Radiation therapy in cochlear implant recipients.

HYPOTHESIS: Processes of scattering and attenuation were investigated to determine the consequence on dose distributions by having a cochlear implant in the field of therapeutic radiation. BACKGROUND: Radiation oncology medical accelerator beams of 6- and 18-MV x-ray energy were used. Five cochlear implants were investigated. METHODS: Each implant model was individually studied using computer dose modeling and through exercises in radiation measurement during live delivery. RESULTS: No side scatter was detected, and negligible backscattering was observed for the primary device housing and electrodes. Attenuation consequences were found to be dependent on the model of cochlear implant studied and specifically dependent on the material composition of each device. CONCLUSION: The maximum attenuated dose change for the study was found to be -8.8% for 6 MV and -6.6% for 18 MV. This study presents the first comparison of therapeutic radiation delivery versus computerized treatment simulation involving cochlear implants.