Comparison between field-in-field technique and the use of conventional wedges for treatment planning of esophageal cancer

Introduction: This study was conducted to evaluate and quantify the treatment planning performance of MLC-optimized field-in-field planning technique (FIF), also named forward IMRT, versus wedge-based three field (W3F) technique in terms of dosimetric and radiobiological parameters for esophageal carcinoma.   Material and Methods: Twenty patients with esophageal cancer were selected. For each patient, two different treatment plans, one W3F and one FIF were created. The plans were delivered on an Elekta linear accelerator equipped with a 40 multi-leaf collimator. The quality and performance of the FIF plans were evaluated and compared with those of W3F plans regarding the conformity index (CI), homogeneity index (HI), mean dose (Dmean), maximum dose (Dmax), and tumor complication probability (TCP) for the planning target volume (PTV). Also, the parameters of the Dmean, and VxGy were used for evaluating the organs at risk (OARs) (including heart, lung, liver, and spinal cord). Moreover, the used monitor units per fraction (MU/fr) were compared between the two plans. Results: A paired t-test statistical analysis did not show any significant differences (P>0.05) between the two treatment plans in terms of the Dmean, Dmax, CI, and HI parameters. The dose sparing parameters of the OARs including the lung V20Gy and Dmean of the liver and lungs were significantly reduced in the FIF plans compared with the W3F ones. Furthermore, the FIF technique indicated the advantage of significant decreasing the used MU/fr. Conclusions: The FIF technique showed evident advantages regarding OAR sparing over the W3F technique for radiotherapy of the esophageal carcinoma patients. The FIF can be considered as a simple and easy-executable treatment planning technique in the clinical situations of esophageal malignancies, especially in clinics with no IMRT.