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Lanfranco Barbieri
MEDICAL
INFRARED THERMOGRAPHY
Laura Venturi “The courage of ideas”
Edited by Arti Grafiche TORNAR
CONTENTS
THEORETICAL PREMISES 1
MEDICAL THERMOGRAPHY 5
MEDICAL APPLICATIONS 6
EXAMPLES 7
FUTURE EXPECTATION 8
PERSONAL CASE STUDY (Preliminary Android Application) 10
IMAGE PROCESSING 11
FINAL ASSESSMENTS 12
ADDENDUM 13
CURRICULUM - Professor Lanfranco Barbieri, born in Pisa, May 29th 1934. Radiology and Physical
Therapy Specialist. Orthopaedics and Traumatology Specialist. Executive director U.O. Radiology of
Carrara and coordinator of the Oncological department of AUSL 1 of Massa Carrara. Author of
numerous scientific memoirs, some of which of monographic nature. One of the top promotors in
Italy of the informatic methodology in medicine: TEAM 2000 (Electronic Technologies Applied in
Medicine) - National Congress that was held in the Auditorium of the “Fiera Internazionale Marmi e
Macchine” of Marina di Carrara (MS) with a Forum of the most relevant industries of the sector -
January 28th and 29th, in the year 2000.
Obtained with ANDROID -THERMAL CAMERA FLIROnE
1
THEORETICAL PREMISES
A few definitions:
a) Thermography: it’s a technology that allows to measure the infrared radiations that are emitted from the
external surface of a warm body and to translate them into images. Infrared rays are a type of energy that is
part of the electromagnetic spectrum and, therefore, it isn’t visible to the human eye.
b) Heat: it’s a type of energy that’s created from the vibro-rotary motion found inside the molecules of any
type of object and it is usually measured in Kelvin (K), Fahrenheit (°F) or Celsius (°C) degrees.
c) Kelvin degrees: (0 Kelvin = −273,15 degrees Celsius - oC). No body emits heat at 0 degrees Kelvin.
d) Second principle of thermodynamics: asserts that heat transfers in an irreversible manner from a
warmer body to a colder one, and this process is tied to the arrow of time. It explains why thermography can
identify pathologies that lie beneath the skin with a different heat value.
e) Black body: (concept introduced by G. Kirchhoff in 1860) is the sample of an ideal body that absorbs all
of the electromagnetic radiation that affects it. Because of this, it appears black since there is no reflected
emitted radiation. It distinguishes itself from the others because, temperature wise, it emits the highest
quantity of energy compared to every wavelength
.
f) Reflectance or reflectivity (p): the percentage of all of the emitted energy that is directly reflected.
Reflectance in a black body is 0. In a body that is highly reflectance it is close to 1.
g) Emissivity (σ): it measures the capability of an object to emit electromagnetic radiations in relation to
that emitted from a black body at the same temperature.
The emissivity of a body depends on various factors, but mainly it depends on the characteristics of the object
and its radiating surface. An exemplar issuer is a black body.
In a black body, the emissivity value equals 1 (100%); in all of the other bodies (real bodies) it’s between 0
and 1 (<1). Since (Kirchhoff) σ + p = 1, it follows that, when the emissivity is high the reflectance is low (p =
1 − σ) and viceversa (σ = 1 − p). In objects, in which the calculated emissivity equals ≤ 0.8, the reflectance
is considered 0 (1 − 0.8). For example, pure aluminium (whose glossy surface is highly reflective) has an
emissivity value of about 0.04% (almost 0); while the human skin has an emissivity value of about 0.98%
(0.98% ± 0.01 according to Steketee)1. Therefore, since σ almost equals 1, reflectance is considered 0 (1 −
0.98).
h) Maximum emissivity (σmax): is the maximum value of the emissivity in relation to wavelength.
i) Wien’s displacement law (T * λ max = 2.8977685...* 10−3): Wien’s displacement law (1893) allows to
determine the wavelength (λ) in which there is the maximum irradiation (λ max) for every temperature of the
radiating body.
j) Sensitivity or accuracy: is the ability of an instrument to identify the heat values of an object.
