光学体表成像辅助乳腺癌根治术后放疗摆位的可行性研究

Feasibility study of optical surface imaging assisted postmastectomy radiotherapy set-up

目的:研究光学体表成像(OSI)在乳腺癌根治术后放疗(PMRT)摆位中的性能,并评估基于3D打印技术的硅胶补偿膜对OSI检测精度的影响。方法:回顾性选择2021年1至4月在四川大学华西医院就诊的PMRT患者16例,在使用锥形束CT(CBCT)校正误差前获取患者无补偿膜时OSI检测的摆位误差OSI no-bolus(OSI n),分析OSI n与CBCT的相关性,利用受试者工作特征曲线(ROC)评估OSI的诊断效能。对于使用3D打印硅胶补偿膜的患者,获取有补偿膜时OSI检测的摆位误差OSI bolus(OSI b),比较OSI n和OSI b的检测精度差异。结果:OSI n与CBCT摆位误差在平移方向呈高度相关(r≥0.80),在旋转方向呈弱相关(r<0.40)。在ROC分析中,y方向的曲线下面积(AUC)最低,且对任意平移方向都有AUC 5 mm≥AUC 3 mm>0.75。在检测精度中,OSI n与OSI b在x和z方向的差异无统计学意义(P>0.05),在y方向的差异有统计学意义(Z=-2.56,P=0.01)。在y方向上,OSI b与OSI n相比检测精度的系统误差增大3.11 mm,随机误差增大1.9 mm。结论:在乳腺癌放疗摆位中OSI尚无法替代CBCT,但检测误差在临床可接受范围内,通过操作训练减轻成像路径上补偿膜等因素的干扰,OSI辅助摆位的性能有望进一步提高。

Objective To investigate the performance of optical surface imaging(OSI)in the postmastectomy radiotherapy setup and to assess the effects of 3D printed silicone bolus on OSI detection precision.Methods A retrospective analysis was conducted for 16 patients treated with left-sided postmastectomy radiotherapy(PMRT)in West China Hopital,Sichuan University from January to April,2021.The setup errors of 16 patients without bolus detected using OSI(OSIno-bolus,OSIn)were obtained before error correction was conducted using cone-beam CT(CBCT).The correlation between OSIn and CBCT was analyzed,and then the diagnostic efficacy of OSI was assessed using the receiver operating characteristic(ROC)curves.The setup errors of six patients with 3D printed silicone bolus detected using OSI(OSIbolus,OSIb)were obtained through off-line image registration,and then the detection precision of OSIn and OSIb in the translational directions was compared.Results The setup errors in the case of OSIn were highly correlated with CBCT in the translational direction(r≥0.80),but were weakly correlated in the rotation direction(r<0.40).In the ROC analysis,the area under the curve(AUC)in the y direction was the lowest and was in the order of AUC5 mm≥AUC3 mm>0.75 for any translational direction.The difference in the detection precision between OSIn and OSIb was not statistically significant in the x and z directions(P>0.05),but was statistically significant in the y direction(Z=-2.56,P=0.01).In the y direction,the systematic error of detection precision in the case of OSIb was 3.11 mm higher than that in the case of OSIn,and the random error of detection precision in the case of OSIb was 1.9 mm higher than that in the case of OSIn.Conclusions OSI cannot yet substitute CBCT in the postmastectomy radiotherapy setup,but its detection error is still within the clinically acceptable range.The performance of OSI-assisted setup is expected to be further improved by mitigating the interference of factors such as bolus in the imaging path through operational training.