体表光学图像引导技术联合图像引导放疗技术等中心双引导复位在乳腺癌调强放疗中的应用

Application of SGRT Combined with IGRT Isocenter Dual-guided Resetting in IMRT for Breast Cancer

【目的】探讨体表光学图像引导技术(SGRT)联合图像引导放疗技术(IGRT)在乳腺癌术后放疗中实施等中心双引导复位的可行性,评估新的复位模式相对于传统复位模式的误差精度差异。【方法】回顾性分析2021年7月13日至2022年10月15日在中山大学肿瘤防治中心ELEKTA infinity加速器放疗的乳腺癌保乳术后患者,按不同复位方式分为模拟机复位组(模拟组)41例和双引导复位组(双引导组)40例。模拟组采用模拟机进行复位,首次用CBCT扫描并记录摆位误差;双引导组采用体表光学设备AlignRT引导摆位并联合CBCT进行等中心双引导复位,记录CBCT配准获取的摆位误差。分别计算并比较两种复位方式的胸壁靶区(CROI)的整体摆位误差、患侧锁骨头区域(SROI)的局部残余误差和复位时间,分析SGRT联合IGRT双引导复位的CBCT误差值分布的优点。【结果】模拟组和双引导组在CROI区域的整体摆位误差(X/cm、Y/cm、Z/cm、Rx°、Ry°、Rz°)中,除了Ry、Rz方向无统计学意义(P>0.05)外,其他方向摆位误差具有统计学意义(P<0.05)。模拟组和双引导组在患侧SROI区域的局部残余误差(X/cm、Y/cm、Z/cm、Rx°、Ry°、Rz°)中,除X、Z轴平移方向无统计学差异(P>0.05)外,其他方向均具有统计学意义(P<0.05)。模拟组的复位时间为(505.36±21.96) s明显大于双引导组的(238.64±28.56) s,t=-24.555,P=0.000,差异具有统计学意义(P<0.05)。分析双引导组的CBCT误差值分布,发现X、Y、Z轴平移误差绝对值均覆盖在0.4 cm以内,而≤0.3 cm的比例分别为95%、93%和93%,Rx、Ry、Rz旋转误差绝对值≤1.5°的比例分别为90%、93%和90%。【结论】在乳腺癌调强放疗中,与传统的模拟机复位模式相比,SGRT联合IGRT进行等中心双引导复位,可以有效校正旋转角度和残余误差,提高放疗的精准度,复位时间更少,可行性高。这种精准、无标记的复位方式可在临床推广使用。

【Objective】 The objective is to investigate the possibility of isocenter dual-guided resetting of surface guided radiation therapy(SGRT) combined with image guided radiation therapy(IGRT) in postoperative radiotherapy for breast cancer. To assess the setup error accuracy between the new resetting mode and the traditional resetting mode.【Methods】 Retrospective analysis was performed on breast cancer patients who underwent ELEKTA infinity accelerator radiotherapy in sun yat-sen university cancer center from July 13, 2021 to October 15, 2022. According to different reset methods, the patients were divided into a simulation group(41 cases) and a dual-guided group(40 cases). The simulation group was reset using a simulator, CBCT scans were performed and setup errors were recorded during the first treatment;The dual-guided group was guided by AlignRT and combined with CBCT for isocenter dual-guided resetting, and the setup error obtained by CBCT registration was recorded. The global setup errors of chest region of interest(CROI), the local residual errors of supraclavicular region of interest(SROI) and the resetting time of the two reset methods were calculated and compared respectively. The advantages of the CBCT error distribution in the dual-guided resetting of SGRT combined with IGRT were analyzed.【Results】 The median of the global setup errors(X/cm, Y/cm, Z/cm, Rx°, Ry°, Rz°) of the simulation group and the median of the dual-guided group in the CROI were statistically significant(P<0.05) except the Rz and Ry directions. The local residual errors of the two groups of the SROI were calculated. The median of the errors of X/cm, Y/cm, Z/cm, Rx°, Ry°, Rz° were statistically significant(P<0.05) except the X and Y axis. The resetting time of the simulation group was significantly longer than that of the dual-guided group(238.64±28.56) s, t=-24.555, P=0.000, and the difference was statistically significant(P<0.05). The CBCT error distribution of the dual-guide group was analyzed, and it was found that the absolute values of translation errors of X, Y and Z axis were all within 0.4 cm, while the proportions of ≤0.3 cm were 95%, 93% and 93%, respectively. The proportions of rotation errors of Rx, Ry and Rz ≤ 1.5 ° were 90%, 93% and 90%, respectively.【Conclusion】 In postoperative radiotherapy of breast cancer, SGRT combined with IGRT for isocenter dual-guided resetting can effectively correct the rotational setup errors and residual errors, and improve the accuracy of radiotherapy with less resetting time and high feasibility, which compared with the traditional simulator resetting mode. This precise, unmarked resetting method can be widely used in clinical practice.