Ruth M Nicol1,2, Sarah C Wayte1, Andrew J Bridges1, Christopher J Koller1. 1. 1 Department of Clinical Physics and Bio-Engineering, Arden Cancer Centre, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK. 2. 2 Radiation Protection, Medical Physics Department, MP 29, Southampton General Hospital, Southampton, UK.
Abstract
OBJECTIVE: To assess the use of a commercial dose management system (GE DoseWatch; GEMS, Milwaukee, WI) for CT dose management for six common CT examinations. METHODS: Data were acquired over several months using GE DoseWatch for six common CT examinations on three CT scanners. The dose length product (DLP) was taken as the dose indicator. The data were analysed using four different filtering methods: study description, the National Interim Clinical Imaging Procedure code, protocol name and a more detailed filtering method (the reference data set). The filtering methods were compared using an analysis of variance and multiple comparison technique. The different scanners were compared using the reference data set. RESULTS: It was found that integrating DoseWatch with the radiology information system provided improved results compared with using the study description. Filtering by study description was found to be a poor indicator of the mean dose for all three scanners and consistently overestimated (p < 0.05) the head and thorax-abdo-pelvis mean DLP values, despite the large sample sizes. Filtering by the National Interim Clinical Imaging Procedure code or protocol name produced mean DLPs which were not statistically different from the reference data. The scanner intercomparison showed some significant differences between the scanners, usually due to different tube current modulation settings. CONCLUSION: The use of a commercial dose monitoring system provided fast and efficient filtering of substantial amounts of data. The filtering method affected the mean DLP value despite large sample sizes. ADVANCES IN KNOWLEDGE: Dose management systems are relatively new in the UK, and this article shares knowledge on the use of one system.
OBJECTIVE: To assess the use of a commercial dose management system (GE DoseWatch; GEMS, Milwaukee, WI) for CT dose management for six common CT examinations. METHODS: Data were acquired over several months using GE DoseWatch for six common CT examinations on three CT scanners. The dose length product (DLP) was taken as the dose indicator. The data were analysed using four different filtering methods: study description, the National Interim Clinical Imaging Procedure code, protocol name and a more detailed filtering method (the reference data set). The filtering methods were compared using an analysis of variance and multiple comparison technique. The different scanners were compared using the reference data set. RESULTS: It was found that integrating DoseWatch with the radiology information system provided improved results compared with using the study description. Filtering by study description was found to be a poor indicator of the mean dose for all three scanners and consistently overestimated (p < 0.05) the head and thorax-abdo-pelvis mean DLP values, despite the large sample sizes. Filtering by the National Interim Clinical Imaging Procedure code or protocol name produced mean DLPs which were not statistically different from the reference data. The scanner intercomparison showed some significant differences between the scanners, usually due to different tube current modulation settings. CONCLUSION: The use of a commercial dose monitoring system provided fast and efficient filtering of substantial amounts of data. The filtering method affected the mean DLP value despite large sample sizes. ADVANCES IN KNOWLEDGE: Dose management systems are relatively new in the UK, and this article shares knowledge on the use of one system.