Helical Tomotherapy for Radiotherapy in Esophageal Cancer: A Preferred Plan With Better Conformal Target Coverage and More Homogeneous Dose Distribution

Abstract 

We compare different radiotherapy techniques—helical tomotherapy (tomotherapy), step-and-shoot IMRT (IMRT), and 3-dimensional conformal radiotherapy (3DCRT)—for patients with mid-distal esophageal carcinoma on the basis of dosimetric analysis. Six patients with locally advanced mid-distal esophageal carcinoma were treated with neoadjuvant chemoradiation followed by surgery. Radiotherapy included 50 Gy to gross planning target volume (PTV) and 45 Gy to elective PTV in 25 fractions. Tomotherapy, IMRT, and 3DCRT plans were generated. Dose-volume histograms (DVHs), homogeneity index (HI), volumes of lung receiving more than 10, 15, or 20 Gy (V₁₀, V₁₅, V₂₀), and volumes of heart receiving more than 30 or 45 Gy (V₃₀, V₄₅) were determined. Statistical analysis was performed by paired t-tests. By isodose distributions and DVHs, tomotherapy plans showed sharper dose gradients, more conformal coverage, and better HI for both gross and elective PTVs compared with IMRT or 3DCRT plans. Mean V₂₀ of lung was significantly reduced in tomotherapy plans. However, tomotherapy and IMRT plans resulted in larger V₁₀ of lung compared to 3DCRT plans. The heart was significantly spared in tomotherapy and IMRT plans compared to 3DCRT plans in terms of V₃₀ and V₄₅. We conclude that tomotherapy plans are superior in terms of target conformity, dose homogeneity, and V₂₀ of lung.

Key Words: Helical tomotherapy, IMRT, Esophageal cancer, Radiotherapy