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X线头影测量术是正畸学和研究颅面形态及其生长的主要方法。头影测量术中已被证实的三种主要的误差是:缺乏清晰度,缺乏对比度以及由于放大和形变而造成的几何误差。头定位仪上头位置的变化可以导致X线透射中的头部变形,是X线片测量误差的基本来源。影象消散是一种在不同强光照射下使影象重叠的电子技术,它只显示两个影象的非重叠部分,使重叠部分消失。该系统包括录象设备、图象贮存及监视系统。本文研究目的是用该系统评价头定位仪中头位置标准化的程度;判断受试者通过监视器移动头部是否能改善头位的可重复性;检验该视频系统是否可以单独作为控制头位置的方法。
X-cephalometry is orthodontic and research craniofacial morphology and the main method of growth. Three major errors have been demonstrated in cephalometry: lack of clarity, lack of contrast, and geometric errors due to magnification and deformation. Changes in the head position of the head positioner can cause head deformation in X-ray transmission, which is a primary source of X-ray measurement error. Image fading is an electronic technique that overlaps images under different glare. It shows only the non-overlapping parts of two images so that the overlapping parts disappear. The system includes video equipment, image storage and surveillance systems. The purpose of this study is to evaluate the degree of head position normalization in the head-positioner using this system; to determine whether the head-head repeatability can be improved by moving the head through the monitor; to verify whether the video system can be used alone as head position method.