前列腺癌调强放疗三维配准与六维配准的摆位误差相关性分析

Correlation between three-dimensional registration and six-dimensional registration in prostate cancer intensity-modulated radiation therapy

目的通过锥形束CT(CBCT)图像与定位CT图像的配准分析前列腺癌调强放疗摆位误差中三维匹配和六维匹配的差异性以及相关性。方法选取2015年8月至2020年8月在中山大学肿瘤防治中心收治的49例前列腺癌患者的图像配准资料,每次治疗前执行1次CBCT扫描,整个疗程共获取637套CBCT图像。最后在医科达MOSAIQ系统中通过CBCT图像与定位CT图像的配准,分析旋转误差与平移误差间的差异,初步以旋转角度1°为界对旋转误差分组,分析其与平移误差的相关性,并探究体位固定装置外扩边界的肿瘤靶区外放边界值(MPTV)大小有无差异。结果冠状位(Rtn)旋转误差与前后方向(Vrt)(r=0.187,P<0.001)、矢状位(Pitch)旋转误差与Vrt(r=0.183,P<0.001)和左右方向(Lat)(r=0.142,P<0.001)、横断位(Roll)旋转误差与Lat(r=0.116,P=0.003)均呈正相关。旋转误差<1°时对平移误差基本上无影响(P>0.05),旋转误差≥1°时,Rtn与Vrt(r=0.208,P<0.001)和Lat(r=0.116,P=0.009)、Pitch与Vrt(r=0.241,P<0.001)和Lat(r=0.153,P=0.005)均呈正相关,Pitch与Vrt呈现中等程度相关。Roll对Vrt、Lat、Lng(上下方向)均无相关性(P>0.05)。三维和六维配准在Vrt、Lat、Lng三个方向的MPTV比较,差异均无统计学意义(均P>0.05)。结论不能使用六维数据应用于三维床的平移,旋转误差>1°时,对平移误差有明显影响。当旋转误差Rtn≥1°时,对治疗床的升降有明显影响,旋转误差Pitch≥1°时,对治疗床的升降及左右有明显影响。

Objective Based on the accurate matching image of cone beam computed tomography(CBCT)and CT-simulation localization system,to compared the dfference and correlation between three-dimensional and six-dimensional matching in set-up error of intensity modulated radiotherapy(IMRT)for prostate cancer were analyzed.Methods The image registration data of 49 patients with prostate cancer admitted to Sun Yat-Sen university cancer center from August 2015 to August 2020 were selected.Each patient underwent one CBCT scan before treatment.A total of 637 CBCT images were obtained during the whole course of treatment.Finally,through the registration of CBCT image and location CT image in the Elekta MOSAIQ system.The above data were collected to analyze The difference between rotation erroe and translation error,preliminarily group the rotation error with the rotation angle of 1°as the boundary was collected and analyzed,and its correlation with translation error was analyzed.The difference in the size of tumor target external projection boundary value(MPTV)of the external expansion boundary of the postural fixation device was explored.Results Rotation errors were positively correlated between Rtn and Vrt(r=0.187,P<0.001),Pitch and Vrt(r=0.183,P<0.001),Lat(r=0.142,P<0.001),Roll and Lat(r=0.116,P=0.003).Rotation error<1°had no effect on translation error(P>0.05).When rotation error≥1°,Rtn was significantly higher than Vrt(P<0.001)and Lat(P=0.009),Pitch was positively correlated with Vrt(P<0.001)and Lat(P=0.005),and Pitch was moderately correlated with Vrt.Roll had no correlation with Vrt,Lat and Lng(P>0.05).There was no significant difference in MPTV between threedimensional and six-dimensional registration in Vrt,Lat and Lng(all P>O.05).Conclusions The six-dimensional data cannot be applied to the translation of the three-dimensional bed.When the rotation error is greater than 1°,it will obviously have a significant impact on the translation error.When the rotation error Rtn≥1°,it will have a significant impact on the lifting of the treatment bed,and when the rotation error Pitch≥1°,it will have a significant impact on the lift and left and right of the treatment bed.