Abstract: Mn-Zn ferrite nanoparticles were synthesized by chemical co-precipitation method and analysed using X-ray synchrotron diffraction data. Pair distribution function (PDF) analysis was used to probe the local structure and revealed that the first-neighbour distances of Fe-Fe and Mn-Zn in the 3.0 up to 3.5˚A range are different from the ones usually reported in the literature. For the sample with the best magnetic behaviour, resonant X-ray scattering (RXS) using three energies close to the absorption edges of Mn, Zn and Fe was applied to determine the cation distribution which explained the previous result from PDF analysis.

Palavras-Chave: nanoparticles; distribution functions; scattering; x-ray diffraction; ferrite; zinc compounds; manganese compounds; magnetic resonance; nmr imaging; images

ICHIKAWA, RODRIGO U.; PARRA, JOAO P.R.L.L.; VALLCORBA, ORIOL; PERAL, INMA; YOSHITO, WALTER K.; SAEKI, MARGARIDA J.; TURRILLAS, XAVIER; MARTINEZ, LUIS G. Cation distribution of Mn-Zn ferrite nanoparticles using pair distribution function analysis and resonant X-ray scattering. EPL, v. 124, n. 5, p. 56001-p1 - 56001-p5, 2018. DOI: 10.1209/0295-5075/124/56001. Disponível em: http://repositorio.ipen.br/handle/123456789/29931. Acesso em: $DATA.

Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.

Como referenciar este item

Abstract: Purpose: This study aimed to characterize and analyze the number of voids and the percentage of void volume within and between the layers of class II composite restorations made using the bulk fill technique or the incremental technique by optical coherence tomography (OCT). Methods and Materials: Class II cavities (43432 mm) were prepared in 48 human third molars (n=24 restorations per group, two class II cavities per tooth). Teeth were divided into four groups and restored as follows: group 1 (FOB), bulk filled in a single increment using Filtek One Bulk Fill (3M Oral Care); group 2 (FXT), incrementally filled using four oblique layers of Filtek Z350 XT (3M Oral Care); group 3 (FBF+FXT), bulk filled in a single increment using Filtek Bulk Fill Flowable Restorative (3M Oral Care) covered with two oblique layers of Filtek Z350 XT (3M Oral Care), and group 4 (FF+FXT), incrementally filled using Filtek Z350 XT Flow (3M Oral Care) covered with two oblique layers of Filtek Z350 XT (3M Oral Care). After the restorative procedure, specimens were immersed into distilled water and stored in a hot-air oven at 378C. Forty-eight hours later, thermal cycling was conducted (5000 cycles, 58C to 558C). Afterward, OCT was used to detect the existence of voids and to calculate the number of voids and percentage of voids volume within each restoration. Data were submitted to chi-square and Kruskal- Wallis tests (a=0.05). Comparisons were made using the Dunn method. Results: Voids were detected in all groups, ranging from 0.000002 (FBF+FXT and FF+FXT) to 0.32 mm3 (FBF+FXT). FF + FXT presented voids in all of the restorations and had a significantly higher number of voids per restoration when compared to the other groups (p,0.05), but restorations with the presence of voids were significantly higher only when compared to FXT (p,0.05). FBF + FXT presented a significantly higher percentage of voids volume than that of FXT (p,0.05). When comparing restorations made using high-viscosity resin-based composites (FOB and FXT), no significant differences regarding number of voids or percentage of voids volume were detected (p 0.05). Conclusions: The use of flowable resin-based composites can result in an increased number of voids and percentage of voids volume in restorations, and this appears to be more related to voids present inside the syringe of the material than to the use of incremental or bulk fill restorative techniques.

Palavras-Chave: dentistry; resins; biological recovery; tomography; optical equipment; images; composite materials; voids; layers

PARDO DIAZ, C.A.; SHIMOKAWA, C.A.K.; SAMPAIO, C.S.; FREITAS, A.Z.; TURBINO, M.L. Characterization and comparative analysis of voids in class II composite resin restorations by optical coherence tomography. Operative Dentistry, v. 45, n. 1, p. 71-79, 2020. DOI: 10.2341/18-290-L. Disponível em: http://repositorio.ipen.br/handle/123456789/31078. Acesso em: $DATA.

Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.

