Standardization of 223Ra by live-time anticoincidence counting and gamma-ray emission determination.

From a commercial supplier, three independent lots of an aqueous solution containing 223Ra in equilibrium with its deteriorating progeny were considered for standardization, by using live-time anticoincidence counting (LTAC) in the Laboratório Nacional de Metrologia das Radiações Ionizantes (LNMRI) Brazil. The ionization chamber calibration factors were obtained using measurements of independent lots of 223Ra in LTAC considering the absolute method in order to evaluate the constancy and reproducibility of the standardization. The calibration factors of three high-performance well-type ionization chamber systems and four commercial well-type ionization chambers were determined. The LTAC results showed that lots 2 and 3 were 1069.88 and 1097.44 kBq/kg, with corresponding relative standard uncertainties 0.12% and 0.20%, respectively. The spectrometry method results of each lot value were classified as positive by ANOVA hypothesis testing. The emission probabilities relating to the X- and γ-rays in region from 81 to 830 keV ware determined. Hence, LNMRI can provide calibration services for 223Ra.

Measurement of the absolute gamma emission intensities from the decay of Th-229 in equilibrium with progeny.

There are few long-lived radionuclides yielding high intensity gamma-rays emission with energies ranging from 100 keV to 500 keV that can be applied as radioactive gamma standard to calibrate HPGe detectors. Furthermore, this energy range represents the main emitted energies of the majority of radionuclides used in nuclear medicine. The Brazilian National Laboratory for Ionizing Radiation Metrology (LNMRI/IRD/CNEN) has attempted to identify radionuclides that have the potential to be used as a calibration source due to their long half-life as well as their emission spectrum. Hence, LNMRI promotes standardization studies of gamma-emitting radionuclides that meet these criteria on order to disseminate them. Thorium-229, with its well-defined energies and relatively high intensities, is one such candidate radionuclide for the energy and full-energy peak efficiency calibration of high-purity gamma spectrometers. Thorium-229 was standardized by the method of 4παß(LS)-γ(NaI(Tl)) live timed anticoincidence counting. The emission intensities of gamma-rays associated with the decay of 229Th have been determined by HPGe gamma ray spectrometry with accuracy and precision. The results are in agreement with current literature data.

Rapid and accurate assessment of the activity measurements in Brazilian hospitals and clinics.

Traceability in Nuclear Medicine Service (NMS) measurements was checked by the Institute of Radioprotection and Dosimetry (IRD) through the Institute of Energy and Nuclear Research (IPEN). In 2016, IRD ran an intercomparison program and invited Brazilian NMS authorized to administer 131I to patients. Sources of 131I were distributed to 33 NMSs. Three other sources from the same solution were sent to IRD, after measurement at IPEN. These sources were calibrated in the IRD reference system. A correction factor of 1.013 was obtained. Ninety percent of the NMS comparisons results are within ±10% of the National Laboratory of Metrology of Ionizing Radiation (LNMRI) value, the Brazilian legal requirement.

Dentists' knowledge of oral health during pregnancy: a review of the last 10 years' publications.

UNLABELLED: Pregnancy is a period in which several physical and emotional changes occur. These changes in pregnant women's mouths promote changes that need to be known by dentists, so that they can provide the necessary care to women. PURPOSE: To gather data from published studies on the knowledge of dentists about the oral health of pregnant women. METHODS: Papers published between 2003 and 2013 containing surveys on the topic under study were searched. Fourteen studies were selected and grouped into work areas. RESULTS: Dentists have doubts and fears about the care of pregnant women, to a greater or lesser degree, especially with regard to the use of X-rays, prescriptions and ideal gestational period of treatment. CONCLUSION: The results suggest a need to improve dentists' knowledge regarding dental care of pregnant women especially as during pregnancy women may acquire new habits relevant to the oral health of their children.

Association between periodontal changes and osteoporosis in postmenopausal women.

OBJECTIVE: To investigate the possible association between periodontal changes and osteoporosis in postmenopausal women through a longitudinal study. METHODS: This longitudinal study included 33 patients. The participants were divided into three groups according to the bone mineral density assessed in the lumbar region: normal bone (G1, n = 15), osteopenia (G2, n = 12) and osteoporosis (G3, n = 6). Periodontal evaluation included clinical attachment level, probing depth, gingival bleeding index and visible plaque index, evaluated by two examiners blinded to systemic bone condition. The statistical process included the t-test for paired samples, with a significance level of 5% to check for changes in periodontal parameters considered at initial and final systemic bone density. RESULTS: The results showed that, after follow-up, there was a significant increase in gingival bleeding index in the group of women who had normal initial bone condition and progressed to osteopenia (after 3 years, 59.89%, p = 0.010) and osteoporosis (after 3 years, 74.37%, p = 0.035). In addition, the group diagnosed with osteopenia at baseline who progressed to osteoporosis after 3 years also showed a significant increase in gingival bleeding index (p < 0.001). CONCLUSIONS: The findings suggest that periodontal changes can be associated with osteoporosis in postmenopausal women.

