A cryotherapy element is an element for carrying out treatment on a diseased area by repeatedly freezing and defrosting said area, thus making the area necrotize. A frozen diseased area reaches a frozen state and an MRI or an x-ray CT device is used in the observation thereof. However, there is a desire for the frozen state to be detected more easily, reliably and accurately. This cryotherapy element is configured from a metal cylinder (1) and a freezing terminal (3) which is inserted inside the cylinder. A diseased area is frozen by the flow of freezing gas in the freezing terminal (3), and is defrosted by the flow of defrosting gas. An ultrasonic vibrator (4) is mounted to the circumferential outer-peripheral surface of the cylinder (1) in an attachable and detachable manner. Ultrasound waves are emitted from the ultrasonic vibrator (4) and reflected waves are received from the boundary between the frozen region of the diseased area and normal tissue. The transmission and reception is carried out by means of a transmitting and receiving unit (5). The time and amplitude of the reflected wave signals received by the transmitting and receiving unit (5) are stored in a memory (22). A processing unit (23) determines the envelope curve surface area of the amplitude from the data, and calculates the size of the frozen area from the surface area.Linvention porte sur un élément de cryothérapie, lequel élément est un élément pour effectuer un traitement sur une zone malade par congélation et décongélation répétées de ladite zone, de façon à produire ainsi une nécrose de la zone. Une zone malade gelée atteint un état gelé, et un dispositif dimagerie par résonance magnétique ou de tomographie par ordinateur à rayons X est utilisé dans lobservation de celle-ci. Cependant, on souhaite que létat gelé soit détecté plus facilement, de façon plus fiable et plus précisément. Cet élément de cryothérapie est configuré à partir dun cylindre métallique (1) et dun terminal de congélation
