[Development of Animation Projector System and Usefulness in Pediatric Head CT]. 
The restlessness of young children often causes motion artifacts on CT images.  We devised a new animation projector system (CT Theater) that enables a child to view an animation during a pediatric head CT examination.  The purpose of this study is to assess the usefulness on a children of a video viewed during a head CT scan.  Children of 3-10 years old who underwent head CT (SOMATOM Definition Flash, SOMATOM Force; Siemens) were analyzed for a period from 6 months before, to 6 months after, introduction of the projector system (before: n=46, after: n=29).  Mobile projector (MP-CL1; Sony) connected with tablet device (iPad; Apple) was put on the CT table near the child's head.  An animation was projected on the child's line of sight inside the gantry.  The animation is projected on the line of sight of the child such that the projector moves with the child on the table.  The number of requests for use made by children was 28/29 (96.6%).  The presence of images without motion artifacts decreased significantly after introduction (before/after introduction: 84.8% vs 100%, p=0.03).  The overall examination success rate tended to increase after introduction (84.8% vs 92.9%, p=0.26).  The overall examination time was significantly reduced (92.4±42.4 s vs 65.1±47.3 s, p<0.001).  We developed an animation projector system that shortened examination time and decreased motion artifacts in pediatric head CT.