Avaliação da influência do volume do campo de visão na determinação da densidade mineral em tomografia computadorizada de feixe cônico e tomografia computadorizada multislice

Abstract

Computed tomography cone beam (CBCT) scans have been used to evaluate the quality of bone. The values of density seem to be influenced by some CBCT inherent variables. However, some variables inherent to CBCT seem to influence the values of density and the influence of FOV volume has not been completely elucidated. The aim of this study was to determine the effects of FOV size on density values in large-volume CBCT and MSCT images. A phantom made up of 3 cylinders containing distilled water, plaster and motor oil was constructed and inserted into an acrylic cylinder filled with distilled water. The phantom was scanned with a CBCT and MSCT device using 3 FOV sizes. Density of each material was evaluated in 40 regions of interest. In CBCT exams there was significant difference between the density values of different FOVs for the 3 materials. In the MSCT there was significant difference only for the oil. A significant correlation between CBCT and MSCT exams for the plaster in all of the FOVs was obtained. The water did not show significant correlation between CBCT and MSCT exams with the FOVs under study. The oil was not correlated in 8 x 8mm FOV and a low correlation of the FOVs 16 x 8mm and 16 x 13mm. The density values determined in CBCT images showed significant interference by varying the size of the FOV. The density values obtained in MSCT examinations showed a statistically significant difference only for oil.