Super-resolution X-ray imaging with hybrid pixel detectors using electromagnetic source stepping

Abstract

With increasing demand for high-resolution X-ray images, the super-resolution method allows to estimate a single high-resolution image from several low-resolution images. Hybrid pixel detectors provide high-quality and low-resolution images, which makes them particularly well suited for super-resolution. However, such detectors consist of a limited number of pixels at high cost. Applying super-resolution with hybrid pixel detectors shows that it is a viable method to obtain high-resolution images. The point-spread function of such detectors can be idealised to be 1 pixel, adding no blur into the image making such detectors the ideal choice for the application of super-resolution X-ray imaging. However, there are charge sharing effects between the pixels caused by the energy and impact position of incoming photons. Utilising an X-ray source, which allows magnetic stepping of the X-ray spot, several slightly shifted images can be obtained without requiring mechanical movements. Registering the shifts between individual images with sub-pixel precision allows to estimate a high-resolution image. With repeatable and equally spaced X-ray spot position patterns, sufficient information can be obtained with only a few images. In this paper, we present the application of super-resolution for X-ray imaging using a Pilatus 100K hybrid pixel detector from Dectris Ltd. and a prototype micro-focus X-ray source from Excillum AB. Moreover, we analyse the image quality for applications in X-ray radiography and tomography. Using a sufficient number of low-resolution images allows us to achieve an increase in resolution, without introducing significant blur or artefacts into the image. Here we quantify the effects on the quality of resulting super-resolution images using different methods of image interpolation, interpolation factors, shifts of the sample on the detector, and amount of low-resolution images.

Lenseless X-ray nano-tomography down to 150 nm resolution: on the quantification of modulation transfer and focal spot of the lab-based ntCT system

“…e.g. Dreier et al [6] for a more detailed description) using linear interpolation prior to averaging, yielding a virtual sampling pitch of 17.8 nm. This approach is analog to the use of slanted edges (as opposed to edges aligned with the detector grid) in order to increase the sampling of edge spread functions (an example of slanted edge analysis can e.g.…”

Lenseless X-ray Nano-Tomography down to 150nm Resolution: On the Quantification of Modulation Transfer and Focal Spot of the Lab-based ntCT System

“…e.g. Dreier et al [30] for a more detailed description) using linear interpolation prior to averaging, yielding a virtual sampling pitch of 17.8 nm. This approach is analog to the use of slanted edges (as opposed to edges aligned with the detector grid) in order to increase the sampling of edge spread functions (an example of slanted edge analysis can e.g.…”

Shunt-type plexiform lesions identified in the Sugen5416/hypoxia rat model of pulmonary arterial hypertension using synchrotron-based phase-contrast micro-CT

“…Following removal of the heart-lung block, the main pulmonary artery was injected with a radiopaque green dye (CDI's Tissue Marking Dye; Cancer Diagnostics, Durham, NC, USA), diluted with an equal volume of tap water to ensure low viscosity. Super-resolution x-ray radiographies of paraffin-embedded lobes were acquired using a laboratory setup as previously described [7], confirming the presence of contrast agent (radiopaque green dye) and thus enabling tracing of corresponding areas between individuals for subsequent high-resolution SPµCT imaging, which was performed at the X02DA TOMCAT beamline of the Swiss Light Source at the Paul Scherrer Institute, Switzerland [1,5]. In short, 4× scan volumes (4.2×4.2×3.5 mm 3 ) with an effective voxel size of (1.63 μm) 3 were acquired from selected areas of interest.…”