Dielectric measurements of skin cancer phantoms up to 50 GHz

Abstract

Background: Skin cancer is a global health issue. Non-invasive detection methods are crucial for early diagnosis, with microwave and millimetre-wave reflectometry offering potential due to their ability to differentiate between healthy and malignant tissues based on dielectric properties. Objectives: The primary objectives were to develop phantom models that accurately represent the dielectric properties and anatomical features of the skin, tumour and fat tissues, extend the understanding of these properties into the millimetre wave spectrum, and assess the effect of the skin layer on tumour detection using dielectric spectroscopy. Research Methodology: The research was conducted in four phases. Phase 1 involved familiarisation with dielectric measurements. Phase 2 focused on fabricating separate skin, tumour, and fat mimics. In Phase 3, two oil-in gelatin phantoms were constructed—one with an 8 mm fat layer embedding a 3 mm deep, 20 mm in diameter tumour, and another also including a 2 mm skin layer. Phase 4 evaluated tumour detection based on dielectric measurements and evaluated the effect of skin in detecting liposarcoma. Results: Both phantoms accurately replicated the dielectric properties of human tissues. With the skin layer, detection was more challenging, particularly at higher frequencies, though the tumour was discernible in the real part of permittivity at lower microwave frequencies and in the imaginary part at higher millimetre wave frequencies. Conclusions: Oil-in gelatin phantoms can accurately replicate dielectric properties of human skin, fat and tumours. While a skin layer reduced tumor clarity, detection was possible at specific frequencies. Recommendations: Further studies with varying skin thicknesses and higher frequencies are recommended for comprehensive analysis. Non-invasive technologies should be prioritized for early cancer detection, and quality assurance protocols should address oil-in-gelatin phantoms’ limited shelf life.