不可手术食管癌患者序贯加量IMRT与同步推量IMRT的剂量学比较分析

Dosimetric analysis of sequential boost intensity-modulated radiotherapy and simultaneous integrated boost intensitymodulated radiotherapy in patients with inoperable esophagus carcinoma

目的对比不可手术食管癌序贯加量调强放射治疗(SB-IMRT)计划与同步推量调强放射治疗(SIB-IMRT)计划在靶区参数上的区别,以及对正常器官的影响程度。方法选择日照市人民医院2018年10月至2022年5月拟行放射治疗的不可手术食管癌患者30例,其中男性25例,女性5例;年龄60~88岁,中位年龄68.2岁;病变长度4.0~17.6 cm,平均病变长度6.37 cm(标准差2.76 cm);临床分期为c Tx N1-2M0-1期。分别制定SB-IMRT与SIB-IMRT两种放射治疗计划,并采用靶区勾画、射束设野、靶区覆盖、剂量均匀性、危及器官(OAR)、处方剂量(CB-CHOP)审核通过放射治疗计划。SIB-IMRT给予剂量方法为在一个计划中临床计划靶区(PCTV)50.4 Gy,肿瘤计划靶区(PGTV)剂量同步给予59.92 Gy,共28次完成。SB-IMRT剂量要求为PCTV 50 Gy,均分25次完成;完成后修改照射野局部加照至10 Gy,均分5次完成。SB-IMRT放射治疗需设计前后两套计划,再做计划叠加处理,合成一套计划后根据处方剂量要求优化计划并记录靶区参数和OAR限量。采用均匀性指数(HI)、适形性指数(CI)、靶区覆盖度(TC)及剂量分布、OAR限量等参数分别评估。结果两组计划的PCTV-Dmax、PGTV-Dmax和PCTV-Dmin剂量差异无统计学意义(均P>0.05),但SIB-IMRT组PCTV-Dmean、PGTV-Dmin、PGTV-Dmean均低于SB-IMRT组,差异有统计学意义[(57.38±1.73)Gy vs(58.13±2.38)Gy、(51.41±4.90)Gy vs(54.76±6.31)Gy、(61.22±2.10)Gy vs(62.86±2.03)Gy。P>0.05]。两组计划的PCTV-TC值比较,差异无统计学意义(P>0.05)。SB-IMRT组CI优于SIB-IMRT组,而HI次于SB-IMRT组,两组间CI、HI值比较,差异有统计学意义(0.55±0.10 vs 0.60±0.11、1.20±0.38 vs 1.24±0.39。P<0.05)。SIB-IMRT组PGTV和PCTV的生物效应剂量(BED)分别为72.74 Gy、59.47 Gy;SB-IMRT组PGTV和PCTV的BED分别为72 Gy、60 Gy。SIB-IMRT组脊髓Dmax、双肺V5和心脏的平均心脏剂量(MHD)低于SB-IMRT组,差异均有统计学意义[(41.83±2.48)Gy vs(43.27±1.99)Gy、(41.06±11.74)Gy vs(42.26±11.52)Gy、(20.77±8.81)Gy vs(22.72±9.23)Gy。P<0.05]。双肺V_(10)、V_(20)、V_(30)、平均肺剂量(MLD)和心脏V_(30)、V40两组间比较,差异无统计学意义(P>0.05)。结论在不可手术食管癌放射治疗中,相似或/和相等处方剂量的SB-IMRT计划和SIB-IMRT计划,前者仅CI略占优势,后者计划一次成型,能同时给予肿瘤靶区和临床预防靶区不同梯度的剂量照射,具有高效、精确,生物效应高、OAR受照剂量更低的优势,值得临床推广。

Objective To compare the difference of dose distribution in target area and organs at risk between sequential boost intensity-modulated radiotherapy(SB-IMRT)and simultaneous integrated boost intensity-modulated radiotherapy(SIBIMRT)for inoperable esophageal carcinoma.Methods From October 2018 to May 2022,a total of 30 inoperable patients with esophagus carcinoma performed radiotherapy were enrolled,which included 25 males and 5 females,aged 60-88 years old with median age of 68.2 years old;lesion length was 4.0-17.6 cm with mean of 6.37 cm(standard deviation 2.76 cm);clinical stage was cTxN1-2M0-1.The SB-IMRT and SIB-IMRT plans were developed respectively,and the radiotherapy plan was approved by target delineation,beam field setting,target coverage(TC),dose uniformity,organ at risk(OAR),and prescription dose(CB-CHOP).The dose method of SIB-IMRT was 50.4 Gy for clinical planning target volume(PCTV)and 59.92 Gy for tumor planning gross target volume(PGTV)in one plan,28 times in total.The dose requirement of SB-IMRT was PCTV 50 Gy with mean of 25 times.Then,the radiation field was modified and locally irradiated to 10 Gy with mean of 5 times.The SB-IMRT was designed 2 sets of plan,and then the plans were superimposed.After integration of a set of plan,it was optimized according to prescription dose requirements,and the target area parameters and OAR limits were recorded.The homogeneity index(HI),conformity index(CI),TC,dose distribution and OAR limits were evaluated respectively.Results There was no significant difference in dosage parameters of PCTV-Dmax,PGTV-Dmax and PCTV-Dmin between 2 groups(all P>0.05),while PCTV-Dmean,PGTV-Dmin and PGTV-Dmean values of SIB-IMRT group were lower than those of SB-IMRT group,and difference was statistically significant[(57.38±1.73)Gy vs(58.13±2.38)Gy,(51.41±4.90)Gy vs(54.76±6.31)Gy,(61.22±2.10)Gy vs(62.86±2.03)Gy.P>0.05].There was no significant difference in PCTV-TC values between 2 groups(P>0.05).The CI of SB-IMRT group was better than that of SIB-IMRT group,while HI was inferior to SB-IMRT group.The difference of CI and HI was statistically significant between 2 groups(0.55±0.10 vs 0.60±0.11,1.20±0.38 vs 1.24±0.39.P<0.05).The biological effect doses(BED)of PGTV and PCTV in SIB-IMRT group were 72.74 Gy and 59.47 Gy,respectively.The BED of PGTV and PCTV in SBIMRT group were 72 Gy and 60 Gy,respectively.The spinal cord Dmax,lung V5 and heart MHD in SIB-IMRT group were lower than those in SB-IMRT group,and the differences were statistically significant[(41.83±2.48)Gy vs(43.27±1.99)Gy,(41.06±11.74)Gy vs(42.26±11.52)Gy,(20.77±8.81)Gy vs(22.72±9.23)Gy.P<0.05].There was no significant difference in V_(10),V_(20),V_(30),mean lung dose(MLD)and heart V_(30),V40 between 2 groups(P>0.05).Conclusion It is demonstrated that in radiotherapy of inoperable esophageal carcinoma by similar or/and equal prescription doses of SB-IMRT plan and SIB-IMRT plan,SB-IMRT only showed slight advantage in CI,while SIB-IMRT could give different gradients of dose irradiation to tumor target area and clinical prevention target area at the same time,which with the advantages of high efficiency,accuracy,high biological effect and lower OAR dose,and is worthy of clinical promotion.