Experimental CT phantom for motion analysis

Aggravation of the reconstructed images on CT scans by motion artifacts is one of the most serious problems in radiological diagnosis. For the analysis of the motion artifacts, a motion analysing phantom for CTs, which rotates at a constant speed in the scanning field, was developed. We investigated the following subjects using the phantom. First, the degree the CT scanner is affected by biological motions, such as respiratory or intestinal motions was investigated. Next, an attempt to construct a drawing of the back projection to explain the motion artifacts by rotational movement of objects theoretically was carried out. The X-ray CT images that were made by the phantom experiments and clinical studies show a good correlation. Drawing diagram was simple and convincing methods to explain the motion artifacts were achieved. Other types of CT scanners were produced similar artifacts. Therefore, we concluded that every type of CT scanners can have similar artifacts under the same conditions. Research of the patterns of motion artifacts will become more important for diagnosing and image processing, when CT scanner technology can scan faster. (author)