Question 2424
{"accessible":false,"alternatives":[{"id":11923,"text":"helical, spiral"},{"id":11922,"text":"helical, topogram"},{"id":11924,"text":"sequential, spiral"},{"id":11925,"text":"surview, spiral"}],"archived":false,"correctAlternativeId":11923,"explanation":"\u003cp\u003eHelical and spiral both refer to the scan mode where the patient is constantly moving while the gantry (i.e., where the x-ray tube and detector are located) constantly spins. Different vendors refer to this mode using different names, so you can think of helical = spiral.\u003c/p\u003e\u003cp\u003eWe quantify the ratio of patient movement through the x-ray beam per gantry rotation using pitch, where pitch = (the distance the patient couch moves in 1 gantry rotation)/(the width of the x-ray beam in the inferior/superior direction, also known as the beam collimation).\u003c/p\u003e","id":2424,"imageUrl":null,"imageAttribution":null,"imageAttributionCaseInfo":null,"firstQuestionPath":"/questions/2424","nextQuestionPath":"/articles/pitch-ct/questions/484","relatedArticles":[{"id":38221,"title":"Helical CT image acquisition","link":"/articles/helical-ct-image-acquisition-1?lang=us"}],"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\u003eWhich of the following groupings refer to the same scan mode for multi-detector CT?\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/2424"}],"attemptsPercentages":[{"alternativeId":"11924","percentage":6},{"alternativeId":"11922","percentage":4},{"alternativeId":"11925","percentage":1},{"alternativeId":"11923","percentage":89}],"promptToLogin":false,"questionManager":false,"articleId":"pitch-ct"}