André Pereira de Almeida

X-ray fluorescence with synchrotron radiation to elemental analysis of lead and calcium content of primary teeth.

Primary teeth were analyzed by micro-SRXRF. The aim of this study was to determine the elemental distribution of lead and calcium in different regions of primary incisor of children living in a notoriously contaminated area (Santo Amaro da Purificação, Bahia State, Brazil). The measurements were performed in standard geometry of 45 degrees incidence, exciting with a white beam and using a conventional system collimation (orthogonal slits) in the XRF beamline at the Synchrotron Light National Laboratory (Campinas, Brazil).

Anatomical variations in primary teeth microelements with known differences in lead content by micro-Synchrotron Radiation X-Ray Fluorescence (μ-SRXRF) – A preliminary study

Shed teeth have been proposed as trace element biomarkers. This study determined variations in the spatial distribution of Ca, K, Zn, Pb, Mn, Cu, and Sr in four anatomical locations: superficial enamel (SE, 0-10μm), subsuperficial enamel (SSE, 10-30μm), primary dentin (PD), and secondary dentin (SD). Five primary incisors were analyzed by micro Synchrotron Radiation X-Ray Fluorescence (μ-SRXRF). Two teeth had low concentrations of lead in the SE (<250μg/g), while three contained very high lead concentrations in the SE (>2000μg/g). Teeth were sliced, and five spot measurements (20μm beam diameter) were accomplished in each location. The data are shown as absolute values and as the ratio between the different elements and Ca. The distribution of K was close to that of Ca. Zn was the third most abundant element, with the highest levels being found in the SE and SD and low levels detected in the PD. Increasing Sr levels were found progressing from the enamel to the dentin, with the highest levels being found in the SD, a distribution that was unique. Pb, Mn, and Cu exhibited a similar trend, with higher signals for these elements detected in the SE. This study provides preliminary data on the heterogeneous distribution of different elements in the tooth, highlighting the importance of the first 10μm of the SE for determination of some elements, such as Zn, Pb, Mn, and Cu.

Application of the SR-PhC-μCT technique with phase retrieval for the characterization of internal and external structures of Rhodnius prolixus

The present work is the second one of a two- part publication on the use of Synchrotron Radiation Phase Contrast microtomography (SR-PhC-μCT) for the study of Rhodnius prolixus morphology. In previous paper the visualization of various detailed features were highlighted thanks to the edge enhancement effects typical of the phase contrast technique, but the contrast between foreground and background remained poor. In this study the same data set have been re-visited with application of a single distance phase retrieval algorithm. The resulting slices showed very high quality images that enable a better visualization of important muscles and neurohemal organs of the central nervous system within the head of Rhodnius prolixus.

Evaluation of rib microstructure in Wistar rats using SR-μCT after radiation therapy simulation for breast cancer

A better understanding of biological interactions that occur after exposure to photon radiation is needed in order to optimize therapeutic regimens and facilitate development and strategies that decrease radiation-induced side effects in humans. In this work, ribs of Wistar rat submitted to radiotherapy simulation were imaged using synchrotron radiation computed microtomography at Elettra Synchrotron Laboratory in Trieste, Italy. Histomorphometric parameters were calculated directly from the 3D microtomographic images and showed significant differences between irradiated and non-irradiated groups.

Application of synchrotron radiation computed microtomography for quantification of bone microstructure in human and rat bones

This work aims to evaluate histomorphometric quantification by synchrotron radiation computed microto-mography in bones of human and rat specimens. Bones specimens are classified as normal and pathological (for human samples) and irradiated and non-irradiated samples (for rat ones). Human bones are specimens which were affected by some injury, or not. Rat bones are specimens which were irradiated, simulating radiotherapy procedures, or not. Images were obtained on SYRMEP beamline at the Elettra Synchrotron Laboratory in Trieste, Italy. The system generated 14 μm tomographic images. The quantification of bone structures were performed directly by the 3D rendered images using a home-made software. Resolution yielded was excellent what facilitate quantification of bone microstructures.

Evaluation of photon irradiation treatment upon calcium content of ribs of Wistar rats using micro-XRF

Therapeutic doses of radiation have been shown to have deleterious consequences on bone health. Among the treatment strategies used for breast cancer treatment, the most used are radiotherapy and chemotherapy. Radiotherapy may be given to destroy the cancer cells using high-dose x-rays. Protocols vary considerably, but generally whole body irradiation totals from 10 to 15 Gy, whereas local therapy totals from 40 to 70 Gy. In clinical practice, the quantitative evaluation of bone tissue relies on measurements of bone mineral density values, which are closely associated with the risk of osteoporotic fracture. Improved survivorship rates of cancer patients receiving radiotherapy increase the importance of understanding the mechanisms and long-term effects of radiation-induced bone loss. In this work, we investigated the variation on calcium distribution in ribs of female Wistar rats (Rattus norvegicus) submitted to photon irradiation with a single dose of 20 Gy. The determination of the calcium distribution ...

