Two-dimensional antiscatter grid: A novel scatter rejection device for Cone-beam computed tomography
Two-dimensional antiscatter grid: A novel scatter rejection device for Cone-beam computed tomography
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DOI：
10.1002/mp.12724
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发表时间：
2018-02-01
期刊：
影响因子：
3.8
通讯作者：
Altunbas, Cem
中科院分区：
文献类型：
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作者：
Alexeev, Timur;Kavanagh, Brian;Altunbas, Cem
目的：散射辐射仍然是基于平板探测器 (FPD) 的锥束计算机断层扫描 (CBCT) 图像质量下降的主要原因。我们一直在研究一种新颖的二维抗散射网格 (2D-ASG) 概念，以降低散射强度，从而提高 CBCT 图像质量。我们首次展示了使用 2D-ASG 原型进行的 CBCT 成像实验，并证明了其在提高 CBCT 图像质量方面的功效。方法：采用钨增材制造带有聚焦 X 射线源隔垫的 2D-ASG 原型，并将其安装在瓦里安 TrueBeam CBCT 系统上。体模的 CBCT 投影是使用 TrueBeam 的开发模式通过偏移探测器几何结构获取的。为了最大限度地减少龙门弯曲的影响，在特定角度的基础上对投影进行了增益校正。使用滤波反投影算法重建 CBCT 图像，并通过测量无防散射网格 (NO-ASG)、传统一维防散射网格 (1D-ASG) 和 2D-ASG 原型采集的图像中的对比度 (CNR) 和 CT 数精度来量化图像质量的改进。结果：与 1D-ASG 和 NO-ASG 的结果相比，使用我们的 2D-ASG 原型实现了对比度分辨率的显着提高收购。与NO-ASG和1D-ASG实验相比，材料插入物的CNR分别提高了86%和54%。使用 2D-ASG，与 NO-ASG 相比，体模的水当量材料部分的 CT 数低估最多减少了 325 HU，与 1D-ASG 相比减少了 179 HU。结论：我们成功地使用 2D-ASG 原型进行了首次 CBCT 成像实验。 2D-ASG 在定性评估中提供了显着更高的 CT 数精度、更高的 CNR 和减少的散射引起的图像伪影。我们坚信，使用 2D-ASG 可能会在 CBCT 中实现更好的软组织可视化，并可能实现需要高 CT 数精度的新型临床应用。 (c) 2017 年美国医学物理学家协会
Purpose: Scattered radiation remains to be a major cause of image quality degradation in Flat Panel Detector (FPD)-based Cone-beam computed tomography (CBCT). We have been investigating a novel two-dimensional antiscatter grid (2D-ASG) concept to reduce scatter intensity, and hence improve CBCT image quality. We present the first CBCT imaging experiments performed with the 2D-ASG prototype, and demonstrate its efficacy in improving CBCT image quality.Methods: A 2D-ASG prototype with septa focused to x-ray source was additively manufactured from tungsten and mounted on a Varian TrueBeam CBCT system. CBCT projections of phantoms were acquired with an offset detector geometry using TrueBeam's developer mode. To minimize the effect of gantry flex, projections were gain corrected on angle-specific bases. CBCT images were reconstructed using a filtered backprojection algorithm and image quality improvement was quantified by measuring contrast-to-noise ratio (CNR) and CT number accuracy in images acquired with no antiscatter grid (NO-ASG), conventional one dimensional antiscatter grid (1D-ASG), and the 2D-ASG prototype.Results: A significant improvement in contrast resolution was achieved using our 2D-ASG prototype compared to results of 1D-ASG and NO-ASG acquisitions. Compared to NO-ASG and 1D-ASG experiments, the CNR of material inserts improved by as much as 86% and 54% respectively. Using 2D-ASG, CT number underestimation in water equivalent material section of the phantom was reduced by up to 325 HU when compared to NO-ASG and up to 179 HU when compared to 1D-ASG.Conclusion: We successfully performed the first CBCT imaging experiments with a 2D-ASG prototype. 2D-ASG provided significantly higher CT number accuracy, higher CNR, and diminished scatter-induced image artifacts in qualitative evaluations. We strongly believe that utilization of a 2D-ASG may potentially lead to better soft tissue visualization in CBCT and may enable novel clinical applications that require high CT number accuracy. (c) 2017 American Association of Physicists in Medicine