2Department of Radition Oncology, Indira Gandhi Institute of Medical Sciences, Patna-India DOI : 10.5505/tjo.2024.4453 OBJECTIVE
The aim of this study was to evaluate and compare the dosimetric characteristics of Intensity-Modulated Radiation Therapy (IMRT), Full-arc Volumetric Modulated Arc Therapy (VMAT-F), and Partial-arc Volumetric Modulated Arc Therapy (VMAT-P) in the management of retinoblastoma.
METHODS
Treatment plans for retinoblastoma patients were created utilizing IMRT, VMAT-F, and VMAT-P techniques.
The prescription dose was set at 45 Gy in 25 fractions. An analysis was conducted on dosimetric
parameters using the cumulative dose-volume histogram (cDVH), including Planning Target Volume
(PTV) coverage (D95%), Conformity Index (CI), Homogeneity Index (HI), and the radiation doses
received by organs at risk (OARs). Additionally, brain dose-volume metrics (V5Gy, V10Gy, V15Gy) and
monitor units (MUs) were evaluated and compared among the three methods.
RESULTS
All treatment techniques achieved 95% coverage of the prescribed dose within the PTV volume. The
VMAT methods significantly improved both the mean and maximum PTV doses compared to IMRT
(p<0.001). Among the VMAT techniques, VMAT-P achieved the highest Conformity Index (1.00±0.01)
and the lowest Homogeneity Index. Additionally, VMAT-P markedly decreased the volume of brain receiving
10 Gy (12.9±2.96%) and 15 Gy (6.78±1.82%) compared to both IMRT and VMAT-F (p<0.001).
IMRT was more effective in preserving contralateral structures, particularly the eyes and lenses. Furthermore,
both VMAT techniques utilized fewer monitor units than IMRT (p<0.001).
CONCLUSION
In this study, VMAT-P achieved an advantageous balance among PTV coverage, conformity, and the
preservation of organs at risk (OARs). It exhibited better conformity and improved sparing of brain
tissue at moderate dose levels compared to both IMRT and VMAT-F.