A method includes positioning an effective amount of a thermal target material at a treatment site of a patient. The treatment site, that is, the location of the thermal target material, comprises a location adjacent to biological tissue to be treated. The thermal target material includes carbon molecules preferably in a carrier fluid. Regardless of the particular structure of the carbon, the carbon molecules in the material heat very rapidly in response to incident microwave radiation and radiate heat energy. The heat energy radiated from an effective amount of the thermal target material when subjected to an effective quantity of microwave energy causes localized heating around the thermal target material. This localized heating may be applied for therapeutic purposes. However, the microwave radiation necessary to produce therapeutically effective heating is insufficient to cause cellular damage in the biological tissue by direct absorption in the tissue.