Guangtao Zhai1, Ziqing Yin2,3, Lunhao Li2,3, Xuefei Song2,3, Yixiong Zhou2,3. 1. Institute of Image Communication and Network Engineering, Shanghai Jiao Tong University, Shanghai, PR China. 2. Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China. 3. Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, PR China.
Abstract
BACKGROUND: Orbital computed tomography (CT) is commonly used for the diagnosis and digital evaluation of orbital diseases. Yet, this approach requires longer scanning time, increased radiation exposure, and, especially, difficult patient positioning that can affect judgment and data processing. According to high-quality research on orbital imaging, computer-assisted surgery, and artificial intelligent diagnostic development, the correction of a coordinate system is a necessary procedure. Nevertheless, existing manual calibration methods are challenging to reproduce and there is no objective evaluation system for errors. PURPOSE: To establish a method for automatic calibration of orbital CT images and implementation of quantitative error evaluation. MATERIAL AND METHODS: A standard three-dimensional (3D) orbit model was manually adjusted, and optimized orbital models were reconstructed based on the initial registration of the skull-bound directed bounding box and the registration of the mutual information method. The calibration error was calculated based on the signed distance field. Seventeen cases of orbital CT were quantitatively evaluated. RESULTS: A new method for automatic calibration and quantitative error evaluation for orbital CT was established. The calibrated model error with ±2 mm accounted for 81.61% ± 6.91% of the total models, and the error of ±1 mm accounted for 53.49% ± 7.07% of the total models. CONCLUSION: This convenient tool for orbital CT automatic calibration may promote the related quantitative research based on orbital CT. The automated operation and small error are beneficial to the popularization and application of the tool, and the quantitative evaluation facilitates other coordinate systems.
BACKGROUND: Orbital computed tomography (CT) is commonly used for the diagnosis and digital evaluation of orbital diseases. Yet, this approach requires longer scanning time, increased radiation exposure, and, especially, difficult patient positioning that can affect judgment and data processing. According to high-quality research on orbital imaging, computer-assisted surgery, and artificial intelligent diagnostic development, the correction of a coordinate system is a necessary procedure. Nevertheless, existing manual calibration methods are challenging to reproduce and there is no objective evaluation system for errors. PURPOSE: To establish a method for automatic calibration of orbital CT images and implementation of quantitative error evaluation. MATERIAL AND METHODS: A standard three-dimensional (3D) orbit model was manually adjusted, and optimized orbital models were reconstructed based on the initial registration of the skull-bound directed bounding box and the registration of the mutual information method. The calibration error was calculated based on the signed distance field. Seventeen cases of orbital CT were quantitatively evaluated. RESULTS: A new method for automatic calibration and quantitative error evaluation for orbital CT was established. The calibrated model error with ±2 mm accounted for 81.61% ± 6.91% of the total models, and the error of ±1 mm accounted for 53.49% ± 7.07% of the total models. CONCLUSION: This convenient tool for orbital CT automatic calibration may promote the related quantitative research based on orbital CT. The automated operation and small error are beneficial to the popularization and application of the tool, and the quantitative evaluation facilitates other coordinate systems.
Keywords:
Orbital computed tomography; automatic coordination; quantitative evaluation; signed distance field