Prashant Srivastava
Department of Mechanical Engineering, IIT(BHU) Varanasi, U. P., India
Amitesh Kumar
Department of Mechanical Engineering, IIT(BHU) Varanasi, U. P., India
Cryotherapy is one of the oldest and efficient technique in which localized application of freezing temperature is used to treat skin lesions. Current method of spraying cryogen on the superficial lesion through single hole nozzle (SHN) makes
cryospray a treatment of choice for lesions larger than 15 mm
in diameter. Less mass flow rate of cryogen associated with
SHN and thermophysical properties of tissue are responsible for
such limitation. It has been observed in the previous study that device modification can minimise the existing limitation. Hence, customised multihole nozzle (MHN) compatible with commercial cryogun is used to spray the cryogen in present study. Moreover, recent innovations in the field of transdermal drug delivery have shown promising results of drug administration through stratum corneum [1], [2]. Therefore, thermophysical properties of tissue
phantom is altered through the administration of adjuvant. A pilot experiment is conducted on tissue phantoms while incorporating nanoparticles as adjuvant in cryospray. Comparative analysis of cryoablation is carried out between nano-phantom (phantom loaded with nanoparticles) and normal-phantom (phantom without nanoparticles). Biodegradable MgO nanoparticles are chosen as adjuvant in the present study. Spraying distance is taken as 18 mm for both the cases. Surface temperature of the phantom is estimated through infrared images. It has been observed from the data extracted through infrared images that presence of adjuvants in the phantom assists in the formation of larger of ice ball. Thus, helps in increasing the dimensions of necrotic zone. The radius of
lethal front and freezing front of nano-phantom is 21 % and 70 % larger than normal-phantom respectively. Proposed approach can be used to enhance the scope of cryospray in the treatment of larger lesions like squamous cell carcinoma, keloids etcetra.