Motion correction for improved target localization with on-board cone-beam computed tomography
Motion correction for improved target localization with on-board cone-beam computed tomography
复制标题
DOI：
10.1088/0031-9155/51/2/005
复制
发表时间：
2006-01-21
影响因子：
3.5
通讯作者：
Xing, L
中科院分区：
文献类型：
--
作者：
Li, T;Schreibmann, E;Xing, L
基于机载成像仪 (OBI) 的锥形束计算机断层扫描 (CBCT) 已在放射治疗诊所中使用，可准确识别治疗位置的目标。然而，由于获取CBCT投影数据时机架旋转相对较慢（通常360度扫描大约需要60 s），患者的呼吸运动会导致重建图像出现模糊、重影、拖尾和畸变等严重问题，严重降低图像质量和目标定位。在这项工作中，我们提出了一种用于慢旋转 CBCT 扫描的运动补偿方法，通过将患者特定的运动模型纳入图像重建中，该模型源自先前通过变形配准获得的同一患者的四维 (4D) 治疗计划 CT 图像。 4D CT 相位的配准导致表示三维 (3D) 变形场的时间序列的变换，或者换句话说，器官运动的 4D 模型。该算法是在二维 (2D) 平行束几何中启发式开发的，并扩展到 3D 锥形束几何。通过对能够进行平移运动和其他复杂运动的数字体模进行模拟，我们证明该算法可以减少局部运动伪影，恢复肿瘤的大小和形状，从而提高使用CBCT作为治疗指导时目标定位和患者定位的准确性。
On-board imager (OBI) based cone-beam computed tomography (CBCT) has become available in radiotherapy clinics to accurately identify the target in the treatment position. However, due to the relatively slow gantry rotation (typically about 60 s for a full 360 degrees scan) in acquiring the CBCT projection data, the patient's respiratory motion causes serious problems such as blurring, doubling, streaking and distortion in the reconstructed images, which heavily degrade the image quality and the target localization. In this work, we present a motion compensation method for slow-rotating CBCT scans by incorporating into image reconstruction a patient-specific motion model, which is derived from previously obtained four-dimensional (4D) treatment planning CT images of the same patient via deformable registration. The registration of the 4D CT phases results in transformations representing a temporal sequence of three-dimensional (3D) deformation fields, or in other words, a 4D model of organ motion. The algorithm was developed heuristically in two-dimensional (2D) parallel-beam geometry and extended to 3D cone-beam geometry. By simulations with digital phantoms capable of translational motion and other complex motion, we demonstrated that the algorithm can reduce the motion artefacts locally, and restore the tumour size and shape, which may thereby improve the accuracy of target localization and patient positioning when CBCT is used as the treatment guidance.