Comparing Dosimetry of Heart and Left Anterior Descending Artery Exposure in Carcinoma Esophagus Patients: Volumetric Arc Therapy Versus Intensity-Modulated Radiotherapy

Introduction Esophageal cancer remains a leading cause of cancer-related mortality worldwide, with chemoradiotherapy being a cornerstone of its treatment. Ensuring precise radiation delivery is critical, as it minimizes exposure to surrounding healthy tissues, particularly vital structures like the heart and the left anterior descending artery (LAD). Volumetric arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) are two advanced radiotherapy techniques that offer enhanced dose conformity and reduced toxicity. This study conducts a retrospective dosimetric analysis to compare the effectiveness of VMAT and IMRT in sparing cardiac substructures and the LAD in patients with carcinoma of the esophagus. Methods Ten patients with middle-third esophageal cancer were treated using the VMAT technique with two coplanar arcs. These patients were retrospectively re-planned with IMRT using 7-9 fields on the Varian TrueBeam linear accelerator between June 2023 and December 2023. VMAT planning involved a two-phase approach: 45 Gy in 25 fractions followed by a boost of 5.4 Gy in three fractions. Dose-volume histograms were analyzed and compared for the planning target volume (PTV), heart and its substructures (including the right atrium, right ventricle, left atrium, and left ventricle), and the LAD. Statistical significance was determined using paired t-tests with a significance level set at P < 0.05. Results PTV coverage was comparable between VMAT and IMRT. VMAT resulted in higher low-dose exposure (V5 and V10) but offered better sparing at moderate doses (V20 and V40) for the heart. The LAD benefited from reduced high-dose exposure with VMAT. For other cardiac substructures, VMAT generally showed higher low-dose exposure but provided superior sparing at moderate doses compared to IMRT. Conclusions VMAT offers notable dosimetric advantages in sparing critical cardiac structures compared to IMRT for treating patients with middle third esophageal cancer. Long-term follow-up studies are needed to assess how these dosimetric benefits influence coronary artery disease and other cardiac complications.