## 3 Results
### Agar Skin Phantom  
Figure 3 illustrates the application of six different cooling methods on the flat agar skin phantoms. The thermograms selected at 5 s into the reheating are displayed. Below each thermogram, the corresponding histograms are shown. The histograms of the vortex cooler and cryo cooler (convective cooling methods) appear relatively narrow and tall, indicating uniform cooling distribution on the skin phantom. Conversely, the cool pack and aluminum medal cooling employ conductive cooling, resulting in wider and less tall histograms compared to the convective cooling methods, suggesting less uniform cooling.  
Notably, this figure reveals a significant factor: the ice and alcohol cooling methods interfere with infrared radiation capture. When using ice for cooling, the melting ice leaves a layer of cold water on the skin phantom, which affects the thermal camera's view. The water absorbs and scatters infrared radiation, causing attenuated and out-of-focus thermograms. Similarly, the evaporative cooling effect of alcohol has a profound influence on thermal imaging. The alcohol vapors obstruct the view of the agar skin phantom, rendering it invisible to the thermal camera. Moreover, the application of substances such as ice, water, and alcohol to the skin is undesirable due to their potential impact on skin integrity and functionality.  
Because of the influence of ice, water and alcohol on the skin and infrared radiation, these cooling methods are no longer considered for application on the ulcerating skin lesion. The four remaining cooling methods, cool pack, vortex cooler, cryo cooler and an aluminum medal, are again applied on the skin phantom. Figure 4 shows the reheating state 5 s after the cooling is removed. It is clearly visible that the convective cooling methods (vortex cooler and cryo cooler) create a more uniform cooling in regard to the ulceration. The conductive methods, cool pack and aluminum medal, clearly cool the ulceration but not the area directly around the ulceration. The cool pack and aluminum medal are not able to make contact with the transition between the bulge and the flat skin surrounding it. This is also clearly visible in the corresponding histograms of the reheating thermogram. The thermograms of the convective methods are narrower than the ones of the conductive methods.  
Due to the adverse effects of ice, water, and alcohol on the skin and infrared radiation, these cooling methods are no longer considered suitable for application on the skin. Therefore, the four remaining cooling methods, namely cool pack, vortex cooler, cryo cooler, and aluminum medal, were reevaluated and applied to the ulcerating skin phantom. Figure 4 illustrates the reheating state, which was captured 5 s after the cooling was removed. It is evident that the convective cooling methods (vortex cooler and cryo cooler) achieve a more uniform cooling effect specifically around the ulceration. Conversely, the conductive methods, cool pack and aluminum medal, effectively cool the ulceration but do not extend their cooling reach to the surrounding skin area. Notably, the cool pack and aluminum medal fail to establish contact with the transitional region between the bulge and the adjacent flat skin as depicted in thermogram. Furthermore, the histograms obtained from the convective methods exhibit narrower profiles compared to those generated by the conductive methods.  
Figure 3: The figure displays the results of six cooling methods along with their corresponding histograms. A round spot visible in the images represents an air bubble, which is an artifact that occurred during the fabrication of the agar phantom. Among the cooling methods, the cool pack, vortex, cryo, and aluminum medal cooling exhibit a more uniform cooling pattern, as evident from the histograms. In contrast, the ice and alcohol cooling methods have a distinct influence on infrared radiation.