What are the principles behind Microwave Imaging?
Living tissues have different electrical properties than those of air. Therefore, the setup usually involves a liquid around the object and where the antenna is also immersed, so that the interface is minimized. When microwave radiation interacts with living tissue, microwaves can be transmitted, reflected or dissipated (by heat). The penetration of the microwaves goes until about 10 cm. The transmitting antenna emits microwaves and other antennas receive the transmitted and reflected waves. (The transmitting antenna can also receive.) There are differences in the properties of healthy tissue and malignant tumors. The tumors cause the waves to suffer scatter and the waves have now different energy (frequency). With the information of the detected waves, an image can be obtained (through some complicated methods) or the signals can be analyzed.
Advantages of Microwave Imaging:
- Low Cost
- Non-ionizing radiation
The main clinical application of Microwave imaging is breast cancer. This is due to several reasons:
1. Breast tissues are usually above the 10 cm penetration limit.
2. Breast cancer screening will greatly benefit from a low cost and non-ionizing radiation, as well as less painful acquisition for the patients.
Image from here.
More about this technique can be read in:
Fear, E., Meaney, P., & Stuchly, M. (2003). Microwaves for breast cancer detection? IEEE Potentials, 22 (1), 12-18 DOI: 10.1109/MP.2003.1180933
Nikolova, N. (2011). Microwave Imaging for Breast Cancer IEEE Microwave Magazine, 12 (7), 78-94 DOI: 10.1109/MMM.2011.942702
Recent news about microwave imaging for breast cancer: