High intensity focused ultrasound (HIFU) provides a unique modality to perform non-invasive surgeries. The thermal ablation technique relies on focusing the non-ionizing acoustic wave within soft tissues to produce a small lesion. HIFU operations are typically attempted by continuous-wave (CW) applications of the beam intervened by wait periods to allow surrounding tissue to cool down. Large contiguous lesions are produced by raster-scanning the beam over the volume of the tumor; a procedure that requires up to three hours for a 2-cm diameter tumor. This is one of the main limitations of HIFU thermal therapy. As part of the ongoing research to accelerate the procedure, we investigate the role of pulsed-HIFU (pHIFU) parameters in the enhancement of the therapeutic gain within the HIFU focus. A therapeutic gain is observed when high duty cycle pHIFU is pulsed at the mechanical resonance of the medium. Up to 50% increase in temperature was measured in lab-prepared tissue mimicking phantoms. The therapeutic gain achieved by pHIFU over cwHIFU is attractive as no modifications on the currently used applicators are required.
University of Minnesota. M.S. thesis. March 2010. Major: Biomedical engineering. Advisor:Emad Ebbini. 1 computer file (PDF)); v, 37 pages. Ill. (some col.)
Al-Qaisi, Muhammad K..
Optimized pulsing of high-intensity focused ultrasound for enhanced therapeutic window.
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