To bin or not to bin? The effect of CT system limiting resolution on noise and detectability
To bin or not to bin? The effect of CT system limiting resolution on noise and detectability
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DOI：
10.1088/0031-9155/58/5/1433
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发表时间：
2013-03-07
影响因子：
3.5
通讯作者：
Pelc, Norbert J.
中科院分区：
文献类型：
--
作者：
Baek, Jongduk;Pineda, Angel R.;Pelc, Norbert J.
我们研究了具有空间分辨率明显更好的计算机断层扫描（CT）探测器的噪声优势（例如，G.因子2）。在X射线CT中，探测器的有效分辨率有时会因合并单元而降低，因为不需要小的单元尺寸和精细采样来实现期望的分辨率（例如，G.具有平板探测器）。我们研究了合并过程对重建图像中的噪声的影响，发现虽然在没有噪声的情况下的图像对于本地系统和合并系统可以是相同的，但是对于存在噪声的相同系统MTF，合并系统总是导致噪声更大的重建图像。重建图像中增加的噪声对病变检测的影响是尺度（频率含量）相关的，其中高分辨率系统与用于成像精细结构（小对象）的分箱系统之间的差异较大。我们显示了模拟图像重建与两个系统的代表性的对象和量化的影响的噪声检测的病变的基础上的数学观察员。通过主观评估的重建图像和量化使用数学观察员，我们表明，对于CT系统的光子噪声是占主导地位的，更高的分辨率在探测器导致更好的噪声性能在任何分辨率的重建图像。
We examine the noise advantages of having a computed tomography (CT) detector whose spatial resolution is significantly better (e. g. a factor of 2) than needed for a desired resolution in the reconstructed images. The effective resolution of detectors in x-ray CT is sometimes degraded by binning cells because the small cell size and fine sampling are not needed to achieve the desired resolution (e. g. with flat panel detectors). We studied the effect of the binning process on the noise in the reconstructed images and found that while the images in the absence of noise can be made identical for the native and the binned system, for the same system MTF in the presence of noise, the binned system always results in noisier reconstructed images. The effect of the increased noise in the reconstructed images on lesion detection is scale (frequency content) dependent with a larger difference between the high resolution and binned systems for imaging fine structure (small objects). We show simulated images reconstructed with both systems for representative objects and quantify the impact of the noise on the detection of the lesions based on mathematical observers. Through both subjective assessment of the reconstructed images and the quantification using mathematical observers, we show that for a CT system where the photon noise is dominant, higher resolution in the detectors leads to better noise performance in the reconstructed images at any resolution.