Bosi Stephen G, Brown Saxby, Sarabipour Sarvenaz, De Deene Yves, Baldock Clive
Department of Radiation Oncology, Prince of Wales Hospital, Randwick, NSW 2031, Australia.
Phys Med Biol. 2009 Jan 21;54(2):275-83. doi: 10.1088/0031-9155/54/2/007. Epub 2008 Dec 16.
A gelatin phantom containing an optically scattering funnel-shaped region of elevated optical density (OD) was used to examine light-scattering-induced artefacts in a cone-beam optical CT scanner used for gel dosimetry. To simulate polymer gel dosimeters, the opacity was introduced by adding a colloidal scatterer to the gelatin. Scatter results in an underestimate of OD (hence dose). In line profiles of OD taken from 3D reconstructions of the funnel, those profiles with a long pathlength through high OD regions exhibited a 'dishing' (or 'cupping') artefact, while those of short pathlength exhibited the opposite effect-'doming'. These phenomena are accounted for by a model that includes the effect of stray, scattered light.
使用含有光散射漏斗形光学密度（OD）升高区域的明胶体模，在用于凝胶剂量测定的锥束光学CT扫描仪中检查光散射引起的伪影。为了模拟聚合物凝胶剂量计，通过向明胶中添加胶体散射体来引入不透明度。散射会导致OD（即剂量）被低估。在从漏斗的三维重建中获取的OD线轮廓中，那些穿过高OD区域的光程长的轮廓表现出“凹陷”（或“杯状”）伪影，而光程短的轮廓则表现出相反的效果——“圆顶状”。这些现象由一个包含杂散光和散射光效应的模型来解释。
