Dosimetric Comparison of Three-Dimensional Conformal Radiotherapy, Dynamic Intensity Modulated Radiation Therapy, and Hybrid Planning for Treatment of Locally Advanced Lung Cancer

The present dosimetric study aimed to evaluate the dosimetric benefits of using three-dimensional conformal radiotherapy (3D-CRT), dynamic intensity-modulated radiation therapy (D-IMRT), and Hybrid CRT/IMRT plans.
In this dosimetric research, 10 patients with locally advanced lung cancer (Stage-IIIB) were selected. The patients with centrally located tumors were particularly chosen to underline the complexity of the treatment plans. We performed 3D-CRT, D-IMRT, and Hybrid CRT/IMRT treatment plans using Varian with the Eclipse treatment planning system. The treatment plans were compared with respect to the doses received by the organs at risk, including total lungs, contralateral lung, ipsilateral lung, heart, spinal cord, esophagus, the dose homogeneity index, and conformity indexes. Paired samples t-test was performed for statistical analyses.
Hybrid method significantly advanced the target conformity index when compared with 3D-CRT and D-IMRT methods (P = 0.000). The total lung volume receiving 5 to 10 Gy was significantly lower in the 3D-CRT plans compared with that in D-IMRT and Hybrid plans (P = 0.025 and P = 0.003). V20 of the total lung was significantly lower in Hybrid plans (P =0.036). The average mean doses to heart in all the plans were similar with no significant differences. There was a statistically significant difference concerning the maximum doses for spinal cord, when D-IMRT plans were compared with 3D-CRT and Hybrid (P = 0.000).
Hybrid technique could be highly conducive to the treatment, while 3D-CRT and D-IMRT techniques are not adequate alone for maintaining the spinal cord, heart, and esophagus in the treatment of LALC patients.