A thermal therapy catheter (28) includes a catheter shaft (32) having an outer surface (52) that is insertable into a body lumen. The catheter shaft (32) carries an energy-emitting element (74). A multi-lobe balloon (71) is positioned around the outer surface (52) of the catheter shaft (32) adjacent to the energy-emitting element (74), with opposing ends of the multi-lobe balloon (71) being sealingly connected to the catheter shaft (32) to form a chamber between the multi-lobe balloon (71) and the outer surface (52) of the catheter shaft (32). A fluid is circulated between the outer surface (52) of the catheter shaft (32) and the multi-lobe balloon (71) in a defined fluid flow path to firmly contact the wall of the body lumen and thereby conductively cool the body lumen tissue while thermally treating targeted tissue at a depth from the body lumen wall.