Como referenciar este item

Abstract: The recent clinical adoption of optical coherence tomography (OCT) angiography (OCTA) has enabled non-invasive, volumetric visualization of ocular vasculature at micron-scale resolutions. Initially limited to 3 mm × 3 mm and 6 mm × 6 mm fields-of-view (FOV), commercial OCTA systems now offer 12 mm × 12 mm, or larger, imaging fields. While larger FOVs promise a more complete visualization of retinal disease, they also introduce new challenges to the accurate and reliable interpretation of OCTA data. In particular, because of vignetting, wide-field imaging increases occurrence of low-OCT-signal artifacts, which leads to thresholding and/or segmentation artifacts, complicating OCTA analysis. This study presents theoretical and case-based descriptions of the causes and effects of low-OCTsignal artifacts. Through these descriptions, we demonstrate that OCTA data interpretation can be ambiguous if performed without consulting corresponding OCT data. Furthermore, using wide-field non-perfusion analysis in diabetic retinopathy as a model widefield OCTA usage-case, we show how qualitative and quantitative analysis can be confounded by low-OCT-signal artifacts. Based on these results, we suggest methods and best-practices for preventing and managing low-OCT-signal artifacts, thereby reducing errors in OCTA quantitative analysis of non-perfusion and improving reproducibility. These methods promise to be especially important for longitudinal studies detecting progression and response to therapy.

Palavras-Chave: ophthalmology; retina; biomedical radiography; tomography; vascular diseases; optical equipment; coherent radiation; images; blood vessels; beam scanners

PRETTO, LUCAS R. de; MOULT, ERIC M.; ALIBHAI, A.Y.; CARRASCO-ZEVALLOS, OSCAR M.; CHEN, SIYU; LEE, BYUNGKUN; WITKIN, ANDRE J.; BAUMAL, CAROLINE R.; REICHEL, ELIAS; FREITAS, ANDERSON Z. de; DUKER, JAY S.; WAHEED, NADIA K.; FUJIMOTO, JAMES G. Controlling for artifacts in widefield optical coherence tomography angiography measurements of non-perfusion area. Scientific Reports, v. 9, p. 1-15, 2019. DOI: 10.1038/s41598-019-43958-1. Disponível em: http://repositorio.ipen.br/handle/123456789/30388. Acesso em: $DATA.

Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.

Como referenciar este item

Abstract: The application of ionizing radiation in diagnostic medicine has increased worldwide in the last decades. Computed Tomography (CT) is the main radiological procedure that contributes to the increase of the collective dose in the population. The aim of this study was to estimate the doses received by patients undergoing CT scans in a public hospital in Santa Catarina - Brazil, employing data from the DICOM header and utilizing the CT-Expo V. 2.7 software. The data were selected from 45 abdominal CT scans consisting of two series: pre-contrast and one post-contrast intravenous, of adult patients performed in December 2020. The spreadsheets with the data extracted from the DICOM headers were provided by the Santa Catarina Telemedicine System (STT). The effective dose and organ doses were calculated by CTDIvol and DLP values using the software. Overall, the organs that showed the higher equivalent doses were the kidneys (19.5 mSv), spleen (18.5 mSv), stomach (18.9 mSv), and liver (18.1 mSv). The estimated effective doses were 7.31 and 8.41 mSv, for non-contrast and contrast-enhanced examinations. The use of software such as CT-Expo can support the estimation of effective doses received by patients through the information extracted from the DICOM header. The presented methodology can be a useful tool to retrospectively estimate the doses in CT services in Brazil.

Palavras-Chave: computer codes; abdomen; computerized tomography; contrast media; dose rates; effective radiation doses; images; monte carlo method; phantoms; radiation doses

SOUZA, D.C.B.; VICENTE, R.; SA, L.V.; SILVA, E.H.; OLIVEIRA, M.V.L.; CIDRAL, M.E.V.; FARIA, C.R.; CAMILO, N.F. Dose estimation in abdominal CT scans using CT-EXPO software. Brazilian Journal of Radiation Sciences, v. 10, n. 3B, p. 1-11, 2022. DOI: 10.15392/2319-0612.2022.2012. Disponível em: http://repositorio.ipen.br/handle/123456789/33502. Acesso em: $DATA.

Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.

