Study of inter-fractional variations and adaptive radiotherapy in pancreatic cancer
10.3760/cma.j.issn.1004-4221.2012.03.021
- VernacularTitle:胰腺癌放疗分次间解剖变化及自适应放疗研究
- Author:
Cheng YANG
;
Li X.ALLEN
;
Jianhua WANG
;
Dingjie LI
;
Ronghu MAO
- Publication Type:Journal Article
- Keywords:
Pancreatic neoplasms/radiotherapy;
Radiotherapy,image-guided;
Radiotherapy,adaptive;
Inter-fractional position variations
- From:
Chinese Journal of Radiation Oncology
2012;21(3):263-266
- CountryChina
- Language:Chinese
-
Abstract:
ObjectiveTo quantitatively characterize the inter-fractional anatomy variations and advantages of dosimetry for the adaptive radiotherapy in pancreatic cancer.MethodsA total of 226 daily CT images acquired from 10 patients with pancreatic cancer treated with image-guided radiotherapy were analyzed retrospectively.Targets and organs at risk (OARs) were delineated by the atlas-based automatic segmentation and modified by the skilled physician.Various parameters,including the center of mass (COM) distance,the maximal overlap ratio (MOR) and the Dice coefficient (DC),were used to quantify the inter-fractional organ displacement and deformation.The adaptive radiation therapy (ART) was applied to handle the daily GT images.The dose distributions parameters from the ART plan were compared with those from the repositioning plan.ResultsThe inter-fractional anatomy variations of pancreas head were obvious in the pancreatic cancer irradiation.The mean COM distance,MOR and DC of pancreas head after the bony or soft tissue alignment and registration was ( 7.8 ± 1.3 ) mm,( 87.2 ± 8.4 )％ and ( 77.2 ±7.9)％ respectively.Compared with the repositioning plan,the ART plan had better target coverage and OARs sparing.For example,the mean V100 of PTV was improved from (93.32 ± 2.89) ％ for repositioning plan to ( 96.03 ± 1.42) ％ for ART plan with t =2.79,P =0.008 and the mean V50.4 for duodenum was reduced from (43.4 ± 12.71 )％ for the repositioning plan to (15.6 ± 6.25)％ for the ART plan with t =3.52,P=0.000.ConclusionsThe ART can effectively account for the obvious inter-fractional anatomy variations in pancreatic cancer irradiation and be used to escalate the radiotherapy dose for the pancreatic cancer,which will lead to a promising higher local control rate.
