目的   探讨与分析实时图像引导系统对乳腺癌保乳术后放射治疗（放疗）摆位误差的影响。方法   选取安阳市肿瘤医院2021年9月—2023年12月收治的乳腺癌保乳术后108例患者为研究对象，按照随机信封抽签法把108例患者分为实时组54例与对照组54例。两组的放疗观察时间均为3个月，对照组给予热塑体模定位，实时组给予实时图像引导系统定位，记录两组的摆位误差与放疗不良反应发生情况。结果   实时组X轴、Y轴、Z轴方向的配准结果误差发生率分别为1.85%、7.41%、1.85%，均低于对照组的14.81%、22.22%、16.67%（χ ² =5.939，P=0.015；χ ² =4.696，P=0.030；χ ² =7.053，P=0.008）。实时组摆位纠正前X轴、Y轴、Z轴误差大于对照组（t分别为38.888、28.106、50.102，P＜0.05），摆位纠正后两组摆位误差对比差异无统计学意义（P＞0.05）。实时组放疗3个月期间的心脏平均受量、肺脏平均受量均少于对照组（t分别为49.942、13.996，P＜0.001）。实时组放疗3个月期间的急性放射性皮肤反应发生率为3.70%，对照组为16.67%，实时组低于对照组（χ ² =4.960，P＜0.05）。结论   实时图像引导系统在乳腺癌保乳术后放疗的应用可减少摆位误差，也能减少患者的心脏平均受量、肺脏平均受量，降低急性放射性皮肤反应发生率。

       Objective  To investigate and analysis the effects of image-guided radiation therapy on the positioning error of radiotherapy after breast conserving surgery for breast cancer．Methods  from September 2021 to December 2023，108 patients with breast cancer after breast conserving surgery in Anyang Cancer Hospital were selected as the study subjects．According to the principle of random envelope drawing，108 patients were divided into the real-time group of 54 patients and the control group of 54 patients．The observation time for radiotherapy in both groups was 3 months．The control group was given thermoplastic phantom positioning，while the real-time group was given image-guided radiation therapy positioning．The positioning errors and incidence of radiotherapy adverse reactions were recorded in both groups．Results  The error rates of registration results in the X-axis，Y-axis，and Z-axis directions of the real-time group were 1.85%，7.41% and 1.85%，respectively，which were significantly lower than the control group（14.81%，22.22% and 16.67%；χ ² =5.939，P=0.015；χ ² =4.696，P=0.030；χ ² =7.053，P=0.008）．The errors in the X-axis，Y-axis and Z-axis before the pendulum correction were greater than that in the control group（t=38.888，28.106，50.102，P＜0.05），and there were no statistically significant difference in positioning errors compared between the two groups after positioning correction（P＞0.05）．The average cardiac and lung uptake during the 3-month period of real-time radiotherapy in the group were significantly lower than those in the control group（t=49.942，13.996，P＜0.001）．The incidence of acute radiation-induced skin reactions during the 3-month period of real-time group radiotherapy was 3.70%，compared to 16.67% in the control group，the real-time group showed a significant decrease（χ ² =4.960，P=0.026＜0.05）．Conclusions  The application of image-guided  radiation therapy in radiotherapy after breast conserving surgery for breast cancer can reduce the positioning error，the average cardiac and pulmonary dose，and the incidence of acute radiation skin reaction．