Seminar Report On Thermal Infrared Imaging Technology
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Functional Near Infrared-Spectroscopy (fNIRS) represents a powerful tool to non-invasively study task-evoked brain activity. fNIRS assessment of cortical activity may suffer for contamination by physiological noises of different origin (e.g. heart beat, respiration, blood pressure, skin blood flow), both task-evoked and spontaneous. Spontaneous changes occur at different time scales and, even if they are not directly elicited by tasks, their amplitude may result task-modulated. In this study, concentration changes of hemoglobin were recorded over the prefrontal cortex while simultaneously recording the facial temperature variations of the participants through functional infrared thermal (fIR) imaging. fIR imaging provides touch-less estimation of the thermal expression of peripheral autonomic. Wavelet analysis revealed task-modulation of the very low frequency (VLF) components of both fNIRS and fIR signals and strong coherence between them. Our results indicate that subjective cognitive and autonomic activities are intimately linked and that the VLF component of the fNIRS signal is affected by the autonomic activity elicited by the cognitive task. Moreover, we showed that task-modulated changes in vascular tone occur both at a superficial and at larger depth in the brain. Combined use of fNIRS and fIR imaging can effectively quantify the impact of VLF autonomic activity on the fNIRS signals.
In order to investigate the origin of the slower systemic changes, we estimated the autonomic responses to cognitive processes using functional thermal infrared (fIR) imaging19. fIR imaging is a non-contact and non-invasive technique that allows - by recording the heat radiated from the skin - to measure and to image the cutaneous temperature distribution and to estimate at a distance a series of autonomic parameters, among which the variation of the cutaneous perfusion20, the heart beat rate21, the sudomotor response22, up to emotional responses and arousal conditions through their thermal signature19,23,24,25,26. fIR imaging provides a powerful method to record the temperature changes and their physiological fluctuations, such as those related to sympathetic regulation of peripheral vascular tone27, since skin temperature is a function of superficial blood flow (SBF).
This study aims to evaluate the thermally-recorded autonomic correlates to cognitive functioning and to investigate the impact of the autonomic outflow on the optical estimation of brain activity. To the best of our knowledge, this is the first attempt to combine fIR imaging and fNIRS measurements for such investigation.
In this study we investigated the contamination of the hemodynamic changes due to brain activity (assessed by means of fNIRS) by the hemodynamic changes related to the ANS activity (assessed by means of thermal IR imaging).
In order to monitor and evaluate the ANS response to the assigned cognitive task, we recorded the variations of the nose tip temperature across the experimental phases. Thanks to the strong connection between skin temperature and the ANS, thermal imaging represents a powerful method to assess the peripheral systemic behavior42. The nose tip region was chosen for two main reasons: i) It reflects the sympathetic vasomotor activity39, thus depending on the cutaneous blood perfusion19,25; ii) it is not directly and anatomically related to the frontal and pre-frontal cortex, thus being able to unveil the autonomic connoted of the responses to the task. Cutaneous blood perfusion is known to be a potential source of artifacts for fNIRS13,14,43. Moreover, thermal cameras do not interfere with NIRS optodes like other instrument do (e.g. the light emitted by Laser Doppler14).
Given the potential influence on the fIR imaging signals, information about the recreational drug use and medical and psychological history were assessed in a telephone interview. Regular recreational drug users (cannabis within the last two months, other recreational drugs within the past year), habitual smokers (>7 cigarettes/week) and individuals reporting chronic illness (e.g., cardiovascular or thyroid conditions), psychological disorders (e.g. depression or anxiety) or taking medication that influences hypothalamic-pituitary-adrenal regulation were excluded from the study24. The study was approved by the Research Ethics Board of the University of Chieti-Pescara and performed in agreement with the Declaration of Helsinki. All participants signed informed consent and could withdraw from the study at any time.
How to cite this article: Pinti, P. et al. Simultaneous fNIRS and thermal infrared imaging during cognitive task reveal autonomic correlates of prefrontal cortex activity. Sci. Rep. 5, 17471; doi: 10.1038/srep17471 (2015).
