Ⅱ期和Ⅲ期直肠癌术后盆腔调强放疗两种计划比较研究

摘要

Objective To explore the optimal method of protecting bone marrow in postoperative concurrent chemoradiotherapy of stage Ⅱ - Ⅲ rectal cancer by comparing two techniques of intensitymodulated radiotherapy (IMRT). Methods Fifteen patients with stage Ⅱ - Ⅲ rectal cancer after surgery had CT simulation. Clinical target volume, small bowel, bladder and bone marrow were contoured. Two IMRT treatment plannings with and without bone marrow-sparing (BMS-IMRT and IMRT) were separately designed. The dose distribution was compared based on that 95％ of the planning target volume received the prescribed dose. Results BMS-IMRT had an advantage over IMRT in terms of conformity indices ( 1. 06∶1. 04, t =- 2. 61, P =0. 023 ), but inferior to I M RT for homogeneity indices ( 0. 81 : 0. 75, t =- 2. 34, P =0.037)). Compared with IMRT, BMS-IMRT reduced the V5, V10, V20, V30, V40 of bone marrow (97.09％∶98.72％, t=-2.34, P=0.037;92.38％∶96.46％, t=-2.41, P=0.033;83.36％∶91.70％, t=-3. 18, P=0.008;51.47％∶69.65％, t=-4.92, P=0.000;36.34％∶49.57％, t=-2.66, P =0. 021 ). The doses received by small bowel and bladder were similar between BMS-IMRT and IMRT, except that the V20 of bladder was lower in BMS-IMRT (77. 32％∶92. 39％, t =-3.52, P=0. 004). Conclusions BMS-IMRT reduces low dose volume of bone marrow without increasing dose to other risk organs. BMS-IMRT might reduce acute hematologic toxicity and increase the feasibility of postoperative concurrent chemoradiotherapy in stage Ⅱ -Ⅲ rectal cancer.%目的 通过对Ⅱ、Ⅲ期直肠癌术后盆腔调强放疗(IMRT)两种计划比较,探讨保护骨髓最佳方案和提高间期放化疗可行性。方法 选取15例Ⅱ、Ⅲ期直肠癌术后患者经增强CT模拟定位后,在计划系统中勾画靶体积。设计对骨髓单独限量和不限量两种计划,在规定计划靶体积至少达95％处方剂量前提下比较靶区剂量分布及小肠、膀胱、骨髓受量体积并配对t检验差异。结果 骨髓单独限量计划靶区适形度(CI值)优于骨髓不限量的(1.06∶1.04,t=-2.61,P=0.023),但剂量均匀性(HI值)差于骨髓未限量的(0.81∶0.75,t=-2.34,P=0.037)。骨髓单独限量计划的骨髓接受低剂量照射体积(V5、V10、V20、V30、V40)小于骨髓未限量的(97.09％:98.72％,t=-2.34,P=0.037;92.38％:96.46％,t=-2.41,P=0.033;83.36％:91.70％,t-3.18,P=0.008;51.47％:69.65％,t=-4.92,P=0.000;36.34％∶49.57％,t=2.66,P=0.021),小肠和膀胱大都相似,只有膀胱V20不同(77.32％∶92.39％,t=3.52,P=0.004)。结论 骨髓单独限量计划显著降低了骨髓低剂量受照体积,在一定程度上降低急性骨髓抑制发生率,增强了同期放化疗在Ⅱ、Ⅲ期直肠癌患者可行性。