Improving quantitative accuracy and tissue visualization in CBCT guided radiation therapy

项目摘要 尽管锥形束计算机断层扫描（CBCT）是最常用的体积图像， 虽然它是一种指导模式，但在治疗监测和患者特异性方面，它的作用受到严重限制。 放射治疗中的治疗修改。由于CBCT的图像质量差，临床医生不能清楚地 可视化软组织以评估解剖变化，从而影响其临床决策。此外，委员会认为， 用于治疗监测的工具，例如可变形配准和剂量计算，不能稳健地运行 由于缺乏CT数量的准确性，目前的CBCT图像。 散射辐射仍然是提高CBCT图像质量的根本问题。因此在 在本项目中，我们提出了二维抗散射格栅（2D Grid）作为一种新的设备来解决散射问题 解决这一问题，并获得适用于治疗监测的高质量CBCT图像。我们的设备 与CBCT现有的防散射格栅相比，其结构和制造方式根本不同。由于其 优化的栅格结构，我们的2D Grid提供更高的初级透射率和更好的散射抑制 性能优于当今最先进的防散射格栅。由于其良好的初级传输和 散射抑制性能，我们的2D Grid提高了对比噪声比和CT数精度， 现有防散射格栅无法达到的水平。 我们假设我们的2D Grid将提供更好的软组织可视化和CT数量 准确性，并且预期可变形配准算法执行得明显更好。来测试我们 假设，我们将开发和优化CBCT（目标）中二维网格实现的数据处理方法 1）。随后，我们将制作2D网格原型，并评估其在临床CBCT中的性能 光子和质子治疗系统（目标2）。在基于体模的评估之后，我们将进行 前瞻性临床试验，以评价改善图像质量的临床效用（目标3）。我们将执行 观察者研究，以量化相对于现有临床CBCT的软组织可视化改善 和金标准螺旋CT，评估变形图像配准精度的提高 算法，并评估图像强度和纹理特征的一致性的改善。 虽然我们的应用主要集中在放射治疗上，但2D Grid可以在其他CBCT中发挥关键作用 例如介入放射学、肢体成像和术中成像。由于其 改进的低对比度可视化性能，我们的2D网格还可以减少成像剂量， CBCT。

PROJECT SUMMARY Even though cone beam computed tomography (CBCT) is the most commonly used volumetric image guidance modality, its role has been severely limited in the context of treatment monitoring and patient-specific treatment modifications in radiation therapy. Due to CBCT’s poor image quality, clinicians cannot clearly visualize soft tissues to assess anatomical changes, thus affecting their clinical decision-making. Moreover, tools for treatment monitoring, such as deformable registration and dose calculation, do not function robustly with today’s CBCT images due to the lack of CT number accuracy. Scattered radiation remains to be the fundamental problem in improving CBCT image quality. Thus, in this project, we propose the two-dimensional antiscatter grid (2D Grid) as a novel device to address the scatter problem and achieve high-quality CBCT images that are suitable for treatment monitoring. Our device has fundamentally different architecture and fabrication than existing antiscatter grids for CBCT. Due to its optimized grid structure, our 2D Grid provides both higher primary transmission and better scatter rejection performance than today’s state-of-the-art antiscatter grids. Due to its favorable primary transmission and scatter rejection performance, our 2D Grid improves the contrast-to-noise ratio and CT number accuracy to levels not achievable with existing antiscatter grids. We hypothesize that our 2D Grid will provide significantly better soft tissue visualization and CT number accuracy, and deformable registration algorithms are expected to perform significantly better. To test our hypotheses, we will develop and optimize data processing methods for 2D Grid implementation in CBCT (Aim 1). Subsequently, we will fabricate 2D Grid prototypes and evaluate their performance in clinical CBCT systems for photon and proton therapy (Aim 2). Following phantom based evaluations, we will conduct a prospective clinical trial to evaluate the clinical utility of improved image quality (Aim 3). We will perform observer studies to quantify the improvement in soft tissue visualization with respect to existing clinical CBCT and gold-standard Helical CT, assess the improvement in accuracy of deformable image registration algorithms, and evaluate the improvement in consistency of image intensity and texture features. While our application is focused on radiation therapy, the 2D Grid can play a key role in other CBCT applications, such as interventional radiology, extremity imaging, and intraoperative imaging. Due to its improved low-contrast visualization performance, our 2D Grid may also allow reduction of the imaging dose in CBCT.