Magnetic field generating inductor for cancer hyperthermia research

Abstract

Purpose -The purpose of this paper is to continue studies previously reported with the primary focus of optimizing an inductor design. The potential benefits of hyperthermia for cancer therapy, particularly metastatic cancers of the prostate, may be realized by the use of targeted magnetic nanoparticles that are heated by alternating magnetic fields (AMFs). Design/methodology/approach -To further explore the potential of this technology, a highthroughput cell culture treatment system is needed. The AMF requirements for this research present challenges to the design and manufacture of an induction system because a high flux density field at high frequency must be created in a relatively large volume. Additional challenges are presented by the requirement that the inductor must maintain an operating temperature between 35 and 398C with continuous duty operation for 1 h or longer. Results of simulation and design of two devices for culture samples and for in vitro tests of multiple samples in uniform field are described. Findings -The inductor design chosen provides a uniform distribution of relatively high magnetic field strength while providing an optimal reduction in the voltage and power requirement. Through development of design and selection of magnetic concentrator, the exposure of the cell cultures to the heat generated by the inductor is minimized. Originality/value -This method of generating uniform high AC magnetic fields in a large volume is beneficial for the study of hyperthermia in cells for a high throughput, necessary for cancer treatment research.

Magnetic hyperthermia therapy for the treatment of glioblastoma: a review of the therapy’s history, efficacy and application in humans

“…A common feature among the different AMF generators that have been designed for MHT is the solenoid coil [111]. When the target region is placed within the coil, it is subjected to a uniform AMF field.…”

Design and construction of a Maxwell-type induction coil for magnetic nanoparticle hyperthermia

“…Low-or radio-frequency (RF) AMFs are particularly advantageous for deep tissue applications because they provide high penetration with essentially no tissue attenuation or reflection; and, they generate less nonspecific tissue heating from interactions with tissue than do higher frequency electromagnetic (EM) fields [10,11]. Design of devices for biomedical applications employing low-frequency AMFs thus reduces to well-established engineering considerations for applicator or coil geometries to produce magnetic fields having desired flux density in a specified volume [10,[12][13][14][15]. Preclinical and clinical experiences with MFH using low-frequency AMFs have established its viability as a treatment for cancer [1][2][3][4][5][6][7][8]16,17].…”

“…Many possible inductor configurations have been considered to generate homogeneous AMFs for hyperthermia with alternating electric currents (AC) [12,13,25,33,35,44,45]. Three basic coil geometries are generally considered: (a) modified air-or solid-core solenoids, some containing additional counter-wound solenoids [13,33,35]; (b) Helmholtz pairs [12,19,44] and, (c) multiple solenoids having specific geometrical placement (e.g., Loney coils) [46,47].…”

Characterization of intratumor magnetic nanoparticle distribution and heating in a rat model of metastatic spine disease

“…Detailed descriptions of the design, build, and characterization of the modified solenoid coil have been published previously. 6,7,33 Briefly, when combined the system is capable of producing a homogeneous flux density AC magnetic field (at 150 kHz) in a cylindrical volume having a 5-cm diameter with a > 6-cm length, for peak-topeak amplitudes between 4 kA/m and 95 kA/m. The field amplitude can be dynamically controlled by adjusting the power supply output voltage.…”