Akademik Veri Yönetim Sistemi
Medical Dosimetry, cilt.50, sa.4, ss.353-359, 2025 (SCI-Expanded)
The objective of this study is to determine the optimal timing and frequency of adaptive radiation therapy (ART) for patients diagnosed with nasopharyngeal and laryngeal cancer who experience anatomical and weight changes during radiation therapy (RT). Thirty patients who exhibited weight changes underwent repeat CT scans on the 10th, 15th, 20th, and 25th treatment days after the initial treatment CT scan. Weight measurements were recorded, and ART plans were implemented over 4 weeks. A total of 150 treatment plans were generated and analyzed based on 16 ART scenarios. Weighted cumulative dose summations were calculated, with the initial plan (iplan) serving as the reference dose distribution. Each ART plan scenario and the iplan were assessed dosimetrically, with statistical results and box plots generated for all critical structures and organs at risk (OARs). On average, weight loss was 9.31% over the treatment period. A reduction in ART applications resulted in decreased planned target volume (PTV) coverage, conformity number (CN), and homogeneity index (HI) for both patient groups. In both groups, median OAR values in ART scenarios were within the acceptable range, except in the spinal cord figures. Increasing the number of ART sessions improved PTV and OAR values. ART evaluations should be individualized based on patient-specific anatomical changes. ART should be considered when a 4.00% or greater weekly weight change is detected. Increasing the number of ART administrations improves cumulative weighted dose sums by bringing dose distributions closer to the iplan.