arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2103.11541physics.med-ph
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X射线相位衬度成像中基于任务的剂量优化的注量自适应

Fluence Adaptation for Task-based Dose Optimization in X-ray Phase-Contrast Imaging

Chengpeng Wu, Yuxiang Xing, Li Zhang, Zhiqiang Chen, Xiaohua Zhu, Xi Zhang, Hewei Gao

摘要:

目的:基于光栅的成像(GBI)和边缘照明(EI)是两种很有前途的XPCI类型,因为可以直接利用传统的X射线源。对于GBI和EI系统,文献中通常采用恒定注量下多次曝光的相位步进采集。然而,这项工作,试图挑战这样一个恒定的通量概念,在相位步进过程中,并提出了一个剂量减少的通量适应机制。方法:近年来,为了提高计算效率,提出了解析多阶矩分析法。在这些算法中,可以通过将加权相位步进曲线(PSC)与一些核函数相加来计算多个对比度,这表明在不同步骤处的原始数据对检索对比度中的噪声具有不同的贡献。基于探测信号的解析反演公式和高斯噪声模型,推导出了一种最优的自适应注量分布,该分布与绝对加权核函数和恒定注量下采集的原始样本PSC的根成正比。结果:为了验证我们的分析,模拟和实验进行GBI和EI系统。模拟结果表明,我们建议的注量分布和典型的常数之间的剂量减少率可以为20%左右的相位衬度,这与我们的理论预测是一致的。虽然实验降噪比略小于理论,合成和真实实验都观察到更好的噪声性能,我们提出的方法。仿真结果还给出了PSCs参数的有效范围,如GBI中的可见度、EI中的标准差和均值,为实际应用提供了指导。

英文摘要:

Purpose: Grating-based imaging (GBI) and edge-illumination (EI) are two promising types of XPCI as the conventional x-ray sources can be directly utilized. For GBI and EI systems, the phase-stepping acquisition with multiple exposures at a constant fluence is usually adopted in the literature. This work, however, attempts to challenge such a constant fluence concept during the phase-stepping process and proposes a fluence adaptation mechanism for dose reduction. Method: Recently, analytic multi-order moment analysis has been proposed to improve the computing efficiency. In these algorithms, multiple contrasts can be calculated by summing together the weighted phase-stepping curves (PSCs) with some kernel functions, which suggests us that the raw data at different steps have different contributions for the noise in retrieved contrasts. Based on analytic retrieval formulas and the Gaussian noise model for detected signals, we derived an optimal adaptive fluence distribution, which is proportional to the absolute weighting kernel functions and the root of original sample PSCs acquired under the constant fluence. Results: To validate our analyses, simulations and experiments are conducted for GBI and EI systems. Simulated results demonstrate that the dose reduction ratio between our proposed fluence distributions and the typical constant one can be about 20% for the phase contrast, which is consistent with our theoretical predictions. Although the experimental noise reduction ratios are a little smaller than the theoretical ones, synthetic and real experiments both observe better noise performance by our proposed method. Our simulated results also give out the effective ranges of the parameters of the PSCs, such as the visibility in GBI, the standard deviation and the mean value in EI, providing a guidance for the use of our proposed approach in practice.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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