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 (8 males, 12 females) were scanned using the 135kVp single-shot volume mode (VMCT135-kVp) whereas other twenty patients (9 males, 11 females) were examined using the 120kVp helical mode (HMCT120-kVp). A physician-interpreter evaluated the subjective conspicuity of 53 structures in the temporal bone on a 5-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 VMCT135-kVp was (69.6±2.5 mGy.cm), which was significantly lower (p 0.001), compared to (186.4±4.3 mGy.cm) for HMCT120-kVp. Similarly, the effective dose (0.15±0.01 mSv) for VMCT135-kVp was reduced by approximately 61.5% relative to (0.39±0.05 mSv) for HMCT120-kVp. In contrast, there was no significant difference in the image noise average between the two protocols (p 0.05). Indeed, the overall analysis of the 53 anatomic structures revealed no differences between the two protocols, and most anatomic structures were identified.Conclusion: For temporal bone, the VMCT135-kVp scan significantly reduces radiation exposure compared to the HMCT120-kVp. The obtained dose was lower compared to the literature-based protocol while maintaining image visualization quality.