We have developed the prototype treatment control system that automatically selects location and intensity of the ultrasound focal zone to deliver the prescribed thermal dose to the target in minimum time without violating explicitly-imposed normal tissue safety constraints. The results of its evaluation in a computer-simulated treatment of a realistic three-dimensional breast cancer patient, reported in this paper, illustrate salient features of the developed prototype, which are necessary to minimize the treatment duration while simultaneously satisfying the normal tissue safety constraints. The performance of the developed control system was then validated in vivo using MR-compatible 256-element ultrasound phased array, developed by us, Tests confirm that the developed system can function in a fully 3D mode and deliver the prescribed volumetric thermal dose to the target without violating the imposed normal tissue constraints by utilizing near real-time three-dimensional MR temperature measurements, and 3D internal model used during on-line optimization of heating trajectory and ultrasound intensity.

References

D. Arora, D. Cooley, T. Perry, J. Guo, A. Richardson, J. Moellmer, R. Hadley, D. Parker, M. Skliar and R. B. Roemer, “MR Thermometry-Based Feedback Control of Efficacy and Safety in Minimum-Time Thermal Therapies: Phantom and In-Vivo Evaluations,” Int. J. Hyperthermia, 22:29-42, 2006.

D. Arora, D. Cooley, T. Perry, M. Skliar and R. B. Roemer, “Direct Thermal Dose Control of Focused Ultrasound Treatments: Phantom and In-Vivo Evaluation,” Phys. Med. Biol., 50:1919-1935, 2005.

D. Arora, M. Skliar, D. Cooley and R. Roemer, “Constrained Predictive Control of Thermal Therapies for Minimum-Time Delivery of Thermal Dose,” IEEE Trans. Control Systems Technology, 15: in press, 2007.

R. Niu, A. Blankespoor, J. Moellmer, R. Roemer, and M. Skliar, “Automatic Control of Focal Trajectory and Intensity of Ultrasound Phased Arrays in Minimum-Time Delivery of Thermal Dose with Imposed Normal Tissue Constraints,” Proc. ISTU'06, in press, 2007.