In the three dimensional computed tomography imaging system, it is impossible to measure the X-ray focus to object-rotating-axis distance (FOD) by direct means, so how to obtain the value of FOD with simple and feasible method is an involved engineering problem. Through acquiring the digital radiography(DR) images of the double-circled object at two imaging positions, the auto-correlation operation was executed, so as to get distance of the two circles- projection center. Then through solving equations, the value of FOD was finally obtained. Experiment results prove that the accuracy of this method can satisfy the requirements of the practical scanning system. This testing method is also easy to realize and of high anti-noise ability. Furthermore, it can be realized automatically by software.
Yang Min, Sun Cuili, Li Baolei.Method for measuring the focal distance of 3D-CT imaging system with high accuracy using image auto-correlation[J] JOURNAL OF BEIJING UNIVERSITY OF AERONAUTICS AND A, 2007,V33(10): 1216-1219
Feldcamp L A, Davis L C, Kress J W. Practical cone-beam algorithm[J]. J Opt Soc Am Al,1984:612-619
�߽�ƽ,����,����,��. ����X ���߳���ϵͳɨ�����������ͶӰͼ��У���о�[J]. �˵���ѧ��̽�⼼��,2001,21(3):165-168 Ni Jianping, Li Zheng, Bai Hongtao,et al. Scanning parameter measure ment and project correction for microfocus X-ray imaging system[J]. Nuclear Electronics & Detection Technology, 2001, 21(3):165-168(in Chinese)
����. ��������̽�����Ķ�ģʽ��ҵCT�����о� .����:�������պ����ѧ��е���Զ���ѧԺ,2004 Yang Min. Research on multi-mode industrial computed tomography based on flat panel detector .Beijing: School of Mechanical Engineering and Automation, Beijing University of Aeronautics and Astronautics,2004(in Chinese)
Jiang Hangyi. Techniques to improve the accuracy and to reduce the variance in noise power spectrum measurement[J].IEEE Transactions on Biomedical Engineering.2002, 49(11):1270-1278
Van Metter Richard, Yorkston John. Factors influencing image quality in digital radiographic system[J]. Proc SPIE Int Soc Opt Eng, 2001, 4320: 244-255