Advanced hyperthermia treatment: optimizing microwave energy focus for breast cancer therapy

This paper presents a fast antenna phase optimization scheme to enable microwave power focusing for breast cancer hyperthermia. The power focusing is achieved through the maximization of the deposited electric field on the target malignant tumor tissue. To do so, a malignant breast tumor, the surrounding breast medium, and the skin of the breast are modeled as a cylindrical structure composed of eccentric cylinders, and electric field distribution is computed analytically in terms of cylindrical harmonics. This approach minimized the computational cost and simplified the breast medium model. To ensure applicability across various breast types, the dielectric properties (DPs) of the main cylinder, symbolizing healthy breast tissue, are averaged from pixel DPs of digital breast phantoms. The hyperthermia problem is posed as maximizing the total electric field at the central point of the tumor which is simply represented as a vector sum of complex quantities in terms of antenna phases. That is, one antenna phase is selected as a reference and the remaining ones are adjusted accordingly. The approach is validated using a circular applicator with eight TMz polarized line sources surrounding realistic digital breast phantoms. Testing involved eight scenarios using two distinct breast media. In the optimal scenario, the peak temperature is achieved 1.3 mm away from the focus point.