A Breast Tumor Monitoring Vest with Flexible UWB Antennas-A Proof-of-Concept Study Using Realistic Breast Phantoms

Abstract

Breast cancers can appear and progress rapidly, necessitating more frequent monitoring outside of hospital settings to significantly reduce mortality rates. Recently, there has been considerable interest in developing techniques for portable, user-friendly, and low-cost breast tumor monitoring applications, enabling frequent and cost-efficient examinations. Microwave technique-based breast cancer detection, which is based on differential dielectric properties of malignant and healthy tissues, is regarded as a promising solution for cost-effective breast tumor monitoring. This paper presents the development process of the first proof-of-concept of a breast tumor monitoring vest which is based on the microwave technique. Two unique vests are designed and evaluated on realistic 3D human tissue phantoms having different breast density types. Additionally, the measured results are verified using simulations carried out on anatomically realistic voxel models of the electromagnetic simulations. The radio channel characteristics are evaluated and analyzed between the antennas embedded in the vest in tumor cases and reference cases. Both measurements and simulation results show that the proposed vest can detect tumors even if only 1 cm in diameter. Additionally, simulation results show detectability with 0.5 cm tumors. It is observed that the detectability of breast tumors depends on the frequency, antenna selection, size of the tumors, and breast types, causing differences of 0.5-30 dB in channel responses between the tumorous and reference cases. Due to simplicity and cost-efficiency, the proposed channel analysis-based breast monitoring vests can be used for breast health checks in smaller healthcare centers and for user-friendly home monitoring which can prove beneficial in rural areas and developing countries.

Keywords: antenna measurements; biodevices; biomedical monitoring; biosensors; breast cancer; dielectric properties; healthcare technology; microwave diagnosis.

Figure 1

(a) Three cylindrical-shaped glandular phantoms: (1) reference, (2) with 1 cm tumor, and (3) with a 2 cm tumor; (b) breast phantom “Very Dense” with 0.5 cm thick fat layer; (c) breast phantom “Dense” with the glandular phantom inserted into the fat phantom; (d) measurement setup with phantoms set on the mannequin torso (1), above which the muscle phantom is first assembled (2), fat (3), glandular (4), and skin (5) phantoms [30].

Figure 2

Antennas used in the vest. (a) UWB monopole antenna design, (b) UWB monopole with flexible laminate substrate, (c) UWB monopole with conductive textile material, (d) Kapton polyamide substrate-based larger monopole [31].

Figure 3

(a) Tissue layer model used in antenna characteristics simulations, (b) S11 parameters of small and larger flexible antennas, (c–h) radiation patterns of small flexible antenna (left side of figure) and larger flexible antenna (right side of figure) at 3 GHz, 5 GHz, and 7 GHz.

Figure 3

(a) Tissue layer model used in antenna characteristics simulations, (b) S11 parameters of small and larger flexible antennas, (c–h) radiation patterns of small flexible antenna (left side of figure) and larger flexible antenna (right side of figure) at 3 GHz, 5 GHz, and 7 GHz.

Figure 4

The developed breast tumor monitoring vest types used in the evaluations: (a) Vest I with smaller flexible antennas and (b) Vest II with larger flexible antennas [31]. The numbers above the antenna pockets indicate the antenna number.

Figure 5

(a) Emma (left) and Laura (right) voxel models used in the simulations, (b) cross-section of Emma voxel (scattered fibroglandular tissue, left) and cross-section of Laura voxel (heterogeneous glandular breast tissue, right).

Figure 6

Channel evaluations between (a) antennas 2 and 5 (Case 1a) and (b) antennas 2 and 7 (Case 1b) for Vest I with Antenna 1 and “Dense” breast phantom.

Figure 7

Channel evaluations between the (a) antennas 2 and 5 (Case 2a) and (b) antennas 2 and 7 (Case 2b) for Vest I with Antenna 1 and “Less Dense” breast phantom.

Figure 8

Channel evaluations in Case 3 between the (a) antennas 2 and 5 (Case 3a) and (b) antennas 2 and 7 (Case 3b) for Vest I with Antenna 2 and “Dense” breast phantom.

Figure 9

Channel evaluations between in Case 4 (a) antennas 2 and 5 (Case 4a) and (b) antennas 2 and 7 (Case 4b) for Vest I with Antenna 2 and “Less Dense” breast phantom.

Figure 10

Channel evaluations for Case 5 between the (a) antennas 1 and 6 (Case 5a) and (b) antennas 3 and 6 (Case 5b) for Vest II with Antenna 3 and “Dense” breast phantom.

Figure 11

Channel evaluations for Case 6 between (a) antennas 1 and 6 (Case 6a) and (b) antennas 3 and 6 (Case 6b) for Vest II with Antenna 3 and “Less Dense” breast phantom.

Figure 12

Case 7: Simulation-based channel evaluations with different tumor sizes: (a) S26 results using Emma voxel (Case 7a) and (b) S16 results using Laura voxel (Case 7b).

Figure 13

Time-domain channel evaluations with different tumor sizes and different IFFT lengths: (a) Impulse response IR26 results using Emma voxel with full band IFFT conversion, (b) IR16 results using Laura voxel, with full band IFFT conversion, (c) IR16 results using Laura, with IFFT conversion to 4.5–5.8 GHz.