Purpose: To investigate and demonstrate potential pitfalls in implementation of CT organ dose calculations in clinical settings
Methods: Our hospital system uses a commercial radiation dose monitoring software to collect clinical radiation dose data from all CT studies. The software acquires and stores radiation dose data from DICOM-compliant radiation dose structured reports (RDSRs) and provides customizable dose reports, high-dose alerts, and many data analysis tools. The software also includes an NCICT Organ Dose calculator, which estimates organ dose and effective dose resulting from patient CT studies, given such details as patient size, CTDIvol and scan region, while matching patient height and weight to a digital phantom in the NCICT phantom library. The body part used for organ dose calculation initially came from the acquisition target region indicated in the RDSR. A simple change was made in the software to instead use the configurable body part associated with the Study Common Name. An audit of the four most common studies was performed, accuracy of scan region was evaluated, and organ doses were recalculated.
Results: For each Study Common Name, acquisition target region varied drastically with scanner and workflow. Protocols that spanned multiple body parts had high variability in target regions, where scan regions were only correctly identified in 33% for Body/Trauma and 66% for Abdomen/Pelvis. The configurable body part improved consistency of organ dose calculations. All C-Spine protocols initially had acquisition target regions of neck or head. After adjustment of body part from head to c-spine, the effective dose increased from 3.8 mSv to 6.89 mSv.
Conclusion: Organ dose calculations for CT can be improved by properly defining scan region based on Study Common Name body part rather than acquisition target region.