BACKGROUND: The frequency of C-arm fluoroscopy procedures is increasing and it has become prudent to increase the awareness of patient radiation exposure to minimize patient risk. There is a strong potential for variability in patient exposure levels and a need for minimizing unnecessary exposure. The variability in C-arm fluoroscopy can be characterized in 2 parts; settings and techniques under the control of the C-arm operator, and the automatic fluoroscope output differences based on equipment type and patient size.
METHODS: The two areas of potential variability were studied in the current literature and through exposure measurement research. In order to examine the inherent variability in patient exposure, radiation exposure data were collected from 99 C-arm units, encompassing 21 medical sites, primarily hospitals, with the C-arm units that were in use at these sites. Measurements were conducted to analyze the variation in patient exposure, overall, per site, and per machine manufacturer, using the standard 1.5 inch aluminum attenuation block. Additional measurements were conducted to analyze the variation as a function of patient thickness using multiple 1 inch thick Lucite plates.
CONCLUSIONS: Significant patient exposure variability exists in C-arm fluoroscopy and there is potential for unnecessary exposure. Based on literature review and measurement results, the ability to minimize patient exposure relies both on the equipment operator and the inherent design of the C-arm equipment. Measurements demonstrated up to a 261% difference in exposure rates when compared between C-arm manufacturers. Comparison within manufacturers suggests that newer models have improved technology, reducing both exposure rates and associated variability. Exposure rates increased as a function of patient thickness, demonstrating about a 350% increase in dose when patient thickness went from 4 to 8 inches. Recommendations for optimizing operator controlled and equipment design factors are presented.