Quality and dosimetric assessment of treatment plan of three-dimensional conformal radiotherapy versus intensity-modulated radiotherapy in high-grade gliomas – A prospective study

Background: High-grade gliomas (HGG) are aggressive central nervous system tumors with a poor prognosis. Techniques such as intensity-modulated radiotherapy (IMRT) aim to improve dose conformity and spare normal tissues compared to three-dimensional conformal radiotherapy (3DCRT). Aims and Objectives: The aim is to assess the dosimetry and treatment quality of 3DCRT versus IMRT in HGG. Materials and Methods: In this prospective study, 30 patients were allocated to 3DCRT (n=15) or IMRT (n=15). Both groups received 59.4 Gy in 33 fractions with concurrent and adjuvant temozolomide. Dosimetric parameters of the planning target volume (PTV) and organs at risk were analyzed. Acute neurological toxicities were assessed. Statistical analysis used Mann–Whitney U and Chi-square/Fisher’s exact tests. Results: Baseline characteristics were comparable (P>0.05). IMRT showed significantly lower PTV Dmax (64.56 vs. 65.69 Gy), Dmean (61.67 vs. 62.57 Gy), D2 (63.23 vs. 64.78 Gy), and D50 (61.65 vs. 62.62 Gy) (all P=0.01). IMRT significantly reduced doses to critical structures, including brain Dmax (62.54 vs. 65.07 Gy), brainstem Dmean (27.74 vs. 32.12 Gy), optic chiasm Dmean (32.91 vs. 45.03 Gy), and pituitary Dmean (28.67 vs. 44.00 Gy) (P≤0.05). Hippocampal and temporal lobe doses were also lower with IMRT. Right cochlea doses were reduced with IMRT (Dmean 26.20 vs. 49.76 Gy, P=0.05). Left eye and lens doses were higher with IMRT (P=0.01). Conformity index was significantly better with IMRT (1.52 vs. 1.61, P=0.003), whereas homogeneity index was similar (P=0.54). Acute neurological toxicities showed no significant differences (P>0.05). Conclusion: IMRT offers superior dose distribution and organ sparing compared to 3DCRT, with comparable toxicity profiles. Larger studies with long-term follow-up are needed.