d suitable for practicing the teachings of this invention in accordance with a seventh embodiment; [0028]FIGS. 10a and 10 b are a side sectional view and a front view, respectively, of a head suitable for practicing the teachings of this invention in accordance with an eighth embodiment; [0029]FIGS. 11a, 11 b and 11 c are a side view, a front view when not in contact with a patient's skin, and a f