Park Cheol-Woo, Kim Jin-Ho, Seo Yu-Kyeong, Lee Sae-Rom, Kang Ju-Hee, Oh Song-Hee, Kim Gyu-Tae, Choi Yong-Suk, Hwang Eui-Hwan
Department of Oral and Maxillofacial Radiology, Graduate School, Kyung Hee University, Seoul, Korea.
Imaging Sci Dent. 2017 Sep;47(3):165-174. doi: 10.5624/isd.2017.47.3.165. Epub 2017 Sep 21.
This study was performed to investigate the influence of object shape and distance from the center of the image on the volumetric accuracy of cone-beam computed tomography (CBCT) scans, according to different parameters of tube voltage and current.
Four geometric objects (cylinder, cube, pyramid, and hexagon) with predefined dimensions were fabricated. The objects consisted of Teflon-perfluoroalkoxy embedded in a hydrocolloid matrix (Dupli-Coe-Loid TM; GC America Inc., Alsip, IL, USA), encased in an acrylic resin cylinder assembly. An Alphard Vega Dental CT system (Asahi Roentgen Ind. Co., Ltd, Kyoto, Japan) was used to acquire CBCT images. OnDemand 3D (CyberMed Inc., Seoul, Korea) software was used for object segmentation and image analysis. The accuracy was expressed by the volume error (VE). The VE was calculated under 3 different exposure settings. The measured volumes of the objects were compared to the true volumes for statistical analysis.
The mean VE ranged from -4.47% to 2.35%. There was no significant relationship between an object's shape and the VE. A significant correlation was found between the distance of the object to the center of the image and the VE. Tube voltage affected the volume measurements and the VE, but tube current did not.
The evaluated CBCT device provided satisfactory volume measurements. To assess volume measurements, it might be sufficient to use serial scans with a high resolution, but a low dose. This information may provide useful guidance for assessing volume measurements.
本研究旨在根据管电压和电流的不同参数，研究物体形状及与图像中心的距离对锥束计算机断层扫描（CBCT）容积准确性的影响。
制作了四个具有预定尺寸的几何物体（圆柱体、立方体、棱锥体和六边形）。这些物体由嵌入水胶体基质（Dupli-Coe-Loid TM；美国伊利诺伊州阿尔西普市GC America公司）的聚四氟乙烯全氟烷氧基组成，封装在丙烯酸树脂圆柱体组件中。使用Alphard Vega牙科CT系统（日本京都旭光伦琴工业株式会社）获取CBCT图像。使用OnDemand 3D软件（韩国首尔CyberMed公司）进行物体分割和图像分析。准确性用容积误差（VE）表示。在3种不同的曝光设置下计算VE。将物体的测量容积与真实容积进行比较以进行统计分析。
平均VE范围为-4.47%至2.35%。物体形状与VE之间无显著关系。发现物体到图像中心的距离与VE之间存在显著相关性。管电压影响容积测量和VE，但管电流不影响。
所评估的CBCT设备提供了令人满意的容积测量结果。为评估容积测量，使用高分辨率但低剂量的连续扫描可能就足够了。该信息可为评估容积测量提供有用指导。
