title: Microwave image reconstruction from 3-D fields coupled to 2-D parameter estimation.
abstract: An efficient Gauss-Newton iterative imaging technique utilizing a three-dimensional (3-D) field solution coupled to a two-dimensional (2-D) parameter estimation scheme (3-D/2-D) is presented for microwave tomographic imaging in medical applications. While electromagnetic wave propagation is described fully by a 3-D vector field, a 3-D scalar model has been applied to improve the efficiency of the iterative reconstruction process with apparently limited reduction in accuracy. In addition, the image recovery has been restricted to 2-D but is generalizable to three dimensions. Image artifacts related primarily to 3-D effects are reduced when compared with results from an entirely two-dimensional inversion (2-D/2-D). Important advances in terms of improving algorithmic efficiency include use of a block solver for computing the field solutions and application of the dual mesh scheme and adjoint approach for Jacobian construction. Methods which enhance the image quality such as the log-magnitude/unwrapped phase minimization were also applied. Results obtained from synthetic measurement data show that the new 3-D/2-D algorithm consistently outperforms its 2-D/2-D counterpart in terms of reducing the effective imaging slice thickness in both permittivity and conductivity images over a range of inclusion sizes and background medium contrasts.
authors.affiliation: Thayer School of Engineering, Dartmouth College, 8000 Cummings Hall, Hanover, NH 03755, USA. qianqian.fang@dart-mouth.edu
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Fang
authors.forename: Paul M
authors.initials: PM
authors.lastname: Meaney
authors.forename: Shireen D
authors.initials: SD
authors.lastname: Geimer
authors.forename: Anatoly V
authors.initials: AV
authors.lastname: Streltsov
authors.forename: Keith D
authors.initials: KD
authors.lastname: Paulsen
mesh_terms: D000465:Algorithms; D001940:Breast / Q000033:anatomy & histology; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008872:Microwaves; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014054:Tomography / Q000295:instrumentation / Q000379:methods*