O'Connell Dylan P, Thomas David H, Dou Tai H, Lamb James M, Feingold Franklin, Low Daniel A, Fuld Matthew K, Sieren Jered P, Sloan Chelsea M, Shirk Melissa A, Hoffman Eric A, Hofmann Christian
Department of Radiation Oncology, University of California Los Angeles, 200 Medical Plaza Suite B265, Los Angeles, California 90095.
Siemens Medical Solutions, USA, Inc., 600 North Wolfe Street, Baltimore, Maryland 21287.
Med Phys. 2015 Jul;42(7):4033-42. doi: 10.1118/1.4922201.
To demonstrate that a "5DCT" technique which utilizes fast helical acquisition yields the same respiratory-gated images as a commercial technique for regular, mechanically produced breathing cycles.
Respiratory-gated images of an anesthetized, mechanically ventilated pig were generated using a Siemens low-pitch helical protocol and 5DCT for a range of breathing rates and amplitudes and with standard and low dose imaging protocols. 5DCT reconstructions were independently evaluated by measuring the distances between tissue positions predicted by a 5D motion model and those measured using deformable registration, as well by reconstructing the originally acquired scans. Discrepancies between the 5DCT and commercial reconstructions were measured using landmark correspondences.
The mean distance between model predicted tissue positions and deformably registered tissue positions over the nine datasets was 0.65 ± 0.28 mm. Reconstructions of the original scans were on average accurate to 0.78 ± 0.57 mm. Mean landmark displacement between the commercial and 5DCT images was 1.76 ± 1.25 mm while the maximum lung tissue motion over the breathing cycle had a mean value of 27.2 ± 4.6 mm. An image composed of the average of 30 deformably registered images acquired with a low dose protocol had 6 HU image noise (single standard deviation) in the heart versus 31 HU for the commercial images.
An end to end evaluation of the 5DCT technique was conducted through landmark based comparison to breathing gated images acquired with a commercial protocol under highly regular ventilation. The techniques were found to agree to within 2 mm for most respiratory phases and most points in the lung.
证明一种利用快速螺旋采集的“5DCT”技术能够产生与用于常规机械产生呼吸周期的商业技术相同的呼吸门控图像。
使用西门子低螺距螺旋协议和5DCT，针对一系列呼吸频率和幅度以及标准和低剂量成像协议，生成麻醉状态下机械通气猪的呼吸门控图像。通过测量5D运动模型预测的组织位置与使用可变形配准测量的组织位置之间的距离，以及通过重建原始采集的扫描，对5DCT重建进行独立评估。使用地标对应关系测量5DCT与商业重建之间的差异。
九个数据集中模型预测的组织位置与可变形配准的组织位置之间的平均距离为0.65±0.28毫米。原始扫描的重建平均精确到0.78±0.57毫米。商业图像和5DCT图像之间的平均地标位移为1.7 |6±1.25毫米，而呼吸周期内肺组织的最大运动平均值为27.2±4.6毫米。由低剂量协议采集的30幅可变形配准图像的平均值组成的图像，心脏部位的图像噪声为6 HU（单标准差），而商业图像为31 HU。
通过与在高度规则通气下使用商业协议采集的呼吸门控图像进行基于地标的比较，对5DCT技术进行了端到端评估。结果发现，对于大多数呼吸阶段和肺内的大多数点，这两种技术的差异在2毫米以内。
