Cochlear Sparing for Brain Tumor Radiotherapy: A Retrospective Study Comparing Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy

Abstract

OBJECTIVERadiation-induced hearing loss is a common complication of radiotherapy in patients with brain tumors.This retrospective study aims to compare Intensity-Modulated Radiotherapy (IMRT) with VolumetricModulated Arc Therapy (VMAT) for the patients with brain tumor concerning the sparing effecton the cochlea by comparing dosimetric parameters.METHODSIn this study, 20 patients with pathological grade IV brain tumors were selected to have planning withVMAT and IMRT for dosimetric comparison concerning organs at risk. Target coverage and dose homogeneitywere evaluated by calculating the conformity index (CI) and homogeneity index (HI) values.The treatment plans were accepted only if they met the set of planning objectives defined in the protocol.RESULTSThe homogeneity and conformity of the two plans were statistically similar. The dose to receive 95%(D95%) of planning target volume (PTV) and the minimum dose received 46 Gy (Dmin) were significantlylower with IMRT compared with VMAT (p=0.01 and 0.001, respectively), but the volume receiving 46Gy (V46Gy) and 60 Gy (V60Gy), and D95%, Dmean, Dmax, Dmin received 60 Gy were not different between twomethods. There was no significant difference in D95%, Dmean, and Dmax for total and contralateral cochleaeamong groups.CONCLUSIONSince VMAT and IMRT planning have the same effect on sparing the cochlea; no superiority can be suggestedamong these two plans during radiotherapy. The choice of plan for the treatment of brain tumorsappears to base on the clinical experience, especially for patients who may experience hearing loss.