Evaluation of Perfusion and Thermal Parameters of Skin Tissue Using Cold Provocation and Thermographic Measurements

Abstract

Measurement of the perfusion coefficient and thermal parameters of skin tissue using dynamic thermography is presented in this paper. A novel approach based on cold provocation and thermal modelling of skin tissue is presented. The measurement was performed on a person's forearm using a special cooling device equipped with the Peltier module. The proposed method first cools the skin, and then measures the changes of its temperature matching the measurement results with a heat transfer model to estimate the skin perfusion and other thermal parameters. In order to assess correctness of the proposed approach, the uncertainty analysis was performed.

Numerical modelling of skin tumour tissue with temperature-dependent properties for dynamic thermography

“…For visual interpretation of the results using the proposed numerical model, Figures 9 and 10 show contours of temperature difference on the skin surface at different times during the dynamic thermography procedure for Clark II and Clark IV, respectively. Both figures use the same temperature scale to show the difference between the tumour level, where the cut-off level is set to 20mK [12], which is the current NETD error of IR cameras. The first picture on both figures (part a) represents the steady-state temperature difference and, as already discussed, the temperature signature for the Clark II tumour is almost negligible compared to the Clark IV, and therefore it is harder to detect using static thermography.…”

“…The constant cooling approach seems to be the most appropriate because of the deep penetration and high temperature contrast during the rewarming period. Strakowska et al [12] also used a constant temperature cooling approach with a Peltier cooling device for their experiment. Therefore, for the numerical model presented in this paper, we used a constant cooling approach, which can be written as:…”

“…Thermography for medical screening or diagnosis can be done in two ways, observing the temperature under steady-state condition (passive or static thermography) or inducing thermal stresses by cooling or heating of the observed tissue and measuring the thermal response during the recovery phase (active or dynamic thermography). Both methods have been used for medical applications; however, recent research on dynamic thermography shows a superior approach over the static one due to uncovering more information about the observed tissue, gathered from the dynamic response [5][6][7][8][9][10][11][12][13]. In this paper, we will focus on the use of dynamic thermography for skin tumour diagnostic.…”

“…This drawback is overcome by dynamic thermography with induced thermal stress to the observed tissue, usually cooling, where a much higher temperature difference or contrast during the thermal recovery is produced [8][9][10][11], which can be easily detected even with the presence of background noise. Temperature resolution or sensitivity of IR cameras nowadays is in the range of 20 − 60mK, depending on the quality of the camera, which is expressed by the NETD (Noise Equivalent Temperature Difference) [2,7,8,12,14]. The NETD is a measure of how well an IR camera detector is able to distinguish between small differences in thermal radiation.…”

“…Because there is some uncertainty in the model parameters such as the value of material properties, geometry, thickness or thermal response, a sensitivity analysis of 56 parameters has been done on Clark II and Clark IV tumours, to determine which parameters have the strongest correlation with the skin temperature response and, therefore, has to be defined more precisely for accurate numerical simulation of dynamic thermography. The sensitivity analysis is also helpful for inverse bioheat problems of this type, because of the information it provides on which of these parameters could be estimated using dynamic thermography as a measurement technique [12].…”