title: 3D parallel-detection microwave tomography for clinical breast imaging.
abstract: A biomedical microwave tomography system with 3D-imaging capabilities has been constructed and translated to the clinic. Updates to the hardware and reconfiguration of the electronic-network layouts in a more compartmentalized construct have streamlined system packaging. Upgrades to the data acquisition and microwave components have increased data-acquisition speeds and improved system performance. By incorporating analog-to-digital boards that accommodate the linear amplification and dynamic-range coverage our system requires, a complete set of data (for a fixed array position at a single frequency) is now acquired in 5.8 s. Replacement of key components (e.g., switches and power dividers) by devices with improved operational bandwidths has enhanced system response over a wider frequency range. High-integrity, low-power signals are routinely measured down to -130 dBm for frequencies ranging from 500 to 2300 MHz. Adequate inter-channel isolation has been maintained, and a dynamic range >110 dB has been achieved for the full operating frequency range (500-2900 MHz). For our primary band of interest, the associated measurement deviations are less than 0.33% and 0.5° for signal amplitude and phase values, respectively. A modified monopole antenna array (composed of two interwoven eight-element sub-arrays), in conjunction with an updated motion-control system capable of independently moving the sub-arrays to various in-plane and cross-plane positions within the illumination chamber, has been configured in the new design for full volumetric data acquisition. Signal-to-noise ratios (SNRs) are more than adequate for all transmit/receive antenna pairs over the full frequency range and for the variety of in-plane and cross-plane configurations. For proximal receivers, in-plane SNRs greater than 80 dB are observed up to 2900 MHz, while cross-plane SNRs greater than 80 dB are seen for 6 cm sub-array spacing (for frequencies up to 1500 MHz). We demonstrate accurate recovery of 3D dielectric property distributions for breast-like phantoms with tumor inclusions utilizing both the in-plane and new cross-plane data.
authors.affiliation: Schulich School of Engineering, University of Calgary, 2500 University Dr. NW, Calgary, Alberta T2N 1N4, Canada.
authors.forename: N R
authors.initials: NR
authors.lastname: Epstein
authors.affiliation: Thayer School of Engineering, Dartmouth College, 14 Engineering Dr., Hanover, New Hampshire 03755, USA.
authors.forename: P M
authors.initials: PM
authors.lastname: Meaney
authors.affiliation: Thayer School of Engineering, Dartmouth College, 14 Engineering Dr., Hanover, New Hampshire 03755, USA.
authors.forename: K D
authors.initials: KD
authors.lastname: Paulsen
mesh_terms: D000465:Algorithms; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D004867:Equipment Design; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation* / Q000379:methods*; D008872:Microwaves; D008954:Models, Biological; D019047:Phantoms, Imaging; D011859:Radiography; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio; D014054:Tomography / Q000295:instrumentation* / Q000379:methods*