Total breathing phase scan (slow scan) method in the free breathing state by multi-detector-row computed tomography scanner in radiotherapy planning

With the new high-speed computed tomography (CT) devices, the longest scan time for a conventional scan is about 2 seconds. Therefore, the all-breathing-phase scan (slow scan) in the free-breathing state, which includes an entire breathing phase of three or four seconds in one imaging section, is impossible. We performed spiral scanning with a low-speed scanning pitch using multi detector-row CT (4MDCT) and examined a method of scanning that was similar to the slow scan method. As a result, with the scanning diagram, we demanded the image data time than a combination of scanning pitch and X-ray tube rotation time, image data time of 6.66 seconds longest in scanning slice thickness 1 mm x 4 detectors and reconstruction slice thickness 2 mm was possible, and the scanning that was similar to the slow scan method was possible. Furthermore, it was good in the image data time when we demanded it from scanning diagram and, as a result of confirmation of image data time by the equal speed turn phantom, agreed. In addition, there is not increase of a radiation exposure dose by this method, and this method is a useful method.