LUCAS RAMOS DE PRETTO
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Resumo IPEN-doc 27949 Laser speckle imaging for osteoporosis evaluation2020 - AMARAL, MARCELLO M.; DEL-VALLE, MATHEUS; RAELE, MARCUS P.; PRETTO, LUCAS R. deOsteoporosis is a common disease characterized by the reduction on Bone Mineral Density (BMD), leading to weakening of bone structure, Chronic pain, deformities and loss of quality of life. In addition to the clinical evaluation, dual-energy X-ray absorptiometry is one of the main techniques to diagnose it. However, this technique uses ionizing radiation to assess the bone structure and therefore cannot be used very often by patients, due to radiological safety reasons. On the other hand, optical techniques are known for its safe use, due to non-ionizing radiation, however, optical techniques do not easily allows the analysis of bone tissue. This limitation could be circumvented in the oral cavity area. In this work we used the Laser Speckle Imaging (LSI) technique to evaluate maxilla and mandible bones after demineralization prosses in an animal in vitro model. Osteoporosis lesions were simulated in sixteen mandible and twelve maxilla slabs using Ethylenediaminetetraacetic Acid (EDTA) 0.5 M for 0 (control) 7, 15 and 30 days. The roughness parameters Ra and Rq were analyzed with optical profilometry (ZeGage, Zygo, USA) to characterize the demineralization process. The LSI images were measured by custom experimental setup. A collimated laser beam at 635 nm and 1.3mW (Thorlabs CPS635R), expanded by a diverging lens (-75 mm), illuminates the sample. The scattered signal was imaged by a CCD camera (Thorlabs - DCC1645-HQ), an adapter (Thorlabs MVLCMC) and objective lens (Thorlabs/Navitar - MVL12X3Z) setting. A custom software was implemented to measure the speckle patches ratio and the speckle contrast ratio from speckle images obtained by a custom LSI setup. The speckle contrast ratio method only differentiate sound from osteoporotic tissue. The speckle patches ratio method presented a negative correlation with the roughness parameter, and consequently with the demineralization level. It was concluded that LSI is a promissory technique for assessment osteoporosis lesions on alveolar bone and, for that, the patches ratio is the best methodology for detecting and differentiating several degrees of demineralization.Resumo IPEN-doc 26544 Optical evaluation of polymer deposition for 3D printing2019 - AMARAL, MARCELLO M.; PRETTO, LUCAS de; RAELE, MARCUS P.3D printing is a technology that is revolutionizing the productive sector [1]. It allows the production of free- form components and systems. It may ¯nd application from biomedical to aerospace engineering, as well as in the production of unique and speci¯c components needed in basic science laboratories. One of the most common approaches for 3D printing is the fused deposition modeling were a plastic ¯lament is fused and the component shape is modeled by layers deposition [2]. The success in the manufacture of the component is related to the addition between successive deposited layers. Increasing the temperature of the ¯lament to ensure perfect adhesion may compromise the desired shape and function characteristics for the component. Scanning Electronic Microscopy (SEM) is the gold standard technique to ensure the ideal condition for the 3D printing and evaluate the bonding between successive layers [2]. However, in this context, SEM is a destructive technique and do not allow real time application. Low Coherence Interferometry (LCI) is an optical technique capable to performing non-destructive tomography evaluation of scatter medium [3]. Using a Michelson interferometer to measure the backscattered light intensity as a function of depth position associated to a lateral scanning it is possible to obtain a cross-section image of the sample [3]. It is non-invasive, relatively inexpensive technique and could allow real time application during manufacturing. The aim of this work was to investigate the use of low coherence interferometry to evaluate the adhesion of successive layers on 3D printed plastic material. A set of samples were manufactured using a 3D printing (Cliever CL1, Brazil), with layer thickness from 100¡250¹m using PLA ¯lament. The sample were evaluated using a SEM and a commercial LCI (OCP930SR - Thorlabs Inc.) and the images were compared. It was possible to observe a correlation on the observed fused ¯laments between the images acquired by SEM and LCI proving that it is possible to use the optical technique as a alternative for 3D printing quality evaluation.