2Department of Physics, V.B.S. Purvanchal University, Prof. Rajendra Singh (Rajju Bhaiya)Institute of Physical Sciences for Study and Research, Jaunpur-India DOI : 10.5505/tjo.2025.4507 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.