论文标题
评估圆锥形束计算机断层扫描中2D抗探测者网格的散射排斥和校正性能
Evaluation of scatter rejection and correction performance of 2D antiscatter grids in cone beam computed tomography
论文作者
论文摘要
目的：我们一直在研究2D Antiscater网格（2D ASG），以减少散射通量并改善锥束计算机断层扫描（CBCT）中的图像质量。在这项工作中，在CBCT实验中研究了2D ASG的两个不同方面，即它们的散射排斥和校正能力。为了纠正通过2D ASG传输的残留散射，它被用作具有新方法的散点测量装置：基于网格的散点采样。方法：为LINAC安装的CBCT几何形状开发了三个聚焦的2D ASG原型，其网格比为8、12和16。在第一阶段，将2D ASG用作散点设备，并且网格比对CBCT图像中评估的CT数量准确性和对比度比率（CNR）的影响。在第二阶段，实现了基于网格的散点抽样方法。 CT数的百分比变化是通过将幻影尺寸从头部更改为骨盆配置来衡量的。分子：当使用2D ASG用作散点拒绝设备时，由于幻影尺寸变化而导致的CT数量变化从23％降低到2-2-6％。 16的网格比产生的CT数变化最低。所有三个2D ASG的CNR都会提高，骨盆大小的幻影量高达两倍。当使用2D ASG原型进行散射排斥和校正时，CT数量变化进一步降低至1.3-2.6％。结论：当仅将2D ASG用作散射拒绝装置时，通过增加电网比率可以实现CT数量精度的实质性提高。即使在较低的网格比率下，2D ASG也可以提供明显的CNR改进。当使用2D ASG与基于网格的散射采样方法结合使用时，它提供了CT数量准确性的进一步提高，而不论网格比率如何，同时保留了2D ASG改善CNR的能力。
Purpose: We have been investigating 2D antiscatter grids (2D ASG) to reduce scatter fluence and improve image quality in cone beam computed tomography (CBCT). In this work, two different aspects of 2D ASGs, their scatter rejection and correction capability, were investigated in CBCT experiments. To correct residual scatter transmitted through the 2D ASG, it was used as a scatter measurement device with a novel method: grid-based scatter sampling. Methods: Three focused 2D ASG prototypes with grid ratios of 8, 12, and 16 were developed for linac-mounted CBCT geometry. In the first phase, 2D ASGs were used as a scatter rejection device, and the effect of grid ratio on CT number accuracy and contrast-to-noise ratio (CNR) evaluated in CBCT images. In the second phase, the grid-based scatter sampling method was implemented. The percent change in CT numbers was measured by changing the phantom size from head to pelvis configuration.Results: When 2D ASG was used as a scatter rejection device, CT number variation due to change in phantom dimensions was reduced from 23% to 2 - 6%. A grid ratio of 16 yielded the lowest CT number variation. All three 2D ASGs yielded improvement in CNR, up to a factor of two in pelvis-sized phantoms. When 2D ASG prototypes were used for both scatter rejection and correction, CT number variations were reduced further, to 1.3 - 2.6%. Conclusions: When 2D ASG was used solely as a scatter rejection device, substantial improvement in CT number accuracy could be achieved by increasing the grid ratio. 2D ASGs could also provide significant CNR improvement even at lower grid ratios. When 2D ASG was used in conjunction with the grid-based scatter sampling method, it provided further improvement in CT number accuracy, irrespective of the grid ratio, while preserving 2D ASG's capacity to improve CNR.
