Bootstrap 法によるセンシトメトリーの測定精度と誤差要因について

概要

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One of the important factors affecting radiographic image quality is the film contrast of the recording system, which may be expressed by the gradient of its characteristic curve. The methods for measuring the gradient have been investigated with regard to their accuracy. It has been published that the most accurate measurement of the sensitometric curves of screen-film systems is an intensityscale X-ray sensitometer employed in the inverse square law of distance. However, in this method, the measuring is rather laborious. In this study, the accuracy of sensitometric curve by the bootstrap method using an aluminium step wedge was examined. The influences on the shape of its curve affected by several factors such as X-ray energy and the scatter factor were examined. We also compared the accuracy of the bootstrap method with the inverse square method by the standard deviation of each density at ten times the sensitometry. The measurements indicated that those factors failed to change the shape the sensitometric curve. At high density of sensitometric curves, the standard deviation at ten times of the bootstrap method were less than the inverse square method using the X-ray tube employed during daily clinical examinations. It is concluded that the bootstrap method is simple and effective to measure the gradient of sensitometric curves except for a laborious type measurement.
社団法人日本放射線技術学会の論文
1991-06-01