Gel phantom preparation for microwave breast cancer imaging

Abstract

Breast cancer is the most common and leading cause of death among women in the world. For this reason, early diagnosis of breast cancer is of great importance. With early diagnosis, a high rate of success is achieved in treatments. There are many methods and devices, which include mammography, ultrasound, magnetic resonance imaging device, or biopsy, used to diagnose breast cancer. The Microwave Imaging Technology has been developed for the last 20 years to detect breast cancer. Microwave is the electromagnetic wave in the the frequency range of 300 MHz – 30 GHz with which humans interact most and which is not strong enough to ionize tissues in the human body. These properties are relative permittivity (′), electrical conductivity (σ) and magnetic permeability. While relative permittivity and electrical conductivity is changing, the magnetic permeability does not change in all human tissues. Each tissue in the breast has different relative permittivity and electrical conductivity. Cancerous tissue has a much higher relative permittivity than normal tissue, and the relative permittivity of it is close to water. It is a huge advantage for microwave imaging because of the significant difference between the two tissues. The aim of this thesis is preparing gel phantoms that able to mimic the breast tissues including cancer tissue. For this aim, firstly poly(acrylic acid) (PAA) gels were synthesized with different properties. When the mechanical properties of the gels were examined, the Young's modulus (E) of the gels increased with the cs-lk ratio, that is, the flexibility decreased. The elongation at break of these gels also decreased with the cs-lk ratio. It was observed that swelling ratios of gels were decreased by increasing cs-lk amounts. The relative permittivities of the solvents/solvent mixtures were found to be close/suitable with ε′ of the breast tissues (normal and cancer tissues). Swellling ratios and dielectric properties of the phantom gels in different solvents/solvent mixtures were investigated. The dielectric properties of gels swollen in these solvent/solvent mixtures were also shown very close to breast tissues (normal and cancer tissues). It was observed that PAA gels are also suitable for mimicking breast tissues (normal and cancer tissues). Beside that, the cancer tissue phantom was clearly seen within the normal tissue phantom in Microwave Breast Imaging device.