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Hyperthermia treatment incorporating magnetic nanoparticles (MNPs) is a hopeful therapy for cancers. Acquiring information about the MNPs' deposition in tumor tissues and modeling magnetic heating in vivo are essential for successful treatment. In this paper, we discuss the inhomogeneous heat generation by MNPs distributed heterogeneously in a liver tumor during arterial embolization hyperthermia (AEH) treatments. In order to more accurately simulate the temperature elevation for an AEH treatment plan, we conducted the following experiments. First, we detected the distribution of magnetic field intensity in the aperture of a ferrite-core applicator. We found that attenuation of the magnetic field focuses mainly on the vertical distance of the aperture, which makes MNPs in tissues have different power loss along the lognitudinal axis. Second, we prepared 20 nm monodisperse lipiodol-soluble MNPs and injected super-selectively through the micro-catheter into the arteries of a rabbit with a VX-2 liver tumor. By histological cuts of the investigated specimen, as well as computed tomography (CT), we found MNPs mainly concentrated on the tumor periphery. Last, from the experimental information, we established a new model for simulating the increasing temperature in the liver tumor based on our inhomogeneous interior-heat-source analysis (IIA). We also compared the simulated results with the two types of homogeneous models. The results showed that IIA gives significantly different results from those for a homogeneous model and thus is preferable when an accurate treatment plan is required during AEH.
Date of Publication: Aug. 2009