## 3 Standardization in Thermographic Research
Concerning the patients: the intrinsic factors that should be taken into account during the implementation and interpretation of the research results are sex, age, anthropometric measurements, body composition, circadian and infradian rhythms, hair density, skin emissivity, medical history, metabolic rate, skin blood flow, genetics, and emotions; those that should be avoided are factors that alter metabolism (smoking, drinking sparkling water and/or hot coffee and tea; a heavy meal a minimum of two hours prior to the investigation; alcohol or drug consumption; and physiotherapy or sports on the image-collection day); also on the day of the examination, the patient must not apply any cosmetics to the tested body surface; the patient should report any infections and any medications taken; the subject's acclimatization or equilibration period should be 15-20 min, while during this process the body surface that will be recorded must be uncovered; to minimize thermal reflections, the person under testing should be as far as possible from all equipment and walls; physical activity during all testing procedures should be kept to a minimum; the analyzed area of the body must not be touched; the examined person should not have any jewelry and should avoid crossing legs or holding arms close to or on the body; seating should be abstained from, to prevent marks that can result in skin temperature changes. 4. Concerning the technical determinants of measurements: in medicine, cameras with a tunable focal length (zoom) are most often used, with a minimum focusing distance of approx. 0.5 m, a row's field of view 25\({}^{\circ}\)\(\times\) 19\({}^{\circ}\), and an angle of divergence equal to or less than 1 mrad; an optimized temperature range (approximately 20-50 \({}^{\circ}\)C) will maximize the sensitivity of the sensor; a larger number of pixels (resolution) means more thermal information; it is important to control the calibration; the distance between the camera and the analyzed object should not be less than 1-1.5 m; in the selection of the ROI, the body region must be perpendicular to the lens of the infrared camera; when setting an ROI manually, including random pixels from the background or from the borders to the ROI in the analysis should be avoided [11; 19; 21; 22; 23]. It should be remembered that for the correct execution and the thermogram, it is required to enter a number of settings into the thermal imaging camera related to the external conditions of thermal imaging. The standardization protocols for thermovision testing are constantly improving, and also in the field of medical research. The latter's guidelines for measuring devices and the methodology of the measurements themselves were included in the report of the International Organization for Standardization in 2017, ISO 18251-1:2017 [24], entitled Medical electrical equipment--deployment, implementation and operational guidelines for identifying febrile humans using a screening thermograph, which is considered to be one of the best conductors for estimating the temperature of the tested object [25]. The American Society for Testing and Materials (ASTM) also made a significant contribution to the development and standardization of thermographic research, developing standards for testing systems and thermographic devices, and proposing methods for determining the basic parameters of thermal imaging cameras [26; 27; 28; 29; 30; 31]. Thermography is used in sports, medicine, and rehabilitation, both in the terms of research on adults and children, and in physiological and pathological conditions. IRT is increasingly applicable in medicine, as well as in rehabilitation, especially in fields related to musculoskeletaletal dysfunctions. Thermal detectors for medical applications need to be safe, easy to use, and inexpensive. It is fast, and simultaneous large-area monitoring is possible.