Quantification of MicroCT Image Intensity and Nanoparticle Concentration in Agarose Gel

In recent years, magnetic nanoparticle hyperthermia has attracted a lot of attentions in cancer treatment due to its ability to confine heat within the tumor with minimal collateral thermal damage to the surrounding healthy tissue.^1–4 The success of the treatment using magnetic nanoparticles depends on careful planning of the heating duration and achieved temperature elevations. It has been demonstrated by previous research that the generated volumetric heat generation rate or Specific Absorption Rate (SAR) should be proportional to the nanoparticle concentration distribution in the tumors. The difficulty encountered by bioengineers is that the nanoparticle concentration distribution is often unknown, since the tissue is opaque. Recently, high-resolution microCT imaging technique has been used to visualize magnetic nanoparticle distribution in tumors. MicroCT has been shown to generate detailed 3-D density variations induced by nanoparticle depositions in both tissue-equivalent gels and tumor tissues.^5–6 However, experimental studies are still needed to quantify the relationship between the microCT pixel index number shown in the scanned images and the actual nanoparticle concentrations.