Narrowband Microwave Breast Screening: Repeatability Study With Phantoms

This work presents experimental results on measurement variability obtained with carbon-based tissue-mimicking phantoms using a prototype microwave breast cancer detection system on narrowband (2012.5 – 2100 MHz), adapted to use 16 flexible monopole antennas previously designed for ultrawideband (2 – 4 GHz). The use of narrowband permits a more accessible and compact system with the final goal of a wearable device for frequent scans, targeting early detection through tracking alterations on patients over time. This motivates the research of phantom measurement repeatability. Our narrowband system is described and results are presented for five measurement dates using two phantoms with skin layers and similar low percentages of glands, along with interchangeable plugs for all-fat and three tumor cases. Preliminary clutter rejection uses average trace subtraction on antenna pairs with same distance in-between. Significant signal distinction is noted between baseline and tumors on specific antenna pairs and some distinction is found on central tendencies over all signals. This is promising as the presence of skin and glands can heavily attenuate microwave signals. High variability is found on distinct measurement dates, increasing the standard deviation across all dates considerably. The measurement noise includes comparatively high and easier to remove systematic offsets as well as other confounders that occasionally increase standard deviation, which may mask signal features. This highlights the need to research further techniques to mitigate this variability between measurements in order to increase reliability of microwave breast screening devices and, even more generally, other biomedical devices based on similar principles.