Objectives: The goal of this study is to develop a novel approach for imaging of lanthanide-based nanoparticles, which emit near-infrared light in response to stimulation with x-rays. Previous efforts to perform x-ray luminescence tomography have focused on first-generation tomographic geometries, acquiring a single line integral at a time [1,2]. Our goal here is to demonstrate that under conditions where light scattering is minimal, direct slice imaging can be achieved using illumination with a sheet beam coupled with detection using a conventional CMOS-based optical camera. This could provide a new means of monitoring response to radiation therapy or nanoparticle-enhanced radiation therapy. Methods: We synthesized europium doped yttrium oxide (Y2O3:Eu3+) nanophosphors. The x-ray source employed was an X_RAD 225Cx animal irradiator, which we modified with a slit collimator, allowing for creation of a sheet beam of x-rays. We used a Canon DSLR 5D Mark II with a F1.4 lens to acquire images of the stimulated illumination. The sample was scanned through the sheet beam and direct images of illuminated slices acquired. Results:We have established the feasibility of the idea as demonstrated in preliminary image data. We have also characterized the linearity of the nanophosphor luminescence with respect to x-ray fluence and their monotonically increasing luminosity with respect to x-ray voltage over a range of 25 to 225 keV. Conclusions:The use of selective plane x-ray illumination coupled with x-ray luminescent nanoparticles allows for direct tomographic imaging without the need to solve an ill-posed inverse problem. While the size and depth of objects that can be imaged by this technique is limited by scattering of the near-infrared light, this technique could allow sensitive imaging of superficial lesions and excised tissue specimens. Future work may allow imaging in larger specimens with modeling of scattering by exploiting the knowledge about the illumination geometry
Date:
2014-05
Relation:
Journal of Nuclear Medicine. 2014 May;55(Suppl. 1):Abstract number 483.
