Oral panorama reconstruction method based on pre-segmentation and Bezier function / 生物医学工程学杂志

For patients with partial jaw defects, cysts and dental implants, doctors need to take panoramic X-ray films or manually draw dental arch lines to generate Panorama images in order to observe their complete dentition information during oral diagnosis. In order to solve the problems of additional burden for patients to take panoramic X-ray films and time-consuming issue for doctors to manually segment dental arch lines, this paper proposes an automatic panorama reconstruction method based on cone beam computerized tomography (CBCT). The V-network (VNet) is used to pre-segment the teeth and the background to generate the corresponding binary image, and then the Bezier curve is used to define the best dental arch curve to generate the oral panorama. In addition, this research also addressed the issues of mistakenly recognizing the teeth and jaws as dental arches, incomplete coverage of the dental arch area by the generated dental arch lines, and low robustness, providing intelligent methods for dental diagnosis and improve the work efficiency of doctors.

Upper eyelid contour symmetry measurement with Bézier curves / Medida da simetria do contorno da pálpebra superior com curvas de Bézier

ABSTRACT Purpose: The purpose of the present work is to measure the interocular upper lid contour symmetry using a new method of lid contour quantification. Methods: The Bézier curve tool of the Image J software was used to extract the right and left upper eyelid contours of 75 normal subjects. Inter-observer variability of 29 right lid contours obtained by two independent observers was estimated using the coefficient of overlap of two curves and an analysis of the differences of the contour peak location. A two-way analysis of variance was used to test the mean value of the coefficient of overlap of the right and left contours in males and females and lid segments. The same analysis was performed to compare the location of the contour peak of the right and left contours. Results: The coefficient of contour overlap obtained by independent observers ranged from 93.5% to 98.8%, with a mean of 96.1% ± 1.6 SD. There was a mean difference of 0.02 mm in the location of the contour peak. Right and left contour symmetry did not differ between females and males and was within the range of the method variability for contour overlap and location of the contour peak. Conclusions: The upper eyelid contour is highly symmetrical. Bézier lines allow a quick and fast quantification of the lid contour, with a mean inter-observer variability of 3.9%.

RESUMO Objetivo: O objetivo do presente estudo é mensurar a simetria interocular do contorno da pálpebra superior por meio de um novo método de quantificação de contorno palpebral com curvas de Bézier. Métodos: A ferramenta de curva de Bézier do software ImageJ foi utilizada para extrair os contornos palpebrais direito e esquerdo de 75 sujeitos normais. A variabilidade interobservador de 29 contornos palpebrais do olho direito obtidos por dois observadores diferentes foi estimada pelo coeficiente de superposição de duas curvas e pela análise das diferenças das posições do pico do contorno. Análise de variância de dois fatores foi empregada para testar a média do coeficiente de superposição entre os contornos direito e esquerdo quanto ao sexo e segmento palpebral. A mesma análise foi utilizada para comparar a localização do pico do contorno dos olhos direito e esquerdo. Resultados: O coeficiente de superposição obtidos por observadores independentes variou ente 93,5% e 98,8% com média de 96,1% ± 1,6 DP. A diferença das médias da localização do pico do contorno palpebral foi de 0,02 mm. A simetria entre os contornos dos olhos direito e esquerdo não diferiu entre o sexo feminino e masculino e esteve na faixa de variabilidade do método para o coeficiente de superposição e localização do pico do contorno. Conclusões: O contorno da pálpebra superior é altamente simétrico. As linhas Bézier permitem uma rápida e prática quantificação do contorno palpebral com uma média de variabilidade interobservador de 3,9%.