Purpose: To compare the dose distribution characteristics of tumor target area, normal tissues and organs at risk in patients with malignant gliomas treated with intensity- modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3DCRT).
Methods: Plans of IMRT and 3DCRT were designed for each of the 96 included patients with malignant gliomas. Tumor dose was 60 Gy, and the dose distribution differences between the target area and normal tissues were compared using dose-volume histogram (DVH).
Results: Gross tumor volume (GTV) doses for 95% of the volume in the plans of IMRT and 3DCRT were as follows: 59.82±0.43, 57.68±0.62 Gy (p<0.05); clinical target volume (CTV): 58.16±0.48, 54.47±0.28 Gy (p<0.05); and planning treatment volume (PTV): 57.38±0.74, 54.21±0.48 Gy (p<0.05). The conformal index (CI) values of IMRT and 3DCRT plans were 0.92±0.15 and 0.73±0.12, respectively (p<0.05), whereas the homogeneity index (HI) values variability of IMRT and 3DCRT were 0.78±0.12 and 1.13±0.09 respectively (p<0.05). For normal brain tissues pituitary and optic chiasm, the maximum dose (Dmax) and the mean dose (Dmean) of lens exposure differed significantly between thw two plans (p<0.05).
Conclusion: The target dose distribution of IMRT was superior to that of 3DCRT in terms of rationality, uniformity and conformal nature. IMRT may be better in protecting normal tissue and increasing the tumor radiation dose compared with 3DCRT.