Impacto do campo de visao triangular convexo de tomografía computarizada de feixe conico na expressao de artefatos associados ao endurecimiento de feixe de raios X e na dose de radiacao: Impact of the convex triangular field of view of cone-beam computed tomography on beam hardening-related artifacts and radiation dose
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2024
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Objetivo: Avaliar o efeito do campo de visão (FOV) triangular convexo na distorção da imagem de materiais metálicos, na magnitude dos artefatos relacionados ao endurecimento do feixe de raios X, e na dose de radiação usando dois aparelhos de tomografia computadorizada de feixe cônico (TCFC). Métodos: A fase experimental da presente tese foi desenvolvida em três etapas: 1. Avaliação da distorção; 2. Avaliação da magnitude dos artefatos e 3. Avaliação dosimétrica. Para a avaliação da distorção, cilindros de cobalto-crômio, guta-percha, titânio e zircônia de dimensões conhecidas foram colocados individualmente em um fantoma de polimetilmetacrilato (PMM). Foram adquiridos 192 volumes de TCFC utilizando os FOVs triangulares convexos (100x80mm) e cilíndricos (80x80mm) dos aparelhos Veraviewepocs R100 (R100) e Veraview X800 (X800). Para determinar a distorção da forma do objeto, dois radiologistas orais e maxilofaciais (ROMFs) mediram as dimensões tomográficas horizontais e verticais dos cilindros usando o software HorosTM. Para avaliação subjetiva da distorção, nove OMFRs visualizaram vídeos de 10 segundos de imagens axiais de TCFC para identificar a forma axial de cada cilindro como triangular convexa, intermediária ou circular. Para avaliação da magnitude dos artefatos, cilindros de amálgama, cobalto-crômio, titânio e zircônia foram colocados individualmente no simulador de PMM e digitalizados usando os FOVs triangulares convexos e cilíndricos do X800, totalizando 60 exames de TCFC. Um ROMF desenhou 15 regiões de interesse (ROIs) de 2x2mm, distribuídas a 0,5, 1,0 e 1,5cm do centro de cada cilindro, usando o software Image J. A média e o desvio-padrão do valor dos tons de cinza de cada ROI foram calculados para cada distância e subtraídos dos valores de uma ROI controle para calcular a média da diferença (MDVC) e o desviopadrão do valor dos tons de cinza (DPVC). Para dosimetria, dosímetros...
Inglés: Aim: To assess the effect of the convex triangular field of view (FOV) on shape distortion of metallic objects and magnitude of artifacts related to the X-ray beam hardening, as in radiation dose using two cone-beam computed tomography (CBCT) devices. Methods: The thesis experimental phase consisted of three stages: distortion assessment, artifact magnitude assessment, and dosimetry assessment.For the distortion assessment, cylinders of chromium-cobalt, gutta-percha, titanium, and zirconia of known dimensions were individually placed in a polymethylmethacrylate (PMM) phantom. 192 CBCT scans were acquired using the convex triangular (100 mm diameter x 80 mm height) and cylindrical (80x80 mm) FOVs of Veraviewepocs R100 (R100) and Veraview X800 (X800) devices (J. Morita, Kyoto, Japan). Two oral and maxillofacial radiologists (OMFRs) measured the horizontal and vertical dimensions of the reconstructed cylinders using HorosTM v. 3.3.6 software (Nimble Co LLC Purview, Annapolis, MD)to assess shape distortion. For subjective assessment of shape distortion, nine OMFRs viewed 10 - second videos of CBCT scans and identified the axial shape of each cylinder as convex triangular, intermediary, or circular. For the assessment of the magnitude of the artifacts, cylinders of amalgam, chromium-cobalt, titanium, and zirconia were individually placed in the PMM phantom and scanned using the convex triangular and cylindrical FOVs of the X800 totalling 60 CBCT scans. An OMFR designed 15 square regions of interest (ROIs) of 2x2 mm distributed at 0.5, 1.0, and 1.5cm from the center ofeach cylinder using Image J software (National Institutes of Health, Maryland, MD). Mean grey value and standard deviation of each ROI were averaged for each distance and subtracted from the values of a control ROI to calculate the grey value mean difference ( GVMD) and grey value standard deviation (GVSD). For dosimetry, optically stimulated luminescence dosimeters were placed in an...
Inglés: Aim: To assess the effect of the convex triangular field of view (FOV) on shape distortion of metallic objects and magnitude of artifacts related to the X-ray beam hardening, as in radiation dose using two cone-beam computed tomography (CBCT) devices. Methods: The thesis experimental phase consisted of three stages: distortion assessment, artifact magnitude assessment, and dosimetry assessment.For the distortion assessment, cylinders of chromium-cobalt, gutta-percha, titanium, and zirconia of known dimensions were individually placed in a polymethylmethacrylate (PMM) phantom. 192 CBCT scans were acquired using the convex triangular (100 mm diameter x 80 mm height) and cylindrical (80x80 mm) FOVs of Veraviewepocs R100 (R100) and Veraview X800 (X800) devices (J. Morita, Kyoto, Japan). Two oral and maxillofacial radiologists (OMFRs) measured the horizontal and vertical dimensions of the reconstructed cylinders using HorosTM v. 3.3.6 software (Nimble Co LLC Purview, Annapolis, MD)to assess shape distortion. For subjective assessment of shape distortion, nine OMFRs viewed 10 - second videos of CBCT scans and identified the axial shape of each cylinder as convex triangular, intermediary, or circular. For the assessment of the magnitude of the artifacts, cylinders of amalgam, chromium-cobalt, titanium, and zirconia were individually placed in the PMM phantom and scanned using the convex triangular and cylindrical FOVs of the X800 totalling 60 CBCT scans. An OMFR designed 15 square regions of interest (ROIs) of 2x2 mm distributed at 0.5, 1.0, and 1.5cm from the center ofeach cylinder using Image J software (National Institutes of Health, Maryland, MD). Mean grey value and standard deviation of each ROI were averaged for each distance and subtracted from the values of a control ROI to calculate the grey value mean difference ( GVMD) and grey value standard deviation (GVSD). For dosimetry, optically stimulated luminescence dosimeters were placed in an...
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Tese (doutor em radiologia odontológica)-- Universidade Estadual de Campinas. Facultade de Odontologia. Área de Radiologia Odontológica
Palabras clave
MATERIALES DENTALES, ODONTOLOGIA - APARATOS E INSTRUMENTOS, POSOLOGIA, RADIOGRAFIA DENTAL, TOMOGRAFIA COMPUTARIZADA DE HAZ CONICO