Dosimetric Analysis and Radiobiological Impact of Radiotherapy Planning Techniques for Esophageal Squamous Cell Carcinoma in terms of Tumor Control Probability and Normal Tissue Complication Probability

A BSTRACT Objective: This study aims to evaluate the radiobiological benefits among the different radiotherapy (RT) planning techniques for esophageal squamous cell carcinoma (ESCC). Materials and Methods: In this experimental study, 35 patients with ESCC cancer were planned for the field-in-field (FIF), three fields (3Fs), and four-field boxes were performed for each patient for a 6 MV photon beam. The parameters of the conformity index (CI), homogeneity index (HI), D mean , D max , tumor control probability (TCP), V 20Gy , and V 30Gy of the heart and lungs, and normal tissue complication probability (NTCP) were analyzed to evaluate treatment plans. Dose distribution in the target volume, the monitor units (MUs) required, and the dose delivered to organs at risk (OARs) were compared for these techniques using the paired-sample t -test. Results: A significant difference was measured between the FIF, 3F, and 4F techniques with respect to CI, dose HI, and TCP for the target organ, as well as the D mean for the heart and liver. For the spinal cord, the FIF technique showed a slight reduction in the maximum dose compared to the other two techniques. In addition, the V 20Gy of the lungs and the NTCP of all OARs were reduced with the FIF method. Conclusion: The FIF technique showed better performance in terms of dose homogeneity in the target, conformity of the radiation field with the target volume, TCP, less dose to healthy organs, and fewer MU, which could improve the TCP and spare the heart, lungs, and spinal cord. Our study provides a prediction of RT outcomes and further guides the individual treatment.