Placa ateromatosa calcificada en radiografía panorámica: aspectos radiográficos y diagnósticos diferenciales / Calcified atheromatous plaque in panoramic radiography: radiographic aspects and differential diagnosis

Las placas de ateroma son conformadas por depósitos de lípidos en las camadas más profundas de las arterias y que siendo estructuras calcificadas pueden ser vistas en radiografías panorámicas. Su aspecto radiográfico debe ser diferenciado de las imágenes que pertenecen a diversas estructuras anatómicas y patológicas radiopacas, puesto que en dicho examen es posible observar asimismo otros hallazgos radiográficos en región cervical. Calcificaciones más a menudo descriptas en la literatura y que consisten en diagnóstico diferencial para las placas ateromatosas son el hueso hioides, cartílago tritícea, el cuerno superior de calcificación del cartílago tiroides calcificada, la epiglotis, los ganglios linfáticos calcificados, los flebolitos, los submaxilares de glándulas salivales y los tonsiolitos. Este estudio tiene como objetivo realizar una revisión de la literatura relativa a las placas ateromatosas y su diferencial diagnóstico con el fin de orientar mejor al dentista en la interpretación de estas imágenes. De esta manera, permite el reenvío de la paciente a un tratamiento preventivo, contribuyendo al desarrollo de la salud pública...

The atheromatous plaques consist of deposits of fat in the inner layers of the arteries and as they are calcified, can be detected on panoramic radiographs. Its radiographic appearance should be differentiated from others anatomical and pathological radiopaque structures, since this examination can also detect other radiographic findings in the neck. The calcifications most frequently described in the literature between anatomical and pathological conditions, and which constitute the differential diagnosis for atheromatous plaques are the hyoid bone, cartilage triticeous, the superior horn of the calcified thyroid cartilage, epiglottis, calcified lymph nodes, the phleboliths, submandibular salivary gland sialoliths and tonsilloliths. This study aims to conduct a review of literature related to atheromatous plaques and their differential diagnoses in order to provide better guidance to the dentist in the interpretation of those images. Thus, the patient can properly receive an early treatment, contributing to the development of public health...

Radioactivity measurements of 177Lu, 111In and 123I by different absolute methods.

The activities of (177)Lu, (111)In and (123)I solutions have been absolutely determined using three different measurement methods. (177)Lu solution was standardized using the 4πß(PC)-γ(NaI) coincidence and 4πß(LS)-γ(NaI) live-timed anticoincidence methods. For the (111)In and (123)I solutions, besides these two mentioned methods, the coincidence sum-peak method was also applied. The measured activities results using these different methods are consistent within the evaluated experimental uncertainties demonstrating the equivalence of these methods. As an additional contribution to nuclear data, the half-lives have been determined using a well type IG12 ionization chamber.

Performance of dose calibrators in Brazilian hospitals for activity measurements.

In order to obtain information on the accuracy of activity measurements in Brazilian hospitals, several intercomparison exercises have been organized since 1998. The first exercise consisted of two intercomparison runs of 131I and 99mTc and had the participation of 21 hospitals localized in Rio de Janeiro city and surroundings. The second, with 131I (47 hospitals) and 123I (12 hospitals), had the participation of hospitals localized in the whole country. The results were analyzed under the statistical point of view and conformity to the norms of Regulatory Authority. These results have shown that such exercises are necessary to improve the quality of the measurements and to identify those instruments that are producing incorrect values.

Metrological capability of the Brazilian laboratories of analyses of radionuclides in environmental samples.

The metrological capability of 24 Brazilian laboratories of radionuclide determinations in environmental samples was analysed for purposes to establish requirements for accreditation of laboratory for each radionuclide. For each type of analysis, the range of activity per unit mass or volume, the range of the reference value and its correspondent uncertainty were described. The accuracy was established using the statistical criteria of USE.P.A. for the laboratory performance classification. The precision of the analyses, expressed by its variation coefficient of the laboratory determinations, was classified in intervals of 5%. The data base was constituted by 3013 results of analyses obtained in 28 intercomparison runs performed from 1991 to 2000, for K, Th, Unat, gross alpha, gross beta, and other 27 radionuclides, in matrices of water, soil, vegetation, air filter and milk. The quality criteria established were the variation coefficient less than 5% and good performance in intercomparison runs. Results included from 5% to 10% are also considered, for special types of matrices and radionuclides.

