Assessment of Adaptive Radiation Therapy for Non-Small Cell Lung Carcinoma using Intensity Modulated Radiation Therapy

Abstract

Objective: This study compared clinical and dosimetric outcomes of ART replanning every 5 fractions versus every 10 fractions in patients with non-small cell lung carcinoma (NSCLC).

Methods: This cross-sectional study was conducted at Al Amal National Hospital of Oncology, Baghdad, Iraq, between July 2024 and April 2025. Thirty patients with unilateral NSCLC treated with intensity-modulated radiotherapy were included. Patients were assigned to two groups: Group 1 underwent ART replanning every 5 fractions, while Group 2 underwent replanning every 10 fractions. Demographic variables, gross tumour volume (GTV) changes, dosimetric parameters (planning target volume D95, lung V20, heart V30, and spinal cord Dmax), Gamma Index, and a composite treatment-quality score were evaluated. Statistical analysis was performed using SPSS version 29, with significance set at p ≤ 0.05.

Results: The groups were comparable in age and weight (p > 0.05). Group 1 demonstrated a significantly greater mean GTV reduction than Group 2 (35.26% ± 3.55 vs. 29.20% ± 3.48; p < 0.0001). Dosimetric parameters were statistically comparable between groups, although more favourable trends were observed in Group 1. The Gamma Index was higher in Group 1 (97.69% ± 1.33) than in Group 2 (97.02% ± 1.41). The composite quality score was significantly superior in Group 1 (8.69 ± 0.23 vs. 7.87 ± 0.18; p < 0.0001). Tumour shrinkage was the primary indication for replanning.

Conclusion: ART replanning every 5 fractions achieves superior tumour volume reduction and overall treatment quality compared with 10-fraction intervals, supporting shorter adaptation schedules for improved therapeutic precision in NSCLC.