Multidetector CT Dose: Clinical Practice Improvement Strategies From a Successful Optimization Program

Purpose

The aims of this study were to collect data relating to radiation dose delivered by multidetector CT scanning at 10 hospitals and private practices in Queensland, Australia, and to test methods for dose optimization training, including audit feedback and didactic, face-to-face, small-group teaching of optimization techniques.

Methods

Ten hospital-based public and private sector radiology practices, with one CT scanner per site, volunteered for the project. Data were collected for a variety of common adult and pediatric CT scanning protocols, including tube current–time product, pitch, collimation, tube voltage, the use of dose modulation, and scan length. A one-day feedback and optimization training workshop was conducted for participating practices and was attended by the radiologist and medical imaging technologist responsible for the project at each site. Data were deidentified for the workshop presentation. During the feedback workshop, a detailed analysis and discussion of factors contributing to dose for higher dosing practices for each protocol occurred. The postoptimization training data collection phase allowed changes to median and spread of doses to be measured.

Results

During the baseline survey period, data for 1,208 scans were collected, and data from 1,153 scans were collected for the postoptimization dose survey for the 4 adult protocols (noncontrast brain CT, CT pulmonary angiography , CT lumbar spine, and CT urography). A mean decrease in effective dose was achieved with all scan protocols. Average reductions of 46% for brain CT, 28% for CT pulmonary angiography, 29% for CT lumbar spine, and 24% CT urography were calculated. It proved impossible to collect valid pediatric data from most sites, because of the small numbers of children presenting for multidetector CT, and phantom data were acquired during the preoptimization and postoptimization phase. Substantial phantom dose reductions were demonstrated at all sites.

Conclusion

Audit feedback and small-group teaching about optimization enabled clinically meaningful dose reduction for a variety of common adult scans. However, access to medical radiation physicists, assistance with time-consuming data collection, and technical support from a medical imaging technologist were costly and critical to the success of the program.

Key Words: Multidetector CT, optimization, dose audit