Split‐focused ultrasound transducer with multidirectional heating for breast tumor thermal surgery

Abstract

This study investigated the feasibility of using a split-focused ultrasound transducer to perform thermal surgery on breast tumors, based on a multidirectional heating scheme. The transducer is a square section of a sphere with a radius of 10 cm. The transducer was tilted such that its acoustic beam was 45 degrees relative to the rib surface, and its focal zone was arranged by a shift of 6 mm away from the center of the planning target volume. The multifocus switching technique was employed to enhance the heating efficiency. When a single transducer was used, the transducer sonicated from a certain position for a given duration, and then rotated sequentially to continue the heating. Computer simulations and in vitro phantom experiments have been studied for this heating system. Both simulation and experimental results demonstrated that the system based on a multidirectional heating scheme is capable of generating a proper thermal lesion within 8 min. Meanwhile, from the simulation results, the rib heating was effectively alleviated by tilting the transducer to induce the total reflection at the muscle/bone interface. While using multiple ultrasound transducers, an appropriate arrangement was designed to have the same configuration of acoustic beams as is used for a single-transducer strategy. The simulation results from the four-transducer strategy indicated that the heating results could be further improved. This study revealed that it is very promising to have an appropriate arrangement of a single split-focused ultrasound transducer with mechanical rotation, or to have multiple split-focused transducers that use multidirectional heating for breast tumor thermal therapy.

3D computational study of non-invasive patient-specific microwave hyperthermia treatment of breast cancer

“…The goal of hyperthermia cancer treatment is to achieve a temperature of approximately 40-45°C in a region which includes the tumor and a margin of healthy tissue while maintaining normal temperatures in surrounding tissue. The negative margin targeted by thermal therapy (Gianfelice et al 2003, Cheng et al 2008) is on the order of 1 cm. This practice is consistent with surgical resection protocols which typically involve the removal of a 1-cm negative margin in an attempt to reduce local recurrence rates (Veronesi et al 1995, Singletary 2002, Schmitz et al 2008, Luini et al 2009).…”

Design aspects of focal beams from high-intensity arrays

“…Currently, the field of therapeutic ultrasonic hyperthermia includes a very wide range of medical applications [3]. Strategies have been developed for the treatment of uterine fibroids [4], breast tumors [5], [6], prostatic hyperplasia [7], [8], thrombolysis [9], liver tumors [10], [11], and brain tumors [12]. Standard commercial imaging probes have been applied to guide ultrasound-based hyperthermia, and more recently, guidance has been built into the same probe [13], [14].…”

Numerical analysis of thermal response of tissues subjected to high intensity focused ultrasound

“…In order to circumvent such limitations and to cover the entire spread of the embedded tumor, lesions must be placed systematically side-by-side. This arrangement can be achieved by moving the transducer mechanically (keeping the sample static) [35,36], using multi-element phased array transducer [37] or with the use of multiple transducers using multidirectional heating scheme [38]. The acoustic intensity of each lesion can be adjusted depending upon the size of the targeted tumor and its location.…”