Evaluating data capture methods for the establishment of diagnostic reference levels in CT scanning

Concerns about the radiation dose associated with CT scanning have led to a call for establishment of diagnostic reference levels. Self-complete surveys have been used extensively to gather this information, however, departmental Radiological Information System's/Picture Archive Communication Systems (RIS/PACS) also hold this information. We compared dosimetry derived from survey with that using RIS/PACSs.

Technical data were collected from a large metropolitan tertiary hospital in WA using both data collection methods for a range of adult CT scanning examinations. Radiation dose was calculated from both datasets and the results evaluated for several indexes of inter-rater agreement.

Radiation dose calculated using self-report survey data differed both systematically and proportionally from that calculated using RIS/PACS data. Differences were not consistent across CT examination type and thus not amenable to simple correction. The disparity was greater and more variable for organ dose than effective dose due to reliance of survey data on "generic" anatomical start and stop limits compared with actual data available on RIS/PACS.

The bias observed in our study indicates that care should be taken when interpreting the results of studies measuring radiation dose using self-complete surveys. The availability of electronic databases that include information required for the evaluation and monitoring of CT radiation dose provides the opportunity to capture better quality data in a cost-effective manner. We recommend that national and local databases are established that routinely capture these data so as to facilitate the development and monitoring of radiation dose associated with CT scanning.