Resolution ratio performance measuring device of cone beam CT and calibration method

Abstract

The invention relates to a resolution ratio performance measuring device of a cone beam CT and a calibration method. The measuring device comprises a transverse resolution ratio measuring module and a longitudinal resolution ratio measuring module. By means of the device, the transverse resolution ratio and the longitudinal resolution ratio of the cone beam CT can be calibrated. The calibration method includes the steps of conducting collecting and three-dimensional reconstructing on the cone beam CT through the two modules of the measuring device, generating an edge expansion function on the central cross section of the transverse resolution ratio measuring module and the central coronal plane of the longitudinal resolution ratio measuring module, calculating a modulation transmitting function on the basis of the edge expansion function, and selecting the space frequencies at the 10% modulation degree as the transverse resolution ratio and the longitudinal resolution ratio of a system of the cone beam CT respectively. The resolution ratio performance measuring device of the cone beam CT and the corresponding calibration method are disclosed. The device has the advantages of being simple in structure and low in cost, and the calibration method has the advantages of being easy to implement and capable of meeting the measuring requirements of the transverse resolution ratio and the longitudinal resolution ratio of the cone beam CT.

Description

technical field [0001] The invention relates to a cone-beam CT resolution performance measuring device and a calibration method, and proposes a device and a corresponding measuring method capable of measuring the lateral (section direction) and longitudinal (Z-direction) resolution of the cone-beam CT. Background technique [0002] Cone beam computed tomography (CBCT or cone beam CT for short) collects multiple X-ray projections based on a flat-panel detector. One scan can display the internal structure of an object in three dimensions. It has isotropic resolution, fast imaging speed, and simple structure. Advantages, it has been widely used in dentistry, radiotherapy, industrial inspection, small animal imaging and other fields. [0003] For cone beam CT system manufacturers or users, the spatial resolution of cone beam CT is a very important performance index, which determines the minimum size that the CBCT system can resolve. This index is of great value for the determin...

AI Technical Summary

Problems solved by technology

This method is simple and direct, but has the following disadvantages: firstly, the method relies on the naked eye observation of the inspector, and is easily affected by human factors; secondly, the line pair interval is discrete, and the image cannot reflect the modulation degree of all spatial frequencies; in addition, the interval is small The production process of the wire pair is complicated, which cannot meet the measurement requirements of the high-resolution CT system

However, the current CT calibration method only considers the lateral resolution, and there is a lack of devices and methods specifically for cone-beam CT resolution measurement.

Images