  A linear combination of spherically symmetric heat sources is shown to
provide optimal stationary thermal distribution in magnetic hyperthermia.
Furthermore, such spatial location of heat sources produces suitable
temperature distribution in biological medium even for assemblies of magnetic
nanoparticles with a moderate value of specific absorption rate (SAR), of the
order of 100 - 150 W/g. We also demonstrate the advantage of using assemblies
of magnetic nanocapsules consisting of metallic iron nanoparticles covered with
non magnetic shells of sufficient thickness in magnetic hyperthermia. Based on
numerical simulation we optimize the size and geometric structure of
biocompatible capsules in order to minimize the influence of strong
magneto-dipole interaction between closely spaced nanoparticles. It is shown
that assembly of capsules can provide sufficiently high SAR values of the order
of 250 - 400 W/g at moderate amplitudes H = 50 - 100 Oe and frequencies f = 100
- 200 kHz of alternating magnetic field, being appropriate for application in
clinics
