Monaco计划系统中Conformality函数对宫颈癌容积旋转调强计划的影响

I mpact of Conformality function in Monaco planning system on volume-modulated arc therapy plan for cervical cancer

目的 探讨Monaco计划系统中Conformality函数的不同参数值对计划质量的影响。方法 选择15例宫颈癌患者,年龄46~74岁,中位年龄51岁。分别采用Conformality函数参数值为0.25、0.50、0.75、1.00,以及不加函数设计容积旋转调强放射治疗(VMAT)计划,评估靶区及危及器官(OAR)剂量学参数和20 Gy、30 Gy、40 Gy等剂量线的体积和计划执行效率。结果 不同Conformality函数参数值计划的靶区剂量学差异均有统计学意义(P <0.05)。Conformality函数参数值为0.25时,靶区的Dmax、Dmin、Dmean与不加函数的增减幅度分别为2.45%、-0.96%、1.48%,适形度指数(CI)、均匀性指数(HI)增加0.05、0.04。当Conformality函数参数值> 0.50时,CI、HI基本无改变。小肠、结肠、左右股骨头的剂量学差异无统计学意义(P> 0.05)。当Conformality函数参数值为0.25时,直肠的V30、V40[(81.80±7.74)%、(63.44±10.23)%]、膀胱V30、V40[(78.82±5.69)%、(56.40±9.33)%]、正常组织V_(20)、V_(30)、V_(40)的体积[(6 137.64±622.88) cm^(3)、(2 903.55±221.08) cm^(3)、(1 862.93±112.81) cm^(3)]最低。Conformality函数在不同参数之下,膀胱、直肠V_(30)、V_(40)差异均具有统计学意义(P <0.05)。随着Conformality函数参数值增大机器参数值随之减小,机器跳数(MU)、控制点个数(CP)、执行时间(DT)在各Conformality函数参数值之间差异均有统计学意义(P <0.05)。结论 对于宫颈癌在Monaco计划系统中恰当使用Conformality函数设计计划可以提高计划质量,参数值设置在0.25~0.75为宜。综合剂量学参数及计划执行效率,推荐使用0.50。

Objective To explore the impaction of different parameter values of Conformality function on the quality of Monaco planning system. Methods A total of 15 patients with cervical cancer were enrolled, which aged 46-74 years old with mean age of 51 years old. The volume-modulated arc therapy(VMAT) plan was designed without the function or with parameters of the Conformality function of 0.25, 0.50, 0.75, 1.00, respectively, and non-function plans were used to evaluate dosimet ric parameters of target area, organs at risk(OAR), volume and plan execution efficiency of 20 Gy, 30 Gy and 40 Gy isodose lines. Results There were statistically significant differences of target dosimetry among different function parameter plans( P <0.05). When the Conformality function parameter value was 0.25, the increase and decrease of Dmax, Dmin, Dmeanand non-function in target area were 2.45 %,-0.96 % and 1.48 %, respectively;the conformity index(CI) and homogeneity index(HI) increased 0.05and 0.04, respectively. When Conformality function parameter value was > 0.50, there was no significant change in CI and HI, and no significant difference in dosimetry between small intestine, colon, left and right femoral head(P > 0.05). When the parameter value was 0.25, rectum V30, V40[(81.80 ± 7.74) %,(63.44 ± 10.23) %], bladder V30, V40[(78.82 ± 5.69) %,(56.40 ± 9.33) %], normal tissue V_(20), V_(30), V_(40)[(6 137.64 ± 622.88) cm^(3),(2 903.55 ± 221.08) cm^(3),(1 862.93 ± 112.81) cm^(3)] showed the lowest. There were sta tistically significant differences in V_(30)and V_(40)of bladder and rectum among different parameters(P < 0.05). With the increase of Conformality function parameteer value, the machine parameter value decreased, and the differences of machine unit(MU),number of control point(CP) and delivery time(DT) in each function parameter value were statistically significant( P < 0.05).Conclusion It is demonstrated that the proper use of Conformality function design in cervical cancer Monaco planning system can improve the plan quality, and the parameter value is appropriate to set between 0.25 and 0.75, and 0.50 is recommended for clinic with comprehensive dosimetric parameters and plan execution efficiency.