| 摘要 |
<p>In a hyperthermia apparatus, ultrasonic waves obtained by using an ultrasonic vibrator are focused in a living body through an acoustic lens (5) and degassed water to form a heating region. In this case, the ultrasonic vibrator is not required to be divided, and the surface of the acoustic lens in contact with the ultrasonic vibrator and the opposite surface are formed in a concave surface, and hills and valleys (5e and d) spreading alternatively in the radial direction are formed on this concave surface, and the portion between these hill and valley are formed in a plane or a curved surface. In accordance with this acoustic lens, the ultrasonic waves are focused on the heating region, and a phase difference is produced by a difference in thickness between the hill part and the valley part, and thereby no undesirable hot spots are produced behind the heating region.</p> |
