The effect of head rotation on cephalometric radiographs
The effect of head rotation on cephalometric radiographs
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DOI：
10.1093/ejo/cjh098
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发表时间：
2005-06-01
影响因子：
2.6
通讯作者：
Koyuturk, AE
中科院分区：
文献类型：
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作者：
Malkoc, S;Sari, Z;Koyuturk, AE
本研究的目的是确定由于头部在垂直 z 轴上旋转而导致的侧位、后前位 (PA) 和颏下 (SMV) 头影测量 X 线照片的潜在投影误差。在这项研究中，使用了一个完整的成人干头骨。头骨以 2 度间隔从 0 度旋转到±14 度。垂直轴（z 轴）用作旋转轴来曝光 15 张侧向和 15 PA 头影测量 X 光照片。将头骨向两侧倾斜，同样以 2 度间隔，以曝光 15 张 SMV 胶片。对所有头颅照片进行了一系列线性和角度测量。结果显示，头颅侧位照片上水平面之间的水平线性和角度测量随着头部位置旋转 14 度而变化，从 16.1% 变化到 44.7%。对于 PA 头影图，水平线性测量（尤其是下颌长度）在头部旋转时的投影误差高达 34.9%。另一方面，SMV 射线照相的投影误差在 3% 至 4% 的限度内。研究结果表明：(1) 头颅侧位片中线性测量和水平面之间的角度测量可能会受到头部旋转的影响，(2) PA 头颅照片中角度测量随着头部旋转的变化而变化较小，(3) SMV 射线照片不易受到头部旋转的影响。头颅侧位片的垂直线性测量和 PA 射线照片的角度测量在最大限度地减少与头部旋转相关的投影误差方面更加可靠。
The aim of this study was to identify the potential projection errors of lateral, postero-anterior (PA) and submentovertex (SMV) cephalometric radiographs due to head rotation in the vertical z-axis. For this investigation, a complete human dry skull of an adult was used. The skull was rotated from 0 to±14 degrees at 2 degree intervals. A vertical axis, the z-axis, was used as the rotational axis to expose 15 lateral and 15 PA cephalometric radiographs. The skull was tilted on each side, again at 2 degree intervals, to expose the 15 SMV films. A series of linear and angular measurements was carried out on all cephalograms.The results revealed that horizontal linear and angular measurements between the horizontal planes on lateral cephalograms were subject to changes from 16.1 to 44.7 per cent with a 14 degree rotation of the head position. For PA cephalograms, again horizontal linear measurements, particularly mandibular length, were subject to a projection error of up to 34.9 per cent with head rotation. On the other hand, projection errors were within the 3–4 per cent limit for SMV radiography. The findings indicate that:(1) linear measurements and the measurement of angles between the horizontal planes are likely to be affected by head rotation in lateral cephalograms,(2) angular measurements demonstrate smaller variations with changing rotation of the head in PA cephalograms,(3) SMV radiographs are less vulnerable to head rotation. Vertical linear measurements of lateral cephalograms and angular measurements of PA radiographs are more reliable in minimizing the projection errors associated with head rotation.