Breast Tissue Mimicking Phantoms for Combined Microwave and Ultrasound Imaging

This paper reports breast tissue mimicking phantoms for combined microwave and ultrasound imaging for breast cancer detection. Coconut oil and canola oil with agar were used to fabricate skin and fat, respectively. Polyvinylpyrrolidone (PVP) was the primary material used to mimic tumor and fibroglandular (FGT) tissues. The microwave properties were measured at frequency range from 200 MHz to 6 GHz. At 5 GHz the skin phantom had a relative permittivity of 30.54 ± 3.51 and an effective conductivity of 2.74 ± 0.25 S/m. The relative permittivity and conductivity of fat phantom were 7.49 ± 1.33 S/m and 0.42 ± 0.10 S/m, respectively. As for FGT and tumor phantoms, the relative permittivity was 52.03 ± 1.35 and 59.33 ± 1.09, and the conductivity was 5.27 ± 0.26 S/m and 5.30 ± 0.16 S/m. A 7.5 MHz hydrophone measured the ultrasound properties. The skin phantom had an attenuation of 4.20 ± 0.53 dB/cm·MHz and a speed of sound of 1487.5 ± 4.65 m/s. For far tissue phantom, these two values were 1.44 ± 0.22 dB/cm·MHz and 1477.4 ± 2.17 m/s. The attenuation and speed of sound for FGT phantom were 0.64 ± 0.05 dB/cm·MHz and 1555.4 ± 10.41 m/s. Also, the tumor phantom had an attenuation of 0.59 ± 0.18 dB/cm·MHz and a velocity of 1535.4 ± 34.25 m/s. The results correlate with the reported breast tissue properties. Therefore, the presented phantom can meet the requirements to mimic both microwave and ultrasound properties for imaging.