Performance evaluation of x-ray differential phase contrast computed tomography (PCT) with respect to medical imaging
Performance evaluation of x-ray differential phase contrast computed tomography (PCT) with respect to medical imaging
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DOI：
10.1118/1.4736529
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发表时间：
2012-08-01
期刊：
影响因子：
3.8
通讯作者：
Flohr, Thomas
中科院分区：
文献类型：
--
作者：
Raupach, Rainer;Flohr, Thomas
目的：要评估的最大性能增益，理论上可以实现与差分相位对比计算机断层扫描（PCT）相比，吸收为基础的CT，适用于在体内medical imaging.Methods：我们开发了一个数学框架，用于分析PCT相对于CT在理想条件下的性能。我们通过解释已发表的PCT实验结果来验证我们的模型。最后，我们利用我们的框架来评估PCT与CT的相对性能，在体内的人体医学成像，调查几个临床相关的材料contraditions.Results：我们表明，PCT相对于CT的性能取决于相衬和吸收对比的比率的检查材料，并增加有效的相干长度和空间分辨率的增加。引入的有效相干长度表征实验PCT设置;它包括光束的相干性以及X射线干涉仪的特性。全身医学CT将不会受益于相衬成像，因为较高的相衬度被低亮度源的PCT设置的低相干长度和有限的空间分辨率过度补偿。PCT的相对性能，这是劣于CT的所有检查的材料对比度在今天的医学CT的分辨率水平，可以通过增加空间分辨率在增加患者剂量的代价。在PCT和CT相同性能的盈亏平衡点，需要比现在高至少1个数量级的辐射剂量。乳腺摄影CT已经在更高的空间分辨率，并可能受益于PCT的一些应用程序在减少患者剂量在平等的图像quality.Conclusions：相位对比成像利用低亮度X射线源在常规全身CT的应用潜力有限。然而，乳腺CT可能受益于相位对比成像。这些结论是由于基本的论点和独立的技术问题（光栅的质量等）是否。都可以解决PCT将仅适用于体内医学成像，如果具有更好的空间相干性的X射线源是常规可用的。(C)2012年美国医学物理学家协会。[http：//dx.doi.org/10.1118/1.4736529]
Purpose: To evaluate the maximum performance gain that can theoretically be achieved with differential phase contrast computed tomography (PCT) compared with absorption-based CT, applied to in vivo medical imaging.Methods: We develop a mathematical framework for analyzing the performance of PCT relative to CT under ideal conditions. We validate our model by interpreting the results of published PCT experiments. Finally, we utilize our framework to evaluate the relative performance of PCT versus CT for in vivo medical imaging of the human body, investigating several clinically relevant material contrasts.Results: We show that the performance of PCT relative to CT depends on the ratio of phase contrast and absorption contrast of the examined materials and increases with increasing effective coherence length and increasing spatial resolution. The introduced effective coherence length characterizes an experimental PCT setup; it comprises coherence of the beam as well as properties of the x-ray interferometer. Whole body medical CT will not benefit from phase-contrast imaging, because the higher phase contrast is overcompensated by the low coherence lengths of PCT setups with low-brilliance sources, and by limited spatial resolution. The relative performance of PCT, which is inferior to CT for all examined material contrasts at the resolution level of today's medical CT, can be improved by increasing spatial resolution at the expense of increased patient dose. At the break-even point of equal performance for PCT and CT, a radiation dose at least 1 order of magnitude higher than today is required. Mammographic CT already operates at higher spatial resolution and may benefit from PCT for some applications in terms of reduced patient dose at equal image quality.Conclusions: Phase-contrast imaging utilizing low-brilliance x-ray sources has limited potential for an application in routine whole body CT. Breast CT, however, may benefit from phase-contrast imaging. These conclusions are due to fundamental arguments and independent of whether technical issues (quality of gratings, etc.) can be solved. PCT will only be suitable for in vivo medical imaging if x-ray sources with much better spatial coherence are routinely available. (C) 2012 American Association of Physicists in Medicine. [http://dx.doi.org/10.1118/1.4736529]