ABSTRACT
X-ray computed tomography (XCT) has become a very important method for non-destructive 3D-characterization and evaluation of materials. Due to measurement speed and quality, XCT systems with cone beam geometry and matrix detectors have gained general acceptance. Continuous improvements in the quality and performance of X-ray tubes and XCT devices have led to cone beam CT systems that can now achieve spatial resolutions down to 1 µm and even below. However, the polychromatic nature of the source, limited photon flux and cone beam artefacts mean that there are limits to the quality of the CT-data achievable; these limits are particularly pronounced with materials of higher density like metals. Synchrotron radiation offers significant advantages by its monochromatic and parallel beam of high brilliance. These advantages usually cause fewer artefacts, improved contrast and resolution.Tomography data of a steel sample and of two multi-phase Al-samples (AlSi12Ni1, AlMg5Si7) are recorded by advanced cone beam XCT-systems with a µ-focus (µXCT) and a sub-µm (nano-focus, sub-µXCT) X-ray source with voxel dimensions between 0.4 and 3.5 µm and are compared with synchrotron computed tomography (sXCT) with 0.3 µm/voxel. CT data features like beam hardening and ring artefacts, detection of details, sharpness, contrast, signal-to-noise ratio and the grey value histogram are systematically compared. In all cases µXCT displayed the lowest performance. Sub-µXCT gives excellent results in the detection of details, spatial and contrast resolution, which are comparable to synchrotron-XCT recordings. The signal-to-noise ratio is usually significantly lower for sub-µXCT compared with the two other methods. With regard to measurement costs "for industrial users", scanning volume, accessibility and user-friendliness sub-µXCT has significant advantages in comparison to synchrotron-XCT.
ABSTRACT
BACKGROUND: Superparamagnetic nanoparticles are currently used as contrast agents for magnetic resonance imaging. These particles can also be used as drug carriers for local chemotherapy, called magnetic drug targeting. Using an external magnetic field, colloidal nanoparticles can be directed to a specific body compartment (i.e. tumor). MATERIALS AND METHODS: After magnetic drug targeting in an experimental rabbit model with a VX2 squamous cell carcinoma, tumor tissue was extracted and embedded in paraffin for histology and X-ray imaging. RESULTS: The distribution of magnetic nanoparticles was detected holistically with X-ray imaging and in detail using Prussian blue staining of histological cross sections. CONCLUSION: The biodistribution of magnetic nanoparticles can be visualized with X-ray imaging and histologically confirmed.