Emissivity = radiations emitted from an object at temperature T
radiations emitted from a black body at temperature T
2
k) Planck constant (h): is a physical constant tied to the quantisation of the microscopical world that appears
in Planck’s law. Its currently known value is: 6.626 * 10−23 J/s.
l) Boltzmann constant (KB): is a proportionality constant empirically derived from Stefan-Boltzmann’s
equation. Its internationally accepted value is: 1.38054 * 10−23 J/K.
Planck’s law (1900) links three variables: temperature (T), irradiated energy (q) and wavelength
(λ). It completes Wien’s displacement law of which it constitutes an extension. In the real world all
objects emit radiations with different principles and have an emissivity value that always equals less
than 1 (σ < 1).
Planck’s law refers to the sample of the black body proposed by Kirchhoff (σ = 1 and p = 0). By
integrating the intensity of the emitted radiations with wavelengths, it is possible, through Planck’s
law, to acquire the electromagnetic spectrum of the emitted radiations: this means its spectral
distribution. The latter highlights how, by raising the temperature, the maximum emissive intensity
(σ max) moves towards shorter wavelengths.
With temperatures less than 500 K there are only infrared radiations with wavelengths higher than
0.8 μm; the visible ones (from violet to red) are included between 0.4 and 0.8 μm.
The temperature of the human skin – measured in 28 different areas – varies between 27.89°C
(301.04 K) ± 3.24 (heels) and 35°C (308.15 K) ± 2.69 (frontal region of the face)2. Since its emissivity
(0.98% ± 0.01) is close to 1, the wavelengths of the emitted radiations are attributable to those of a
black body at its same temperature, and therefore, predictable through the spectral curves of Planck.
Planck’s law is important in the physics of the elementary particles and it’s the basis of quantum
mechanics. It also allows to implement other useful relations to obtain theoretical predictions and/or
formalise laws deducted by experimentation. Amongst these, there is the Stefan-Boltzmann law
(1879) that allows to obtain from the values of the emitted radiations those of the temperature.
As a matter a fact, Stefan-Boltzmann’s law asserts that:
“The radiated energy that’s emitted from anybody in the time interval Δt is proportionate to the fourth
power of the absolute temperature”.
Distribution of the spectral curves in a black body
For temperatures of about 6000 K, the maxi-mum emissivity (σmax) occupies the range of the visible light (from 0.4 to 0.78 λ μm). For inferior heat values it moves to the right in the range of the infrared (where λ > 0.8 μm). The oblique line in the image represents the maximum values of emissivity with the tem-perature variation.
q/∆t = σKBST4
3
Where: q = radiated energy; σ = emissivity of the body; KB = Boltzmann constant; S = area of the
body in square metres; T = absolute temperature of the body in Kelvin degrees. Therefore, knowing
the values of Δt, σ, S and KB and calculating q, it is possible to obtain the value of T.
But if:
• Δt = 1 (unit of time)
• σ = 1 (emissivity of a black body)
• S = 1 (unit of surface),
then Stefan-Boltzmann’s law can be simplified to:
and can be expressed as follows:
“The total radiated energy per unit of surface from a black body for unit of time is directly proportional
to the fourth power of the absolute temperature”.
Stefan-Boltzmann’s law states that the amount of emitted energy is proportionate to the fourth power
(T4) of the absolute temperature.
Considerations – the human skin has a baseline emissivity of about 1 (0.98% ± 0.01) and emits
radiations with wavelengths similar to those of a black body at more than 26.85°C (300 K). These
emissive characteristics, that are very close to those of the ideal black body, make it so that, the
human skin is defined as “a close-to-perfect emisser, and theoretically speaking, particularly suitable
for the thermographic diagnostic”.
The physics of black bodies, Wien’s displacement law, Stefan-Boltzmann’s law, and Planck’s law all
trace back to the second half of the 19th century, and to the beginning of the 20th; therefore, it is
obvious that the technology of the time couldn’t allow an adequate application.
Even though in the last few years, ground-breaking products have made an appearance, the real
breakthrough came with the digital era and the development of micro-electronics, other than the
interest for the detection of the infrared radiations that could be useful in different fields: the most
important of all, the military field (the modern infrared detectors and the related protocols of use
were initially developed in the USA laboratories of defence).
