The present invention is directed to systems and methods for thermal therapy, especially to detection-guided, -controlled, and temperature-modulated interstitial thermal therapy. Thermal therapy may be used to treat the tissues of a patient. In the case of interstitial thermal therapy, energy is applied to generate heating of the tissue to affect treatment, such as, for example, thermally inducing tissue damage (e.g. thermally-induced tissue necrosis), which may be useful in treating tumors and/or other diseased tissues. Since targets for thermal therapy are internal to the patient, the use of detection guidance may be useful in locating and monitoring treatment of a target tissue.