Contrast-Enhanced Microwave Cancer Detection Using Angle-of-Arrival Approach

This article proposes a novel contrast-enhanced microwave cancer detection (MCD) system to accurately detect the location of a tumor targeted by nanoscale contrast agents. This system adopts the angle-of-arrival (AoA) positioning approach that is conventionally applied to the region where plane waves dominate the propagation. Hence, to ensure the effectiveness of the AoA approach when it is working in close proximity to the human body, a new algorithm is proposed to transfer the antenna’s radiation pattern from the far-field to the detection region where spherical waves can still be observed. This AoA-based MCD system requires fewer antennas than other radar-based positioning approaches, thereby creating a low-profile hardware architecture. In addition, during the detection process, a differential technique is incorporated in order to track the signal change due to the administration of contrast agents, which can significantly suppress the noise inside the biological medium. The AoA-based differential MCD system is numerically studied on an anatomically realistic breast phantom subject to a variety of signal-to-noise ratios (SNRs). The results show that the proposed system can successfully locate the tumor with an average resolution of 0.6 mm. When the SNR in the biological medium is 10 dB, the average positioning error is less than 1.5 mm with sensitivity maintained above 60%, which surpasses the performance of other similar systems. The system is also experimentally validated with a physical breast phantom and stepper-motor-driven rotating antennas, where the reconstructed image shows a minor deviation of 3.61 mm with that of the simulated one.