The impact of temporal inaccuracies on 4DCT image quality
The impact of temporal inaccuracies on 4DCT image quality
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DOI：
10.1118/1.2717404
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发表时间：
2007-05-01
期刊：
影响因子：
3.8
通讯作者：
Brinkmann, D. H.
中科院分区：
文献类型：
--
作者：
Mutaf, Y. D.;Antolak, J. A.;Brinkmann, D. H.
靶区的准确描绘是图像引导放射治疗成功的关键因素之一，并且采用多种成像方式来提高靶区识别的准确性。四维 (4D) 技术被纳入计算机断层扫描 (CT) 等现有辐射成像技术中，以考虑目标体积的移动性。然而，在某些情况下，当未实施进一步的质量保证措施时，这些方法会导致目标描绘进一步不准确。常见的不准确性的一个来源是呼吸周期的错误识别以及在构建 4D 患者模型时使用的呼吸阶段分配。这项工作的目的是强调 4DCT 图像采集过程中最佳呼吸相位分配的重要性，并对不准确的相位分配对整体图像质量的影响进行定量评估。通过与呼吸相位的独立计算进行比较来评估相位分配的准确性。错位的相位分配表现为重建图像中的变形和伪影。这些效应被量化为由球形模型表示的目标物体的定位中的体积差异。使用梅奥诊所（明尼苏达州罗切斯特）设计和制造的完全可编程运动模型进行测量。还演示了基于案例的独立检查和纠正程序的实施，重点是该程序在临床环境中的使用。对该机构进行的临床 4D 扫描的审查显示，与我们的独立计算相比，约 40% 的病例的阶段分配存在差异。结论是，为了改进图像重建，应该对每个临床 4DCT 病例进行分类程序的独立检查。 (c) 2007 年美国医学物理学家协会。
Accurate delineation of target volumes is one of the critical components contributing to the success of image-guided radiotherapy treatments and several imaging modalities are employed to increase the accuracy in target identification. Four-dimensional (4D) techniques are incorporated into existing radiation imaging techniques like computed tomography (CT) to account for the mobility of the target volumes. However, these methods in some cases introduce further inaccuracies in the target delineation when further quality assurance measures are not implemented. A source of commonly observed inaccuracy is the misidentification of the respiration cycles and resulting respiration phase assignments used in the construction of the 4D patient model. The aim of this work is to emphasize the importance of optimal respiration phase assignment during the 4DCT image acquisition process and to perform a quantitative assessment of the effect of inaccurate phase assignments on the overall image quality. The accuracy of the phase assignment was assessed by comparison with an independent calculation of the respiration phases. Misplaced phase assignments manifest themselves as deformations and artifacts in reconstructed images. These effects are quantified as volumetric discrepancies in the localization of target objects represented by spherical phantoms. Measurements are performed using a fully programmable motion phantom designed and built at Mayo Clinic (Rochester, MN). Implementation of a case based independent check and correction procedure is also demonstrated with emphasis on the use of this procedure in the clinical environment. Review of clinical 4D scans performed in this institution showed discrepancies in the phase assignments in about 40% of the cases when compared to our independent calculations. It is concluded that for improved image reconstruction, an independent check of the sorting procedure should be performed for each clinical 4DCT case. (c) 2007 American Association of Physicists in Medicine.