Effect of bone on cryospray outcomes through thermal measurements

The cryospray technique is used as a treatment method for cancerous lesions on the skin surface by destroying the cancer cells with the help of rapid freezing. The present study attempts to explore the effect of bone on the cryospray outcomes, which is missing entirely in the literature and is more realistic than the previous studies. The experiment is performed on the skin-mimicking gel surface, and the bone is mimicked by a Chlorinated Polyvinyl Chloride (CPVC) pipe. The gel and pipe resemble the same thermal properties of skin and bone respectively. In order to record the temperature history, thermocouples are arranged at specified locations. Rapid freezing is obtained by spraying the liquid nitrogen on the gel surface with the help of cryospray CS1 using a single-hole nozzle (SHN). A single freeze-thaw cycle of 250 s is carried out for spray. The nozzle spraying distance is varied as 13, 18, and 23 mm. The results obtained from the study are more practical, and the end temperature and cooling rate are significantly enhanced compared to the previous study. The thermal images observe the unsymmetrical necrotic area on the surface from the centre of the spray (CS). The extent of axial and circumferential spread forms an oval shape, and the lateral spread is observed more due to the effect of bone than in the earlier study, which was based on a lesion surface. The study revealed a significant influence of bone on the cryospray outcomes.