3D X-ray based Method for Diagnostics of Spinal Deformities
Research Funding: The “OrthoLine” research and production company has provided funding for the research study. Conflict of interest: The authors have no conflicts of interest to declare. Research Objective: to revise the “arc angle” parameter for estimating the value of spinal curvature and, if necessary, to search for another parameter or to develop another method for mathematically correct estimation of spinal deformity value. Materials and methods. The critical analysis has been performed both theoretically and experimentally. It has been demonstrated that the angle parameter is incorrect, and another estimation parameter and procedure should be developed. A method of 3D X-ray diagnostics and construction of 3D structure using two orthogonal projections of two-dimensional spine image involve several procedures. Software-based scaling and horizontal-wise image synchronization, synchronised selection of spinal arc on images and construction of a geometric image of the studied arc are performed stepwise. Software-based measurements of a number of geometric parameters on 2D images, utilised for mathematical analysis and construction of a 3D picture of geometric spine images, are made, and geometric parameters of some arcs, among which the arc plane curvature and azimuth angle are assumed to be the major ones, are found. 2D X-ray diagnostics was performed using a light-dose device AGFA DX – D 300, which allows having the images of the entire spinal column in a single shot. Results. A method for the 3D X-ray diagnostics of the pathologically deformed spine has been proposed. The relationship between the deformity value and severity and the true arc curvature and azimuth angle of the arc plane position between frontal and lateral planes of the trunk has been established. There have been developed the procedures for software-based examination of 2D orthogonal images of the trunk projections and computation of parameters of the 3D spine state along with constructing its true image. There has been created a two-parameter function, with correction factors, of spinal deformity degree based on comparative estimations of radiographic images, measured parameters, and posture of the pathologically deformed trunk, made by independent experts. Conclusion. The developed method of 3D X-ray diagnostics and analysis of radiographs eliminates critical errors of conventional method. What principally distinguishes this method is a research object, namely, a three-dimensional state of the spine rather than two-dimensional on the frontal projection, and the use of the arc curvature parameter and azimuth angle of the arc plane position instead of mathematically erroneous angle parameter – the Cobb angle. The method of (3D) X-ray diagnostics provides new beneficial properties of the 2D spondylography based on state-of the-art digital technologies.