Many commercial scanners for medical use, use semiconductor materials that are highly sensitive.
Among these, there is indium antimony (InSb) that’s considered to be particularly suitable for the
emissive characteristics of the human skin, and they are calibrated taking into consideration:
a) the emissivity values of the spectral curves of Planck of black bodies;
b) the emissivity values of the wavelengths that define the temperatures of skin in the ranges
of those values that are considered normal (8 – 14 μm // σmax ~ 9.66 μm) and those consi-
dered abnormal.
The constructive diagram of Thermal Imaging Camera is the following:
Input → Transducer → Signal amplifiers → Display
q = KB T4
However, it should be kept into consideration, that the theoretical estimates always
deviate from the practical results.
4
The current thermographs then use sophisticated optical systems to optimise the images and pos-
sess other components that are essential to its functioning.
These are:
• Autofocus
• Colour display (palettes)
• High resolution (Acquisition matrix ≥ 320 x 240 pixel)
• Digital memory
• Temperature measured in K and/or oC
• Adjustable emissivity and reflectivity
• Dedicated post-processing and software
• Vocal annotation.
Nowadays, the thermographic researches are of great scientific importance, not only in the medical
field, but also in other numerous practical applications with measured thermographic values closest
to those theoretically expected.
Images obtained with Thermal Imaging Camera FLIROnE
A B
[1] J. Steketee – Spectral emissivity of skin and pericardium. Phys Med. 686-94, 1973.
[2] Cabrera IN, Wu SSH, Haas F. and Lee MHM. - Computerized Infrared Imaging: Normative Data on 110 Patients.
Arch Phys Med Rehabil, 2001; 82; 1499.
Thermogram of two bodies at different temperatures
(hand and container of cold-water).
It is important to notice the different thermal colouring in
the respective contiguous areas.
Red fades into yellow around the hand, while in the proxi-
mity of the container blue fades into green.
Inside, the cold water has an emissivity value of about 0
(dark colour).
The plastic covering (blue) acts as an insulator with the
surroundings (air).
In other words, all the colours of the palette can be seen.
A) Sample of pork liver at cold
temperature.
B) Circumscribed superficial ca-
loric increase after application of
underling heat source.
5
MEDICAL THERMOGRAPHY
Thermography or non-contact thermography uses one or more thermographic cameras and
identifies possible pathologies of the whole body, even for more superficial organs, such as the skin,
thyroid and, specifically, breasts (Breast thermography).
Since the digitalisation of modern equipment, certain types of software have made an appearance,
and they allow to help with the diagnosis (CAD – Computer Aided Detection System).
When we talk about an infrared camera’s sensitivity, we are talking about its capacity to visualise a
good-quality image even if the thermal contrast is low (indicated with Δ).
The sensitivity is reported in NEDT (Noise Equivalent Difference Temperature), and this measure
unit allows to know the minimal quantity radiation to produce and diversify signals; it is expressed in
Kelvin degrees (0 Kelvin (K) = − 273,15 degrees Celsius).
The second principle of thermodynamics states that heat transfers in an irreversible manner from a
hotter body (in this case a neoplasm) to a cooler one (in this case skin), and this process is linked
to the arrow of time. Therefore, it’s understandable why the minimal cutaneous heating can identify
an underlying pathology even if it’s deep, but without being able to recognize its morphological and
structural characteristics.
Medical diagnosis uses passive thermography, which doesn’t require any type of external heat
source, while in other cases the active thermography is required, in which the reflected infrared rays
are measured like, for example, with planets that are illumined by the sun.
Another interesting method is the so-called “dynamic”, which consists in the cooling of the area of
interest, and then you measure the TRT – Thermal Recovery Time.
The TRT is the different times of heating that occur in different tissues: it’s as if there were a
momentary and reversible simulation of local cadaveric cooling, that allows the vital recovery once
the temperature reduction cause is taken away.
With this technique it is possible to distinguish the minimal variations in temperature in the various
phases of thermal recovery and it is obvious that metabolically more active tissues, like tumors, heat
up sooner and with more intensity. Moreover, it adds specificity to the already high level of sensitivity
of the normal thermography, because TRTs are different for each type of tissue.
