An apparatus and method for providing hyperthermia treatments in a deposit surrounded by tissue in a body is disclosed. A radio frequency antenna array is used to direct a radio frequency signal at a selected frequency into the deposit so that the radio frequency signal will have a selected wavelength in the deposit to selectively heat the deposit to a temperature greater than the surrounding tissue through resonant heating within the deposit. An injectable medium is injected in the deposit to increase a dielectric value and/or conductivity value of the deposit. The injectable medium is selected to increase a specific absorption rate of the radio frequency signal within the deposit relative to the surrounding tissue.