非小细胞肺癌3～5个脑转移瘤优选调强放疗的可行性研究

The feasibility of choosing intensity-modulated radiotherapy to treat 3 - 5 brain metastases from non- small cell lung cancer

目的探讨调强放疗（IMRT）技术治疗非小细胞肺癌3～5个脑转移瘤的优势。方法选择30例已完成IMRT的非小细胞肺癌1～5个脑转移病例，设计全脑放疗（WBRT）加三维适形放疗（3DCRT）、WBRT加立体定向放疗（SRT）计划，用剂量体积直方图分析3种技术之间的优势并Wilcoxon非参数检验。结果全组患者IMRT计划靶体积（PTV）肩部的D99%明显高于WBRT＋3DCRT和WBRT＋SRT（Z=-4．72、P=0．000和Z=-4．72、P=0．000）；对3—5个脑转移瘤的13例患者IMRT的胛V斜坡的D10％和尾部的D5％明显低于WBRT＋3DCRT与WBRT＋SRT[（35．1±1．42）Gy、（36．5±2．86）Gy与（36．2±2．57）Gy（Z=-3．18、-3．18，P=0．001、0．001）和（37．7±2．91）Gy、（39．1±3．56）Gy与（38．7±3．67）Gy（Z=-4．11、-3．02，P=0．000、0．002）]。全组患者WBRT＋SRT总机器跳数比IMRT减少达38．7％，IMRT、WBRT＋3DCRT与WBRT＋SRT的分别为14756．3、9614．8、9043．2MU（Z=-4．78、-4．78，P：0．000、0．000）。3种技术对1—2个转移瘤的周围脑组织剂量相似，3—5个转移瘤的则调强技术最优。结论IMRT技术能提高靶区最小剂量和降低周围脑组织受量，特别对3～5个转移瘤的优势更突出。

Objective This study evaluates the feasibility of intensity-modulated radiation therapy （IMRT） to treat patients with 1 -5 brain metastases from non-small cell lung cancer （NSCLC）. Methods 30 IMRT patients with brain metastases for NSCLC studied retrospectively. Whole brain radiotherapy plus three-dimensional eonformal radiotherapy （ WBRT ＋ 3DCRT ） and WBRT plus stereotactie radiotherapy （WBRT ＋ SRT ） plans were generated. Planning target volume （PTV） and organs at risk dose were measured and compared by dose volume histogram. Differences were analyzed in the three techniques by Wilcoxon Z -test. Results D99% of the shoulder （ D99% -D90% ） from IMRT were higher than from WBRT ＋ 3DCRT and WBRT ＋ SRT in all cases. From D15% of slope （ D90% -D10% ） to D5% of tail （ D10% -D1% ）, IMRT were lower than WBRT ＋3DCRT and WBRT ＋ SRT （Z = -4. 72,P =0. 000 and Z = -4. 72,P =0. 000）. D10% andD5% of IMRTwere （35.1±1.42） Gyand （37.7±2.91） Gy, WBRT＋3DCRTwere （36.5± 2. 86 ） Gy and （39.1 ± 3.56） Gy ; WBRT ＋ SRT were （ 36.2 ± 2. 57） Gy and （38.7 ± 3.67 ） Gy. IMRT vs WBRT ＋ 3DCRT and WBRT ＋ SRT were significant （ Z = - 3.18, - 3.18, P = 0. 001,0. 001 and Z = -4. 11, -3.02, P = 0. 000,0. 002 ） in 13 patients with 3 -5 brain metastases. The total mean monitor units were 14756. 3,9614. 8 and 9043.2 for IMRT, WBRT ＋ 3DCRT and WBRT ＋ SRT plans, respectively, with a 38.7% reduction from IMRT to WBRT ＋ SRT （Z = -4.78, -4. 78 ,P =0. 000,0. 000）. The brain doses around metastases were similar in the three techniques with 1 -2 metastases, but IMRT was the best with 3 -5 metastases. Conclusions IMRT can advance brain metastases dose and improve the planning target minimum dose and spare the dose around brain metastases. Only IMRT is the best choice for just sparing the dose around brain metastases among 3 -5 brain metastases.