基于双靶X线球管的双束X射线的金标成像实时跟踪可行性-《中国医学物理学杂志》

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Title:: Feasibility of real-time gold markers tracking by a double-anode-target X-ray tube CBCT

文章编号:: 1005-202X（2022）09-1094-07

作者:: 胡咪1; 胡逸民2; 全红1; 1.武汉大学物理与科学技术学院，湖北武汉 430000； 2.中国医学科学院中国协和医科大学肿瘤医院放疗科，北京 100021

Author(s):: HU Mi1; HU Yimin2; QUAN Hong1; 1. School of Physics and Technology,Wuhan University, Wuhan 430000, China 2. Department of Radiotherapy, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China

关键词:: 双靶点X线球管; 坐标重建; 金标记; 实时跟踪

Keywords:: Keywords: double-anode-target X-ray tube coordinate reconstruction gold marker real-time tracking

分类号:: R812

DOI:: DOI:10.3969/j.issn.1005-202X.2022.09.007

文献标志码:: A

摘要:: 目的：探究新型双靶X线球管的最优靶间距并建立一种基于此球管的双束X射线的金标记成像实时跟踪算法，实现实时CBCT图像引导放疗。方法：将植入金标记的模体置于医科达Synergy加速器治疗床的床面上，利用该加速器配置的CBCT获取金标记的kV-X射线零度投影图像。在同一机架角，平移模体在床面上的位置，使其处于间距为2~12 mm的等差对称位置，分别得到金标记的两次kV-X射线零度投影图像。然后从叠加的金标投影图像中提取模体两个位置处的金标记的2D投影位置。将相应的2D金标投影位置反向投影至模拟的双靶靶点位置。利用两条投影线相交的几何原理，重建出金标记在模体中的3D坐标，实现靶区内金标记位置的跟踪。结果：模体位于床面上间距在2~12 mm的对称位置时，对应于靶间距为2~12 mm的双靶X线球管的双束平行X射线。当模体位置相距7 mm及以下时，无法成功从叠加投影图像中检测出金标记的2D投影坐标，无法重建金标记的3D位置；仅当模体位于8 mm及以上的对称位置时，金标记2D投影坐标才得以检测到，检测精度为（±0.176、±0.140） mm，此时重建3D坐标的检测精度平均可以达到（±0.242、±0.392、±1.036） mm。结论：当双靶的靶间距大于等于8 mm时，根据金标记投影图像能较精确地重建出金标记的3D坐标。

Abstract:: Abstract: Objective To explore the optimal target spacing of a novel double-anode-target X-ray tube, and to realize real-time CBCT image-guided radiotherapy by proposing an algorithm for real-time gold markers tracking based on this innovated tube. Methods The phantom with pre-implanted gold markers was put on the treatment couch of Elekta Synergy linear accelerator, and the kV-X-ray zero-degree projection images of the gold markers were obtained by the CBCT configured by the accelerator. At the same gantry angle, the phantom on the treatment couch was translated, so that it is in an equidistant symmetrical position with a spacing of 2 to 12 mm, and two kV-X-ray zero-degree projection images of the gold marks were obtained. Then the 2D projected coordinates of the gold markers were extracted from the overlayed projection images, and the corresponding 2D projected coordinates of the markers were backprojected to the simulated double-anode-target positions. Finally, the geometric principle of the intersection of two projection lines was used to reconstruct the 3D coordinates of the gold markers in the phantom for realizing the tracking of the gold markers in the target area. Results When the phantom was located at a symmetrical position with a spacing of 2 to 12 mm on the couch, it corresponded to two parallel X-rays of a double-anode-target X-ray tube with a target spacing of 2 to 12 mm. When the symmetrical distance of the phantom was no more than 7 mm, the 2D projected coordinates of the gold markers could not be successfully read out from the overlayed projection images, and there was no way to reconstruct their 3D coordinates. Only when the phantom was in a symmetrical position with a spacing of 8 mm or larger than 8 mm, the 2D projected coordinates of the gold markers were detectable, with a detection precision of (±0.176, ±0.140) mm, and the precision of reconstructed 3D coordinates reached (±0.242, ±0.392, ±1.036) mm. Conclusion The 3D coordinates of the gold markers can be accurately reconstructed according to the double-anode-target X ray tube images, when the double-anode-target spacing was equal to or larger than 8 mm.

《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]

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