Reliable identification of sphere-shaped femoral heads in 3D image data
Heinrich Martin Overhoff, Sven Ehrich, Ute von Jan · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1999
A new method is presented, which enables the reliable measurement of the femoral head sphere parameters (center coordinates and diameter) from tomographic image data, even when the raw data are erroneous. The hip joints of 13 newborns were scanned by a self developed 3-D ultrasound system. After automatic image segmentation, the femoral head is represented by spatially arranged voxel clouds. The 3-D image data are substantially corrupted by different types of errors. Moreover, the data only describe a segment of a sphere, whose area is about 10% of the sphere. This circumstance increases the identification problem. The problem of fitting the sphere parameters is solved by a robust technique based on rejection strategies for irrelevant points and data sets. The method was applicable in 21 of 26 cases. Substantial differences between automatically and expert determined sphere parameters were only observed for highly corrupted data sets, where the identification problem is inherently unstable. The identification method yielded correct and reliable identification of geometric measures from 3-D ultrasound image volumes and promises to be applicable also for other parameterized geometries and other tomographic image modalities as X-ray CT or MRI.