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目的探讨X射线摄影测量出现误差的原因,提高X射线测量的准确性。方法自行研制X射线摄影效应尺,由底尺、高度尺和活动尺三大部分构成,分别刻以灌注铅胶的刻度,用于实际测量。检测焦片距100cm、物片距20cm时显示图像尺寸与实际尺寸的大小。结果各公司平板显示范围未能达到所标识的43 cm×43 cm,Kodak 7500、GE、佳能、西门子4家公司实际显示范围分别为41.5 cm、40.5 cm、42.5 cm、41.0 cm。而焦片距100 cm、物体厚度20 cm进行曝光时,底尺显示43.0 cm时,实际物体尺寸仅有36.0 cm,7.0 cm的物体盲区未被显示。结论为避免图像放大引起的失真,摄影时使用X射线摄影效应测定尺即可进行准确测量,减少误差。
Objective To investigate the causes of errors in X-ray photography and to improve the accuracy of X-ray measurement. Methods Self-developed X-ray photogrammetric ruler consists of three parts, ie foot ruler, height ruler and movable ruler, which are engraved with scale of perfusion lead glue for actual measurement. Detection of focal distance 100cm, 20cm from the film when the image size and the size of the actual size. Results The range of flat panel displays of various companies failed to reach the standard 43 cm × 43 cm. The actual display ranges of Kodak 7500, GE, Canon and Siemens were 41.5 cm, 40.5 cm, 42.5 cm and 41.0 cm, respectively. When the focal length is 100 cm and the object thickness is 20 cm, the actual object size is only 36.0 cm when the scale is displayed at 43.0 cm. The blind area of 7.0 cm is not displayed. Conclusion To avoid distortions caused by image magnification, accurate measurements can be made using X-ray photogrammetry to reduce errors.