The characterization of an ultrasound spherical phased array for the ablation of deep-seated tissue

• Published in: Applied acoustics 2012-05, Vol.73 (5), p.529-534
• Main Authors: Ji, Xiang, Shen, Guofeng, Bai, Jingfeng, Chen, Yazhu
• Format: Article
• Language: English
• Subjects: Ablation; Biological and medical sciences; Focus pattern; HIFU; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Miscellaneous. Technology; Spherical phased array; Ultrasonic investigative techniques
• ISSN: 0003-682X; 1872-910X
• DOI: 10.1016/j.apacoust.2011.12.008

In this paper we have developed and evaluated a spherical phased array ultrasound applicator for deep tissue ablation. The 90-element prototype array has a 21cm aperture and an 18cm radius of curvature with a 5cm wide central hole. Annular distribution with circular elements is used to reduce the number of elements. The array is constructed with piezoelectric (PZT-8) circular planar elements that are 1.4cm in diameter and 0.2-cm thick. With the water-muscle propagation path, the array offers an effective beam focusing depth of at least 8cm in the muscle layer. Simulation results show that the array provides good beam focusing and steering capability over a cylindrical volume of approximately π×1×1×4 cm3 (up to 10mm off center over ranges from 15cm to 19cm). We also present its beam focusing and steering capability in deep tissue through a series of ex vivo experiments by measuring discoloration areas after sonications. The ex vivo experiments show a similar focal range as that found in the simulations.