X-ray fluoroscopic system

An X-ray fluoroscopic system comprising:

• an X-ray source;
• an X-ray camera disposed at a position to which X-ray from said X-ray source is made incident;
• an XY table that is provided between said X-ray source and said X-ray camera and used for positioning an object of fluoroscopy mounted thereon;
• and
• a rotating mechanism that relatively rotates said X-ray camera and said XY table around an axis orthogonal to said XY table,
• wherein the system further comprises:
• rotational tracking means for calculating a moving amount of said XY table necessary in maintaining the state where an observed point of said object of fluoroscopy is positioned within the field of view of said X-ray camera, in order to automatically move said XY table for tracking said observed point, by an arithmetic operation that uses each rotational angle at each time when said X-ray source and said XY table are relatively rotated, and a distance h between said X-ray source and said observed point;
• and
• update means of data for tracking which uses a defined value or an arbitrary input value as an initial value of said distance h between said X-ray source and said object of fluoroscopy, which is used in said arithmetic operation by said rotational tracking means, and updates said distance h used by said rotational tracking means, by using a shift amount of said observed point which is obtained by specifying said observed point on an image after tracking.