Comparison of radiation doses imparted during 128-, 256-, 384-multislice CT-scanners and cone beam computed tomography for intra- and perioperative cochlear implant assessment

Purpose: To examine radiation-doses imparted during multislice (MSCT) and cone-beam computed-tomography (CBCT) for perioperative examination of cochlear-implant insertion.

Methods: Radiation-doses were assessed during standardized petrous-bone CT-protocols at different MSCT ((I) single-source CT-scanner Somatom-Definition-AS+, (II) 2nd generation of dual-source CT-scanner Somatom-Definition-Flash, (III) 3rd generation of dual-source CT-scanner Somatom-Force and at the CBCT Ziehm-Vision-RFD3D ((IV) (a) RFD-3D (Standard-modifier), (b) RFD-3D (Low-dose-modifier)). Image quality was examined by two radiologists appraising electrode-array placement, quality-control of cochlear-implant surgery and complications based on real patients' examinations (n=78).

Results: In MSCT-setting following radiation-doses were assessed (CTDI_w; DLP): (I) 21.5mGy; 216mGycm; (II) 19.7mGy; 195mGycm; (III) 12.7mGy; 127mGycm; in the CBCT setting radiation doses were distributed as follows: (IV) (a) 1.9mGy; 19.4mGycm; (b) 1.2mGy; 12.9mGycm. Overall, image quality was evaluated as good for both, MSCT- and CBCT-examinations, with a good interrater reliability (r=0.81).

Conclusion: CBCT bears considerable dose-saving potential for the perioperative examination of cochlear-implant insertion while maintaining adequate image quality.