Retrospective comparisons of the dosimetric differences between coplanar and non‑coplanar volume‑modulated arc therapy in patients with pediatric brainstem glioma

The present study aimed to compare the dosimetric characteristics of non-coplanar (NC) and coplanar volumetric modulated arc therapy (VMAT) in the treatment of pediatric brainstem glioma, to inform clinical decision-making and improve therapeutic strategies. A retrospective analysis was performed on 10 pediatric patients diagnosed with brainstem glioma who received radiotherapy at Department of Radiotherapy, Fujian Children's Hospital (Fuzhou, China). Using the Eclipse 15.5 treatment planning system, both coplanar VMAT and NC-VMAT plans were generated for each patient. Key dosimetric parameters, including the conformity index (CI), homogeneity index (HI), dose to organs at risk, γ passing rate and treatment time, were compared between the two planning approaches. Compared with standard VMAT, NC-VMAT demonstrated significantly improved dosimetric performance in target coverage, with superior CI (1.045±0.003 vs. 1.095±0.010; P<0.01) and HI (0.066±0.003 vs. 0.849±0.004; P<0.001). NC-VMAT also resulted in significantly reduced radiation doses to critical structures, including the left (L) and right (R) lenses (lens-L: 2.89±0.30 Gy vs. 4.13±0.40 Gy; lens-R: 2.94±0.27 Gy vs. 4.07±0.32 Gy; P<0.05), cochleae (cochlea-L: 35.20±1.97 Gy vs. 42.03±2.21 Gy; cochlea-R: 36.71±1.64 Gy vs. 42.18±1.54 Gy; P<0.001) and optic chiasm (45.11±0.62 Gy vs. 50.63±0.40 Gy; P<0.05). However, standard VMAT showed better sparing of the temporal lobes (TLs) (TL-L: 19.77±1.55 Gy vs. 24.91±0.88 Gy; TL-R: 19.61±1.44 Gy vs. 24.77±0.86 Gy; P<0.005) and normal brain tissue (13.98±0.10 Gy vs. 15.40±0.17 Gy; P<0.001). In conclusion, NC-VMAT demonstrates clear dosimetric advantages in the radiotherapeutic management of pediatric brainstem gliomas. These findings may contribute meaningfully to improving the precision, safety and clinical outcomes of radiotherapy for children affected by this challenging condition.