基于光学识别及图像引导的胸部肿瘤放疗摆位系统的研究

目的开发一套摆位验证系统,以减少胸部肿瘤放射治疗病人的摆位误差,提高放疗精确度。方法在放射治疗摆位时将三个小金粒放置在病人骨性结构的表皮上,其位置呈三角形分布,此外,小金粒之间距离尽可能小,在Matlab 2010软件平台上自行开发一套摆位验证系统,采用图像配准的方式识别病人体表上预先放置的三个小金粒的位置,并计算出每个小金粒的二维坐标值(X,Y),以此作为量化放疗摆位误差的依据,指导技术员进行精确摆位校准。在本研究中,选取一例病人,对其8次放疗摆位时,校准前和校准后的小金粒坐标位置误差值进行比较分析。结果经过摆位验证系统的检验和校准后,金粒1在X轴方向的摆位误差dX1减少了4.5～7.3 mm,在Y轴上的摆位误差dY1的位置误差减少5.6～8.1 mm;金粒2的dX2位置误差减少5.6～7.8 mm,dY2位置误差减少5.7～7.8 mm;金粒3的dX3位置误差减少5.3～8.4 mm,dY3位置误差减少6.0～7.0 mm。结论通过使用自行开发的摆位验证系统,可使放疗摆位精度得到较大提高。但本方法的不足之处在于其目前还无法对因病人体型变化所造成的误差进行定量分析。

Research on System for Thorax Tumor Radiation Positioning Based on Optical Recognition and Image-Guidance

Objective To develop a set of position verification system, in order to reduce the positioning error of radiation therapy for the breast tumor patients and improve the precision of the radiation treatment. Methods When we do the radiation therapy position, three small gold particles should be put on the skin of patients＇ bony structure, and the location distribution of the three gold particles should be triangle, moreover, the distance between the gold particles should be short as possible. On the platform of Matlab 2010 software, we developed a set of system for position verification, the system adopted the method of image registration to distinguish the position of small goal particles on the patient＇s body surface, then calculated the 2 dimension coordinate value （X, Y） of the small gold particle, which could be used to quantize the displacement of radiation therapy position, in order to guide the therapist to verify the positioning error. In this paper, we selected one patient for 8 times of radiotherapy position, and the location error results of each time of the gold particles before position verification were compared with the ones after verification. Results After test and verification through the system, the position error on X axis-dX1 of the first gold particle tended to be reduced by 4.5-7.3 mm, the one on Y axis-dY1 tended to be reduced by 5.6-8.1 mm;the dX2 of the second gold particle reduced by 5.6-7.8 mm and the dY2 reduced by 5.7-7.8 mm;the dX3 of the third gold particle reduced by 5.3-8.4 mm and the dY3 reduced by 6.0-7.0 mm. Conclusions Through the system of position verification developed by ourselves, we can improve the precise of the radiation therapy position. But the defect of this method performs that we can not solve the problem that to do the quantitative analysis for the error which results from the patient body changes.