Hagness, “Development of anatomically realistic numerical breast phantoms with accurate dielectric properties for modeling microwave 632

Abstract—Computational electromagnetics models of mi-crowave interactions with the human breast serve as an invaluable tool for exploring the feasibility of new technologies and improv-ing design concepts related to microwave breast cancer detection and treatment. In this paper, we report the development of a col-lection of anatomically realistic 3-D numerical breast phantoms of varying shape, size, and radiographic density which can readily be used in finite-difference time-domain computational electro-magnetics models. The phantoms are derived from T1-weighted MRIs of prone patients. Each MRI is transformed into a uniform grid of dielectric properties using several steps. First, the struc-ture of each phantom is identified by applying image processing techniques to the MRI. Next, the voxel intensities of the MRI are converted to frequency-dependent and tissue-dependent dielectric properties of normal breast tissues via a piecewise-linear map. The dielectric properties of normal breast tissue are taken from the recently completed large-scale experimental study of normal breast tissue dielectric properties conducted by the Universities of Wisconsin and Calgary. The comprehensive collection of numeri-cal phantoms is made available to the scientific community through an online repository. Index Terms—Biomedical applications of electromagnetic radia-tion, biomedical electromagnetic imaging, breast cancer detection, breast cancer treatment, finite-difference time-domain (FDTD) methods, microwave hyperthermia, microwave imaging