OBSERVATIONS ON THE USE OF FERROMAGNETIC IMPLANTS FOR INDUCTING HYPERTHERMIA.

The authors discuss the physical parameters which characterize this method and give illustrations from initial clinical investigations in animals. The physical parameters studied include magnetic field strength, frequency, load size, field uniformity, coil designs, and the heating potential of implant materials and configurations. Calculations consistent with experimental results predict a maximum heating frequency of the order of 500 kHz for large cross-sectional loads, such as the human abdomen, and 1. 9 MHz for smaller loads, such as the human brain. An experimental technique is introduced for accurate quantitative evaluation of the heating potentials of ferromagnetic materials in a gelled phantom medium. A spiral sheet coil design is described and recommendations are given for proper E-Field shielding of induction coils for clinical applications. A brief discussion of techniques of implanting the ferromagnetic materials is also given. Finally, several in vivo animal studies are presented to illustrate the use of the technique for treating tumors in pelvis, thorax, oral-pharynx, and brain.

Duke Scholars

Author Mark Wesley Dewhirst Radiation Oncology