Image quality evaluation of flat panel and image intensifier digital magnification in x-ray fluoroscopy.
Image quality evaluation of flat panel and image intensifier digital magnification in x-ray fluoroscopy.
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DOI：
10.1118/1.1487858
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发表时间：
2002-07
期刊：
影响因子：
3.8
通讯作者：
Y. Srinivas;D. Wilson
中科院分区：
文献类型：
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作者：
Y. Srinivas;D. Wilson
放射学中使用的介入设备的尺寸通常在一个像素的数量级，放射科医生求助于图像放大来更好地可视化这些小设备。传统的像增强器(II)系统使用模拟放大，X射线曝光量与视野(FOV)成反比，以保持相机的光输出。平板(FP)探测器无法进行模拟放大，必须使用不会降低小型设备像素局部面积效应的数字内插法来放大图像。我们定量研究了数字和模拟放大的图像质量，使用临床相关任务在使用真实探测器模型创建的X射线透视图像序列中检测部分展开的支架。采用II类模拟放大率的标准曝光策略，分别从23 cm视野下的标称每帧43.65nGy5.0microR增加到17 cm和14 cm视野下的每帧79.9nGy9.15microR和117.81 nGy13.49microR。对比敏感度显著提高(p0.1)剂量节约。基于信号检测理论的时空人体观察者模型成功地预测了人体数据，并被用于预测与图像放大相关的其他条件。模型预测定量地表明，当信号大小相对较小时，放大是最有用的，FP数字放大可以在不增加曝光量的情况下改善支架部署任务的图像质量。综上所述，结果表明，与模拟放大相比，FP数字放大具有实用价值和剂量效率。
Interventional devices used in radiology often have dimensions on the order of a pixel, and radiologists resort to image magnification to better visualize such small devices. Traditional image intensifier (II) systems use analog magnification with x-ray exposure inversely proportional to the area of field of view (FOV) so as to maintain light output for the camera. Analog magnification is impossible with flat panel (FP) detectors, and images must be magnified using digital interpolation that does not reduce the pixel partial area effect for small devices. We quantitatively investigated image quality of digital and analog magnification using a clinically relevant task of detecting a partially deployed stent in x-ray fluoroscopy image sequences that were created using realistic detector models. Using the standard exposure strategy for II analog magnification, exposure was increased from a nominal 43.65 nGy (5.0 microR) per frame at 23 cm FOV to 79.9 nGy (9.15 microR) per frame and 117.81 nGy (13.49 microR) per frame at 17 cm and 14 cm FOV, respectively. Contrast sensitivity improved significantly (p0.1) dose savings. A spatiotemporal human observer model based on signal detection theory successfully predicted the human data and was used to predict other conditions associated with image magnification. Model predictions quantitatively showed that magnification is most useful when signal size is relatively small and that FP digital magnification can improve image quality for the stent deployment task without increasing exposure. In conclusion, the results show that FP digital magnification can be useful and dose efficient as compared to analog magnification.