Fundamental Study of Three Dimensional Fine Structure Analysis of Jaw Bone

同一骨标本的CT值不能在不同条件下的小视场CT（专为牙科设计的CT）扫描中测量到相同的值。这种现象在很大程度上取决于标本的轮廓和尺寸，即使受试者在有限的视野范围内被覆盖也会发生。在为牙科设计的CT上，CT值的不稳定被认为是由于视图有限导致的所谓投影数据不完整而发生的。然而，这种解释可能并不正确，因为即使物体尺寸足够小，在我们的结果中可以覆盖在视野范围内，CT值也会发生不稳定。一些特殊的视觉图像处理方法，如切片和，虽然提高了图像的信噪比，但失去了视轴的特殊分辨率。采用全身CT和牙科专用CT，测量均匀的铝+铜（5%）合金锥体（CT值超过3000H.U上限）。在牙科CT上出现的非均匀、更均匀的CT值说明了CT像素密度的非线性特征。在这一点上也证明了为牙科设计的CT与数字断层扫描非常接近。牙科专用CT在使用w线进行的全身MD-CT与牙科专用CT的空间分辨率可见性测试中并不是特别出色，但由于牙科专用CT的非线性特性，没有考虑MTF，因此并不明显。设计了小的HA模型，这样就可以在没有人工制品的情况下测量小孔和线。对于300μm的孔洞，MD-CT无法检测到，而牙科专用的CT可以检测到。CT对牙髓学的优势体现在这一点上。小视场CT（专为牙科设计的CT）使用像CT一样的像素值来分析三维结构似乎并不容易。我们的研究结果显示了类似于骨内容物的CT小影的重要性。少

CT values of the same bone specimen can not be measured as the same value at small field of view CT (CT designed for the dentistry) scans in different conditions. This phenomenon depended on the contour and size of the specimen greatly, and occured even if subjects were covered within limited view. The un-stability of the CT value at the CT designed for the dentistry was believed to happened by so-called the imcomplete projection data that caused by limited views. However, this explanation may not be true, because the un-stability of the CT value occurs even if objects size were enough small that could be covered within the field of views in our result. Also some special viewing image processing like slices sum methods improve the image quality like S/N but loose the special resolution for view-axis.By using both the whole body CT and CT designed for the dentistry, an uniform aluminum + copper (5%) alloy cone (CT value beyond the upper limit of 3000H.U.) were measured. The the non-unif … More orm CT values at CT designed for the dentistry indicated the non-linear characters of the pixel density of the CT.Also it was proved that CT designed for the dentistry was very close to Digital-Tomography with this point.The CT designed for the dentistry was not especially excellent in visible test of spaceal resolution using W-wires at the comparison between MD-CT for the whole body and CT designed for the dentistry, though it wasn't clear because MTF wasn't being taken into consideration because of the non-linear character of the CT designed for the dentistry.Small HA phantoms were designed so that small hole and line can be measured without aritifacts.Holes with the size of 300μm could not be detected by MD-CT, while it could be detected by the CT designed for the dentistry. The predominance of the CT for the dentistry for the endodontics was shown in the point.It seemed to be not easy to analyze the three dimensional structure by small field of view CT (CT designed for the dentistry) using pixel value like CT. The result of our study show the importance of small CT phantom that similar to bone at contents. Less