precision in thermotherapy is obtained by providing a reverse gelling polymer composition which gels when its temperature is raised above body temperature . the composition is injected into the blood supply of the tissue being treated , at the beginning of thermotherapy . the temperature increase caused by the heating gels the composition , which temporarily blocks the flow of blood in the region being treated . this improves the predictability and stability of treatment . on cessation of heating , the composition liquefies , removing the temporary embolization . the use of local heating can also expedite removal of tumors and the like from soft organs , even when the heating itself has no therapeutic effect .