磁性粒子を発熱体とした温熱療法の基礎的検討その1 −温熱療法に適した磁性粒子の理論および実験的検討−

抄録

Magnetic materials suitable for hyperthermia are discussed taking their magnetic properties, practical limitations of treatment conditions and instrumentation into consideration. The experimental results suggest that either ferromagnetic particle with very low anisotropy constant or superparamagnetic particles with a moderate anisotropy constant are suitable. Considering the magnetic- and biocompatibility of the particles, superparamagnetic Fe₃O₄ with a diameter of 11-13 nm is considered most appropriate. Fe₃O₄ particles of various diameters were successfully synthesized using coprecipitation and thermal decomposition and their heating rates were experimentally verified. The heat generated depends on the particle diameter and solid concentration. The temperature of 3 ml Fe₃O₄ suspension with an average particle diameter of 14 nm and solid concentration of 4 wt.% rose from room temperature to 100 °C, when it was exposed to an ac magnetic field strength and frequency of 3.2 kA/m and 600 kHz respectively for 10 minutes.