Question 2426
{"accessible":false,"alternatives":[{"id":11931,"text":"gantry rotation speed"},{"id":11930,"text":"modulation transfer function"},{"id":11932,"text":"shutter speed"},{"id":11933,"text":"tube power"}],"archived":false,"correctAlternativeId":11931,"explanation":"\u003cp\u003eCT scanners require roughly 270° worth of data in order to produce an image. For cardiac imaging, where vessels and the walls of the heart can move quickly, the faster we collect 270° worth of data the less distance the heart structures will move and therefore, fewer\u0026nbsp;motion artefacts will be seen in the images.\u003c/p\u003e\u003cp\u003e“Normal” CT images use 360° worth of data, cardiac imaging which uses 270° is called “short scan” imaging. In general,\u0026nbsp;vendors will use varying degrees of angular range as a function of pitch, and all of these details will be proprietary secrets. But at the end of the day, if you want to freeze cardiac motion, you want a very short gantry rotation time!\u003c/p\u003e","id":2426,"imageUrl":null,"imageAttribution":null,"imageAttributionCaseInfo":null,"firstQuestionPath":"/questions/2426","nextQuestionPath":null,"relatedArticles":[],"alsoUsedIn":[{"id":1351,"kind":"Course","title":"2022 Virtual Conference Private Use - page 1351","link":"https://radiopaedia.org/courses/2022-virtual-conference-private-use/pages/1351"},{"id":1200,"kind":"Course","title":"2022 Virtual Conference Private Use - page 1200","link":"https://radiopaedia.org/courses/2022-virtual-conference-private-use/pages/1200"},{"id":248,"kind":"LiveSchedule","title":"248","link":"https://radiopaedia.org/admin/live_schedules/248"},{"id":163,"kind":"LiveSchedule","title":"163","link":"https://radiopaedia.org/admin/live_schedules/163"},{"id":1299,"kind":"Course","title":"2022 Virtual Conference Private Use - page 1299","link":"https://radiopaedia.org/courses/2022-virtual-conference-private-use/pages/1299"},{"id":1299,"kind":"Course","title":"Imaging Physics Lectures - page 1299","link":"https://radiopaedia.org/courses/imaging-physics-lectures/pages/1299"}],"stem":"\u003cp\u003eThe ability to “freeze” motion in CT is related most closely with what parameter?\u003c/p\u003e","menuLinks":[{"text":"Report problem with question","url":"https://docs.google.com/forms/d/e/1FAIpQLSfO3soWYhOjJ7yErSysyCe5V4A1CqW7WK3rDA7MtAkecMGqNw/viewform?entry.1624461248\u0026entry.553583435=https://radiopaedia.org/questions/2426"}],"attemptsPercentages":[{"alternativeId":"11932","percentage":12},{"alternativeId":"11931","percentage":67},{"alternativeId":"11930","percentage":16},{"alternativeId":"11933","percentage":5}],"promptToLogin":false,"questionManager":false,"articleId":"cardiac-ct"}