High Intensity Focused Ultrasound Optimal Device Design for Targeted Prostate Cancer Treatment: A Numerical Study

A parametric study was performed to design a device capable of treating small targeted regions within the prostate using high intensity focused ultrasound, while sparing the surrounding organs and minimizing the number of elements. The optimal focal length (L), operating frequency (f), element size (a) and central opening radius for lodging an imaging probe (r) of a device that would safely treat tissue within the prostate were obtained. Images from the Visible Human Project were used to determine simulated organ sizes and treatment locations. Elliptical tumors were placed throughout the simulated prostate and their lateral and axial limits were selected as test locations. Using graphics processors, the acoustic field and Bio-Heat Transfer Equation were solved to calculate the heating produced during a simulated treatment. L, f, a and r were varied from 45 to 75 mm, 2.25 to 3 MHz, 1.5 to 8 times the wavelength and 9 to 12.5 mm, respectively. The resulting optimal device was a 761-element concentric-ring transducer with L = 68 mm, f = 2.75 MHz, a = 2.05λ and r = 9 mm. Simulated thermal lesions showed that it was possible to treat target tumors consistent with reported locations and sizes for prostate cancer.