Segmentation of X-ray micro-computed tomography using Neural Networks trained with Statistical Information: Application to biomedical images

In the present work we describe ongoing research on the application of Artificial Neural Networks (ANNs) trained with Statistical Information in order to segment a slice of a Rhodnius Prolixus insect (vector of the Chagass disease) µCT scan. The images were acquired at the Synchrotron Radiation for MEdical Physics (SYRMEP) beam line at the Elettra Laboratory (Trieste, Italy). Two specialized ANNs were trained with statistical information for the segmentation task. The first ANN segmented the image of interest in two regions (one of them with white pixels and the other with non-white pixels), considering the enhancement of intensity due to phase contrast effect and despite the complexity of the image. The second ANN was able to recognize, amongst the white pixels, the ones related to the insect region. Preliminary results demonstrate the viability of the method in the segmentation of X-ray µCT.

Analysis of calcium distribution in femur of female rats submitted to different chemotherapy regimens

The most used treatment strategies for breast cancer (BC) are surgery, chemotherapy, and/or radiotherapy. Premenopausal women undergoing adjuvant chemotherapy BC treatment have significant bone loss from the first year after the treatment. This high bone mineral density loss can lead to an increased risk of fractures. Doxorubicin associated with Cyclophosphamide (AC) is a multidrug widely used for BC treatment, although this association can cause severe side effects. Today it is been discussed the use of the Docetaxel and cyclophosphamide (TC) association for BC treatment. The influence on the bone during chemotherapy regimens that include taxanes, like docetaxel, is unknown. Data from the “Women`s Health Initiative” show that postmenopausal BC survivors have a 15% greater risk of developing fractures than women without a history of BC. In this study, it was evaluated parameters involved in osteoporosis when rats were subjected to a chemotherapy regimen (TC) and/or irradiation (IR). Female Wistar rats, 03 months old, were divided into 3 groups: control, TC+IR (G1) and AC+IR (G2). The animals were euthanized 5 after months the end of treatment and their femurs were excised and dissected. Sections of 10 μm thick were used for μXRF analysis at the National Laboratory of Synchrotron Light. The uteri of these rats were collected and weighed Statistical analyzes were performed using GraphPad Prism, and values were compared using ANOVA and Tukey post-hoc test. The obtained results showed that animals from G2 had a significant reduction (p<;0.05) of uterine mass when compared to control. The qualitative analysis performed by μXRF showed that the animals from G2 had iron in bone composition of the femurs. This same result was not observed in animals from G0 and G1 groups. These results suggest that early menopause occurs and osteoporosis begins, probably because of the absence, or reduced, production of estrogen. The presence of iron in the G2 samples indicates the process of osteoporosis, because according to literature, this ion is competitive with calcium ions.

Segmentation of Synchrotron Radiation micro-Computed Tomography Images using Energy Minimization via Graph Cuts

The research on applications of segmentation algorithms to Synchrotron Radiation X-Ray micro-Computed Tomography (SR-μCT) is an open problem, due to the interesting and well-known characteristics of SR images, such as the phase contrast effect. The Energy Minimization via Graph Cuts (EMvGC) algorithm represents state-of-art segmentation algorithm, presenting an enormous potential of application in SR-μCT imaging. We describe the application of the algorithm EMvGC with swap move for the segmentation of bone images acquired at the ELETTRA Laboratory (Trieste, Italy).

Segmentation of Synchrotron Radiation X-Ray µCT images using energy minimization via Graph Cuts for quantitative analysis

Synchrotron Radiation (SR) X-Ray micro-Computed Tomography (µCT) enables magnified images that might be used as a non-invasive and non-destructive technique with a high space resolution for the qualitative and quantitative analysis of images. The research on applications of segmentation algorithms to SR-µCT is an open problem, due to the interesting and well-known characteristics of SR images for visualization, such as the high resolution, high brilliance and the phase contrast effect. We describe the application of the Energy Minimization via Graph Cuts algorithm (EMvGC) with swap move for the segmentation of SR-µCT images acquired at the Elettra Laboratory (Trieste, Italy). The EMvGC algorithm represents state-of-art segmentation algorithm which is fast and accurate, with outstanding results in several areas of computer vision, presenting an enormous potential of application in SR-µCT imaging.