HIFU probe for treating tissue with in-line degassing of fluid

An apparatus for treating the prostrate from a position in a rectum of a patient, the apparatus comprising:

• a transrectal probe including an expandable acoustic membrane covering at least a portion of the probe and a transducer positioned behind the expandable acoustic membrane, the transducer being configured to emit ultrasound energy and to sense ultrasound energy;
• and
• a controller operably coupled to the transducer, the controller being configured to operate the transducer in an imaging mode wherein at least one image of the tissue is obtained from ultrasound energy sensed by the transducer and in a therapy mode wherein a plurality of treatment sites are treated with a HIFU Therapy with the transducer;
• and
• a fluid circulation system in fluid communication with a fluid pathway including an area adjacent a face of the transducer between the transducer and the acoustic membrane, the fluid circulation system including
• a pump configured to circulate a fluid throughout the fluid circulation system and the fluid pathway of the probe;
• a chiller configured to reduce a temperature of the fluid;
• a degasser configured to remove dissolved gases from the fluid, the degasser including a vacuum pump;
• and
• a fluid adjustment member including a fluid reservoir, the fluid adjustment member being configured to both remove fluid from the fluid circulation system and to add additional fluid to the fluid circulation system, wherein a first portion of the additional fluid is to be introduced to the fluid to expand the expandable acoustic membrane to contact the rectum of the patient when the probe is positioned in the rectum of the patient and a second portion of the additional fluid is to be introduced into the fluid to further expand the expandable acoustic membrane to position the transducer relative to the prostrate of the patient in a direction generally transverse to a longitudinal axis of the transrectal probe.