H.S. Rocha

First experiments on diffraction-enhanced imaging at LNLS.

Diffraction-enhanced images have been obtained using two silicon crystals in a non-dispersive set-up at the XRD2 beamline at the Brazilian Synchrotron Light Laboratory (LNLS). A first asymmetrically cut silicon crystal using the (333) reflection vertically expanded the monochromated beam from 1 mm to 20 mm allowing the imaging of the whole sample without movements. A symmetrically cut Si(333) second crystal was used as a Bragg analyzer. Images of biological samples including human tissue were recorded using a direct-conversion CCD detector resulting in enhancement of the contrast compared with absorption-contrast images.

Elemental distribution mapping on breast tissue samples

The main of this work is to determine the elemental and absorption distribution map in breast tissue samples by X-ray fluorescence and X-ray transmission microtomography. The experiments were performed at the X-ray fluorescence beamline (D09B-XRF) in the Brazilian Synchrotron Light Source (LNLS), Campinas, Brazil. A quasi-monochromatic beam produced by a multilayer monochromator was used as an incident beam. The sample was placed on a high precision goniometer and translation stages that allow rotating as well as translating it perpendicularly to the beam. The fluorescence photons were collected with an energy dispersive HPGe detector placed at 90 degrees to the incident beam, while transmitted photons were detected with a fast Na(Tl) scintillation counter () placed behind the sample on the beam direction. All the tomographic images were reconstructed using a filtered-back projection algorithm. In the breast tissue samples, it was possible to determine the distribution of Zn, Cu and Fe in healthy tissue and tumor.

Diffraction-enhanced imaging microradiography applied in breast samples

The diffraction-enhanced imaging (DEI) is a powerful tool to observe tumors and other diseases in breast tissue and provide more precise diagnostics. In this work DEI was used to analyze breast tissues details that have poor attenuation contrast. An X-ray imaging system with DEI techniques was developed using synchrotron radiation. The DEI experiment was performed in D10A-XRD2 beamline at the Brazilian Synchrotron--LNLS. The pre-monochromator, upstream of the beamline was adjusted to 10.7 keV. The samples were positioned between two channel-cut Si(333) in non-dispersive geometry mounted in a double axes diffractometer. A direct conversion water-cooled CCD camera of 1242 pixel x 1152 pixel of 25 microm x 25 microm each was used as a two-dimensional detector in scanning mode. The DEI system could show details in low attenuation tissues based on the contrast imaging obtained by attenuation, refraction gradient and ultra-small angle scatter characteristics. In this work the capacity to observe different types of structures and details in breast tissues were investigated.

X-ray transmission microtomography using synchrotron radiation

This work reports the feasibility of a non-destructive synchrotron radiation X-ray transmission imaging technique development at Brazilian synchrotron light source. The quality control image parameters (spatial and density resolution and noise) are given and microtomograms presented. Microtomograms of biomedical samples are presented. The tomography system was mounted into the XRF beamline that uses a high-intensity white beam with 12 keV effective energy, and maximum width and height equals to 11 and 1 mm, respectively. The detector used to collect the data was a 512-pixel Hamamatsu linear array with width of 50 μm (36 μm of sensitivity length) and cooled by a Peltier junction, causing the temperature falling down to 15°C. The samples were placed over a computer controlled table with 0.5° angular resolution and turned around the center covering 360°. To reconstruct the sample a parallel beam filtered back-projection algorithm was used.

Enhanced contrast radiography with channel-cut crystals at the LNLS

An analyzer-based x-ray phase contrast imaging (PCI) setup based on channel-cut crystals at the Laboratorio Nacional de Luz Sincrotron (LNLS—Brazilian Synchrotron) is presented. The contrast, visibility, signal-to-noise ratio and spatial resolution of the acquired images were characterized. The potential of PCI for enhancing details of different features with the same x-ray attenuation coefficient is exploited together with cross section simulations of the PCIs acquired at different angular positions on the rocking curve (RC). The present results show that this setup can be used as a standard PCI setup at the LNLS.

