摘要目的:比较AlignRT光学引导方法与传统标记线方法对摆位精度的影响，探究患者胸廓特征参数对光学引导摆位精度的影响。方法:回顾性选择2022年7月至2023年9月在安徽省肿瘤医院接受保乳术后放疗的60例乳腺癌患者病例资料，根据摆位方式平均分为传统十字线摆位(标记线组)和体表光学引导放疗(SGRT)摆位(SGRT组)，每组30例。以锥束CT扫描结果为金标准，对比分析两组三维摆位误差及临床靶体积-计划靶体积(CTV-PTV)靶区外放边界。定义多组患者胸廓特征参数，分析各胸廓特征参数SGRT摆位误差的相关性。结果:SGRT组和标记线组的三维方向摆位误差均值分别在0.2和0.5 cm以内，且两组三维方向摆位误差及总位移的差异具有统计学意义( z＝－2.93、－3.22、－2.59、－4.76， P<0.05)；SGRT组将CTV-PTV靶区外扩边界由传统标记法的0.5 cm缩小至0.3 cm；胸廓纵横比H/W、患侧夹角α1、健侧夹角α2与 x方向摆位误差呈正相关( r＝0.49、0.59、0.71， P<0.05)；而患侧及健侧乳腺高度D1、D2与 z方向摆位误差呈负相关( r＝－0.46、－0.49， P<0.05)。 结论:对于保乳术后放疗患者，SGRT能获得比传统标记线方法更精确的放疗摆位，可以有效缩小靶区外扩范围。同时，SGRT监测精度受患者胸廓特征参数影响，临床中需重点关注体型偏厚、体宽偏窄以及乳腺腺体偏小的保乳放疗患者。

abstractsObjective:To compare the impact of the AlignRT-based optical guidance method with the traditional marker line method on the accuracy of positioning, and explore the effect of patient′s different thoracic characteristic parameters on the precision of optical guidance positioning.Methods:A total of sixty breast cancer patients who received post breast-conserving radiotherapy at Anhui Cancer Hospital from July 2022 to September 2023 were retrospectively selected. Then these patients were equally divided into traditional cross hairs set-up (marker line group) and surface-guided set-up (SGRT group). The cone-beam CT scanning results were used as the gold standard, the three-dimensional set-up errors and the CTV-PTV target area external radiotherapy boundaries of two groups were studied comparatively. Multiple patient′s thoracic characteristic parameters were defined and the correction between each parameter and set-up error of SGRT was analyzed.Results:The mean value of three-dimensional set-up errors in the SGRT group and the marker line group was within 0.2 cm and 0.5 cm, respectively. The differences in three-dimensional set-up errors and total displacements between two groups were statistically significant ( z=-2.93, -3.21, -2.59, -4.76, P<0.05). The SGRT group reduced the CTV-PTV boundary from 0.5 cm of conventional marker line group to 0.3 cm. The thoracic aspect ratio H/W, the affected side pinch angle α1, and the healthy side pinch angle α2 were positively correlated with the x-direction posing error ( r=0.49, 0.59, 0.71, P<0.05); whereas, the affected side and the healthy side mammary gland heights D1 and D2 were negatively correlated with the z-direction posing error ( r=-0.46, -0.49, P<0.05). Conclusions:For breast-conserving postoperative radiotherapy patients, SGRT can obtain a more accurate radiotherapy set-up than the traditional marker line method, and can effectively reduce the target area externally expanded range. Meanwhile, the monitoring accuracy of SGRT is affected by the patient′s thoracic characteristic parameters, and clinical attention should be paid to breast-conserving radiotherapy patients with thick body shape, narrow body width, and small breast glands.