Author: Hadley Anna DeBrosse, Edward J. Stafford, Kevin A. Wunderle 👨🔬
Affiliation: Ohio State University, The Ohio State University 🌍
Purpose: To investigate automatic dose response curves from fluoroscopes across multiple manufacturers for an abdominal imaging protocol.
Methods: ADRC response for multiple fluoroscopes were evaluated using a water equivalent phantom of varying thickness for the unit’s default abdominal imaging protocol. Tube potential, tube current, and displayed air KERMA rate were recorded for each water equivalent thickness. Data were acquired from two fixed c-arm fluoroscopes from vendor A (System A and B), one from vendor B (System C), and one mobile c-arm fluoroscope from vendor C (System D).
Results: All systems exhibited an increase in displayed air KERMA rates with respect to increasing phantom thickness, though to different magnitudes and by utilizing different technique factor changes. While all systems generally increased tube voltage with increasing thickness, the system from manufacturer B initially increased tube current with a constant tube potential to increase the displayed air KERMA rate. System B also increased the tube current with increasing attenuator thickness but showed local decreases correlating with changes in spectral filtration. Both systems from manufacturer A held tube current constant throughout the full range of attenuator thicknesses. When comparing all four systems, the two systems from vendor A had consistently higher displayed air KERMA rates at lower phantom thicknesses: less than 25cm water-equivalence. After this point, the system from vendor B resulted in the highest air KERMA rates, while the mobile system from vendor C resulted in consistently lower dose than the other systems.
Conclusion: The data presented show that, for equivalent imaging applications, systems behave differently when comparing fluoroscope style (mobile vs fixed) as well as manufacturer. Furthermore, manufacturers have different approaches to modulating dose with respect to increasing water equivalent thickness. Physicists and clinicians should consider a system’s unique response curves when purchasing and optimizing for a particular service and clinical application.