Correction of image artifacts from treatment couch in cone-beam CT from kV on-board imaging
Correction of image artifacts from treatment couch in cone-beam CT from kV on-board imaging
复制标题
DOI：
10.3233/xst-2011-0296
复制
发表时间：
2011-01-01
影响因子：
3
通讯作者：
Amols, Howard
中科院分区：
文献类型：
--
作者：
Ali, Imad;Ahmad, Salahuddin;Amols, Howard
目的：探讨图像伪影所造成的标准治疗床上的锥束CT（CBCT）图像从千伏车载成像仪和开发一种算法的基础上，空间域滤波，以消除图像伪影CBCT引起的治疗cushion.Methods：图像伪影CBCT引起的治疗cushion.Methods：通过扫描用于量化CT图像性能的体模进行量化。这是通过使用kV机载成像仪扫描常规治疗床上和空气中的体模设置来执行的。开发了一种算法，通过使用两次扫描处理锥束射线照相投影来过滤治疗床的图像伪影：一次扫描体模和治疗床，第二次扫描仅治疗床。该算法基于逐个像素地去除体模和治疗床扫描的每个投影中治疗床引起的射束衰减。净床过滤的投影，然后用于重建CBCT.Results：我们发现，治疗床造成相当大的图像伪影：CT数的均匀性下降，变化高达15%，和噪声CBCT扫描与幻影加沙发（3.5%）是高于空气中的幻影（1.5%）。空间域滤波技术将噪声降低了1.5%以上，将均匀性提高了2倍，并消除了从治疗床滤波投影重建的CBCT中与标准治疗床相关的振铃和条纹伪影。这种过滤技术已成功地测试过滤其他硬件对象，如患者固定身体fix.Conclusions：标准治疗床造成图像伪影CBCT从千伏车载成像系统。在这项工作中开发的空间域滤波技术，通过预处理CBCT重建前的投影，提高CBCT的图像质量。该技术可能有助于从CBCT中过滤可能导致图像质量下降的其他硬件对象。
Purpose: To investigate image artifacts caused by a standard treatment couch on cone-beam CT (CBCT) images from a kV on-board imager and to develop an algorithm based on spatial domain filtering to remove image artifacts in CBCT induced by the treatment couch.Methods: Image artifacts in CBCT induced by the treatment couch were quantified by scanning a phantom used to quantify CT image performance. This was performed by scanning the phantom setup on a regular treatment couch and in air with the kV on-board imager. An algorithm was developed to filter image artifacts from the treatment couch by processing of cone-beam radiographic projections using two scans: one scan of the phantom and treatment couch and a second scan of the treatment couch only. This algorithm is based on a pixel-by-pixel removal of beam attenuation due to the treatment couch from each projection of the phantom and couch scan. The net couch-filtered projections were then used to reconstruct CBCT.Results: We found that the treatment couch causes considerable image artifacts: CT number uniformity is degraded and varies as much as 15%, and noise in CBCT scans with phantom plus couch (3.5%) is higher than for the phantom in air (1.5%). The spatial domain filtering technique reduces noise by more than 1.5%, improves uniformity by a factor of 2, and removes ringing and streaking artifacts related to the standard treatment couch in CBCT reconstructed from couch-filtered projections. This filtering technique was tested successfully to filter other hardware objects such as a patient immobilization body-fix frame.Conclusions: The standard treatment couch causes image artifact in CBCT from kV on-board imaging systems. The spatial domain filtering technique developed in this work improves image quality of CBCT by preprocessing the projections prior to CBCT reconstruction. This technique might be useful to filter other hardware objects from CBCT which may contribute to the degradation of image quality.