Authors: Doan Trung Hiep, Tran Ba Bach, Nguyen Dinh Long.
ABSTRACT
Objective: Compare the dose delivery indexes for the treatment volume and the dose to the critical organ between the 3D-CRT technique and the volumetric arc modulated radiotherapy technique (VMAT) in radical radiotherapy of thoracic esophageal cancer.
Subjects and methods: We performed VMAT and 3D-CRT planning on 05 patients with thoracic esophageal cancer. All dose calculation parameters on the DVH of each plan were analyzed.
Results: The CI index for PTV of VMAT was significantly better than 3D-CRT and was statistically significant (p = 0.0000). The HI index for PTV was not statistically different between 3D-CRT and VMAT (p = 0.6631). Comparing the dose calculation indexes between the two techniques showed that: for the lung, the V5Gy and V10Gy indices of 3D-CRT were lower, while the important indexes V20Gy and V30Gy of VMAT were better (p values were 0.0004; 0.0019; 0.0054; 0.0230, respectively). The radiation dose to the heart of VMAT was statistically lower for all three indices V30Gy, V40Gy, and V50Gy (p values were 0.0116, 0.0022, and 0.0049, respectively). The dose to the spinal cord of VMAT was also statistically significantly lower than that of 3D, with p = 0.0005.
Conclusion: VMAT results in radiation dose calculation that meets the standards of esophageal radiotherapy based on all dose calculation standards for PTV as well as reduces radiation dose to critical organs such as the spinal cord, lungs, and heart. Combined VMAT can be applied to patients with thoracic esophageal cancer.
