Dornier C, Dorsaz-Brossa L, Thévenaz P, Casagni F, Brochut P, Mombelli A, Vallée Jp
CO Voirets, Chemin des Voirets 22, Case postale 605, CH-1212 Grand-Lancy 1, Switzerland.
Dentomaxillofac Radiol. 2004 Jul;33(4):220-5. doi: 10.1259/dmfr/71716997.
To develop software for automated registration and intensity calibration of serial dental radiographs for the analysis of longitudinal changes in bone density.
Serial dental radiographs were acquired using a positioning device designed to minimize projection divergence. Each radiograph included an image of a standardized aluminium wedge. The radiographs were scanned on a flatbed scanner (AGFA Duo Scan) with a spatial resolution of 300 dpi, and pixel intensity coded in 16-bit grey scale. The intensity was calibrated using serial images of selected areas with defined thickness of the aluminium wedge. A robust B-splines multiresolution registration algorithm was implemented to overcome the acquisition misalignment. Radiographs, taken before and after periodontal therapy, were subtracted to assess bone density evolution.
The intensity calibration decreased the maximum intensity variations between serial radiographs from 30+/-17% to 1+/-1% (mean+/-standard deviation), and improved the visual comparison between the radiographs. The registration stage allowed correcting the misalignment of the radiographs on the scanner screen and superimposing the radiography contents. The observed residual motion was about 0.02+/-0.01 mm.
Very user-friendly software was developed. The manipulator needs to scan the radiographs only one time. The software performs all subsequent processing steps.
开发用于自动配准和强度校准系列牙科X光片的软件，以分析骨密度的纵向变化。
使用旨在最小化投影发散的定位装置获取系列牙科X光片。每张X光片都包含一张标准化铝楔的图像。X光片在平板扫描仪（爱克发Duo Scan）上以300 dpi的空间分辨率进行扫描，像素强度以16位灰度编码。使用具有确定厚度的铝楔选定区域的系列图像对强度进行校准。实施了一种稳健的B样条多分辨率配准算法以克服采集时的未对准。对牙周治疗前后拍摄的X光片进行相减以评估骨密度变化。
强度校准将系列X光片之间的最大强度变化从30±17%降低到1±1%（平均值±标准差），并改善了X光片之间的视觉比较。配准阶段能够校正X光片在扫描仪屏幕上的未对准情况并叠加X光片内容。观察到的残余移动约为0.02±0.01毫米。
开发了非常用户友好的软件。操作人员只需扫描一次X光片。软件会执行所有后续处理步骤。
