Program Information
Real-Time, Image-Frame-Specific Magnification Factor Determination During Fluoroscopically-Guided Interventions
P Choudhary*, S Vijayan , B Karthikeyan , Z Xiong , S Rudin , D Bednarek , University at Buffalo, Buffalo, NY
Presentations
SU-E-702-5 (Sunday, July 30, 2017) 1:00 PM - 1:55 PM Room: 702
Purpose: To provide real-time update of the magnification factor of a selected patient feature-of-interest for each image frame during fluoroscopically-guided interventional procedures.
Methods: At the start of a procedure, image frames are captured at two angles of the gantry or two views with a biplane system. The feature-of-interest is identified in each image and its image coordinates are used to determine the 3D spatial coordinates of that feature relative to the imaging system geometry. The gantry angulation, source-to-image-receptor distance and image-receptor magnification mode are tracked throughout the procedure using the imaging-system digital-network bus so that the magnification factor for each subsequent frame of each gantry position can be automatically determined. In the spatial-coordinate determination method, projection lines from the focal spot through the feature to the image planes are determined at each angle and the nearest points of intersection on the lines for two views is determined. For this study, a lead bead was used as the object-of-interest and distance between these points on the lines was used as a measure of error. Minimization of this error using the bead phantom allows calibration of the image-pixel coordinates and gantry angles.
Results: The highest accuracy is obtained when the original “calibration” images are obtained at 90 degrees apart. Using the lead bead phantom, the minimum distance of intersection of the projection lines for the two images allowed the magnification factor to be determined within less than 1%.
Conclusion: Once the feature-of-interest spatial coordinates are determined, the physician can use any subsequent image frame to size that feature using an updated magnification factor, which is automatically calculated. This is important when decisions are to be made relating to features such as vessel diameter or aneurysm neck or dome size during the procedure without the need to interrupt the interventional action to recalibrate.
Funding Support, Disclosures, and Conflict of Interest: This research was supported in part by NIH Grant R01EB002873 and Toshiba Medical Systems Corp.
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