Cochlear Sparing for Brain Tumor Radiotherapy: A Retrospective Study Comparing Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy
Gülşen Pınar SOYDEMİR GÖÇER1,Elif Eda ÖZER1
1Department of Radiation Oncology, Bakırköy Dr. Sadi Konuk Education and Research Hospital, İstanbul-Turkey DOI : 10.5505/tjo.2020.2275 OBJECTIVE
Radiation-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 Volumetric Modulated Arc Therapy (VMAT) for the patients with brain tumor concerning the sparing effect on the cochlea by comparing dosimetric parameters.

In this study, 20 patients with pathological grade IV brain tumors were selected to have planning with VMAT and IMRT for dosimetric comparison concerning organs at risk. Target coverage and dose homogeneity were 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.

The 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 significantly lower with IMRT compared with VMAT (p=0.01 and 0.001, respectively), but the volume receiving 46 Gy (V46Gy) and 60 Gy (V60Gy), and D95%, Dmean, Dmax, Dmin received 60 Gy were not different between two methods. There was no significant difference in D95%, Dmean, and Dmax for total and contralateral cochleae among groups.

Since VMAT and IMRT planning have the same effect on sparing the cochlea; no superiority can be suggested among these two plans during radiotherapy. The choice of plan for the treatment of brain tumors appears to base on the clinical experience, especially for patients who may experience hearing loss. Keywords : Brain tumor; cochlea; IMRT; radiotherapy; VMAT