Cochlear duct length measurement in dependency of variant radiation doses in a Photon-Counting CT

Introduction Precise knowledge about the cochlear duct length (CDL) is necessary for an individualized selection and implantation of the CI electrode carrier. The level of detail of the preoperative imaging modality depends on the selected radiation dose and examination time of the CT imaging. In previous studies, an impressive reduction of the radiation dose in a Photon-Counting CT could be demonstrated, compared to a conventional CT scan. The aim of the work was to evaluate the dependency of the CDL measurements in a Photon-Counting CT at different radiation doses.

Methods 5 human cadaveric body donors were examined with scan modes of a Photon-Counting CT. Different radiation doses were applied measured by the Computed Tomography Dose Index (CTDI). A reference scan for a high image quality was performed with a CTDI of more than 150 mGy. According to the study protocol, imaging was done with descending CTDIs of 27.1 mGy, 7.6 mGy and 4.8 mGy. Afterwards, measurement of the CDL with 3D-curved multiplanar reconstruction was performed. For comparison purposes a conventional CT scan with a radiation exposure of up to 47.32 mGy was used.

Results Different radiation doses in a Photon-Counting CT led to only slight differences of the CDL measurement with deviation up to 5 % by 3D-curved multiplanar reconstruction. CDL measurements were well comparable to results of conventional CT images.

Conclusion  Measurements of the CDL using a Photon-Counting CT revealed only minor differences when using a different radiation dose. There were no significant differences compared to the conventional CT. Further studies will follow to show, how measurements of the CDL can be performed in a Photon-Counting CT, when using data sets with an inserted CI-electrode.

Publication History

Article published online:
12 May 2023