then be calculated as
Reference_mean=(Reference_min+Reference_max)/2
Reference_mean as calculated above can then be used as the `Mean`
in the algorithm described earlier for generating thermal mosaic.
Use RGB color codes to generate Color mosaic.
* * * * *