Ultrasonic therapy applicator and method of determining position of ultrasound transducers

A method for determining a position of ultrasound transducers disposed in a thermal therapy applicator, the method comprising:

• with a controller in communication with said thermal therapy applicator, rotating said thermal therapy applicator, disposed in a subject, such that an acoustic window in said thermal therapy applicator is oriented in a predetermined direction;
• acquiring a three-dimensional image of said subject, including said rotated thermal therapy applicator, with a magnetic resonance imaging apparatus;
• with said controller, automatically identifying at least first and second fiducial markers in a first plane, said ultrasound transducers between said first and second fiducial markers;
• with said controller, automatically identifying at least a third fiducial marker in a second plane, the second plane orthogonal to the first plane,
• wherein:
• said at least a third fiducial marker comprises a length of said acoustic window, said defined in a tube disposed in a cylindrical shaft of said thermal therapy applicator,
• said tube is opaque to ultrasound,
• said ultrasound transducer are disposed in the tube, and
• said third fiducial marker is different than said first and second fiducial markers;
• and
• with said controller, using said at least first, second, and third fiducial markers to automatically determine said position of said ultrasound transducers, said ultrasound transducers coupled to a printed circuit board disposed in said tube.