Room: AAPM ePoster Library
Purpose: The purpose of this work was to compare radiation output between factory-default and clinically-used protocols for a single-plane flat-panel-detector based fluoroscopy system.
Methods: output and image quality were measured on a Siemens Artis-Pheno system with factory-default protocols, followed by repeat measurements after these protocols were configured for clinical use. Radiation output rate measurements were performed at 30cm from the image receptor (SID: 100cm; 1cm field-of-view) for “Card” and “Neuro/Carotid” protocols in three dose modes (low, normal, high) during fluoroscopy and cine acquisitions using a calibrated Radcal AGMS-D solid-state detector (measurements were repeated thrice). Indicated radiation output rates were also compared using 4cm of Aluminum attenuation for different dose modes. Exposure rates at the input surface of the detector were measured with 2mm of added Copper filtration, using a calibrated Radcal 60cc ion-chamber. Subjective evaluations of high-contrast resolution were performed with a wire-mesh pattern and a line-pair-per-mm object, and of low-contrast resolution were performed using an Aluminum resolution sheet with different sized-objects.
Results: After protocols were configured for clinical use, increases in the measured dose rates (at 30cm from the image receptor) ranged from 60% to 242% for different dose modes during fluoroscopy (within regulatory limits) and averaged at 142% during cine acquisitions relative to measurements performed with factory-default protocols. This increase in dose rates also reflected in increases in dose rates with fixed attenuation of 4cm of Aluminum (range: 41%-181% across dose modes) and in the exposure rate at the input surface of the detector. Changes were also noted in high- and low-contrast resolution reflecting protocol configuration changes.
Conclusion: data shows the need for configuring factory-default protocols for clinical applications and for subsequent physics evaluation given the magnitude of changes associated with radiation dose utilization and corresponding image quality.