Current thermal cameras have a sensitivity (accuracy) of 0.05 0C; in a matter of a
fraction of a second, they allow to visualize vast areas of the human body;
they produce images between 10 0C and 55 0C; they have spatial resolution
of 25-50 µm and they have a better software in order to analyse specific
anatomical areas of interest, like for example, breasts.
In the USA, a “Thermologist” is a specialist who reads and interprets a thermogram
and is an expert in distinguishing possible diversity in symmetric models of heat, like,
for example, two breasts.
Many of these thermal variants are easily explainable and don’t require further
assessments.
6
MEDICAL APPLICAZIONS
From:
MEDICAL INFRARED IMAGING
Donald R. Peterson. CRC Press. London/New York. 2012. Medical applications of thermography: Oncology (breast, skin, etc.) Pain (management/control) Vascular disorders (diabetes, DVT) Arthritis/rheumatism Neurology Surgery (open heart, transplant, etc.) Ophthalmic (cataract removal) Tissue visibility (burns, etc.) Dermatological disorders Monitoring efficacy of drugs and therapies. Thyroid Dentistry Respiratory (allergies, SARS) Sport and rehabilitation medicines.
From: “Total Body Thermography LLC”
Unexplained pain Artery Inflammation Breast disease Disc Disease Fibromyalgia Sprain/Stain Referred Pain Syndrome RSD Stroke Screening Digestive Disorders Whiplash
ESE Dental and TMJ Inflammatory Pain Referred Pain Syndrome Nerve damage Vascular disease Skin Cancer Arthritis Back Injures.
From: “ebme” – MEDICAL THERMOGRAPHY Breast Pathologies Extra-cranial Vessel Disease Neuro-musculo-skeletal Lover Extremity Vessel Disease Respiratory Dysfunctions Digestive Disorders Urinary Diseases Cardiovascular and Circulatory Disorders Lymphatic Dysfunction Reproductive Disorders Nervous Dysfunction
Endocrine Disorders Locomotors Disorders Surgical Assistance Skin Problems Ear, Nose, and Throat Dysfunction Dentistry Dental and TMJ Inflammatory Pain Referred Pain Syndrome Nerve damage Vascular disease Skin Cancer
From: “L.F. Balbinot, L.H. Canani, C.C. Robinson, M. Achaval and M.A. Zaro.
- Plantar thermography is useful in the early diagnosis of diabetic neuropathy. CLINICS (San Paulo) 2012. Dec. 67(12): 1419-1425”. A - Plantar thermographic image in a diabetic patient, showing Interdigital Anisothermal.
B - Plantar thermographic image in a control subject, with regular appearance.
7 EXAMPLES
In comparison: image obtained with Thermal Imaging Camera FLIROnE.
8 FUTURE EXPECTATIONS
Image-based diagnostic is evolving towards new frontiers. Health demand and
the possible potential damages caused by external energetic sources or improper
physical contacts (compressions, means of contrast, etc.) is orienting users
towards alternative methods instead of the current ones. The unmoderated use of
certain methods like CT, PET, and MRI, that up until now have been considered
harmless or of moderate risk, is convincing people to review them.
An example of development that doesn’t keep count of the potential negative
effects that it has on someone’s health or doesn’t create excessive amounts of
discomfort doesn’t seem so desirable.
Echography, thermography and the 3D Full Body Bio-Electro-Scan or Full Body
Functional Scan are considered to be such harmless methods, that they can be
defined as physiological or functional. The latter is a very advanced technology
that allows to obtain numerous vitals with an accuracy of 89%, other than the three-
dimensional representations of internal organs like with the use of CT or MRI. Since
its physical presupposition is the measurement of the bio-impedance of the internal
interstitial fluids, it doesn’t use any additional energetic source and it’s non-
invasive. It was developed by Russian and German scientists in order to control
the vitals of the astronauts without interfering with the sensitive electronic circuits
on board: therefore, it is considered to be - with digital thermography - an emerging
harmless method. Advanced software that is admissible to the neuronal web, has
already brought some substantial improvements to the traditional images, but the
challenge for the future, especially regarding tumors, is to recognize pre-neoplastic
situations. As a matter a fact, in the first stages, the normal cells, or only partially
atypical, prevail on the tumoral ones; in the next stages the situation tends to
overturn, the neoplastic growth increases exponentially and therapies seem to
become less effective.
