The incidence of radiation-induced pneumonitis after radiotherapy treatment of esophageal malignancy is of great concern. The study aims to evaluate the feasibility, assessing the risk of radiation pneumonitis (RP) with dosimetric and radiobiological outcomes treated with volumetric modulated arc therapy (VMAT) in esophageal cancer patients.
METHODS
Twenty patients of esophageal cancer that had received radiotherapy using VMAT in our department
were retrospectively analyzed. Each of the patient's treatment plan was analyzed with conformity index
(CIRTOG), volume covering 95% isodose line (V95%), isodose line covering 95% of the target (ID95%), dose
homogeneity index (DHI), low-dose volume of the organs-at-risks (OARs), normal tissue complication
probability (NTCP), and risk factor (RF) of the OARs.
RESULTS
The prescription dose ranged from 45 to 54 Gy. The mean value of CIRTOG, V95%, ID95%, DHI, total MU, and
the intensity-modulated radiation therapy ratio was 1.12±0.07, 96.58±2.43%, 95.57±2.48%, 0.92±0.03,
741.50±135.50, and 4.01±0.72, respectively. The median value of NTCP was 0.17. The observed value of
RF in the lung and heart was 0.61±0.13 and 0.86±0.43, respectively.
CONCLUSION
The VMAT technique reduces the toxicity rate of the patient and the dosimetric as well as the radiobiological
parameters with the quantitative analysis of dose-volume parameters such as Dmean, V20Gy, RF, and
NTCP may be used to assess the probability of post-radiotherapy RP.