Methods and apparatus for intraocular brachytherapy
Methods and apparatus for intraocular brachytherapy are disclosed in which a cannula is introduced into the eye for delivery of radiation to a target tissue. Techniques for properly locating the cannula with respect to the target tissue, for protecting non-target tissue, for regulating heat generated by x-ray emitters, and for combining therapies are disclosed.
1. A method of positioning a device for local delivery of radiation to intraocular sub-retinal target tissue a pre-determined space relative to the target tissue comprising:
providing a device comprising a cannula sized for insertion into an eye and having a proximal end and a distal end; a radiation-emitting source adapted to be located in the distal end of the cannula; and an ultrasound transducer located in the distal end of the cannula adapted to directionally emit ultrasonic radiation toward the target tissue;
calibrating the ultrasound transducer in accordance with a predetermined spacing for the distal end of the cannula from the sub-retinal target tissue so as to generate a signal when the predetermined spacing is achieved;
introducing the cannula into an eye through an access site on the eye; and
moving the distal end of the cannula toward the sub-retinal target tissue until the signal generated by the ultrasound transducer is perceived by a user.
2. The method of claim 1 wherein the ultrasound transducer is located in the distal end of the cannula proximal to the radiation-emitting source.
3. The method of claim 1 wherein the ultrasound transducer is located in the distal end of the cannula distal to the radiation-emitting source.
4. The method of claim 1 wherein the signal generated by the ultrasound transducer is an audible signal.
5. The method of claim 1 wherein the signal generated by the ultrasound transducer is a visual signal.
6. A method of positioning a first cannula within an eye for delivery of a therapeutic treatment to a target tissue within the eye comprising:
introducing the first cannula into the eye through an access site on the eye;
introducing a second cannula into the eye through an access site on the eye, the second cannula including an ultrasound transducer;
positioning the distal end of the first cannula between the ultrasound transducer associated with the second cannula and the target tissue; and
moving the distal portion of the first cannula toward the target tissue until a predetermined spacing between the distal end of the first cannula and the target tissue is achieved, at which time a signal is generated by the ultrasound transducer.
7. The method of claim 6 wherein the signal generated by the ultrasound transducer is an audible signal.
8. The method of claim 6 wherein the signal generated by the ultrasound transducer is a visual signal.