标题： DIGS：使用形变感知的4D高斯点云动态CBCT重建和低秩自由形态形变模型 显示英文标题

标题： DIGS: Dynamic CBCT Reconstruction using Deformation-Informed 4D Gaussian Splatting and a Low-Rank Free-Form Deformation Model

摘要： 三维锥束CT（CBCT）在放疗中被广泛使用，但由于呼吸运动会产生运动伪影。一种常见的临床方法是将投影数据按呼吸阶段进行排序，并按阶段重建图像，但这种方法无法考虑呼吸的变异性。动态CBCT则在每个投影处重建图像，无需按阶段排序即可捕捉连续运动。4D高斯点云（4DGS）的最新进展为建模动态场景提供了强大的工具，但其在动态CBCT中的应用仍鲜有研究。现有的4DGS方法，如HexPlane，使用隐式运动表示，计算成本较高。虽然已经提出了显式的低秩运动模型，但它们缺乏空间正则化，导致高斯运动不一致。为了解决这些限制，我们引入了一种基于自由形变（FFD）的空间基函数和一个形变感知框架，通过在统一形变场下耦合高斯均值位置、尺度和旋转的时间演化来强制一致性。我们在六个CBCT数据集上评估了我们的方法，与HexPlane相比，图像质量更优且速度提升了6倍。这些结果突显了形变感知4DGS在高效、运动补偿的CBCT重建中的潜力。代码可在https://github.com/Yuliang-Huang/DIGS获取。 显示英文摘要

摘要： 3D Cone-Beam CT (CBCT) is widely used in radiotherapy but suffers from motion artifacts due to breathing. A common clinical approach mitigates this by sorting projections into respiratory phases and reconstructing images per phase, but this does not account for breathing variability. Dynamic CBCT instead reconstructs images at each projection, capturing continuous motion without phase sorting. Recent advancements in 4D Gaussian Splatting (4DGS) offer powerful tools for modeling dynamic scenes, yet their application to dynamic CBCT remains underexplored. Existing 4DGS methods, such as HexPlane, use implicit motion representations, which are computationally expensive. While explicit low-rank motion models have been proposed, they lack spatial regularization, leading to inconsistencies in Gaussian motion. To address these limitations, we introduce a free-form deformation (FFD)-based spatial basis function and a deformation-informed framework that enforces consistency by coupling the temporal evolution of Gaussian's mean position, scale, and rotation under a unified deformation field. We evaluate our approach on six CBCT datasets, demonstrating superior image quality with a 6x speedup over HexPlane. These results highlight the potential of deformation-informed 4DGS for efficient, motion-compensated CBCT reconstruction. The code is available at https://github.com/Yuliang-Huang/DIGS.