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