I.objective
The composition method with acquiring 25 image not only lack perfection in compensating the geometrical distortion but could also cause inaccurate connection problem of compensating the geometrical distortion but could also cause inaccurate connection problem of continuing bone structure due to the enlargement ratio difference of ruller and bone, density difference in image composition process. This paper studies those mentioned problems through the experiments.
II. Object and method
Experiment 1 After attaching 3 step wedge(Pb) on detector and 2 ruller on upper, lower part of the step wedge, we have exposed them to create density difference between 1st image and 2nd image, then examined if there were any errors. Experiment 2 1st 100cm ruller was attached on the center of detector, and by escalating the distance between 2nd 100cm ruller and detector 5cm, 10cm, 15cm respectively, we investigated if there any errors caused by enlargement ratio. Experiment 3 The ruller was placed on detector, a joint photographing was performed through spot photographing after fully operating the electric field photographing to include hip joint ankle joint part and we have compared the values from two methods.
III. Result A horizontal axis error was caused when photopraphing is not poerated in equal density since the image shifted horizontally in accordance with the difference of Pb step wedge 1 due to the density difference, as the result of Epperiment 1. Result of experiment 2, refer to the table below, Result of experiment 3, refer to the table below
Ⅳ. Conclusion The horizontal axis error was caused by density difference, as the result of experiment1, an error was also caused by enlargement ratio difference of ruller and bone, as the result of experiment 2 and in experiment 3, vertical axis error was caused by geometrical distortion. Through these experiments, we came up with the methods of calculating precise snlargement ratio of detector and bone structure through composition acquired 2~5 images of patient’s frontal, lateral images and also by measuring the exact length of the bone through spot photographing. However, those methods could not guarantee the accurate compensation due to increasing radiation exposure level and he flexion from articular surface within bone anatomy structure. Current, method, the composition of acquired 2~5 images, requires the solution for described problems of the experiment results.
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