Scatter and veiling glare estimation based on sampled primary intensity.
Scatter and veiling glare estimation based on sampled primary intensity.
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DOI：
10.1118/1.598744
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发表时间：
1999-11
期刊：
影响因子：
3.8
通讯作者：
Y. Zhou;T. Mathur;S. Molloi
中科院分区：
文献类型：
--
作者：
Y. Zhou;T. Mathur;S. Molloi
散射和遮蔽眩光是视频密度碘定量的主要误差来源。标准射束停止技术，例如放置在患者面前的铅条或铅盘阵列，先前已用于测量数字射线照相图像中的散射和遮蔽眩光。然而，这些技术显著增加了患者的X射线暴露。为了克服这一局限性，基于采样的原始强度的散射测量技术进行了研究。该技术使用铅板中的孔径阵列来对初级X射线强度进行采样。这些位置的散射眩光强度通过从包含主眩光和散射眩光的开放场图像中减去采样的主强度来计算。所计算的散射眩光值可以被内插或与数字滤波相结合，以逐个像素地估计散射眩光强度。使用Lucite阶梯体模和拟人胸部体模对该技术进行了评价。使用双三次插值和数字滤波技术估计散射和遮蔽眩光的平均均方根百分比误差分别为8.02%和7.53%。用双三次插值法和数字滤波法估算的平均均方根百分误差分别为10.01%和8.91%。来自孔径阵列的X射线面积乘积（EAP）仅为来自开放视野的EAP的4.38%。这些结果表明，散射眩光强度可以准确地估计与最小的X射线曝光使用采样的主要强度。
Scatter and veiling glare are predominant sources of error in videodensitometric iodine quantification. Standard beam stop techniques such as lead strips or an array of lead discs, placed before the patients, have previously been used to measure scatter and veiling glare in digital radiographic images. However, these techniques significantly increase patient x-ray exposure. In order to overcome this limitation, a scatter measurement technique based on sampled primary intensity has been investigated. This technique uses an array of apertures in a lead sheet to sample the primary x-ray intensity. The scatter-glare intensity in these locations is calculated by subtracting the sampled primary intensity from an open field image which contains both primary and scatter-glare. The calculated scatter-glare values can be interpolated or combined with digital filtration to estimate the scatter-glare intensity on a pixel by pixel basis. The technique was evaluated using a Lucite step phantom and an anthropomorphic chest phantom. The average rms percentage errors of scatter and veiling glare estimation using bi-cubic interpolation and digital filtration techniques were 8.02% and 7.53%, respectively. The average rms percentage errors of primary intensity estimation using bi-cubic interpolation and digital filtration techniques were 10.01% and 8.91%, respectively. The x-ray exposure-area product (EAP) from the aperture array was only 4.38% of the EAP from the open field. These results indicate that the scatter-glare intensity can be accurately estimated with minimal x-ray exposure using sampled primary intensity.