2Department of Radiation Oncology, İstanbul University Oncology Institute, İstanbul-Türkiye DOI : 10.5505/tjo.2026.4876 OBJECTIVE
This study aimed to investigate the dosimetric evaluation of intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), and HYBRID plans for craniospinal irradiation (CSI) in Halcyon.
METHODS
VMAT, IMRT, and HYBRID plans were generated for ten pediatric patients. In VMAT plans, triple arcs were utilized for cranial fields. Two full arcs were employed with avoidance sectors for each isocenter of spine fields. In IMRT plans, two opposing lateral fields in the brain and a single posterior field for each isocenter in the spinal region were used. This study obtained HYBRID plans by summing VMAT and IMRT plan. Plans were compared regarding homogeneity, conformity, and organs at risk doses.
RESULTS
The VMAT plan exhibited a significantly better conformity index than IMRT and HYBRID. The lowest V2 and V5 for body-PTV were obtained in IMRT plans. Compared with IMRT and HYBRID, V10 and V20 of lung, V25 of heart, and Dmean of left eye, thyroid, heart, esophagus, bowel, and liver were lower in VMAT plans.
CONCLUSION
The HYBRID was superior in terms of PTV dose coverage and homogeneity, and the best protection for many organs was provided in VMAT for CSI.