Study on Dosimetric Superiority of Forward Planned Intensity-Modulated Radiotherapy Treatment of Thoracic Esophageal Squamous Cell Carcinoma

Abstract

Aim and Objectives: The study was conducted to to compare the dosimetric superiority between the Field in Field and Box techniques. Meterials and Methods: We have taken 22 Patients of Ca esophagus for our study from our Institute database. Patients were already treated Box (4 fields) plan. Retrospectively additional Field in Field (FIF) plan was created with Planning target volume (PTV) prescription dose of 59.4Gy in 33 fractions. Prescription dose of 95% of PTV was chosen for the comparison between two treatment planning strategies. The Dose volume histogram (DVH) was used to analyze and compare various plan quality index and doses to the organs at risk (OARs). For each patient, two treatment plans were created: Box 4FB and FIF. The parameters compared included the conformity index (CI), homogeneity index (HI), Conformation number (CN), DMean, DMax, V20Gy and V30Gy of the heart and lungs, and monitor units per fraction (MU/fr). Results: A paired t-test analysis significant differences (P < 0.05) between the two techniques in terms of the CI, HI, and CN when the FIF was applied. The Dmax of the PTV, lung, and spinal cord were also significantly better with the FIF. Moreover, the V20Gy of the significantly reduced when the FIF was used and the MU/fr was significantly decreased. The FIF technique enables better dose distribution in the PTV and reduces dose to OARs in esophageal radiotherapy. Conclusion: Although all plans were within acceptable limits, dosimetric comparison of different planning techniques revealed that FIF had statistically significant differences from Box planning technique in terms of planned target volume (PTV) coverage, OAR protection, HI, CI, CN, MU and treatment duration. From the aspect of treatment duration and MU parameters, FIF technique can be considered as an alternative planning option.