An RF phased array applicator designed for hyperthermia breast cancer treatments

Abstract

An RF phased array applicator has been constructed for hyperthermia treatments in the intact breast. This RF phased array consists of four antennas mounted on a Lexan water tank, and geometric focusing is employed so that each antenna points in the direction of the intended target. The operating frequency for this phased array is 140 MHz. The RF array has been characterized both by electric field measurements in a water tank and by electric field simulations using the finite-element method. The finite-element simulations are performed with HFSS software, where the mesh defined for finite-element calculations includes the geometry of the tank enclosure and four end-loaded dipole antennas. The material properties of the water tank enclosure and the antennas are also included in each simulation. The results of the finite-element simulations are compared to the measured values for this configuration, and the results, which include the effects of amplitude shading and phase shifting, show that the electric field predicted by finite-element simulations is similar to the measured field. Simulations also show that the contributions from standing waves are significant, which is consistent with measurement results. Simulated electric field and bio-heat transfer results are also computed within a simple 3D breast model. Temperature simulations show that, although peak temperatures are generated outside the simulated tumour target, this RF phased array applicator is an effective device for regional hyperthermia in the intact breast.

Electric field distribution of human breast tissue

“…11. Breast Tumor model used by previous researchers [11]. A more detailed model is necessary to study in-depth characteristics and behavior of breast cancer cells and tissues.…”

A Phase I/II Study of Neoadjuvant Liposomal Doxorubicin, Paclitaxel and Hyperthermia in Locally Advanced Breast Cancer

“…Operating frequencies range between 140MHz and 156 MHz, depending on the cup used and the breast size, with power levels from 60 to 200 W. Due to the variation in the breast volume (from 200 cc to 700 cc), different cup sizes were used. Although minimum sampled temperatures give a crude indication of the temperature distribution, the CEM43T90, CEM43T50, the T90 and T50 were determined for each of the HT fractions from tumour points temperatures [16]. Thermometry was performed following RTOG guidelines; however, the majority of patients had one catheter placed interstitially to map temperature every 0.5 cm [17].…”

Thermal Therapy, Part IV: Electromagnetic and Thermal Dosimetry

“…The details of the FEM and its implementation for bioelectromagnetic problems are available. [74][75][76][77][78][79][80][81][82][83][84][85][86] …”