RESUMO
Maximum points of breast density have been strongly associated with breast cancer masking than global breast density, which is a widely used measure today. The objective of this work was to verify the correlation between two measures of global breast density (VBDGLOBAL and DABGLOBAL) and a measure of maximum point breast density (VBDMP). Mammographic images of 4.020 patients were analyzed using the Volpara software, which calculated or extracted the variables needed for the study from the DICOM header. Two-tailed partial correlation tests were performed between the variable VBDGLOBAL with VBDMP and DABGLOBAL with VBDMP in the following contexts: keeping PA and CBT constant, keeping only CBT constant, and keeping only PA constant. The Pearson test was also used to verify the bivariate correlation between VBDGLOBAL with VBDMP and DABGLOBAL with VBDMP. For the two-tailed partial correlation tests between VBDGLOBAL with VBDMP, keeping the CBT and PA variables constant resulted in r = 0.845 (p < 0.05). When kept constant only the CBT, r = 0.875 (p < 0.05), and keeping only the PA constant r = 0.866 (p < 0.05). Pearson's test showed r = 0.883 (p < 0.05). For the two-tailed partial correlation tests between the DABGLOBAL with VBDMP quantities, the results were r = 0.675 (p < 0.05), r = 0.725 (p < 0.05) and r = 0.701 (p < 0.05) for constant CBT and PA, constant CBT and constant PA, respectively, while the Pearson test resulted in r = 0.738 (p < 0.05). We conclude that a woman who has high global breast density is also highly likely to have maximum points of breast density.
Assuntos
Densidade da Mama , Neoplasias da Mama , Humanos , Feminino , Brasil , Mamografia/métodos , SoftwareRESUMO
BACKGROUND: According to the European Reference Organization for Quality Assurance Breast Screening and European Diagnostic Services, the spatial accuracy of reconstructed images and reconstruction artifacts must be evaluated in digital breast tomosynthesis (DBT) quality control procedures. PURPOSE: To propose a computational algorithm to evaluate the geometric distortion and artifact spreading (GDAS) in DBT images. MATERIAL AND METHODS: The proposed algorithm analyzed tomosynthesis images of a phantom that contains aluminum spheres (1â mm in diameter) arranged in a rectangular matrix spaced 5â cm apart that was inserted in 5-mm-thick polymethylmethacrylate (PMMA). RESULTS: The obtained results were compared with the values provided by the algorithm developed by the National Coordinating Center for the Physics of Mammography (NCCPM). In the comparison, the results depended on the dimensions of the region of interest (ROI). This dependence proves the benefit of the proposed algorithm because it allows the user to select the ROI. CONCLUSION: The computational algorithm proved to be useful for the evaluation of GDAS in DBT images, in the same way as the reference algorithm (NCCPM), as well as allowing the selection of the ROI dimensions that best suit the spreading of the artifact in the analyzed images.
Assuntos
Artefatos , Polimetil Metacrilato , Algoritmos , Alumínio , Humanos , Mamografia/métodosRESUMO
PURPOSE: To introduce and evaluate a method developed for the direct measurement of mammographic x-ray spectra using a CdTe spectrometer. The assembly of a positioning system and the design of a simple and customized alignment device for this application is described. METHODS: A positioning system was developed to easily and accurately locate the CdTe detector in the x-ray beam. Additionally, an alignment device to line up the detector with the central axis of the radiation beam was designed. Direct x-ray spectra measurements were performed in two different clinical mammography units and the measured x-ray spectra were compared with computer-generated spectra. In addition, the spectrometer misalignment effect was evaluated by comparing the measured spectra when this device is aligned relatively to when it is misaligned. RESULTS: The positioning and alignment of the spectrometer have allowed the measurements of direct mammographic x-ray spectra in agreement with computer-generated spectra. The most accurate x-ray spectral shape, related with the minimal HVL value, and high photon fluence for measured spectra was found with the spectrometer aligned according to the proposed method. The HVL values derived from both simulated and measured x-ray spectra differ at most 1.3 and 4.5% for two mammography devices evaluated in this study. CONCLUSION: The experimental method developed in this work allows simple positioning and alignment of a spectrometer for x-ray spectra measurements given the geometrical constraints and maintenance of the original configurations of mammography machines.
