质子笔形束调强技术在颅脑肿瘤放疗中应用价值

Application value of intensity modulated proton therapy in radiotherapy of intracranial tumors

目的比较质子调强放疗(IMPT)、光子调强放疗(IMRT)、光子容积旋转调强放疗(VMAT)计划在颅脑内肿瘤患者放疗中剂量学优势。方法选取山东省肿瘤医院质子中心2022-07-26-2022-11-08收治的10例颅脑内肿瘤患者分别设计IMPT、IMRT、VMAT计划,统计有代表性的剂量学数据:靶区适形度指数(CI),靶区均匀性指数(HI),梯度指数(GI),靶区最大点剂量、平均剂量,颅脑内平均剂量,2 Gy剂量对应体积(V2 Gy),5 Gy剂量对应体积(V5 Gy),10 Gy剂量对应体积(V10 Gy)以及脑干最大点剂量。结果IMPT计划靶区平均剂量为(51.57±0.49)GyE,低于IMRT[(52.30±0.31)Gy]和VMAT计划[(52.38±0.35)Gy],Z值分别为-3.161和-3.180,均P=0.001。IMPT计划靶区覆盖率为(99.39±1.53)%,优于IMRT[(99.30±0.76)%]和VMAT计划[(98.75±1.19)%],Z值分别为2.190和2.608,P值分别为0.029和0.009。VMAT计划CI为0.88±0.03,高于IMRT(0.85±0.07)和IMPT计划(0.47±0.18),Z值分别为-3.515和-3.742,均P<0.001。IMPT计划V2 Gy为(492.16±172.51)cm3,优于IMRT[(1052.14±349.8)cm3]和VMAT计划[(1165.9±320.12)cm3],Z值分别为-3.213和-3.515,P值分别为0.001和<0.001;V5 Gy为(391.53±156.04)cm3,优于IMRT[(826.00±318.16)cm3]和VMAT计划[(802.19±341.54)cm3],Z值分别为-2.986和-2.910,P值分别为0.003和0.004;V10 Gy为(286.98±150.47)cm3,优于IMRT计划[(520.42±281.48)cm3],Z=-2.079,P=0.038。结论光子IMRT、VMAT和质子IMPT技术均能满足临床要求。相比于光子,质子放疗有更少的低剂量区。但对于靠近靶区的危及器官,IMPT相比于IMRT和VMAT在控制最大点剂量方面无明显优势。

Objective To compare the dosimetric advantages of intensity modulated proton therapy(IMPT),intensity modulated radiation therapy(IMRT),and volume modulated arc therapy(VMAT)plans in radiotherapy for patients with intracranial tumors.Methods Ten patients with intracranial tumors admitted to the Proton Center of Shandong Cancer Hospital from July 26,2022to November 8,2022were selected to design IMPT,IMRT,and VMAT plans respectively.Representative dosimetry data were calculated:target conformability index(CI),target homogeneity index(HI),gradient index(GI),maximum target dose,average dose,average intracerebral dose,V2Gy,V5Gy,V10Gy,and the maximum dose received by the brainstem.Results The average dose of the IMPT program target area was(51.57±0.49)GyE,which was lower than that of IMRT[(52.30±0.31)Gy]and VMAT plan[(52.38±0.35)Gy],with Z values of-3.161and-3.180,respectively,both P=0.001.The coverage rate of the IMPT program target area was(99.39±1.53)%,which was superior to IMRT[(99.30±0.76)%]and VMAT plan[(98.75±1.19)%],with Z values of 2.190and 2.608,and Pvalues of 0.029and 0.009,respectively.The CI of VMAT plan was 0.88±0.03,higher than that of IMRT(0.85±0.07)and IMPT plan(0.47±0.18),with Zvalues of-3.515and-3.742,respectively,both P<0.001.The V2Gyof the IMPT plan was(492.16±172.51)cm3,which was superior to the IMRT[(1052.14±349.8)cm3]and the VMAT plan[(1165.9±320.12)cm3],the Zvalues were-3.213and-3.515,respectively,and the Pvalues were 0.001and<0.001,respectively.V5Gywas(391.53±156.04)cm3,which was superior to the IMRT[(826.00±318.16)cm3]and VMAT plan[(802.19±341.54)cm3],with Zvalues of-2.986and-2.910,and Pvalues of 0.003and 0.004,respectively.V10Gywas(286.98±150.47)cm3,which was superior to the IMRT plan[(520.42±281.48)cm3],Z=-2.079,P=0.038.Conclusions IMRT,VMAT and IMPT can meet the clinical requirements.Proton radiotherapy has fewer low-dose regions than photons.However,for the endangered organs close to the target,IMPT has no obvious advantage over IMRT and VMAT in controlling the maximum point dose.