Investigation of basic imaging properties in digital radiography. 5. Characteristic curves of II-TV digital systems.
Investigation of basic imaging properties in digital radiography. 5. Characteristic curves of II-TV digital systems.
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数字放射线摄影中基本成像特性的研究。
DOI：
10.1118/1.595932
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发表时间：
1986
期刊：
影响因子：
3.8
通讯作者：
Chan,HP
中科院分区：
文献类型：
--
作者：
Fujita,H;Doi,K;Giger,ML;Chan,HP
设计了一种简单的方法来确定图像增强器（II）-TV数字成像系统的特性曲线，该特性曲线将输出像素值与输入相对X射线强度相关联。为了提供入射到II上的宽范围X射线强度，我们使用了由9个厚度增量为6.3 mm的阶梯组成的铝阶梯楔，以及0.81 mm厚的铜板。将X射线场严格准直到阶梯楔所占据的区域，以减少面纱眩光的影响。通过使用屏幕-胶片系统确定通过阶梯楔的每个阶梯透射的相对X射线强度。由特性曲线的斜率导出系统的梯度曲线。用Siemens Digitron 2系统获得的结果表明，其特征曲线和梯度曲线取决于所用基质的大小，但不随II场的大小而改变。用II-TV数字系统在不同曝光水平下测量碘衰减曲线，证明了特征曲线的有效性。
A simple method was devised to determine the characteristic curve of image intensifier (II)–TV digital imaging systems, which relates the output pixel value to the input relative x‐ray intensity. To provide a wide range of x‐ray intensities incident on the II, we used an aluminum stepwedge consisting of nine steps with thickness increments of 6.3 mm, together with an 0.81‐mm‐thick copper plate. The x‐ray field was narrowly collimated to the area occupied by the stepwedge in order to reduce the effect of veiling glare. The relative x‐ray intensities transmitted through each step of the stepwedge were determined by using screen–film systems. The gradient curve of the system was derived from the slope of the characteristic curve. Results obtained with a Siemens Digitron 2 system showed that its characteristic and gradient curves depended upon the matrix size used, but did not change with the II field size. The validity of the characteristic curve was demonstrated by measurement of iodine attenuation curves obtained with the II–TV digital system at different exposure levels.