Katoh T, Sakamaki K, Nakamura T
Bull Tokyo Med Dent Univ. 1981 Sep;28(3):91-8.
Quantitative observations of bone mineral distribution in the maxillo-mandibular bone are of great interest in the clinical field. Radiographic densitometry is the most simple method but the film density is influenced by the X-ray exposure and processing conditions and by the soft tissue layers. This fluctuation can be corrected from the image of the wedge of the reference material simultaneously projected with the object on the same film. There is no other method than the dual energy technique to correct the effect of the soft tissue layer to be applicable in the maxillo-mandibular region. Two radiograms of the object obtained by a different beam quality represent the different X-ray contrast. When the penetrated fractions of the incident X-rays through the object at different energies are obtained from the film density and the characteristic curve of the film and substituted for the first order simultaneous equation whose coefficients are the mass attenuation coefficients of the bone mineral and soft tissue to the X-rays of the respective energy, the bone mineral content is obtained as the solution of the equation in the form of the product of the mineral density and the thickness of the bone (mg/cm2). This paper shows the principle of the method and the results of the experiment which agreed closely with the data obtained by the chemical assessment.
对上颌 - 下颌骨中骨矿物质分布进行定量观察在临床领域具有重要意义。放射密度测定法是最简单的方法，但胶片密度受X射线曝光和处理条件以及软组织层的影响。这种波动可以通过与物体同时投影在同一张胶片上的参考材料楔形块的图像进行校正。除了双能技术外，没有其他方法可用于校正软组织层的影响，该技术适用于上颌 - 下颌区域。通过不同射线质量获得的物体的两张射线照片代表不同的X射线对比度。当从胶片密度和胶片的特性曲线获得不同能量下穿过物体的入射X射线的穿透分数，并代入其系数为骨矿物质和软组织对相应能量X射线的质量衰减系数的一阶联立方程时，骨矿物质含量以矿物质密度与骨厚度的乘积形式（mg/cm²）作为方程的解得出。本文展示了该方法的原理以及实验结果，这些结果与通过化学评估获得的数据非常吻合。
