Improving image accuracy of region-of-interest in cone-beam CT using prior image.
Improving image accuracy of region-of-interest in cone-beam CT using prior image.
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DOI：
10.1120/jacmp.v15i2.4628
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发表时间：
2014-03-06
影响因子：
2.1
通讯作者：
Cho S
中科院分区：
文献类型：
--
作者：
Lee J;Kim JS;Cho S
在疾病的诊断随访中，例如使用重复CT扫描进行肾脏钙评分或肝脏脂肪含量评估，需要定量准确和一致的CT值，同时患者的辐射剂量成本较低。感兴趣区（ROI）成像技术因其在ROI外的屏蔽几何结构而被认为是CT扫描中合理的剂量降低方法。然而，由ROI外部的缺失数据引起的重建图像中的图像伪影可能降低整体图像质量，并且更重要的是，可能显著降低ROI的图像精度。在这项研究中，我们提出了一种方法，以提高图像的准确性的ROI和减少成像辐射剂量，通过利用外部的ROI数据从以前的扫描在重复的CT应用。我们进行了数值和实验研究，以验证我们提出的方法。在一项数值研究中，我们使用了一个XCAT体模，其肝脏和胃的大小从一次扫描到另一次扫描不断变化。与现有的数据外推方法相比，所提出的方法可以提高肝脏的图像精度，因为误差从44.4 HU降低到-0.1 HU，以补偿ROI外的缺失数据。还使用了接受放射治疗的每日CBCT扫描的患者的重复锥形束CT（CBCT）图像，以实验方式证明所提出方法的性能。结果显示ROI内的图像准确度有所提高。误差幅度从−73.2 HU降至18 HU，并有效减少了整个图像中的图像伪影。PACS编号87.57 Q‐
In diagnostic follow‐ups of diseases, such as calcium scoring in kidney or fat content assessment in liver using repeated CT scans, quantitatively accurate and consistent CT values are desirable at a low cost of radiation dose to the patient. Region‐of‐interest (ROI) imaging technique is considered a reasonable dose reduction method in CT scans for its shielding geometry outside the ROI. However, image artifacts in the reconstructed images caused by missing data outside the ROI may degrade overall image quality and, more importantly, can decrease image accuracy of the ROI substantially. In this study, we propose a method to increase image accuracy of the ROI and to reduce imaging radiation dose via utilizing the outside ROI data from prior scans in the repeated CT applications. We performed both numerical and experimental studies to validate our proposed method. In a numerical study, we used an XCAT phantom with its liver and stomach changing their sizes from one scan to another. Image accuracy of the liver has been improved as the error decreased from 44.4 HU to −0.1 HU by the proposed method, compared to an existing method of data extrapolation to compensate for the missing data outside the ROI. Repeated cone‐beam CT (CBCT) images of a patient who went through daily CBCT scans for radiation therapy were also used to demonstrate the performance of the proposed method experimentally. The results showed improved image accuracy inside the ROI. The magnitude of error decreased from −73.2 HU to 18 HU, and effectively reduced image artifacts throughout the entire image. PACS number: 87.57. Q‐
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