Irradiated dose to unprotected lymph node stations in the VMAT and IMRT treatment of patients with upper thoracic esophageal cancer
10.3760/cma.j.issn.0254-5098.2020.01.006
- VernacularTitle: 上胸段食管癌调强放射治疗中淋巴结意外照射的剂量学研究
- Author:
Jiahao WANG
1
;
Pengjun ZHAO
;
Lixia XU
;
Jianjun LAI
;
Qinghua DENG
;
Bing XIA
Author Information
1. Department of Radiation Oncology, Hangzhou Cancer Hospital, Hangzhou 310002, China
- Publication Type:Journal Article
- Keywords:
Esophageal cancer;
Irradiated dose to unprotected LNS;
VMAT;
IMRT
- From:
Chinese Journal of Radiological Medicine and Protection
2020;40(1):36-41
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To compare the irradiated dose to unprotected lymph node stations (LNS) between volume-modulated arc therapy (VMAT) and 5-field intensity-modulated radiotherapy (5F-IMRT) in the treatment of patients with upper thoracic esophageal cancer.
Methods:A total of 20 patients were selected for re-planning. LNS were not included in the GTV and CTV, instead, LNS were contoured as normal tissues. However, LNS were not constrained in the VMAT and 5F-IMRT inverse optimization for protection. Dosimetric parameters of conformal index (CI), homogeneity index (HI) of targets, V95, V110 of planning target volume (PTV), Dmean, V5, V20, V30 of lung, Dmean, V25 of heart, Dmax of spinal cord, MU, as well as the equivalent uniform dose (EUD) and V40 of LNS were compared between the two plans.
Results:5F-IMRT was superior in PTV_V95% (t=-9.4, P<0.05), but worse in terms of CI (t=-5.3, P<0.05) compared with VMAT. 5F-IMRT reduced the V5 of lung by 10.9% (t=-7.8, P<0.05) and the Dmax of spinal cord by 9% (t=-10.2, P<0.05), but increased the MU (t=-6.2, P<0.05) compared with VMAT. The average EUD and V40 of LNS in upper thoracic were significantly increased by 4.7% and 2.4% in 5F-IMRT compared with VMAT, respectively. The irradiated doses to LNS were significantly associated with the volume of PTV (R=0.716-0.933, P<0.05) expect for 106tbL.
Conclusions:The irradiated doses to unprotected LNS were less for IMRT plans and were highly associated with PTV volume in patients with upper thoracic esophageal cancer.
