Craniospinal Irradiation of Pediatric Medulloblastoma, Dosimetric Comparison between Helical Tomotherapy, and Conventional Radiation Therapy

Background: Dosimetric comparison between 3D-conformal radiation therapy (3D-CRT) and helical tomotherapy (HT) in pediatric Medulloblastoma (MB) receiving craniospinal irradiation (CSI). Method: This was a retrospective dosimetric study on five pediatric male patients diagnosed as MB, who were planned to receive CSI post-surgery. Treatment plans for 3D-CRT and HT were generated. Comparison was made in terms of planning target volume (PTV) coverage, homogeneity index (HI), conformity index (CI), organs at risk (OAR) dose, and treatment time (TT). Results: HT increased the minimum dose up to PTV (81% vs. 74%) with better CI and HI (1.024 vs. 0.36 and 1.078 vs. 1.21, respectively). HT decreased the mean and maximum dose to OAR, except for higher mean dose of larynx, oral cavity, pharynx, and comparable V5 of lungs. TT of 3D CRT was shorter than HT (76 seconds vs. 545 seconds). Conclusion: HT was found to be a better treatment option in all the MB cases receiving CSI regarding PTV, conformity, homogeneity, and most of OAR, while TT was shorter in 3D-CRT plan.