Room: Exhibit Hall | Forum 1
Purpose: A photon-counting detector capable of imaging at 1000 fps is being investigated to evaluate the details of blood flow in vascular pathology. Extending this imager to clinical use requires consideration of the patientâ€™s radiation dose. This study looks at the dose requirements of the imager and compares them to doses typically used for fluoroscopy and digital angiography (DA).
Methods: The beam intensity at the Actaeon Xcounter image receptor, which has 100-micron pixels, was varied by placing different thicknesses of aluminum (from 7 mm up to the RQA5 phantom thickness of 21 mm) in the beam at the x-ray tube so that the input-exposure dynamic range could be determined. Technique parameters were set to 70 kVp, and 100 mA. A 6-cc PTW ionization chamber was placed in the beam to measure exposure and the values were inverse-square corrected to the position of the imager input. Images of contrast flow through an aneurysm model were evaluated at the different dose rates.
Results: For the 7 mm Al attenuator, the average image-pixel count was 150 and the dose-per-frame (DPF) was 94.5 Î¼R, which is comparable to DA. The RQA5 phantom approximates a human head and the DPF for the images acquired was 15.5 Î¼R, with an average pixel count of 33. At both dose levels, flow details could be seen in images of an aneurysm model. With a blood-flow velocity of 30 cm/s with the RQA5 phantom, transit of the blood could be tracked in 133 frames requiring a total dose comparable to about 2 minutes of fluoroscopy.
Conclusion: The Actaeon imager has been shown to provide high temporal and spatial resolution, allowing visualization of detailed blood-flow patterns in vascular pathology. Its wide dynamic range should enable HSA to be performed within acceptable patient dose levels.
Funding Support, Disclosures, and Conflict of Interest: The research was supported in part by Canon Medical Systems