Fields of study that were considered to be separate up until this point, actually have
common roots: every external detection (macroscopic, but also microscopic)
derives from primary events that take place at a molecular, atomic and sub-atomic
level, and we shouldn’t be surprised if, through the detection of the emitted
electromagnetic curves from various materials, it is possible to trace back to the
diagnosis of a tumor without necessarily getting any samples.
:
OPTICAL BIOPSY
Diagnosed non-invasive
melanoma only with the
multispectral use of
images
(histological assessment).
Latvia University,
Riga, Latvia.
9
Thermography is potentially already able to identify local hyperaemia before breast
neoplasms (typical/atypical cellular hyperplasia), or the tumor in its next stages
(DCIS), but it doesn’t give any certainties at the moment; as a matter a fact, other
pathologies can simulate cancer. Moreover, improvements and in-depth analysis
are still being studied. Such as: the simultaneous or differentiated use of infrared
bands of low, medium and high frequency; the insertion of different types of spectral
filters in order to minimize noise; the possibility of deciphering, through the use of
mathematical procedures and graphical representations1 (for example fractal
analysis), the characteristics of the different thermographic images with their
respective informative content in the areas of interest (or ROI).
Recently (2016), an article2 by three Iranian bioengineers came out (University of
Teheran). In this article, a unique method is presented, that allows to identify breast
cancer in the areas of interest of thermograms obtained with the same
recommended procedures by the international protocols. These authors believe
that this method would have an accuracy close to 100%, making following
histological tests not necessary; this would then guarantee an immediate approach
to cures with positive effects on survival and mortality. These cures would make it
so that one mustn’t wait for the breast cancer to appear in mammograms in the
nodular form: which takes about 4-5 years.
Algorithms that could allow the use of computerized screenings are being studied
for breast exams. An important research field is that of spectroscopy in the thermal
band of infrared rays (hyper-spectroscopy), and it is considered to be able to
directly identify tumors.
Lastly, micro-technologies already allow the use of small, manageable, and low
cost thermo-cameras, with the purpose of a future use in routine diagnostic
application.
Image obtained with a thermo-camera for Android FLIROnE.
It is a scanning Thermal Imaging Camera that can be used with iOS devices (smartphones and/or tablets – connector lightning).
Thyroid
Essential characteristics:
1) size: L. 72 mm x D. 26
mm x H. 18 mm – weight:
78 grams;
2) VGA camera with
thermic interval of 0,1°C;
3) operating temperature:
from 20°C to 120°C;
4) sensor: 160 x 120
pixels;
5) battery power:350 mA-h
6) Pallett colour: black/white, multicolour, contrast, hot/cold, iron;
7) User interface: mobile application;
8) cost: about 300 euro.
In alternative:
Thermal Imaging Camera Fluke Thermal Seek Compact Android (206 x 146 pixels – 9Hz).
10 PERSONAL CASE STUDY
BENIGN BREAST PATHOLOGIES DOCUMENTED WITH “Thermal Camera FLIROnE”
Multiple post-traumatic Partial resolution after 6 days. Nodular thermic emission
hematomas. with a benign appearance. (Most extended to the left). Fibroma. Ultrasound confirmations.
PAINFUL SYNDROMES DOCUMENTED WITH “Thermal Camera FLIROnE”.
Right shoulder pain. Bilateral low back pain. Pain in the 30- 40 finger-left foot. Peri-arthritis (RX: Sub A.D.B. (RX: arthrosis). Trauma - (RX: negative). calcification).
VARIOUS DOCUMENTED WITH “Thermal Camera FLIROnE”.
