Computed tomography overexposure as a consequence of extended scan length.

Introduction: This study aimed to raise awareness around the increased effective dose as scan length chosen is increased from standard protocol

Methods: The Monte Carlo-based software CT-Expo (G. Stamm (Medizinische Hochschule Hannover, Hannover, Germany) and H.D. Nagel (SASCRAD, Buchholz, Germany)) was used to simulate the effective dose increase as the scanned region of the standard protocol increased.

Results: The results of this study show that for scans with a high computed tomography dose index (CTDI)vol the patient could be exposed to an extra 1 mSv within 6 cm of overscan. Protocols that investigated large scan areas may not see a significant relative dose reduction because of the use of a lower CTDIvol ; however, radiation exposure should be kept as low as reasonably achievable.

Conclusion: There is significant dose optimisation potential when strictly adhering to appropriate scan lengths within each imaging protocol wherever possible.