Biological tissues analysis by XRF microtomography

The main of this work is to determine the elemental distribution in breast and prostate tissue samples in order to verify the concentration of some elements correlated with characteristics and pathology of each tissue observed by the X-ray transmission microtomography (microCT). The experiments were performed at the X-ray fluorescence beamline of the Brazilian Synchrotron Light Laboratory. The microCT images were reconstructed using a filtered-back-projection algorithm and the XRF microtomographies were reconstructed using a filtered-back-projection algorithm with absorption corrections.

Alpha-1-Antitrypsin Deficiency Presenting as Neonatal Cholestasis: Predictors of Outcome and Effect of Ursodeoxycholic Acid

Background and objective: Alpha-1-antitrypsin deficiency presenting as neonatal cholestasis occurs in a small percentage of affected individuals. The prognosis is variable, from “healing” to liver cirrhosis and/or severe hepatocellular failure, requiring liver transplantation. We researched for predictors of outcome, including the effect of ursodeoxycholic acid. Methods: Retrospective cohort study of 27 cases of neonatal cholestasis due to alpha-1-antitrypsin deficiency, in the period between 1985 and 2013. Inclusion criteria: patients with neonatal cholestasis and ZZ phenotype. Exclusion criteria: presence of other diagnosis or known risk factors for developing neonatal cholestasis. We analyzed several clinical, biochemical, histological and therapeutic variables. Patients were categorized into two groups: favorable outcome (n=18), unfavorable outcome (n=9). We also divided the patients as treated (n=16), and untreated (n=11) with ursodeoxycholic acid. Results: Splenomegaly at admission (P=0.006) and persistent jaundice at 6 months old (P=0.007) were associated with unfavorable outcome. The values of conjugated bilirubin (P=1.000), aspartate aminotransferase (P=1.000), alanine aminotransferase (P=0.371) and gamma-glutamyltransferase (P=0.667) were not significantly different in both groups of outcome. Early treatm e nt with ursodeoxycholic acid was associated with a favorable outcome (P=0.011). Treated patients did not differ significantly from the untreated-ones in biochemical parameters (conjugated bilirubin, aspartate aminotransferase, alanine aminotransferase and gamma-glutamyltransferase), and had significantly lower alpha-1-antitrypsin serum levels (P=0.015). Conclusion: Splenomegaly at admission and persistence of jaundice at 6 months old were predictive for bad prognosis, and early treatment with ursodeoxycholic acid might have interfered positively in the outcome.

Elemental distribution images in prostate samples by X-ray fluorescence microtomography.

An X-ray transmission microtomography (CT) system combined with an X-ray fluorescence microtomography (XRFμCT) system was implemented in the Brazilian Synchrotron Light Laboratory (LNLS), in order to determine the elemental distribution in prostate samples aiming at establishing a correlation between the concentration of some elements and the characteristics and pathology of the tissues. The CT images were reconstructed using a filtered-back projection algorithm and the XRFμCT images were reconstructed using a filtered-back projection algorithm with absorption corrections.

X-ray transmission microtomography facility at the National Synchrotron Light Laboratory

This work reports the feasibility of a nondestructive synchrotron radiation X-ray transmission imaging technique development at Brazilian synchrotron light source. The quality control image parameters (spatial and density resolution and noise) were available and tomography preliminaries were evaluated. Microtomograms of biomedical samples are presented. The tomographic system was mounted into the XRF beamline that uses a high intensity white beam with 12 keV effective energy, and maximum width and height equals to 11 mm and 1 mm, respectively. The detector used to collect the data was a 512-pixel EG&G Reticon linear array with width of 50 /spl mu/m (36 /spl mu/m of sensitivity length ) and cooled by a Peltier junction, causing the temperature falling down to 15/spl deg/C. The samples were placed over a computer controlled table with 0.5 degree angular resolution and turned around the center covering 360 degrees. To reconstruct the sample was used a parallel beam filtered backprojection algorithm.