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  1. 1. Thermography Dr. Nidhi Mathur
  2. 2. Thermogaphy A medical science that performs diagnostics using highly detailed and sensitive infrared images. Dr. Nidhi Mathur
  3. 3. Thermogram A regional temperature map of the surface of a part of the body made by a thermograph. Dr. Nidhi Mathur
  4. 4. <ul><li>Thermal readings have been used in medicine for thousands of years. </li></ul><ul><li>The Greek physician Hippocrates wrote, </li></ul><ul><ul><li>In whatever part of the body excess of heat or cold is felt, the disease is there to be discovered. </li></ul></ul>Dr. Nidhi Mathur
  5. 5. Dr. Nidhi Mathur
  6. 6. <ul><li>Medical Thermography </li></ul><ul><li>                                        </li></ul><ul><li>Medical Thermography (digital infrared thermal imaging - DITI ) is used as a method of research for early pre-clinical diagnosis and control during treatment. </li></ul><ul><li>The intrinsic safety of this method makes infrared Thermography free from any limitations or contra- indications. </li></ul><ul><li>Thermography is a non-invasive, non-contact tool that uses the heat from your body to aid in making diagnosis of a host of health care conditions. </li></ul><ul><li>Thermography is completely safe and uses no radiation. </li></ul>Dr. Nidhi Mathur
  7. 7. <ul><li>It has two parts, </li></ul><ul><ul><li>the IR camera or detector and </li></ul></ul><ul><ul><li>a standard PC or laptop computer. </li></ul></ul><ul><li>These systems have only a few controls and relatively easy to use. </li></ul>Dr. Nidhi Mathur
  8. 8. <ul><li>Two categories of detectors are commonly found. </li></ul><ul><ul><ul><li>based on thermal effects and include thermocouples, bolometers, thermopiles and pyroelectric detectors. </li></ul></ul></ul><ul><ul><ul><li>relies on quantum effects and include photoconductors, and photovoltaic diodes. </li></ul></ul></ul><ul><li>Uncooled detector which can be fabricated into high resolution FPA's. These are currently becoming available in a range of IR viewers. </li></ul>Dr. Nidhi Mathur
  9. 9. Basics Dr. Nidhi Mathur
  10. 10. <ul><li>any object whose temperature is above 0 °K radiates infrared energy. </li></ul><ul><li>The amount of radiated energy is a function of the object's temperature and its relative efficiency of thermal radiation, known as emissivity. </li></ul><ul><li>Radiated energy (power) is proportional to the body's temperature, raised to the 4th power. </li></ul><ul><li>This energy can be measured and an instrument calibrated to indicate the corresponding temperature of the surface it's &quot;looking at.&quot; </li></ul><ul><li>Instruments which &quot;scan&quot; an object and create an image or spatial map of surface temperatures are referred to as thermal imagers. </li></ul>Dr. Nidhi Mathur
  11. 11. <ul><li>Difference between infrared film and thermography </li></ul><ul><li>IR film is sensitive to infrared (IR) radiation in the 250°C to 500°C range, while the range of thermography is approximately -50°C to over 2,000°C. </li></ul><ul><li>So, for an IR film to show something, it must be over 250°C or be reflecting infrared radiation from something that is at least that hot. </li></ul>Dr. Nidhi Mathur
  12. 12. Dr. Nidhi Mathur
  13. 13. <ul><li>Thermography makes use of the infrared (IR) spectral band of the electromagnetic spectrum. </li></ul><ul><li>IR involves four bands: </li></ul><ul><ul><ul><li>near infrared (0.75-3 μm), </li></ul></ul></ul><ul><ul><ul><li>middle infrared (3-6 μm), </li></ul></ul></ul><ul><ul><ul><li>far infrared (6-15 μm) and </li></ul></ul></ul><ul><ul><ul><li>extreme infrared (15-100 μm). </li></ul></ul></ul><ul><li>Infrared video cameras are passive (emits no energy), but merely collects the thermal radiation emitted from the surface of the human body. </li></ul><ul><li>In active Thermography , an energy source is required to produce a thermal contrast between the feature of interest and the background. The active approach is necessary in many cases given that the inspected parts are usually in equilibrium with the surroundings. </li></ul>Dr. Nidhi Mathur
  14. 14. <ul><li>IR cameras don’t see temperature. </li></ul><ul><li>The IR camera captures the radiosity of the target it is viewing. </li></ul><ul><li>Radiosity is defined as the infrared energy coming from a target modulated by the intervening atmosphere, and consists of </li></ul><ul><ul><ul><ul><li>emitted, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>reflected and sometimes </li></ul></ul></ul></ul><ul><ul><ul><ul><li>transmitted IR energy . </li></ul></ul></ul></ul>Dr. Nidhi Mathur
