System for treatment of diseased tissue using controlled ultrasonic heating
The present invention provides a method and apparatus for delivering and controlling thermal therapy to a volume of diseased tissue. Specifically, the invention includes using thermal imaging and other inputs to determine an acoustic (ultrasonic) treatment regime employing interstitial ultrasound applicators to deliver a required therapeutic temperature or thermal dose to the affected region in a body or organ. Various aspects of the treatment that can be controlled include individual transducer element operating power and frequency, as well as the rate of cooling and rotation of the entire applicator.
1. A system for delivering thermal treatment to diseased tissue in a treatment volume, comprising:
an ultrasonic thermal applicator including at least one transducer element that is driven by a transducer driving signal having a driving frequency and a driving amplitude, said at least one transducer element providing a nominally directional ultrasonic beam into the treatment volume;
a magnetic resonance (MR) imaging apparatus adapted for acquiring MR thermometry data from the treatment volume and providing an output comprising real-time quantitative thermal imaging information for the treatment volume including information representing a plurality of input control temperatures at a corresponding plurality of control point locations of said treatment volume;
a treatment control system including treatment planning software to locate or define a volume corresponding to said treatment volume, based on said MR thermometry data, and further including a treatment controller receiving said real-time quantitative thermal imaging information including said input control temperatures from said MR imaging apparatus and providing an output to control said transducer driving signal, said transducer driving signal depending at least in part on said input control temperatures; and
a thermal applicator motion controller including a motor assembly receiving a motor control signal from said treatment controller and being designed and configured in a closed-loop control system to rotate said ultrasonic thermal applicator, and consequently said nominally directional ultrasonic beam, in an angular motion about an axial dimension of the ultrasonic thermal applicator, said angular motion depending at least in part on said input control temperatures.
2. The system of claim 1 , wherein the ultrasonic thermal applicator comprises a multi-element transducer having at least two separately-phased ultrasonic elements.
3. The system of claim 1 , wherein the ultrasonic thermal applicator comprises an elongated member adapted for insertion into an interstitial space within the diseased tissue.
4. The system of claim 3 , wherein the elongated member of the ultrasonic thermal applicator substantially defines an axis corresponding to a length of the applicator.
5. The system of claim 4 , wherein the at least one transducer element comprises an active face that projects a nominally directional ultrasonic beam from the active face of the ultrasonic thermal applicator into the treatment volume substantially along a plane parallel to said axis.
6. The system of claim 1 , wherein said thermal applicator motion controller comprises a bearing mechanically coupled to said motor assembly, the bearing adapted for operation within a magnetic resonance imaging (MRI) chamber, and designed and arranged to provide a rotational degree of freedom to rotate the thermal applicator about an axis of rotation.
7. The system of claim 1 , further comprising a fluid flow apparatus including a fluid flow channel proximal to the thermal applicator that provides temperature control to regions of space proximal to the fluid flow channel.
8. The system of claim 1 , wherein the treatment controller comprises hardware and software for carrying out a pre-planned treatment regimen based on a set of initial conditions and said real-time quantitative thermal imaging information and further based on said input control temperatures measured at a corresponding plurality of control point locations on a surface of said treatment volume.
9. The system of claim 1 , wherein the treatment controller comprises hardware and software for dynamically determining a treatment regimen based on conditions and said real-time quantitative thermal imaging information collected during the progress of a treatment.
10. The system of claim 1 , wherein said motion controller provides a sequence of pulses that control said motor assembly to rotate the thermal applicator about its axis, said sequence of pulses designed to minimize electromagnetic interference put out by the motion controller during use.