MUKESH ZOPE, DEEPALİ PATIL, DEVRAJ SINGH
Turkish Journal of Oncology - 2025;40(2):151-162
OBJECTIVE This study aims to compare Intensity-Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) through dosimetric evaluation and assessment of normal tissue complication probability (NTCP). METHODS A retrospective study was conducted involving 50 HNC patients with tumors located in the oropharynx, tongue, base of tongue, and oral cavity. Treatment plans were developed using the Eclipse Treatment Planning System for a Varian TrueBeam linear accelerator. Prescribed doses of 54Gy, 60Gy, and 70Gy delivered over 35 fractions using Simultaneous Integrated Boost techniques. Both plans were analyzed for target coverage, conformity, homogeneity, External Irradiation Index, and sparing of normal tissues. NTCP was calculated for critical structures, including the parotid glands, spinal cord, and brainstem. RESULTS IMRT demonstrated superior target coverage for PTV_70Gy, with higher D95% (96.6±1.31 vs. 96.1±0.64, p=0.048) and D98% (95.3±1.37 vs. 94.3±1.00, p=0.001). In contrast, VMAT exhibited enhanced treatment efficiency, significantly lowering the number of monitor units (465±43.40 vs. 1561±187.60, p=0.001) and the External Irradiation Index. VMAT also provided better sparing of the left parotid gland (Dmean: 34.8±15.5 vs. 35.5±15.6, p=0.016). The NTCP analysis indicated similar risks of xerostomia between the two techniques. CONCLUSION VMAT presents significant dosimetric and clinical benefits compared to IMRT in the treatment of head and neck cancer. It delivers improved conformity, shorter treatment durations and better sparing of organs at risk.
