A piecewise patch-to-model matching method for image-guided cardiac catheter ablation

Accurate and fast fusion and display of real-time images of anatomy and associated data is critical for effective use in image guided procedures, including image guided cardiac catheter ablation. We have developed a piecewise patch-to-model matching method, a modification of the contractive projection point technique, for accurate and rapid matching between an intra-operative cardiac surface patch and a pre-operative cardiac surface model. Our method addresses the problems of fusing multi-modality images and using non-rigid deformation between a surface patch and a surface model. A projection lookup table, K-nearest neighborhood search, and a final iteration of point-to-projection are used to reliably find the surface correspondence. Experimental results demonstrate that the method is fast, accurate and robust for real-time matching of intra-operative surface patches to pre-operative 3D surface models of the left atrium.     

中上段食管癌图像引导放疗中摆位误差及靶区外放边界的确定

目的 应用锥形束CT（CBCT）测量食管癌调强放疗的摆位误差,从而确定靶区外放距离;分析不同的靶区外放距离对肺和脊髓正常组织的影响。方法 选择2012年12月至2013年12月的12例中上段食管癌患者,根据每周1次CBCT所得的60组测量数据确定患者左右、头脚以及前后方向的摆位误差,根据实际测量的摆位误差结果以及靶区运动大小得出靶区外放距离,针对临床靶区CTV外放5 mm得到的计划靶区PTV以及根据实际测量摆位误差外放得到的计划靶区PTV分别制定调强治疗计划,在保证计划靶区PTV覆盖率相同（V₉₅≥95%）的情况下对两种计划的危及器官受量进行比较和统计学分析,评价参数包括双肺的V₅、V₂₀、V₃₀、平均剂量D_mean以及脊髓受量D_{1 cm³}。结果 食管癌调强放疗在左右、头脚以及前后3个方向的摆位误差分别是（2.02±1.74）、（2.02±1.93）、（2.03±1.89）mm。上段食管癌由临床靶区（CTV）到计划靶区（PTV）的外放距离为左右4.7 mm、头脚8.5 mm、前后5.6 mm;中段食管癌为左右5.0 mm、头脚11.0 mm、前后6.2 mm。两种计划比较,双肺的V-5、V₂₀、V₃₀、平均剂量D_mean和脊髓受量D_1cm³的差异有统计学意义（t=-8.23、－5.55、－4.66、－6.87、－4.67,P<0.05）。结论 根据CBCT测量结果确定摆位误差以及文献报道结果得出食管癌靶区外放边界,对于临床治疗有一定的参考意义。     

肺癌锥形束CT图像不同配准方式的误差分析

目的 研究肺癌锥形束CT(CBCT)图像配准的影响因素.方法 选取2007年间本科采用CBCT作为在线校位的肺癌放疗患者20例.每位患者在疗程中6～19次治疗采集了CBCT图像.根据肺内病变位置与椎体关系分为病变靠近椎体组(A组)和病变远离锥体组(B组),对比两组摆位误差差异.同时对该组病例分别选取从治疗初期、中期和后期CBCT图像,请4位医生分别采用骨配准和灰度配准,比较不同医生间和不同配准方式间差异.结果 A组和B组在头脚、左右、前后方向上的摆位误差分别为-1.31、1.24、-1.88 mm和0.10、1.37、-1.26 mm(t=0.07、0.05、-0.12,P=0.554、0.652、0.321).4位医生骨配准摆位误差头脚方向分别为-0.05、-0.01、0.05、-0.16(F=-0.01,P=0.887),左右方向分别为0.56、0.35、0.51、0.43 mm(F=-0.01,P=0.880),前后方向分别为-1.16、-1.20、-0.88、-1.03 mm(F=0.04,P=0.555);灰度配准摆位误差头脚方向分别为-0.32、-0.34、-0.39、-0.37 mm(F=-0.01,P=0.874),左右方向分别为0.34、0.54、-0.04、0.27 mm(F=-0.03,P=0.622),前后方向分别为-1.12、-1.15、-1.13、-1.04 mm(F=0.00,P=0.812).结论 采用相同配准框和图像质量下,肺癌患者肺内病变位置、不同配准方式和不同医生对图像引导放疗中CBCT图像配准无明显影响.

Abstract：

Objective To analyze the influencing factors of cone-beam CT (CBCT) imagine registration in lung cancer. Methods From Mar. 2007 to Dec. 2007, 20 patients with lung cancer were treated with IGRT. The imagines of CBCT were collected from 6 to 19 fractions during the patients' radiotherapy. To compare the difference of set-up errors between the two groups according to the distance from the lesion in lung to the centrum. At the same time, CBCT imagines from the first, middle and the last fraction of these patients' radiotherapy were registrated in bone and grey methods by four doctors. The difference of set-up errors between different doctors and registrated methods were compared. Results The mean values of set-up errors were ＜2 mm in the two groups without significant difference (x:-1.31mm vs 0. 10 mm (t=0. 07,P=0.554);y:1.24 mm vs 1.37 mm (t=0. 05,P=0. 652);z: - 1.88mm vs -1.26mm (t= -0. 12,P=0.321)). The mean values of set-up errors were ＜ 1.3 mm in four doctors and registrated methods without significant difference, for bone registration,x: -0. 05 mm, -0. 01 mm,0. 05 mm, -0.12 mm and -1.31 mm ( F=-0.01,P=0.887) ;y:0.56 mm,0.35 mm,0.51 mm and 0.43 mm (F= -0.01,P=0.880);z: -1.16 mm, -1.20 mm, -0.88 mm and -1.03 mm (F= -0.04,P=0. 555 ), for grey registration ,x: -0.32 mm, -0.341 mm, -0.395 mm and - 0.37 mm(F=-0.01, P=0.874);y:0.34 mm,0.54 mm, -0.04 mm and 0.27 mm (F= -0.03,P=0.622);x:-1.12 mm,- 1.15 mm, - 1.13 mm and - 1.04 mm (F=0. 00,P=0. 812). Conclusions With the same registrated box and imagine quality, the location of the lesions in lung, registred methods and different doctors are not the influencing factors for CBCT imagine registration.