Anatomically and Dielectrically Realistic Microwave Head Phantom With Circulation and Reconfigurable Lesions

Abstract

Abstract-Phantoms provide valuable test platforms for developing medical devices. Solid materials in particular allow fabrication of stable and robust models. This paper presents a novel, anatomically realistic, multi-layered head phantom made from dielectrically accurate, stable, easily mouldable, lowcost tissue-mimicking materials for testing of microwave diagnostic systems. Also incorporated is a mechanism for inserting reconfigurable lesions and a novel circulatory system modelling physiology. Tissue-mimicking materials composed of graphite, carbon black, and polyurethane with small volumes of acetone or isopropanol were fabricated and dielectric properties were measured across the 1-8.5 GHz band. The tissue-mimicking material properties were adjusted until their dielectric properties matched those of reference values for target tissues of interest, thereby emulating: weighted aggregates of head tissues external to the brain, tissues comprising the brain, and blood. 3D printed anatomically realistic head and brain moulds cast the phantom mixtures for each layer. Cylindrical holes in the brain layer allow insertion of pathological lesion phantoms, such as haemorrhages. Tubing embedded in the brain layer forms a symmetrical loop providing a novel simplistic model of circulation. The resulting head phantom is anatomically realistic, dielectrically stable, enables pathology modelling, and has, uniquely, a circulatory loop.This novel head phantom provides a valuable test platform for microwave diagnostic studies.

Experimental Validation of Microwave Tomography with the DBIM-TwIST Algorithm for Brain Stroke Detection and Classification

“…Gelatine emulsions made of oil, water and gelatine are popular recipes for preparing such phantoms, as they are cheap and easy to alter, but can suffer from dehydration. McDermott et al have proposed an alternative method of constructing solid phantoms made of ceramic and carbon powder, in which solid phantoms were fabricated with polyurethane, graphite, carbon black and isopropanol, to mimic the dielectric properties of the brain and the average properties of the layers surrounding the brain [37]. Solid phantoms are electrically and mechanically stable as well as reusable, but are more difficult to fabricate, time consuming, more expensive than the liquid phantoms, and not easy to modify for additional adjustments in properties or geometry.…”

Development of an Anthropomorphic Phantom of the Axillary Region for Microwave Imaging Assessment

“…Several authors proposed various alternatives to model anatomical regions for MWI applications. Examples include breast [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ], and head phantoms [ 24 , 25 , 26 ]. However, outside our research groups, no one has yet developed an antropomorphic phantom of the axillary region suitable for MWI evaluation.…”

Anthropomorphic Breast and Head Phantoms for Microwave Imaging

“…If such bubbles are present, they would behave as small high-contrasted diffractors, which would greatly perturb the electromagnetic field within the phantom. Solid TMMs do not present these drawbacks; however, phantoms made of such materials [23] are not reconfigurable as solid TMMs are not adjustable in order to account for changes linked, for example, to the appearance of a tumor or of a stroke. By contrast, liquid mixtures allow us to avoid air bubbles and stability problems and they are adjustable, as they can easily be replaced.…”