Dunkerley David A P, Funk Tobias, Speidel Michael A
Dept. of Medical Physics, University of Wisconsin, Madison, WI, USA.
Triple Ring Technologies, Inc, Newark, CA, USA.
Proc SPIE Int Soc Opt Eng. 2016 Feb 27;9783. doi: 10.1117/12.2216892. Epub 2016 Mar 25.
Scanning-beam digital x-ray (SBDX) is an inverse geometry x-ray fluoroscopy system capable of tomosynthesis-based 3D catheter tracking. This work proposes a method of dose-reduced 3D tracking using dynamic electronic collimation (DEC) of the SBDX scanning x-ray tube. Positions in the 2D focal spot array are selectively activated to create a region-of-interest (ROI) x-ray field around the tracked catheter. The ROI position is updated for each frame based on a motion vector calculated from the two most recent 3D tracking results. The technique was evaluated with SBDX data acquired as a catheter tip inside a chest phantom was pulled along a 3D trajectory. DEC scans were retrospectively generated from the detector images stored for each focal spot position. DEC imaging of a catheter tip in a volume measuring 11.4 cm across at isocenter required 340 active focal spots per frame, versus 4473 spots in full-FOV mode. The dose-area-product (DAP) and peak skin dose (PSD) for DEC versus full field-of-view (FOV) scanning were calculated using an SBDX Monte Carlo simulation code. DAP was reduced to 7.4% to 8.4% of the full-FOV value, consistent with the relative number of active focal spots (7.6%). For image sequences with a moving catheter, PSD was 33.6% to 34.8% of the full-FOV value. The root-mean-squared-deviation between DEC-based 3D tracking coordinates and full-FOV 3D tracking coordinates was less than 0.1 mm. The 3D distance between the tracked tip and the sheath centerline averaged 0.75 mm. Dynamic electronic collimation can reduce dose with minimal change in tracking performance.
扫描束数字X射线（SBDX）是一种反向几何X射线荧光透视系统，能够基于断层合成进行三维导管跟踪。本文提出了一种利用SBDX扫描X射线管的动态电子准直（DEC）进行剂量降低的三维跟踪方法。二维焦点阵列中的位置被选择性激活，以在被跟踪导管周围创建感兴趣区域（ROI）X射线场。基于从两个最新的三维跟踪结果计算出的运动矢量，为每一帧更新ROI位置。该技术通过在胸部体模内沿三维轨迹拉动导管尖端时采集的SBDX数据进行评估。从为每个焦点位置存储的探测器图像中回顾性生成DEC扫描。在等中心处，对一个直径为11.4厘米的体积内的导管尖端进行DEC成像，每帧需要340个激活焦点，而全视野模式下为4473个焦点。使用SBDX蒙特卡罗模拟代码计算了DEC与全视野（FOV）扫描的剂量面积乘积（DAP）和皮肤峰值剂量（PSD）。DAP降低到全视野值的7.4%至8.4%，与激活焦点的相对数量（7.6%）一致。对于带有移动导管的图像序列，PSD为全视野值的33.6%至34.8%。基于DEC的三维跟踪坐标与全视野三维跟踪坐标之间的均方根偏差小于0.1毫米。被跟踪尖端与护套中心线之间的三维距离平均为0.75毫米。动态电子准直可以在跟踪性能变化最小的情况下降低剂量。
