Tumor Boundary Estimation Through Time-Domain Peaks Monitoring: Numerical Predictions and Experimental Results in Tissue-Mimicking Phantoms

A method to estimate the boundary of a tumor using an interstitial microwave probe was evaluated in numerical and phantom models. This method utilizes time-domain signal reflection from the tumor/liver interface to provide information about tumor boundary in both radial and axial directions. Using computational experiments, tumors with radial diameters up to 25 mm were estimated with less than 1 mm error. Axial diameters were estimated with at most 5 mm error. Accuracy seemed to increase with radial diameter but decreased with axial diameter. Phantom experiments confirmed the computational results. These early results indicate that the proposed method may be used to estimate tumor boundary in both radial and axial dimensions without imaging. The technique may also be applicable in other situations that contain dielectric contrast between a volume of tissue and its background, such as monitoring tumor ablation growth. Additional work is needed to validate and optimize this method in tumor models.