胃食管交界腺癌术后静态IMRT、VMAT和HT剂量学比较

A dosimetric comparison of static intensity-modulated radiotherapy, volumetric-modulated arc therapy, and helical tomotherapy after surgery for gastroesophageal junction adenocarcinoma

目的评价胃食管交界腺癌根治术后不同照射技术对靶区和正常组织剂量分布的影响，为临床治疗方法提供优选方案。方法对9例行根治性食管近端胃切除术或全胃切除术后的胃食管交界腺癌患者分别进行5个野静态IMRT、双弧VMAT和HT计划设计．通过DVH评价不同照射技术对靶区CI、HI和对OAR受量影响。放疗剂量45Gy（1．8Gy／次），同期每天口服替吉奥80mg／m2。放疗日分2次口服。结果HT靶区CI和HI好于IMRT和VMAT。对肠道和骨髓保护HT亦优于IMRT和VMAT。VMAT左肾V20、V30和心脏V30低于IMRT和HT，而IMRT双肺V5、V10较低；V20和Dmean三种技术差异不大。子野跳数平均数VMAT〈IMRT〈HT。结论3种放疗技术均能较好达到临床要求，但HT在保证最好靶区CI、HI前提下，对小肠和脊髓保护方面有优势，可能有助于降低患者相关不良反应发生。

Objective To investigate the effects of different irradiation techniques on dose distribution in target volume and normal tissues after the radical surgery for gastroesophageal junction adenocarcinoma,and to provide the optimal regimen for clinical treatment. Methods A total of 9 patients with gastroesophageal junction adenocarcinoma who underwent radical esophagus-proximal gastrectomy or total gastrectomy were enrolled. The therapeutic regimens of five-field static intensity-modulated radiotherapy （IMRT）, volumetric-modulated arc therapy （VMAT）, and helical tomotherapy （HT） were designed for each patient, and the dose-volume histogram was used to evaluate the effects of different irradiation techniques on the conformity index （CI） and homogeneity index （HI） of target volume and the surrounding normal tissues. The prescribed dose was 45 Gy at 1.8 Gy/fraction. The patients received oral S-1 as concurrent chemotherapy at a dose of 80 rag/（ m2 ~ d） twice a day during radiotherapy. Results Compared with IMRT and VMAT, HT had better CI and HI of the target volume,as well as a better protective effect on the intestinal tract and bone marrow. Compared with IMRT and HT,VMAT had a lower V20 and V30 for the left kidney and a lower V30 for the heart, while IMRT had lower V5 and V10 for both lungs;V20 and mean dose showed no significant differences between the three techniques. HT had the highest mean sub-field hop count, followed by IMRT and VMAT. Conclusions IMRT, VMAT, and HT can meet the clinical requirements, but besides ensuring the best CI and HI of the target volume, HT has a good protective effect on the intestine and spinal cord and＇ can help to reduce the incidence of adverse events in patients.