Basothelioma left ankle. Left psoriatic lesion. Thermographic control. Knee metal prothesis. [1] Kermani S., Samadzadehaghdam N., EtehadTavakol M. – Automatic color segmentation of infrared breast using Gaussian mixture model. Int. J. L ight Election Opt. 2015; 126:3288-94. [2] AmirEhsan Lashcary, Fatemeh Pak, Mhoammad Firoutzmand – Full Intelligent Cancer Classification of Thermal Breast Images to Assist Physician in Clinical Diagnostic Application. Journal of Medical Signals & Sensor. 2016.
10
11
PERSONAL IMAGE PROCESSING (Examples)
with GIMP (GNU - Image Manipulation Program).
Bilateral carcinomas (micro-calcifications enhanced).
Nipple
Curvilinear thermo-vascular patterns on the left (hormone imbalance?)
)
3D thermography. Binary Segmented Image Final segmentation.
((B.S.I.) black and white).
12 FINAL ASSESSMENTS In the general scientific field, the main topic of discussion is: "Thermography can replace or
supplement mammography in screening?"
A broader view, however, allows other assessments of non-secondary relevance.
The current image diagnostics provides important macroscopic information that we might call
"anatomical", but it doesn’t allow to go beyond that, even by keeping into consideration further
improvements. Furthermore, it generally requires expensive equipment, that isn’t easy to use, that
occupies a lot of space and, therefore, can only be used in adequately equipped facilities.
Thermographic images allow to detect the first responses that tissues offer to "metabolic stress",
both in the general and in the regional areas, even with low-volume devices.
Generally, it has been shown, for example, that this method can detect prodromal thermal variations
that precede flaccid fever states - and this opens wide application areas especially in the massive
preventive selection of infectious diseases (airports, reception centres, frontier crossings, etc.)1.
At a regional level, it is possible to objectively and accurately locate the areas of thermal anomalies
in various pathologies, to evaluate their severity and to follow their evolution by monitoring the
transformations occurring locally until their healing2.
It can also provide diagnostically reliable information in any environment: from structured centres
(hospitals, emergency rooms, etc.) to peripheral locations where, for example, non-risky activities
take place. Lastly, according to some3, it can be used directly by patients, but only in certain
circumstances.
Therefore, modern thermography has a huge implementation flexibility that does not match other
methodics; this is all made possible by the great technological development that has allowed to
obtain images that are sufficiently diagnostic, even with the use of small and easy-to-use gadgets.
IN PARTICOLAR THE THERMOGRAPHY ALLOWS:
• select other services on a temporal (immediate, medium term, delayed) and typological (RX, TC, RMI etc.) basis;
• to avoid more challenging examinations, when the result is negative or remains the same in check-ups;
• monitor patients on the spot and in real time;
• to decide what’s best in cases of emotional stress (accidents, natural catastrophes, etc.);
• identify false pathologies.
It is presumable, moreover, that the decisive turning point, above all for the more aggressive
pathologies (tumors), could have merged into one image, "pixel" by "pixel", two images: the morpho-
anatomical (specificity) and the thermo-functional one (sensitivity). Already today this advanced
technology (IR-FUSION TECHNOLOGY), developed by FLUKE, allows to obtain more intuitive and
comprehensible representations, merging thermographic and visual images together - even in rapid
sequence (full frame). [1] – C. M. Hinnerichs, A. Prein, G. Gonzalez – Infrared Thermography for Febrile Screening in Public Health. LAP LAMBERT Academic Publishing. 2015. [2] – R. Lasanen – Infrared thermography in the evaluation of skin temperature. Application in musculoskeletal temperature. Publications of the University of Eastern Finland. October, 9, 2015. [3] – K. Gobin, K. Louison – An Android Application for Detection and Self-monitoring of the Diabetic Foot Ulcer. The Journal the Association of Professional Engineers of Trinidad and Tobago. Vol. 45, N 1, July 2017, pp 4 -10.
13 ADDENDUM
MAMMOGRAPH
RX Matrix = TC Matrix
Thermograph
Infrared rays
COMPUTER
IR-RX Fusion Technology
– Image subtraction –software.
DISPLAY
Compressor (σ = 0,98% ± 0.01)
A single click or two clicks
Thermal Camera + RX source
X - rays
Constructive model of a “THERMAL-MAMMOGRAPH”
INFRARED THERMOHRAPHY BOOKS
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