Laboratoire Anthropologie Moléculaire et Imagerie de Synthèse, Faculté de Chirurgie Dentaire, Université Paul Sabatier, Centre Hospitalier Universitaire, Service de Médecine Légale, Hôpital de Rangueil, 37 allées J Guesde, 31000 Toulouse, France.
Dentomaxillofac Radiol. 2012 Dec;41(8):649-55. doi: 10.1259/dmf/81804525.
The various types of cone beam CT (CBCT) differ in several technical characteristics, notably their spatial resolution, which is defined by the acquisition voxel size. However, data are still lacking on the effects of voxel size on the metric accuracy of three-dimensional (3D) reconstructions. This study was designed to assess the effect of isotropic voxel size on the 3D reconstruction accuracy and reproducibility of CBCT data.
The study sample comprised 70 teeth (from the Institut d'Anatomie Normale, Strasbourg, France). The teeth were scanned with a KODAK 9500 3D® CBCT (Carestream Health, Inc., Marne-la-Vallée, France), which has two voxel sizes: 200 µm (CBCT 200 µm group) and 300 µm (CBCT 300 µm group). These teeth had also been scanned with the KODAK 9000 3D® CBCT (Carestream Health, Inc.) (CBCT 76 µm group) and the SCANCO Medical micro-CT XtremeCT (SCANCO Medical, Brüttisellen, Switzerland) (micro-CT 41 µm group) considered as references. After semi-automatic segmentation with AMIRA® software (Visualization Sciences Group, Burlington, MA), tooth volumetric measurements were obtained.
The Bland-Altman method showed no difference in tooth volumes despite a slight underestimation for the CBCT 200 µm and 300 µm groups compared with the two reference groups. The underestimation was statistically significant for the volumetric measurements of the CBCT 300 µm group relative to the two reference groups (Passing-Bablok method).
CBCT is not only a tool that helps in diagnosis and detection but it has the complementary advantage of being a measuring instrument, the accuracy of which appears connected to the size of the voxels. Future applications of such measurements with CBCT are discussed.
不同类型的锥形束 CT（CBCT）在几个技术特性上有所不同，尤其是它们的空间分辨率，由采集体素大小定义。然而，关于体素大小对三维（3D）重建的度量准确性的影响的数据仍然缺乏。本研究旨在评估各向同性体素大小对 CBCT 数据 3D 重建准确性和可重复性的影响。
研究样本包括 70 颗牙齿（来自斯特拉斯堡解剖学研究所，法国）。这些牙齿使用 KODAK 9500 3D® CBCT（Carestream Health，Inc.，马恩拉瓦莱，法国）进行扫描，该仪器具有两种体素大小：200 µm（CBCT 200 µm 组）和 300 µm（CBCT 300 µm 组）。这些牙齿还使用 KODAK 9000 3D® CBCT（Carestream Health，Inc.）（CBCT 76 µm 组）和 SCANCO Medical micro-CT XtremeCT（SCANCO Medical，Brüttisellen，瑞士）（micro-CT 41 µm 组）进行了扫描，这些仪器被视为参考。使用 AMIRA®软件（Visualization Sciences Group，马萨诸塞州伯灵顿）进行半自动分割后，获得牙齿体积测量值。
Bland-Altman 方法显示，尽管与两个参考组相比，CBCT 200 µm 和 300 µm 组存在轻微低估，但牙齿体积没有差异。与两个参考组相比，CBCT 300 µm 组的体积测量值的低估具有统计学意义（Passing-Bablok 法）。
CBCT 不仅是一种有助于诊断和检测的工具，而且具有作为测量仪器的补充优势，其准确性似乎与体素大小有关。本文还讨论了未来使用 CBCT 进行此类测量的应用。
