Imaging characteristics of intravascular spherical contrast agents for grating-based x-ray dark-field imaging – effects of concentrations, spherical sizes and applied voltage

Abstract

this study investigates the x-ray scattering characteristics of microsphere particles in x-ray-gratingbased interferometric imaging at different concentrations, bubble sizes and tube voltages (kV). Attenuation (ATI), dark-field (DFI) and phase-contrast (PCI) images were acquired. Signal-to-noise (SNR) and contrast-to-noise ratios with water (CNR w) and air as reference (CNR a) were determined. in all modalities, a linear relationship between SnR and microbubbles concentration, respectively, microsphere size was found. A significant gain of SNR was found when varying kV. SNR was significantly higher in DFI and PCI than ATI. The highest gain of SNR was shown at 60 kV for all media in ATI and DFI, at 80 kV for PCI. SNR for all media was significantly higher compared to air and was slightly lower compared to water. A linear relationship was found between CNR a , cnR w , concentration and size. With increasing concentration and decreasing size, cnR a and cnR w increased in DFI, but decreased in PCI. Best cnR a and cnR w was found at specific combination of kV and concentration/size. Highest average cnR a and cnR w was found for microspheres in ATI and PCI, for microbubbles in DFI. Microspheres are a promising contrast-media for grating-based-interferometry, if kV, microsphere size and concentration are appropriately combined. Contrast differences in conventional X-ray imaging rely on the varying degree of attenuation of x-rays penetrating different types of tissue. Contrast is highest in imaging materials with large differences in atomic number, material density, or both, such as bone or lung. However, in clinical radiography structures with only slight density differences, such as the tissue composition within inner organs, need to be examined as well, limiting the usefulness of x-ray attenuation imaging (ATI). Current research focuses on the phase change when the x-ray beam passes through the imaging object. Besides attenuation, alterations in phase change in different types of soft tissue provide additional contrast information. Here, image contrast is generated from interference of the x-ray wave front, caused by a phase shift of the x-ray wave while passing through the object. The phase of a wave front cannot be measured directly. Therefore, the imaging method requires a translation from phase shift to intensity differences. There are various approaches to retrieve phase information from x-ray imaging, including free-space propagation

Clinical research progress of callisperes® of drug-loaded microsphere arterial chemoembolisation in the treatment of solid tumors

“…Therefore, it is not easy to combine with coagulation molecules in the blood and lead to vascular embolism. At the same time, considering that the specific gravity of human blood is about 1.05 [ 47 ], and the particular gravity of DEB before and after drug loading fluctuates between 1.04 and 1.07, both DEB before and after drug loading can float in the blood vessels [ 48 ]. According to DEB's biological characteristics, it can be seen that DEB can load high-dose drugs, with strong sustained release ability and good biocompatibility, which provides a solid foundation for the subsequent application of DEB-TACE.…”

X-Ray Lithography for Nanofabrication: Is There a Future?

“…A further application is the X-ray grating interferometry used for medical imaging, tomography, biology, and material inspection. The latest developments in the field are the X-ray dark-field imaging system, which uses three different gratings (Pfeiffer et al, 2009;Notohamiprodjo et al, 2020), and the phase-contrast imaging with a far-field interferometer. In the latter instrument, 200-nm period multilayer gratings are used, manufactured by LIGA (Wen et al, 2013).…”

Reflective x-ray masks for x-ray lithography

“…Many x-ray optical elements, such as x-ray refractive lenses [4], collimators [5], and diffraction gratings [6] are manufactured by this technique. Diffraction gratings in particular have found applications in many fields such as medicine, tomography, biology [7,8], and XRL has the potential to fabricate about 1 µm linewidth gratings [9].…”