Calibration method, device and calibration phantomof geometric parameters in CT (computer tomography) system

Abstract

The invention provides calibration method, device and calibration phantom of the geometric parameters in a CT (computer tomography) system. In the method, the calibration phantom is placed on a rotary table positioned between a light source and a detector, the calibration phantom comprises a calibration plate, as well as a small ball A and a small ball B which are arranged on the calibration plate, the calibration phantom is rotated for a circle along with the rotary table, and a center point coordinates of projection images of the small ball A and the small ball B are collected by the detector; the coordinate of an intersection point of a projective point line of projection ellipses of the small ball A and the small ball B is calculated and obtained according to the center point coordinates of the projection images and and the center coordinates of the projection ellipses of the small balls, and the torsion angle of the detector, the distance from the light source to the detector, the projection center point coordinate of the light source on a imaging plane, the swinging angle of the detector and the distance from the light source to the rotary table can be calculated based on the coordinate of the intersection point of the projective point line and a elliptic equation. The invention can calibrate a plurality of parameters, and can sufficiently meet the requirement of subsequent CT image correction.

Description

【Technical field】 [0001] The present invention relates to geometric parameter calibration in CT system, and more particularly, to a calibration method, device and calibration phantom of geometric parameters in CT system. 【Background technique】 [0002] The basic principle of Computed Tomography (CT) is that X-rays pass through an object from all directions, and a computer program is used to analyze and measure all attenuated X-ray projections, reconstruct tomographic images, and obtain three-dimensional images. It can observe the internal structure of the object and obtain the internal information of the object without destroying the object. For decades, CT technology has been widely used in various fields such as medicine, pharmacy, materials science, industry, agriculture, engineering and archaeology. [0003] Micro-CT is a new type of equipment for high-resolution three-dimensional imaging using the principle of X-ray imaging. It can perform high-resolution three-dimensi...

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Problems solved by technology

However, this solution can only calibrate the coordinates of the projection center point of the light source on the detector plane

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