Center for Advanced Radiotherapy Technologies, Department of Radiation Oncology, University of California San Diego, La Jolla, CA, USA.
J Xray Sci Technol. 2011;19(2):139-54. doi: 10.3233/XST-2011-0283.
X-ray imaging dose from serial Cone-beam CT (CBCT) scans raises a clinical concern in most image guided radiation therapy procedures. The goal of this paper is to develop a fast GPU-based algorithm to reconstruct high quality CBCT images from undersampled and noisy projection data so as to lower the imaging dose. The CBCT is reconstructed by minimizing an energy functional consisting of a data fidelity term and a total variation regularization term. We develop a GPU-friendly version of a forward-backward splitting algorithm to solve this problem. A multi-grid technique is also employed. We test our CBCT reconstruction algorithm on a digital phantom and a head-and-neck patient case. The performance under low mAs is also validated using physical phantoms. It is found that 40 x-ray projections are sufficient to reconstruct CBCT images with satisfactory quality for clinical purposes. Phantom experiments indicate that CBCT images can be successfully reconstructed under 0.1 mAs/projection. Comparing with the widely used head-and-neck scanning protocol of about 360 projections with 0.4 mAs/projection, an overall 36 times dose reduction has been achieved. The reconstruction time is about 130 sec on an NVIDIA Tesla C1060 GPU card, which is estimated ∼ 100 times faster than similar regularized iterative reconstruction approaches.
X 射线成像剂量来自连续锥束 CT（CBCT）扫描，在大多数图像引导放射治疗程序中引起临床关注。本文的目的是开发一种基于 GPU 的快速算法，以便从欠采样和噪声投影数据中重建高质量的 CBCT 图像，从而降低成像剂量。通过最小化由数据保真项和全变差正则化项组成的能量泛函来重建 CBCT。我们开发了一种适用于 GPU 的前向-后向分裂算法的版本来解决这个问题。还采用了多网格技术。我们在数字体模和头颈部患者病例上测试了我们的 CBCT 重建算法。还使用物理体模验证了低 mAs 下的性能。结果表明，40 个 X 射线投影足以重建出用于临床目的的具有令人满意质量的 CBCT 图像。体模实验表明，在 0.1 mAs/投影下可以成功重建 CBCT 图像。与广泛使用的 0.4 mAs/投影、360 个投影的头颈部扫描方案相比，总剂量降低了 36 倍。在 NVIDIA Tesla C1060 GPU 卡上的重建时间约为 130 秒，估计比类似的正则化迭代重建方法快 100 倍左右。
