IMRT与3D-CRT治疗胸部食管癌的剂量学评价

The Dosiology Evaluation of IMRT vs. 3D-CRT for Thoracic Esophageal Cancer

目的:比较分析调强放疗(IMRT)和三维适形放疗(3D-CRT)计划在胸段食管癌治疗中的剂量学优劣。方法:选择我院行根治性放疗的胸段食管癌30例进行研究,根据不同部位进行亚组分析,瓦里安Eclipse计划系统制定放疗计划,按照不同部位食管癌的靶区勾画原则进行靶区勾画。处方剂量分别为:IMRT计划,CTV 51Gy/30F,GTV 66Gy/30F;3D-CRT计划,CTV 50Gy/25F,GTV66Gy/33F。相关的剂量学参数包括:靶区剂量和危及器官百分体积受照射剂量。结果:IMRT与3D-CRT比较,GTVmean(c Gy)两种技术之间差异无统计学意义;而CTVmean(c Gy)分别为5 921±256和6 255±289(P=0.000),IMRT低于3D-CRT;两肺平均剂量(MLD)(c Gy)、V30、V20、心脏V40、V30、脊髓Dmax方面,两者均有显著性差异,IMRT明显低于3D-CRT;双肺V10差异无统计学意义(P=0.492);双肺V5分别为60.9±19.2和53.9±12.8(P=0.004),IMRT高于3D-CRT。胸上段病变与中下段病变IMRT计划比较,GTVmean和CTVmean方面,两者之间差异均无统计学意义;两肺受照射的平均剂量(c Gy)、V30、V20、V10、V5、心脏V40、V30、脊髓最大剂量,两者差异均有统计学意义(P<0.05),上段病变明显低于中下段病变。结论:IMRT与3D-CRT技术相比,IMRT具有更好的剂量适形性,特别是胸上段病变,而且IMRT能够显著降低脊髓Dmax和MLD,以及双肺>10 Gy剂量的受照体积,但双肺V5有所增加。

Objective： To evaluate the dosimetry superiority of IMRT compared with 3D-CRT for thoracic esophageal cancer. Methods： Thirty patients with thoracic esophageal cancer who accepted radical radiotherapy in our hospital were included in this study. Varian Ecelipse treatment planing system was used to devise IMRT and 3D-CRT treatment plan. The target region of esophageal cancer was delineated according to target volume delineating principles of different segments. The prescription dose of IMRT were 51 Gy /30 F in CTV and 66 Gy /30 F in GTV,50 Gy /25 F in CTV and 66 Gy /33 F in GTV for 3D-CRT. Main dosimetry parameters included target region dose and percentage by volume dose of OAR.Results： No significant difference was found in GTVmean and V10 when comparing IMRT with 3D-CRT,while the CTVmean,MLD,V30,V20 of lung,V40,V30 of heart,Dmax of spinal cord in IMRT were lower than those of 3D-CRT respectively with significant difference. V5 of lung in IMRT and 3D-CRT were 60. 9 ± 19. 2 and 53. 9 ± 12. 8 respectively with significant difference（ P = 0. 004）. Comparing the IMRT planning for middle-lower segment esophageal cancer with that for upper segment esophageal cancer,there was no statistical difference in GTVmean and CTVmean,while MLD,V30,V20,V10,V5 of lung,V40,V30 of heart for upper segment esophageal cancer were significantly lower than those of middle-lower segment esophageal cancer. Conclusion： IMRT is superior to 3D-CRT in dose distribution,especially for upper esophageal cancer. IMRT can obviously reduce Dmax and MLD of spinal cord,and percentage by volume dose of more than 10 Gy for lung. While for V5 of lung,IMRT is higher than 3D-CRT.