Multi-element ultrasound phased array applicator for the ablation of deep-seated tissue

Abstract

SHEN Guo-feng * ( ), BAI Jing-feng ( ), LI De-hui ( ) YU Ying ( ), QIAO Shan ( ), CHEN Ya-zhu ( ) Abstract: High-intensity focused ultrasound (HIFU) has attracted increasing interests as a promising noninvasive modality for the treatment of deep tumors in the thoracic and abdominal cavity. A 90-element HIFU spherical phased array applicator operated at 1 MHz has been developed for deep tissue ablation. The spherical array with a 5 cm wide central hole has a 21 cm diameter and an 18 cm radius of curvature. Annular element distribution with unequal element spacing is used to reduce the number of elements. The array is constructed with piezoelectric lead zirconate titanate (PZT-8) circular elements that are 1.4 cm in diameter and have a wall with thickness of 0.2 cm. The array offers an effective ablating depth of at least 8 cm in the tissue for both simulations and ex vivo experiments. The simulations demonstrate that the developed array can steer the focus with good quality of intensity distributions up to 6 mm off center over ranges from 17 to 21 cm when the water depth is set at 11 cm.We also present the beam focusing capability in deep tissue through a series of ex vivo experiments by measuring discoloration areas after sonications. These results indicate that the developed array is ideal for the ablation of deep-seated tissue.

A random phased-array for MR-guided transcranial ultrasound neuromodulation in non-human primates

“…Sparse annular arrays have also been designed, typically to hold a second device in the central void space, such as a focused transducer that enables multi-frequency sonications, or an imaging probe for co-registered FUS and ultrasound imaging (Ebbini et al 2006, Hand et al 2009, Ji et al 2011. These arrays have similar properties to full spherical caps but can have slightly elevated axial and side lobes, increasing risk for off-target heating in thermal therapy (Stephens et al 2011).…”

Evaluation of a novel therapeutic focused ultrasound transducer based on Fermat’s spiral

“…Hand et al (2009) validated the conclusions of the work of Gavrilov and Hand (2000) experimentally. Finally, Ji et al (2011) presented an annular phased array design with a comparatively low element number (90) of large diameter. Commercially, sparse phased arrays have been introduced by Insightec in 2003 (the ExAblate 2000 system) (Tempany et al 2003), followed by the Sonalleve system by Philips in 2009 (Enholm et al 2010).…”

Improved positioning methods based on MR images in the MR-guided PHIFU system

“…The phased method [1]- [2] converses the electric power to the sound energy by adjusting the amplitude and phase of every transducer element. Then, the focused tissues absorb the ultrasound and converse it into thermal energy.…”