TITLE:
The Application of Image Guided Radiotherapy on the Precision of Intensity Modulated Radiotherapy in Patients with Locally Advanced Rectal Cancer
AUTHORS:
Chengtao Wang, Zhenyu Wang, Mengzhen Min, Xiaobi Yu, Jun Dong, Bixiu Wen
KEYWORDS:
Rectal Cancer, IMRT, IGRT, OBI, Setup Deviation
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.7 No.4,
November
1,
2018
ABSTRACT: Objective: To investigate the effect of onboard image (OBI)
system-based image guided radiotherapy (IGRT) on the precision of fractionated
intensity modulated radiotherapy (IMRT) for patients with locally advanced rectal
cancer. Methods: The IGRT validation images of the 12 patients with
rectal cancer were obtained after initial setup by the OBI system of Varian
Novalis TX linear accelerator, and registered to the planning CT image system.
Subsequently, the setup deviations on three
translational directions [ventral-dorsal direction (VD), cranial-caudal
direction (CD) and lateral direction (LD)] for the three-validation phase
including Pre-treatment (Pre-RT1), repositioning (Pre-RT2) and Post-treatment
(Post-RT) were obtained and comparatively analyzed. Results: The
frequency of setup deviation of ≤2.0 mm in the lateral, cephalocaudal and
ventral direction was 83.01%, 65.71%, and 68.91%, respectively for Pre-RT1;
100%, 98.72% and 100%, respectively for Pre-RT2; 100%, 97.76%, and 99.68%,
respectively for Post-RT. Compared with the Pre-RT1 phase, the ranges of setup
deviation on Pre-RT2 and Post-RT phases possessed a significant contraction
trend. The absolute values of setup deviations on the three translation
directions between the Pre-RT1 and Pre-RT2 or Post-RT were statistically
significant (p Conclusion: Application
of OBI-based daily IGRT may help improve the precise delivery of fractionated
IMRT by decreasing the inter- and intra-fractionated setup deviation in the ventral-dorsal
direction, cranial-caudal direction and lateral direction for patients with
locally advanced rectal cancer.