Method and device for determining CT system parameter

A method for determining a computed tomography (CT) system parameter, wherein a CT system comprises an X-ray source and a detector;

• and the method comprises:
• controlling a mould body to move between the X-ray source and a detection surface of the detector and acquiring X-ray projections of the mould body during movement on the detection surface, wherein the mould body has a first plane and a second plane perpendicular to each other, and the first plane and the second plane are always perpendicular to the detection surface during the movement of the mould body;
• determining a first straight line and a second straight line according to the acquired X-ray projections, wherein the first straight line is a straight line of a projection line segment of an edge of the first plane in boundary line segments of the acquired X-ray projections, the second straight line is a straight line of a projection line segment of an edge of the second plane in the boundary line segments of the acquired X-ray projections, a plane determined by the first straight line and a focus of the X-ray source is perpendicular to the detection surface, and a plane determined by the second straight line and the focus of the X-ray source is perpendicular to the detection surface;
• and
• determining an intersection point of the first straight line and the second straight line as coordinates of a foot of a perpendicular of the focus of the X-ray source on the detection surface, wherein a CT coordinate system parameter comprises the coordinates of the foot of the perpendicular.