Research Of Scatter Calibration Algorithm For Cone Beam Computed Tomography

In the non-destructive testing of objects field, CT(Computed Tomography) has the incomparable advantages of the other equipment, which can obtain the projection by high energy X rays in at different angles and reconstruction images. And then the internal structure and information of the object to be detected can be analyzed, which is widely used especially in the field of medical diagnostics and industrial non-destructive testing.The cone-beam CT Based on flat panel detector has a lot of characteristic, such as shot data acquisition time, high spatial resolution and high-ray utilization and so on. In recent years it is gradually applied to the actual medical diagnosis, as dental CT has also become the focus of today’s research and development. However the scattered photons in the X-ray detected objects will make serious cupping artifacts in the reconstructed image, which may result in decreased image quality and bring some trouble for the doctor’s diagnosis. To find the method to remove scattering artifacts, some parts of the research, the article contains the following sections:1) In accordance with the correction methods rely on the technical means, introduce the details of various correction algorithms by editing domestic and foreign advanced papers of scattering artifacts correction. The different algorithms adapt to the experimental conditions is summed up and list the strengths and weaknesses of the calibration results and algorithms.2) Geometric relationships of cone beam CT system based on flat panel detector are studied. Design experiments for the scatter attenuation grid algorithm and prove that this method can remove the cupping artifacts of water phantom image and improve image contrast, which verifies the feasibility of the BAG algorithm in medical cone-beam CT image reconstruction process.3) There are two problems in BAG algorithm including long data acquisition time and high rays receiving does by patients. The combination of image sequence processing and Gaussian two-dimensional filtering method can reduce the received ray dose by57%of the original method. The experimental results verify the correction algorithm can be improved to remove the cupping artifacts, and acquire the same the same experimental results with the original BAG method.Through this study we find the algorithm can significantly inhibit cupping artifacts in cone-beam CT scanning process, which is of great help to improve the quality of the reconstruction image. In addition, because of the image sequence processing, the patients’ receiving rays’ dose greatly are reduced. It is the real solution to the problem of the BAG algorithm applications in medical CT, which made a certain contribution to the research and development of dental cone beam CT.