Question 485
{"accessible":false,"alternatives":[{"id":2436,"text":"blood"},{"id":2437,"text":" bone"},{"id":2439,"text":"iodine"},{"id":2438,"text":"muscle"},{"id":2440,"text":" water "}],"archived":false,"correctAlternativeId":2440,"explanation":"\u003cp\u003eThe\u0026nbsp;\u003cstrong\u003eHounsfield unit\u0026nbsp;(HU)\u0026nbsp;\u003c/strong\u003eis a quantity commonly used in\u0026nbsp;\u003ca href=\"https://radiopaedia.org/articles/computed-tomography\"\u003ecomputed tomography (CT)\u003c/a\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003escanning to express\u0026nbsp;CT numbers\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003ein a standardized and convenient form. Hounsfield units, created by and named after\u0026nbsp;\u003ca href=\"https://radiopaedia.org/articles/godfrey-hounsfield\"\u003eSir Godfrey Hounsfield\u003c/a\u003e,\u0026nbsp;are obtained from a\u0026nbsp;linear transformation of the measured\u0026nbsp;\u003ca href=\"https://radiopaedia.org/articles/attenuation-coefficient\"\u003eattenuation coefficients\u003c/a\u003e. This transformation is based on the arbitrary definitions of air and water as having Hounsfield unit values of -1000 and 0 respectively.\u0026nbsp;\u003c/p\u003e","id":485,"imageUrl":null,"imageAttribution":null,"imageAttributionCaseInfo":null,"firstQuestionPath":"/questions/2308","nextQuestionPath":null,"relatedArticles":[],"alsoUsedIn":[],"stem":"\u003cp\u003eHounsfield units are calculated by quantifying the difference between a coefficient of a particular tissue and that of...\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/485"}],"attemptsPercentages":[{"alternativeId":"2438","percentage":2},{"alternativeId":"2439","percentage":3},{"alternativeId":"2436","percentage":1},{"alternativeId":"2440","percentage":91},{"alternativeId":"2437","percentage":4}],"promptToLogin":false,"questionManager":false,"articleId":"hounsfield-unit"}