  15. 15. <ul><ul><ul><ul><li>I.E. = E.E. + T.E. + R.E. </li></ul></ul></ul></ul><ul><li>Incident Energy  energy profile when viewed through a thermal imaging device, </li></ul><ul><li>Emitted Energy  generally what is intended to be measured, </li></ul><ul><li>Transmitted Energy  energy that passes through the subject from a remote thermal source, and </li></ul><ul><li>Reflected Energy  amount of energy that reflects off the surface of the object from a remote thermal source. </li></ul>E.E. R.E. T.E. I.E. Dr. Nidhi Mathur
  16. 16. <ul><li>A Black Body is a theoretical object which will radiate Infrared Radiation at its Contact Temperature. </li></ul><ul><li>If a thermocouple on a Black Body Radiator reads 50 degrees Celsius, the radiation the Black Body will give up will also be 50 degrees Celsius. </li></ul><ul><ul><li>Therefore a true Black Body will have an emissivity of 1. </li></ul></ul><ul><li>Since there is no such thing as a Black Body, the Infrared Radiation of normal objects will appear to be less than the Contact Temperature. </li></ul><ul><li>The rate (percentage) of emission of Infrared Radiation will thus be a fraction of the true Contact Temperature. </li></ul><ul><ul><ul><li>This fraction is called Emissivity. </li></ul></ul></ul>Dr. Nidhi Mathur
  17. 17. Dr. Nidhi Mathur
  18. 18. <ul><li>Emissivity </li></ul><ul><li>Emissivity is a term representing a material's ability to emit thermal radiation . </li></ul><ul><li>Each material has a different emissivity and it can be quite a task to determine the appropriate emissivity for a subject. </li></ul><ul><li>A material's emissivity can range </li></ul><ul><ul><ul><li>from 0.00 (completely not-emitting) </li></ul></ul></ul><ul><ul><ul><li>to 1.00 (completely emitting); </li></ul></ul></ul><ul><li>the emissivity often varies with temperature. </li></ul>Dr. Nidhi Mathur
  19. 19. <ul><li>For opaque objects, the emissivity and reflectivity are complementary . High emissivity means low reflectivity and vice versa. The conservation of energy law shows us that: </li></ul><ul><li>                   (1.1) </li></ul><ul><li>where emissivity is  , reflectivity  , and transmissivity  . For opaque targets,  = 0 and the equation reduces to: </li></ul><ul><li>             (1.2) </li></ul><ul><li>So far, we discussed emissivity as a material surface property. It is that, and more. </li></ul><ul><li>The shape of an object affects its emissivity. </li></ul><ul><li>For semi-transparent materials, the thickness will affect emissivity. </li></ul><ul><li>Other factors affecting emissivity include: </li></ul><ul><ul><ul><ul><li>viewing angle, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Temperature and, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Wavelength. </li></ul></ul></ul></ul><ul><li>The wavelength dependence of emissivity means that different IR cameras can get different values for the same object. And they would both be correct! </li></ul>Dr. Nidhi Mathur
  20. 20. <ul><li>Emissivites may also change when some materials are at a different temperature. </li></ul><ul><li>To make a temperature measurement of an object: </li></ul><ul><ul><li>thermographer will refer to the emissivity table to choose the emissivity value of the object which is then entered into the camera. </li></ul></ul><ul><ul><li>camera's algorithm will correct the temperature by referring to the emissivity percent and calculate a temperature that would more closely match the actual Contact Temperature of the object. </li></ul></ul>Dr. Nidhi Mathur
  21. 21. Dr. Nidhi Mathur
  22. 22. FLIR ThermaCam P25 Dr. Nidhi Mathur Temperature Range Accuracy (% of reading) Measurement Corrections Lens recognition and measurement correction -40°C to 120°C Range 1 0°C to 500°C Range 2 Up to 1500°C Optional Up to 2000°C Optional +/- 2°C (+/- 2%) Reflective Ambient, distance, relative humidity, external optics, Automatic, based on user imput Automatic
  23. 23. <ul><li>Thermography is filling the gap in clinical diagnosis ... </li></ul><ul><li>X-ray, CT, Ultrasound, MRI, etc., are tests of anatomy </li></ul><ul><li>EMG is a test of motor physiology </li></ul><ul><li>DITI is unique in its capability to show physiological change and metabolic processes .  It has also proven to be a very useful complementary procedure to other diagnostic modalities. </li></ul><ul><li>Unlike most diagnostic modalities, DITI is non invasive . It is a very sensitive and reliable means of graphically mapping and displaying skin surface temperature. </li></ul><ul><li>Medical DITI can offer considerable financial savings by avoiding the need for more expensive investigations. </li></ul>Dr. Nidhi Mathur
