ETX和CBCT两种图像引导技术在肝癌SBRT中的摆位误差比较分析

Comparative study on setup error of ETX and CBCT image guidance technology in SBRT of liver cancer

目的比较ExacTrac X-ray(ETX)和锥形束CT(CBCT)两种图像引导系统在肝癌立体定向放射治疗(SBRT)中的摆位误差。方法选择2019年4月至2020年12月在江苏省苏北人民医院接受SBRT放射治疗的30例肝癌患者,将其随机分为ETX组和CBCT组,每组15例。获取各组校正前后的误差,包括左右(X)、头脚(Y)和前后(Z)方向上的平移误差和绕前后方向上的旋转误差(Z_(r))。结果ETX组误差校正前后各方向误差比较,差异有统计学意义(P<0.05)。CBCT组校正前后各方向误差比较,差异有统计学意义(P<0.05)。CBCT组与ETX组校正后残留误差值比较,差异无统计学意义(P>0.05)。结论ETX和CBCT各有优缺点,但两者均能有效减少摆位误差。从减小肝癌SBRT摆位误差角度出发,采用灰度配准的CBCT误差纠正精度较采用骨性配准的ETX更高。

【Objective】To compare the positioning errors of ExacTrac X-ray(ETX)and cone beam CT(CBCT)image guidance systems in stereotactic body radiation therapy(SBRT)for liver cancer.【Methods】Thirty patients with liver cancer who received SBRT treatment from April 2019 to December 2020 were selected and divided into two groups,ETX and CBCT with 15 cases in each group,and the errors before and after correction of each group were obtained.The translation error in left and right(X),head and feet(Y)and front and back(Z)directions,and the rotation error(Z_(r))in the forward and backward directions were analyzed by paired t test with SPSS.【Results】(1)For the ETX group and the CBCT group,the residual error statistics(mean±standard deviation)in each direction after correction were significantly reduced(P<0.05);(2)After correction,the residual error statistics for the ETX group(mean±standard deviation)was slightly larger than that in the CBCT group,but it was not statistically significant(P>0.05).【Conclusion】ETX and CBCT have their own advantages and disadvantages,but they can effectively reduce the positioning error,but from the perspective of reducing the positioning error of liver cancer SBRT,the error correction accuracy of CBCT using gray-scale registration is higher than that of ETX using bone registration.