The paper reports on the effect of therapeutic-like irradiation of a water based magnetic
fluid with magnetite particles double-surfacted with oleic acid on its magnetic heating
characteristics. To assess the effect of irradiation, a quantity of the initial sample
was retained as the reference sample. The other part of the ferrofluid was irradiated
with a photon beam (with the energy of 10 MeV and the dose of 50 Gy) and with an electron
beam (of the energy of 9 MeV and the dose of 50 Gy).The frequency dependence of the
complex magnetic permeability, mu(omega) = mu'(omega)-i mu ''(omega), was affected
only in the case of the electron irradiated sample and over the approximate range
of 10-100 kHz.The dynamic light scattering investigation revealed a small increase
of the average of the size of light scattering entities and of the polydispersity
index of the sample irradiated with electrons compared to the reference sample.Magnetic
heating experiments, performed at the frequency of 100 kHz and with various amplitudes
of magnetic field, H, (of 25, 50, 75 and 100 Oe) did not reveal significant difference
in the heating rate values of the reference sample and of the irradiated samples.
Therefore, magnetic hyperthermia can be involved in the therapy plan, in the same
period of time as the radiation therapy, provided at the frequency of the alternating
magnetic field larger than the frequency corresponding to the Brownian relaxation
peak.
