Conference Paper

Axillary lymph node (ALN) microwave tomography (MWT) presents significant challenges related to the limited angular view and the limited space for antenna placement in the underarm region, which restricts the measurement domain and, consequently, the information available for image reconstruction.
In this context, we assess a strategy to enhance information retrieval by performing two consecutive measurements, with the antenna set rotated by half the angular antenna spacing. Our MWT system consists of six monopole antennas (0.8-2.5GHz) immersed in a glycerol bath and surrounding a CT-derived axillary region phantom mimicking fat tissue with one ALN embedded. Our reconstruction algorithm employs the distortedBorn iterative method combined with the two-step iterative shrinkage/thresholding for the inversion. Our numerical results compare single-step acquisitions and two-step acquisition reconstructions, and demonstrate reliable target detection in the 0.8–1.0GHz band with improved performance using two-step acquisition. The 1.1–1.9 GHz range proved unsuitable due to clutter presence, while clear improvements in the detection are observed in the 2.0–2.5GHz band when employing the two-step measurements strategy. Our experimental results, obtained with the two-step acquisition method, confirmed stable detection at
0.8–1.0GHz, while presenting clutters in the 2.0-2.5GHz band, suggesting that the two-step acquisition method is not sufficient to overcome the instability associated with higher frequencies.