应用六自由度床的直肠癌盆腔放疗患者的不同固定方式比较分析

目的 探讨在使用六自由度床的情况下,接受盆腔放疗的直肠癌患者的固定方式选择.方法 通过对北医三院放射治疗科2015年11月1日至2016年3月25日行盆腔放射治疗的27例直肠癌患者整个疗程中的六自由度床校正摆位误差的分析,比较低温热塑膜和真空垫的固定效果.热塑膜体网入组17例患者(组1),负压真空垫组入组10例患者(组...

Comparative analysis of different fixation methods for rectal cancer patients with pelvic radiotherapy based on 6-DOF bed

Objective To explore the choice of fixation options for rectal cancer patients receiving pelvic radiotherapy under the condition of using a 6-DOF(six-degree-of-freedom)bed.Methods Twenty-seven patients with rectal cancer who underwent pelvic radiotherapy in our department from November 1,2015,to March 25,2016,were analyzed of the setup errors to evaluate the fixation effect of low-temperature thermoplastic film and vacuum pad.Results There were significant differences in X,Y,Z,RX,RY,and RZ in the heat-shrinkable film mesh group before and after the 6-DOF bed correction(t=0.732,1.408,-2.335,5.237,-3.154,-1.130;P<0.05).There were significant differences in Z,RX,and RY directions in the negative pressure vacuum pad group before and after the correction 6-DOF bed(t=-13.128,9.945,-5.993;P<0.05),but there was no significant difference in X,Y and RZ directions(t=1.706,6.508,-5.34;P>0.05).The results showed that during the treatment,the thermoplastic membrane mesh group had a proper correction effect.Before the 6-DOF bed correction,the setup errors of the two groups were statistically different only in the direction of RY(t=2.226,P=0.027)and RZ(t=-2.686,P=0.008),and there was no significant difference in other directions(P>0.05).Moreover,the setup errors in the RZ direction of the vacuum pad fixation group were smaller than that of the thermoplastic film body mesh group,indicating that the vacuum pad fixation effect in the patient's body's long axis is ideal.After 6-DOF bed correction,the setup errors of the two groups were statistically different only in the Z direction(t=3.267,P=0.001),but there was no significant difference in other directions(P>0.05).Moreover,the thermoplastic film mesh group's setup errors in the Z direction were smaller,which indicated that the thermoplastic film mesh group had better fixation efficiency in Z direction after a 6-DOF bed correction.Before a 6-DOF bed correction,the PTV extension boundary of X,Y,and Z of group 1 was 0.33 cm,0.61 cm,and 0.90 cm,respectively;The PTV extension boundary of X,Y,and Z of group 2 was 0.39 cm,0.42 cm,and 0.99 cm,respectively.After a 6-DOF bed correction,the PTV extension boundary of X,Y,and Z of group 1 was 0.09 cm,0.06 cm,and 0.08 cm,respectively;the PTV extension boundary of X,Y,and Z of group 2 was 0.12 cm,0.2 cm,and 0.57 cm,respectively.The results showed that the thermoplastic film mesh group had better fixation efficiency.Conclusion In this study,we recommend using heat shrinkable mesh for the fixation of rectal cancer patients receiving pelvic radiotherapy,when the 6-DOF bed is used.