Dosimetric comparison of three different techniques for craniospinal irradiation

Background: To evaluate the dosimetric gains of Intensity-Modulated Radiation Therapy (IMRT) versus 3D-Conformal Radiotherapy (3D-CRT) using either 6MV or 15MV for Craniospinal axis Irradiation (CSI) in pediatric patients.
Methods: A total of 30 treatment plans for ten patients receiving CSI were evaluated retrospectively using Monaco Software (Version Monaco Medical Systems Inc., Version 5.11.2.). Three different delivery plans (3D-CRTwith6MV, 15MV, and IMRT) were made for each case. The homogeneity index (HI) of the planning target volume (PTV) and organs at risk (OARs) doses were assessed.
Results: The coverage of PTV-spine V95was significantly better in the IMRT plan than in the other two conformal plans. The coverage of PTV-brain V95 was the least in the 3D-CRT plan using 15 MV and was better in the 6 MV plan.
The maximum dose was significantly higher in the 3D-CRT plan using 6 MV than IMRT and 15 MV plans. The homogeneity index of the PTV spinewas significantly better in the IMRT plan than in the two conformal plans. Regarding the integral dose, it was significantly higher for the IMRT plan as compared to the other two plans.
Conclusions: For craniospinal irradiation, IMRT offers better results regarding PTV homogeneity and critical OARs sparing when compared to 3D-CRT using 6MV& 15MV.IMRTresults in increased integral dose, which is of major concern in pediatric patients.