Temperature is one of the important parameters to tell the condition of internal process, material and even quality of the desired output. A qualitative but accurate conclusion can be drawn by observing the temperature profile of any surface. On the other hand higher temperature also indicates obvious loss of energy in the form of heat. Therefore temperature monitoring would give ample indication of the condition of the material, process quality and explore the possibility of energy conservation avenues. With the on-line condition monitoring technology becoming an inevitable part of maintenance strategy in today?s scenario, non-contact type temperature monitoring methods have become more popular. Infrared Thermography is such a non-contact type technique which provides a fast, reliable and accurate temperature profile of any material surface. Thermography is nothing but the temperature profiling of a surface or point. As the name suggests, infrared thermography is based on Infrared(IR) technique. The principle underlying this technique is that every object emits certain amount of IR energy and the intensity of this IR radiation is a function of temperature. In an electromagnetic spectrum the IR region appears between 0.8 micron to 1000 micron wavelength (See Figure 1). This wavelength of IR spectrum is more than that of a visible spectrum. The IR energy which can directly represent the surface temperature can be detected and quantified by the help of IR scanning system.
Infrared Predictive Maintenance (IR/PM) activities, especially as they relate to predicting electrical/mechanical systems equipment failure, are increasing in popularity. This is in no small part due to the efforts of the IR industry to educate engineering and maintenance department managers as to the advantages of predicting, and subsequently preventing, problems from becoming system failures by using infrared thermographic equipment and/or contract services. However, many companies and plants have failed to achieve what they really need: An extensive and effective Infrared Predictive Maintenance Program. One "Hot Spot" survey per year does not make a successful infrared program. The annual survey of equipment, regardless of whether the imaging is performed by a contractor or by an in-house group, should only be a part of the program. For a program to be effective it must be accepted by management as well as other maintenance personnel. Getting other maintenance people involved in Infrared Thermography is a good way of gaining acceptance not to mention the fact that, more people scanning equipment will find more problems, more quickly, resulting in payback more quickly for the plant. This paper discusses the approach which I am implementing with varying degrees of success at my client's plant sites and which could be implemented in plants with existing IR imagers. In the past, I have considered my services a very valuable part of my client's maintenance activities. They have obviously concurred, since I have returned to their facilities year after year. However, when I left a site, I was leaving with the only means of performing infrared testing. Now, I see my role changing. My goal as an infrared thermographer is to report potential problems on their critical electrical/mechanical systems prior to failure in a timely and cost-effective manner. However, there are two problems: 1) I do not inspect everything that needs to be inspected. While performing infrared surveys, we literally walk past hundreds of pieces of equipment that are in different stages of failure. But, we have been given a limited number of hours or days to check critical systems, so we pass by this equipment. 2) There is nothing remedial about infrared thermography itself. Sometimes repairs are either not made or not correctly made. In some facilities I report the same problems or types of problems on the same pieces of equipment year after year. To address these two issues, I have set out to provide my clients with what they need: The start of (or at very least the chance to start) an effective IRIPM Program where my services are a part of the overall program, but not the program itself.
Infrared thermal imaging is a rapid and non-invasive procedure for mapping skintemperature distribution of the human body. Advanced software and high-resolutioninfrared detectors has allowed for a renaissance in the use of infrared thermalimaging or thermography in medical research and practice. After a review of theory,technology and methodology of medical infrared imaging, the remainder of the bookconsists of a collection of clinical case studies demonstrating the wide variety ofapplications of thermography in modern medicine. The combined expertise from anumber of centres is used to create this database of images and cases that will beinvaluable for medical researchers and practitioners in making diagnoses andmeasuring treatment efficacy. This book is recommended reading for practising andtraining radiographers, medical physicists and clinicians.
Francis Ring is a pharmacologist and clinical scientist with 50 years' experiencein quantitative infrared thermal imaging in medicine. He currently leads theMedical Imaging research Group at the Faculty of Advanced Technology, Universityof Glamorgan, UK, and has published more than 300 papers in this area. 2b1af7f3a8