  24. 24. <ul><li>Medical DITI can graphically display the very subjective feeling of pain by objectively displaying the changes in skin surface temperature that accompany pain states. </li></ul><ul><li>Medical DITI can show a combined effect of the autonomic nervous system and the vascular system, down to capillary dysfunctions. </li></ul><ul><li>Since the body is very symmetrical with regard to temperature, subtle temperature asymmetry's can be easily identified. </li></ul><ul><li>Medical DITI is a monitor of thermal abnormalities present in a number of diseases and physical injuries. </li></ul>Dr. Nidhi Mathur
  25. 25. Factors Affecting Examination <ul><li>ambient room temperature at which the examination is performed </li></ul><ul><li>length of time allowed for patient equilibration to the ambient temperature </li></ul><ul><li>type of equipment utilized </li></ul><ul><li>type of floor covering </li></ul><ul><li>presence or absence of windows which can alter room temperature </li></ul><ul><li>type of heating or air conditioning for thermal regulation of the room. </li></ul><ul><li>usage of lotions , deodorants and cosmetics on the skin </li></ul><ul><li>ingestion of vasodilator and vasoconstrictor substances (ie:caffeine) </li></ul><ul><li>medications taken by the patient </li></ul>Dr. Nidhi Mathur
  26. 26. Because our bodies are generally symmetrical, when unusual bits of tissue are present or normal parts of the body are reacting strangely, this is evident in our body’s thermal “footprint,” so to speak. Dr. Nidhi Mathur
  27. 27. Applications Dr. Nidhi Mathur
  28. 28. <ul><ul><ul><li>Condition monitoring </li></ul></ul></ul><ul><ul><ul><li>Medical imaging </li></ul></ul></ul><ul><ul><ul><li>Infrared Mammography </li></ul></ul></ul><ul><ul><ul><li>Veterinary medicine </li></ul></ul></ul><ul><ul><ul><li>Night vision </li></ul></ul></ul><ul><ul><ul><li>Process control </li></ul></ul></ul><ul><ul><ul><li>Nondestructive testing </li></ul></ul></ul><ul><ul><ul><li>Surveillance in security, law enforcement and defence </li></ul></ul></ul><ul><ul><ul><li>Chemical imaging </li></ul></ul></ul><ul><ul><ul><li>Volcanology </li></ul></ul></ul>Dr. Nidhi Mathur
  29. 29. Medical Applications Dr. Nidhi Mathur
  30. 30. <ul><li>The medical fields in which Infrared Imaging is used are: </li></ul><ul><li>Oncology - Deals with cancerous lesions. The cancerous and pre cancerous lesions show an increase in vascularity and temperature in the affected area. </li></ul><ul><li>Vascular disorders- Deals with bleeding disorders. The Digital Infrared camera captures any deviation from the normal within a blood vessel. Hemorrhages and clots within blood vessels can be identified by these Infrared cameras. </li></ul><ul><li>Respiratory disorders - Deals with breathing disorders. The Digital Infrared camera helps in finding out the physiological changes within the respiratory organs. </li></ul>Dr. Nidhi Mathur
  31. 31. <ul><li>Surgery - Deals with invasive procedures done in order to treat a patient. Infrared cameras give a helping hand to the surgeons when they are performing micro surgeries. </li></ul><ul><li>Tissue viability- Deals with the vitality of tissues. Infrared cameras help in detecting the vitality by ensuring adequate blood supply to the tissues. </li></ul><ul><li>Skeletal and neuromuscular diseases- Deals with bones, nerves, and muscle disorders. Even the smallest of hairline cracks within a bone can be captured by Digital Infrared camera because of its very high resolution. Similarly Infrared cameras play a major role in identifying neuromuscular diseases. </li></ul>Dr. Nidhi Mathur
  32. 32. <ul><li>breast oncology, </li></ul><ul><li>dentistry, </li></ul><ul><li>neurology, </li></ul><ul><li>orthopedics, </li></ul><ul><li>occupational medicine, </li></ul><ul><li>pain management, </li></ul><ul><li>vascular medicine/cardiology and </li></ul><ul><li>veterinary medicine. </li></ul>Dr. Nidhi Mathur
  33. 33. Disease Monitoring – Viral Infections Veterinarian Thermal Imaging   Dental Thermal Imaging – Focal Tooth Infection Migraine Headache Deep Vein Thrombophlebitis Multiple sclerosis Vascular Disease Pain Evaluation Dr. Nidhi Mathur
  34. 34. Dr. Nidhi Mathur