Development of a radiological method for the measurement of bone mineral content in bone disease

1.使用数字图像扫描仪的高速图像处理系统使用数字图像扫描仪（Sharp JX 450）通过GPIB接口与个人计算机（Fijitsu FM 11）连接，可在2分钟内读取X射线图像。该图像输入系统的特性估计如下。1)有效像素尺寸为0.143mm。2)为了测量胶片密度，应取输出灰度的对数。3)最大可测量的膜密度为1.5。4)量化灰度的有效精度为64。因此，该系统的粗糙性能不足以用于定量分析的输入装置。为了补偿这些误差，对软件系统进行了改进，并对X射线的束流质量进行了强化。然后，物体厚度的动态范围变得与micro-denditometer系统的动态范围相当。为了提高图像处理速度，增加了浮点处理板。驱动软件正在开发中。2.羟基磷灰石植入后周围新骨生长过程的观察用组织学方法和本方法对羟基磷灰石植入后1个月~ 1年的周围新骨生长过程进行了观察。植入后1个月新生骨开始钙化，3个月后新生骨长到磷灰石棒周围。术后1年，新生骨增厚，并被成熟的板层骨所取代.本方法的观察结果与组织学观察结果基本一致。一个月后未检测到骨矿物质。术后3个月测骨密度0.3g/cm ~ 2。矿物质含量在植入后一年内没有变化。3.总结本方法可直观观察骨矿含量的变化。目前，只能观察到薄的物体。我们正计划改进该系统，以观察更厚的物体。

1. High speed image processing system using a digital image scanner Using a digital image scanner (Sharp JX450) interfaced throygh GPIB to an personal computer (Fijitsu FM11), an X-ray image could be read within 2 minutes. The characteristics of this image input system was estimated as follows. 1) Effective pixel size was 0.143mm. 2) To measure the film density, the logalithm of the output gray level should be taken. 3) The maximum measurable film density was 1.5. 4) The efective precission of the quiantamized gray level was 64. The crude performance of this system was, therefore, insufficient for the input device for the quantitative analysis. To compensate them, the soft ware system was modified and the beam quallty of the x-rays was hardened. Then the dynamic range to the object thickness became comparable to that of the michro-denditometer system. In order to improve the image processing speed, a floating point processior boad was added. The driving soft ware is on the development. 2. Observation of the growing process of new bone arround of the implanted hydroxyapatite The growing process of new bone arround of the implanted hydroxyapatite was observed from one month to one year by the hisological method and the present method. The new bone began to be calcified at one month after the implant, and grew to surround the apatite rod at three months after the operation. At one year after, the new bone grew thick and be replaced by matured lamelar bone. The observation by the present method gave the similar result to the histological observation. The bone mineral was not detected after one month. 0.3g/cm2 bone mineral was measured at three months after the operation. The mineral content did not varied to one year after the implant. 3 Summary The present mathod enable the indistructive observation of the change in the bone mineral content. In the present, only the thin object could be observed. We are planning to improve the system to observe the thicker objects.