Dosimetric comparisons of craniospinal axis irradiation using helical tomotherapy, volume-modulated arc therapy and intensity-modulated radiotherapy for medulloblastoma

Abstract

BACKGROUND: To evaluate the potential dosimetric gains of helical tomotherapy (HT) versus intensity-modulated radiotherapy (IMRT) and volume-modulated arc therapy (VMAT) for craniospinal axis irradiation (CSI) of medulloblastoma. METHODS: -test for various dosimetric parameters. RESULTS: HT yielded the highest CI in all PTV coverage including PTV of gross tumor volume (PGTV) (HT: 0.7163; VMAT: 0.6688; IMRT: 0.6096), PTVbrain (HT: 0.8490; VMAT: 0.8384; IMRT: 0.7815) and PTVspine (HT: 0.5904; VMAT: 0.5862; IMRT: 0.5797). Meanwhile, HT yielded better HI in PGTV (HT: 0.0543; VMAT: 0.0759; IMRT: 0.0736), PTVbrain (HT: 0.5525; VMAT: 0.5619; IMRT: 0.5554) and PTVspine (HT: 0.0700; VMAT: 0.0782; IMRT: 0.0877). As for OARs, HT demonstrated marked superiority in critical organs including maximal/mean doses of brainstem PRV, optical chiasm and optic nerves. CONCLUSIONS: For CSI of medulloblastoma, HT offers superior outcomes in terms of PTV conformity, PTV homogeneity and critical OAR sparing as compared with IMRT/VMAT.