An Evaluation of Treatment Volume Coverage and Dose Delivered to Vital Organs in the Management of Low-Grade Brain Gliomas Using Three-Dimensional Conformal Radiotherapy (3Dcrt) Compared to Intensity-Modulated Radiation Therapy (Imrt); [ﻣ ﯾ ﻪﺴي ﺑﯿﻦ مارآ شور ود ﺸﺨﺑ ﯽ ﻣﺎﺘﮐ ﺎﺑ ﯿﻦ ﻣﺎﺘﮐ و ﯿﻦ ﺑ ﺎﺑ هاﺮﻤﻫ ﯽﺴﺣ ﯽ ﻌﺿﻮﻣ ﯽ د ﯿﻢ ن]



Ghalehtaki R ; Razmkhah M ; Kazemian A ; Farzin M ; Salarvand S ; Kolahdouzan K ; Saraee E
Source: Tehran University Medical Journal Published:2025

Abstract

Background: Gliomas are the most common primary brain tumors in adults, with low-grade gliomas making up 15% of cases. These slow-growing tumors often occur in young adults. Radiotherapy is one of the treatment options. New radiotherapy techniques like IMRT may reduce complications by sparing normal tissue. The study aims to determine which tumors benefit most from IMRT based on tumor location and size. Methods: Patients diagnosed with low-grade glioma who were referred for treatment at the Cancer Institute of Imam Khomeini Hospital between September 2017 and September 2020 were included in this study. All patients underwent CT simulation with a thermoplastic mask for immobilization. A diagnostic MRI (performed within two weeks prior) was fused with the planning CT to define the target volume (GTV/CTV), with contours verified by a neuroradiologist. A doctor outlines the treatment volume and critical organs for both 3D and IMRT techniques. Radiotherapy physics experts design treatment plans using both techniques, which are then approved by a radiation oncologist. The treatment volume coverage and doses to critical organs are compared between the two techniques. Results: Among 25 patients, 14 patients (56%) with single-lobe involvement, 7 (28%) with two lobes, and 4 (16%) with multifocal disease. Right-side brain involvement was seen in 32%, with the frontal lobe most affected. IMRT significantly reduced the mean and maximum cochlear dose on the treatment side in all patients. It also lowered the mean chiasma dose in those with both lobes involved and reduced cochlear dose on the opposite side in frontal lobe cases. No significant difference was found between the techniques for patients with multiple lobe involvement. Conclusion: According to our study on 25 patients with low-grade glioma, it was shown that there is no clear difference between the two techniques. Given the young age and long survival of LGG patients, IMRT may be preferred when hearing preservation is a priority. Further studies with larger cohorts are needed to confirm these findings. © 2025 Ghalehtaki et al. Published by Tehran University of Medical Sciences. This work is licensed under a Creative Commons Attribution-Non-Commercial 4.0 International license (https://creativecommons.org/licenses/by-nc/4.0/). Non-commercial uses of the work are permitted, provided the original work is properly cited.