Dosimetry of Three-Dimensional Conformal Radiotherapy (3D-CRT) Versus Volumetric Modulated Arc Therapy (VMAT) in Hypopharyngeal Cancer

Abstract

 Objectives: IMRT or VMAT is the standard for curative treatment of hypopharyngeal carcinoma. In our setting, 3D-CRT is widely used due to limited IMRT availability. This study aimed to compare dosimetry between these techniques.

Methods: A retrospective, bicentric study included 30 patients with hypopharyngeal squamous cell carcinoma (15 3D-CRT, 15 VMAT). Prescribed doses were 70 Gy/35 fractions for 3D-CRT and 64–70 Gy for VMAT. Target volumes and organs at risk were analyzed per ICRU 50 standards.

Results: PTV coverage at V95% was comparable. VMAT reduced hot spots (V107%: 0.10% vs 47.46%, p < 0.001) and improved dose homogeneity (HI: 0.08 vs 0.81, p < 0.001). VMAT also lowered spinal cord maximum dose (40.85 vs 47.40 Gy, p < 0.001) and parotid mean doses (left: 28.12 vs 38.01 Gy, right: 28.27 vs 38.57 Gy; p < 0.05).

Conclusion: In resource-limited settings, 3D-CRT ensures adequate tumor coverage. VMAT provides better dose homogeneity and spares organs at risk, potentially reducing toxicity and improving quality of life.