Increasing robustness, compactness and cost-effectiveness of edge-illumination X-ray phase contrast imaging as a key step towards translation into real-world applications

Novel laboratory implementations of the Edge Illumination X-Ray Phase Contrast imaging (EI-XPCi) method were presented in this thesis, with the aim of facilitating its commercial translation. A portable system, based on compact piezoelectric motors, was developed to enable the easy transportation of the setup. Tests on the system positioning accuracy were presented, and images of standard samples were benchmarked against those obtained with the existing prototype based on stepper motors. An alternative EI implementation, which simultaneously allows the use of cheaper X-ray sources and the realisation of more compact setups, was also presented. An additional ``source mask'' introduced in a standard EI setup allows to section the large focal spot of a conventional tube into multiple sub-sources, creating a corresponding number of spatially shifted images, which need to be disentangled through dedicated algorithms. A proof-of-principle experiment provided results in agreement with simulated predictions, demonstrating the feasibility of the approach. A quantitative study on the dependence of the angular sensitivity on the source-to-detector distance (at constant system magnification, tube settings and total exposure time) was also presented. Results of a simulation based on the assumption of Poisson-distributed noise in the images (valid for photon counting detectors) were compared with experimental ones obtained by using an integrating detector. The observed discrepancies were successfully related to the additional noise sources present in an integrating detector, thus indirectly validating the simulation model. The adaptation of EI with a laser-plasma source was investigated through a proof-of-concept experiment, with the aim of realizing a system providing a synchrotron-like performance with a more compact and accessible setup. Non-ideal experimental conditions affecting the system performance were discussed, while the results of the source characterization were used to establish some basic requirements that must be satisfied to successfully implement EI with these ``new generation'' X-ray sources

Associations between Sociodemographics and Pediatric Osteosarcoma Characteristics

https://openworks.mdanderson.org/sumexp23/1022/thumbnail.jp

Comparing signal intensity and refraction sensitivity of double and single mask edge illumination lab-based x-ray phase contrast imaging set-ups

Double mask edge illumination (DM-EI) set-ups can detect differential phase and attenuation information from a sample. However, analytical separation of the two signals often requires acquiring two frames with inverted differential phase contrast signals. Typically, between these two acquisitions, the first mask is moved to create a different illumination condition. This can lead to potential errors which adversely affect the data collected. In this paper, we implement a single mask EI laboratory set-up that allows for a single shot retrieval of the differential phase and attenuation images, without the need for a high resolution detector or high magnification. As well as simplifying mask alignment, the advantages of the proposed set-up can be exploited in one of two ways: either the total acquisition time can be halved with respect to the DM-EI set-up or, for the same acquisition time, twice the statistics can be collected. In this latter configuration, the signal-to-noise ratio and contrast in the mixed intensity images, and the angular sensitivity of the two set-ups were compared. We also show that the angular sensitivity of the single mask set-up can be well approximated from its illumination curve, which has been modelled as a convolution between the source spatial distribution at the detector plane, the pre-sample mask and the detector point spread function (PSF). A polychromatic wave optics simulation was developed on these bases and benchmarked against experimental data. It can also be used to predict the angular sensitivity and contrast of any set-up as a function of detector PSF

Laboratory implementation of edge illumination X-ray phase-contrast imaging with energy-resolved detectors

Edge illumination (EI) X-ray phase-contrast imaging (XPCI) has potential for applications in different fields of research, including materials science, non-destructive industrial testing, small-animal imaging, and medical imaging. One of its main advantages is the compatibility with laboratory equipment, in particular with conventional non-microfocal sources, which makes its exploitation in normal research laboratories possible. In this work, we demonstrate that the signal in laboratory implementations of EI can be correctly described with the use of the simplified geometrical optics. Besides enabling the derivation of simple expressions for the sensitivity and spatial resolution of a given EI setup, this model also highlights the EI’s achromaticity. With the aim of improving image quality, as well as to take advantage of the fact that all energies in the spectrum contribute to the image contrast, we carried out EI acquisitions using a photon-counting energy-resolved detector. The obtained results demonstrate that this approach has great potential for future laboratory implementations of EI. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Significance of survivin immunoreactivity and morphometric analysis of HPV-induced cervical dysplasia

Genomic integration of high-risk human papilloma virus in the nucleus of cervical epithelial mucosal cells leads to epithelial dysplasia. The aim of this study was to determine the relevance of correlation between epithelial survivin expression and the degree of human papilloma virus (HPV)-induced cervical epithelial dysplasia, and to establish the significance of morphometric analysis of the nuclear area in the assessment of the degree of cervical dysplasia. This retrospective study included 99 women with primary, previously untreated lesions, and colposcopic findings indicating dysplasia, in whom a cytological test by Papanicolaou method was interpreted according to the Bethesda criteria as lowgrade squamous intraepithelial lesion (LSIL), high-grade squamous intraepithelial lesion (HSIL), and atypical squamous cells of undetermined significance (ASCUS). We performed human papilloma virus (HPV) typing by PCR for evidence of viruse types 16, 18, 31, 33. After biopsy of the cervical mucosa, we performed hematoxylin-eosin (H-E) and Periodic Acid Schiff (PAS) staining, and immunohistochemical and morphometric analysis of tissue samples. The control group consisted of 12 women without dysplasia and without a verified infection of cervical high-risk HPV. A high statistical correlation between the degree of dysplasia and expression of survivin was found in patients with different types of cervical dysplasia (p = 0.003). We observed a high statistical difference between the area of nuclei at different degrees of cervical dysplasias (p = 0.000). The high-grade cervical dysplasia had a more than 2-fold higher level of ranking in comparison to low-grade dysplasia, and a more than 10-fold higher ranking than the control group without cervical dysplasia

A laboratory based edge-Illumination x-ray phase-contrast imaging setup with two-directional sensitivity

We report on a preliminary laboratory based x-ray phase-contrast imaging system capable of achieving two directional phase sensitivity thanks to the use of L-shaped apertures. We show that in addition to apparent absorption, two-directional differential phase images of an object can be quantitatively retrieved by using only three input images. We also verify that knowledge of the phase derivatives along both directions allows for straightforward phase integration with no streak artefacts, a known problem common to all differential phase techniques. In addition, an analytical method for 2-directional dark field retrieval is proposed and experimentally demonstrated

Time-dependent reduction of structural complexity of the buccal epithelial cell nuclei after treatment with silver nanoparticles

Recent studies have suggested that silver nanoparticles (AgNPs) may affect cell DNA structure in in vitro conditions. In this paper, we present the results indicating that AgNPs change nuclear complexity properties in isolated human epithelial buccal cells in a time-dependent manner. Epithelial buccal cells were plated in special tissue culture chamber / slides and were kept at 37°C in an RPMI 1640 cell culture medium supplemented with L-glutamine. The cells were treated with colloidal silver nanoparticles suspended in RPMI 1640 medium at the concentration 15 mg L−1. Digital micrographs of the cell nuclei in a sample of 30 cells were created at five different time steps: before the treatment (controls), immediately after the treatment, as well as 15 , 30 and 60 min after the treatment with AgNPs. For each nuclear structure, values of fractal dimension, lacunarity, circularity, as well as parameters of grey level co-occurrence matrix (GLCM) texture, were determined. The results indicate time-dependent reduction of structural complexity in the cell nuclei after the contact with AgNPs. These findings further suggest that AgNPs, at concentrations present in today's over-the-counter drug products, might have significant effects on the cell genetic material