Novel systems for delivering therapeutic agents to target tissues are disclosed. The guidewire (520) and cannula (500) configurations enable rapid and repeated treatments of the target tissue without the need for subsequent imaging. The cannula is coupled to a source of ultrasound, radiation, radiofrequency energy, or chemotherapeutic agents which can then be delivered to from the cannula the target tissue. The system can be used to treat tumors that are small or surgically inoperable. In addition the system can be used to treat lymphatic tissue that may contain metastases from the tumors.