Intercomparison of 131I and 99mTc activity measurements in Brazilian nuclear medicine services.

This work outlines the quality assurance program for the activity measurements of the most used radionuclides at Brazilian Nuclear Medicine Services (NMS). The program aims to guarantee that the patient is given the correct prescribed amount of activity in diagnostic or therapeutic applications. This accurate administration depends upon proper use and calibration of the activity meters by the NMS. Underestimation of administered activity in diagnostic practices could delay correct diagnosis disturbing the value of the investigation. On the other hand, the overestimation would be worse, mainly in therapeutic applications, because an unnecessarily high absorbed dose would be delivered to the patient. The preliminary results of intercomparison for 131I and 99mTc showed that many activity meters used at NMS's present problems giving results up to 41% greater than the reference values determined at the National Metrology Laboratory for Ionizing Radiation (LNMRI) which is recognized as the Brazilian authorized metrology laboratory for ionizing radiation. These results have demonstrated that the NMS should improve the accuracy of the activity measurements of the radionuclides administered to the patients and establish the traceability to the national standards of measurements. These standards are based on a pressurized well-type ionization chamber installed at LNMRI and calibrated with reference sources standardized by absolute methods. The protocol of the intercomparison and recommendations made in order to minimize errors in measuring procedures are described and results are discussed.

The infrared intensities and polar tensors of the fluorochloromethanes.

The polar tensors of CF3Cl, CF2Cl2 and CFCl3 have been calculated using recent measurements of their gas phase infrared fundamental intensities. The polar tensors obtained for CF2Cl2 and CFCl3 are in very good agreement with those obtained previously since the more recent experimental intensity results are in good agreement with those reported earlier. For CF2Cl2 rhoC = +1.626, rhoF = -0.577 and rhoCl = -0.26e whereas rhoC = +1.369, 0.478 and rhoCl = 0.297e for CFCl3. However, two sets of significantly different mean dipole moment derivatives are obtained from the experimentally measured intensities of CF3Cl reported by two different laboratories. On the other hand, the differences in the mean derivatives of these two sets are not large enough so that results from electronegativity models, potential models for core ionization energies and quantum chemical calculations at the Moller-Plesset 2 and B3LYP density functional levels are sufficient to indicate which set is the correct one. As such average values of rhoC = +1.907+/-0.178e, rhoF = -0.590+/-0.056e and rhoCl = -0.139+/-0.013e obtained from both sets of polar tensor elements are recommended for the CF33Cl mean dipole moment derivatives.

[Clinical and comparative study of the image quality of 3 digital radiographic systems, E-speed film and digitalized film]]. / Estudo clínico comparativo da qualidade de imagem de três sistemas radiográficos digitais, filme E-speed e filme digitalizado.

The aim of this study was to evaluate, subjectively, the image quality of two CCD digital systems, a digital storage phosphor system, a digitized film and an E-speed film. Five objects were radiographed with 50, 60 and 70 kVp, with exposure times of 0.08, 0.13, 0.2, 0.4 and 0.8 s. In order to maximize the fidelity of the results, the dental X-ray unit employed was submitted to an evaluation so that the relation between exposure time and dose could be established. A good reproducibility was obtained. Six evaluators analyzed 375 images, using a scoring scale which ranged from 0 to 4. The results revealed different responses, indicating that the storage phosphor system had the best performance, in the various exposures employed. However, it was possible to conclude that all systems studied, except for the Sens-A-Ray, can offer images in ideal conditions for the diagnosis, as long as their latitudes are respected.

The infrared fundamental intensities and polar tensor of CF4.

Atomic polar tensors of carbon tetrafluoride are calculated from experimental fundamental infrared intensities measured by several research groups. Quantum chemical calculations using a 6-311 + + G(3d, 3p) basis set at the Hartree-Fock, Möller-Plesset 2 and Density Functional Theory (B3LYP) levels are used to resolve the sign ambiguities of the dipole moment derivatives. The resulting carbon mean dipole moment derivative, pC = 2.051 e, is in excellent agreement with values estimated by a MP2/6-311 + + G(3d, 3p) theoretical calculation, 2.040 e, and by an empirical electronegativity model, 2.016 e. The pC value determined here is also in excellent agreement with the one obtained from the CF4 1s carbon ionization energy using a simple potential model, 2.059 e. Crawford's G intensity sum rule applied to the fundamental intensities of CH4, CH3F, CH2F2 and CHF3 results in a prediction of a 1249 km mol(-1) intensity sum for CF4 in good agreement with the experimental values of 1328 +/- 37.9, 1208.0 +/- 54.4 and 1194.8 +/- 7.4 km mol(-1) reported in the literature.