An Investigation into Using Ultrasound for Skin Cancer Therapy

Abstract

Basal cell carcinoma (BCC) is one of the most prevalent forms of skin cancer, particularly in the Southern Hemisphere, due to high UV exposure. Focused ultrasound (FUS) is a non- invasive treatment technique however its current clinical modalities relies on using high intensity ultrasound that causes thermal ablation of the target tissue, which induces damage to healthy tissues and also causes pain; thus, it is less suitable for sensitive areas like the skin, which has the highest concentration of sensory receptors. This research investigates non-invasive therapeutic techniques using low intensity focused ultrasound to selectively target cancer cells while minimizing the impact on healthy cells. This study integrates dynamical modelling, analytical and numerical solutions, and experimental validation using cancer-mimicking microbeads. Toward the end, the tests were conducted on ex-vivo human tissue samples with histologically confirmed BCC. A comprehensive mathematical model was employed to simulate the dynamic response of healthy and cancerous cells to ultrasonic excitation based on the unique biomechanical properties of healthy and cancer cells. Resonant frequencies were determined using steady state and transient analytical and numerical simulations at various stages of neoplastic transformation. An experimental rig was developed to test the hypothesis. The mechanical properties of healthy and cancerous cells were mimicked using polyacrylamide hydrogel microbeads. It was found that when the beads were insonated, the cancer-mimicking microbeads ruptured at a rate four times higher than the healthy cells. Ex-vivo human tissue samples with BCC were also insonated using ultrasound at a predetermined frequency. Visible improvements were observed in the tissue while keeping the healthy tissue intact, which indicates some degree of selective cellular disruption. The findings suggest that the resonance-based selective targeting of cancer cells can induce mechanical disruption, and this establishes a foundation for the selective treatment of cancer and understanding its mechanics, thus paving the way for future refinement and potential clinical applications.