Combination applicator for simultaneous heat and radiation

We present the development of operator and patient friendly conformal applicators that can deliver moderate temperature hyperthermia simultaneously with radiation in superficial tissue overlying contoured anatomy. This applicator combines the uniform heating capabilities of large area conformal microwave array (CMA) flexible printed circuit board applicators with a patient interface (coupling bolus) that facilitates positioning of brachytherapy sources at a fixed distance (e.g. 1.5 cm) from the skin. A customized inverse treatment planning program (IPSA) was used to optimize spacing of a parallel array of source catheters and separation distance from skin, and to characterize the effects of bolus thickness and conformal array curvature on radiation dose uniformity. Performance of a 15 cmx15 cm combination applicator was evaluated in flat and contoured homogenous muscle tissue models. Results demonstrate effective heating and radiation distributions to 1-1.5 cm depth and out to the periphery of the array. This applicator should prove useful for treatment of diffuse chestwall disease located over contoured anatomy that is difficult to treat with external beam radiation. By applying heat and radiation simultaneously for maximum synergism of modalities, this device should expand the number of patients that can benefit from effective thermoradiotherapy for superficial disease.