Task-based assessment of breast tomosynthesis: Effect of acquisition parameters and quantum noise
Task-based assessment of breast tomosynthesis: Effect of acquisition parameters and quantum noise
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DOI：
10.1118/1.3357288
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发表时间：
2010-04-01
期刊：
影响因子：
3.8
通讯作者：
Nishikawa, R. M.
中科院分区：
文献类型：
--
作者：
Reiser, I.;Nishikawa, R. M.
目的：层析成像是一种很有前途的乳房成像方法。采集和重建参数的选择对层析合成重建图像的外观有很大影响。这项研究的目的是调查断层合成乳房成像由于扫描参数和量子噪声的限制。基于数学观测器模型在信号精确已知(SKE)检测任务中的性能来评估层析合成图像质量。方法：使用预白化观测器模型估计SKE可检测性(d(‘))。利用滤波后的噪声来模拟结构化的乳房背景。对直径从0.05厘米到0.8厘米的设计结节的可探测性进行了估计。层析合成切片采用迭代最大似然期望最大化方法进行重建。断层合成扫描角度在15度至60度之间变化，观看次数在11度至41度之间，X射线总量为无穷大，6x10(5)和6x10(4)。结果：在固定角度采样距离的情况下，增大角度扫描范围可以提高对所有信号大小的检测能力。大尺度信号几乎不受量子噪声或角度采样的影响。对于小尺度信号，量子噪声和不充分的角度采样降低了可检测性。在高量子噪声水平下，3度或更低的角度步长足以避免图像退化。在较低的量子噪声水平下，增加角度采样总是会导致更高的可检测性。断层合成切片中的可探测性与单个投影中的可探测性的比率显示出一个峰值，该峰值随着角度范围的增加而向更大的信号尺寸移动。对于给定的角度范围，随着观看次数的增加，峰值向更小的信号方向移动。在所有评估的条件下，这一比率大于1。结论：采集参数对病变检测的影响取决于信号大小。层析合成扫描角度对所有信号大小的可检测性都有影响，而量子噪声和角度采样只影响小尺度信号的可检测性。
Purpose: Tomosynthesis is a promising modality for breast imaging. The appearance of the tomosynthesis reconstructed image is greatly affected by the choice of acquisition and reconstruction parameters. The purpose of this study was to investigate the limitations of tomosynthesis breast imaging due to scan parameters and quantum noise. Tomosynthesis image quality was assessed based on performance of a mathematical observer model in a signal-known exactly (SKE) detection task.Methods: SKE detectability (d(')) was estimated using a prewhitening observer model. Structured breast background was simulated using filtered noise. Detectability was estimated for designer nodules ranging from 0.05 to 0.8 cm in diameter. Tomosynthesis slices were reconstructed using iterative maximum-likelihood expectation-maximization. The tomosynthesis scan angle was varied between 15 degrees and 60 degrees, the number of views between 11 and 41 and the total number of x-ray quanta was infinity, 6x10(5), and 6x10(4). Detectability in tomosynthesis was compared to that in a single projection.Results: For constant angular sampling distance, increasing the angular scan range increased detectability for all signal sizes. Large-scale signals were little affected by quantum noise or angular sampling. For small-scale signals, quantum noise and insufficient angular sampling degraded detectability. At high quantum noise levels, angular step size of 3 degrees or below was sufficient to avoid image degradation. At lower quantum noise levels, increased angular sampling always resulted in increased detectability. The ratio of detectability in the tomosynthesis slice to that in a single projection exhibited a peak that shifted to larger signal sizes when the angular range increased. For a given angular range, the peak shifted toward smaller signals when the number of views was increased. The ratio was greater than unity for all conditions evaluated.Conclusion: The effect of acquisition parameters on lesion detectability depends on signal size. Tomosynthesis scan angle had an effect on detectability for all signals sizes, while quantum noise and angular sampling only affected the detectability small-scale signals.