Como referenciar este item

Abstract: The greatest impact of the tomography technology currently occurs in medicine. The success is due to the fact that human body presents standardized dimensions with well-established composition. These conditions are not found in industrial objects. In industry, there is a great deal of interest in using the tomography in order to know the inner part of (i) manufactured industrial objects or (ii) the machines and their means of production. In these cases, the purpose of the tomography is: (a) to control the quality of the final product and (b) to optimize the production, contributing to the pilot phase of the projects and analyzing the quality of the means of production. This scan system is a non-destructive, efficient and fast method for providing sec-tional images of industrial objects and it is able to show the dynamic processes and the dispersion of the ma-terials structures within these objects. In this context, it is important that the reconstructed image may present a great spatial resolution with a satisfactory temporal resolution. Thus, the algorithm to reconstruct the imag-es has to meet these requirements. This work consists in the analysis of three different iterative algorithm methods, namely the Maximum Likelihood Estimation Method (MLEM), the Maximum Likelihood Trans-mitted Method (MLTR) and the Simultaneous Iterative Reconstruction Method (SIRT. The analyses in-volved the measurement of the contrast to noise ratio (CNR), the root mean square error (RMSE) and the Modulation Transfer Function (MTF),in order to know which algorithm fits the conditions to optimize the system better. The algorithms and the image quality analyses were performed by Matlab® 2013b.

Palavras-Chave: tomography; iterative methods; computerized tomography; algorithms; quality control; diagnostic techniques; images; image scanners

VELO, A.F.; ALVAREZ, A.G.; HAMADA, M.M.; MESQUITA, C.H. Evaluation of iterative algorithms for tomography image reconstruction. Brazilian Journal of Radiation Sciences, v. 7, n. 2A, p. 1-16, 2019. DOI: 10.15392/bjrs.v7i2A.660. Disponível em: http://repositorio.ipen.br/handle/123456789/29981. Acesso em: $DATA.

Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.

Como referenciar este item

Abstract: OBJECTIVES: Conventional imaging methods are excellent for the morphological characterization of the consequences of osteonecrosis; however, only specialized techniques have been considered useful for obtaining functional information. To explore the affinity of radiotracers for severely devascularized bone, a new mouse model of isolated femur implanted in a subcutaneous abdominal pocket was devised. To maintain animal mobility and longevity, the femur was harvested from syngeneic donors. Two technetium-99m-labeled tracers targeting angiogenesis and bone matrix were selected. METHODS: Medronic acid and a homodimer peptide conjugated with RGDfK were radiolabeled with technetium-99m, and biodistribution was evaluated in Swiss mice. The grafted and control femurs were evaluated after 15, 30 and 60 days, including computed tomography (CT) and histological analysis. RESULTS: Radiolabeling achieved high (>95%) radiochemical purity. The biodistribution confirmed good blood clearance 1 hour after administration. For Tc-99m-hydrazinonicotinic acid (HYNIC)-E-[c(RGDfK)(2), remarkable renal excretion was observed compared to Tc-99m-methylene diphosphonate (MDP), but the latter, as expected, revealed higher bone uptake. The results obtained in the control femur were equal at all time points. In the implanted femur, Tc-99m-HYNIC-E-[c(RGDfK)(2) uptake was highest after 15 days, consistent with early angiogenesis. Regarding Tc-99m-MDP in the implant, similar uptake was documented at all time points, consistent with sustained bone viability; however, the uptake was lower than that detected in the control femur, as confirmed by histology. CONCLUSIONS: 1) Graft viability was successfully diagnosed using radiotracers in severely ischemic bone at all time points. 2) Analogously, indirect information about angiogenesis could be gathered using Tc-999m-HYNIC-E-[c(RGDfK)(2). 3) These techniques appear promising and warrant further studies to determine their potential clinical applications.

Palavras-Chave: skeleton; implants; viability; tracer techniques; radioactive tracers; necrosis; mice; animals; angiogenesis; femur; technetium isotopes; technetium 99; biological models; images

SCHIPER, LUIS; FAINTUCH, BLUMA L.; BADARO, ROBERTO J. da S.; OLIVEIRA, ERICA A. de; CHAVEZ, VICTOR E.A.; CHINEN, ELISANGELA; FAINTUCH, JOEL. Functional investigation of bone implant viability using radiotracers in a new model of osteonecrosis. Clinics, v. 71, n. 10, p. 617-625, 2016. DOI: 10.6061/clinics/2016(10)11. Disponível em: http://repositorio.ipen.br/handle/123456789/26969. Acesso em: $DATA.

Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.

Como referenciar este item