Radiation Dose Optimization during Temporal Bone CT Examination Using One-Shot Axial Volumetric Acquisition

Introduction: The optimization of radiation exposure when exploring small and complex anatomical structures is the most important issue for temporal bone CT. The objective of this study is to use single-shot volume acquisition in order to minimize the dose and compare the obtained image quality to a conventional helical technique. Material and Methods: Twenty patients (۸ males, ۱۲ females) were scanned using the ۱۳۵kVp single-shot volume mode (VMCT۱۳۵-kVp) whereas other twenty patients (۹ males, ۱۱ females) were examined using the ۱۲۰kVp helical mode (HMCT۱۲۰-kVp). A physician-interpreter evaluated the subjective conspicuity of ۵۳ structures in the temporal bone on a ۵-point scale using multiplanar reconstruction (MPR). In addition, the image noise in both techniques was quantified by analyzing it in three different regions of interest (ROIs). Radiation dose reduction was noted and compared with literature-based effective dose dosimetry data.Results: The mean dose-length-product (DLP) for the VMCT۱۳۵-kVp was (۶۹.۶±۲.۵ mGy.cm), which was significantly lower (p<۰.۰۰۱), compared to (۱۸۶.۴±۴.۳ mGy.cm) for HMCT۱۲۰-kVp. Similarly, the effective dose (۰.۱۵±۰.۰۱ mSv) for VMCT۱۳۵-kVp was reduced by approximately ۶۱.۵% relative to (۰.۳۹±۰.۰۵ mSv) for HMCT۱۲۰-kVp. In contrast, there was no significant difference in the image noise average between the two protocols (p> ۰.۰۵). Indeed, the overall analysis of the ۵۳ anatomic structures revealed no differences between the two protocols, and most anatomic structures were identified.Conclusion: For temporal bone, the VMCT۱۳۵-kVp scan significantly reduces radiation exposure compared to the HMCT۱۲۰-kVp. The obtained dose was lower compared to the literature-based protocol while maintaining image visualization quality.

Keywords:

Computed Tomography , Volumetric , Temporal bone