ABSTRACT
OBJECTIVE@#To propose a sensitivity test method for geometric correction position deviation of cone-beam CT systems.@*METHODS@#We proposed the definition of center deviation and its derivation. We analyzed the influence of the variation of the three-dimensional spatial center of the steel ball point, the projection center and the size of the steel ball point on the deviation of geometric parameters and the reconstructed image results by calculating the geometric correction parameters based on the Noo analytical method using the FDK reconstruction algorithm for image reconstruction.@*RESULTS@#The radius of the steel ball point was within 3 mm. The deviation of the center of the calibration parameter was within the order of magnitude and negligible. A 10% Gaussian perturbation of a single pixel in the 3D spatial coordinates of the steel ball point produced a deviation of about 3 pixel sizes, while the same Gaussian perturbation of the 2D projection coordinates of the steel ball point produced a deviation of about 2 pixel sizes.@*CONCLUSION@#The geometric correction is more sensitive to the deviation generated by the three-dimensional spatial coordinates of the steel ball point with limited sensitivity to the deviation generated by the two-dimensional projection coordinates of the steel ball point. The deviation sensitivity of a small diameter steel ball point can be ignored.
Subject(s)
Algorithms , Calibration , Cone-Beam Computed Tomography , SteelABSTRACT
Several proteins associated with apoptosis were analyzed to investigate the progress of presbycusis based on cell apoptosis. Four proteins of caspase-3, XIAP, Sir2 T1 and cytochrome C which were associated with apoptosis were selected. Influence and progress of four proteins on presbycusis were analyzed. Apoptosis is the key factor which causes presbycusis, including apoptosis of cochlear hair cells, cochlear spiral ganglion cells and primary auditory cortical neuron. There is a close relationship between the four proteins and apoptosis of hearing related cells. These four kinds of protein factors played a role in the progress of presbycusis and are expected to serve as a target for the treatment of presbycusis.