Assuntos
Mamografia , Raios X , Neoplasias da Mama/diagnóstico por imagem , Feminino , Humanos , Fótons , Análise EspectralRESUMO
OBJECTIVE: The aim of this human study was to evaluate the radiation doses in the buccal cavity and face, during panoramic, spiral conventional tomography, and helicoidal computerized tomography exams. MATERIAL AND METHODS: Lithium fluoride TL detectors (TLD-100) were placed on the skin at anatomic points such as parotid glands, submandibular glands, thyroid glands, and crystalline to assess the skin entrance dose in 19 patients who were to undergo dental implant surgery. RESULTS: In the panoramic exam, maximum doses were observed near the parotid glands at 1.57 (±18%) mGy on the right and 1.89 (±18%) mGy on the left. In the spiral conventional tomography exam, the maximum dose was 4.41 (±21%) mGy near the right and left parotid glands, whereas near the right or left submandibular glands, the maximum doses reached 40.7 (±18%) mGy. In the helicoidal computerized tomography for mandibular and maxilla exams, the maximum dose was 40.9 (±15%) mGy near the parotid glands and 41.0 (±18%) mGy near the submandibular glands. Near the thyroid and eye lens, doses were lower than 0.23 (±21%) in all exams. CONCLUSION: Regardless of the exam target area, the submandibular and parotid glands represented the most irradiated organs. This data suggests that efforts should be made by professionals to improve and optimize methods in order to reduce doses without losing the information necessary for treatment planning.
Assuntos
Arcada Edêntula/diagnóstico por imagem , Glândula Parótida/diagnóstico por imagem , Radiografia Panorâmica/efeitos adversos , Glândula Submandibular/diagnóstico por imagem , Tomografia Computadorizada Espiral/efeitos adversos , Carga Corporal (Radioterapia) , Calibragem , Implantação Dentária Endóssea , Humanos , Cristalino/diagnóstico por imagem , Mandíbula/diagnóstico por imagem , Maxila/diagnóstico por imagem , Planejamento de Assistência ao Paciente , Doses de Radiação , Dosimetria Termoluminescente/instrumentação , Glândula Tireoide/diagnóstico por imagemRESUMO
Objetivo- Avaliar as características e os resultados do atendimento de pacientes hipertensos em serviços especializados. Métodos-Estudo prospectivo de avaliaçäo de pacientes submetidos a diagnóstico, a tratamento e a seguimento em serviço especializado de hipertensäo. Objetivou-se analisar o comportamento de uma populaçäo com vistas a alguns parâmetros bem definidos, tais como: atraso, faltas, abandono aos retornos marcados e observância à terapêutica proposta, em períodos de um ano e no total de tempo compreendido entre janeiro de 1995 e maio de 1998. Resultados-A observanciâ aos esquemas prescritos e às orientaçöes oferecidas aos pacientes, neste grupo estudado, considerando as condiçöes específicas de atendimento implementadas foi similar àquelas descritas na literatura. Entretanto, a implementaçäo de esquemas de orientaçöes e programas educacionais peculiares mostraram maior observância ao tratamento sem, no entanto, modificar os percentuais de controle da pressäo arterial, fator que, sabidamente, depende de outros aspectos. Conclusäo-A constituíçäo de serviços multidisciplinares com programas específicos de atendimento e orientaçäo aos pacientes leva, através de um melhor conhecimento da doença, à maior observancia às orientaçöes terapêuticas sem, entretanto, haver modificaçäo dos percentuais de pacientes controlados.(au)
Assuntos
Humanos , Educação de Pacientes como Assunto , HipertensãoRESUMO
Este trabalho apresenta os resultados da determinação experimental dos coeficientes de conversão da grandeza de calibração kerma no ar para a nova grandeza da ICRU de monitoração de área, H*(d). As medidas foram realizadas nas profundidades 10, 50 e 60 mm de uma esfera de PMMA de 30 cm de diâmetro em feixes de raios-X de radiodiagnóstico.