Imaging phantom

Physics

Internal medicine

Pedagogy

Nuclear medicine

Mathematics

Optics

Cancer

Tomosynthesis

Psychology

Tracking (education)

Isocenter

Nuclear physics

Fluoroscopy

Geometry

Computer science

Mammography

Breast cancer

Computer vision

Medicine

Medical Physics

Purpose: Scanning beam digital x‐ray (SBDX) is an inverse geometry fluoroscopic system with high dose efficiency and the ability to perform continuous real‐time tomosynthesis at multiple planes. This study describes a tomosynthesis‐based method for 3D tracking of high‐contrast objects and present the first experimental investigation of cardiac catheter tracking using a prototype SBDX system. Methods: The 3D tracking algorithm utilizes the stack of regularly spaced tomosynthetic planes that are generated by SBDX after each frame period (15 frames/s). Gradient‐filtered versions of the image planes are generated, the filtered images are segmented into object regions, and then a 3D coordinate is calculated for each object region. Two phantom studies of tracking performance were conducted. In the first study, an ablation catheter in a chest phantom was imaged as it was pulled along a 3D trajectory defined by a catheter sheath (10, 25, and 50 mm/s pullback speeds). SBDX tip tracking coordinates were compared to the 3D trajectory of the sheath as determined from a CT scan of the phantom after the registration of the SBDX and CT coordinate systems. In the second study, frame‐to‐frame tracking precision was measured for six different catheter configurations as a function of image noise level ( mean detected x‐ray fluence at isocenter). Results: During catheter pullbacks, the 3D distance between the tracked catheter tip and the sheath centerline was (mean standard deviation). The electrode to centerline distances were comparable to the diameter of the catheter tip (2.3 mm), the confining sheath (4 mm outside diameter), and the estimated SBDX‐to‐CT registration error . The tip position was localized for all 332 image frames analyzed and 83% of tracked positions were inside the 3D sheath volume derived from CT. The pullback speeds derived from the catheter trajectories were within 5% of the programed pullback speeds. The tracking precision of ablation and diagnostic catheter tips ranged from at the highest image fluence to at the lowest fluence. Tracking precision depended on image fluence, the size of the tracked catheter electrode, and the contrast of the electrode. Conclusions: High speed multiplanar tomosynthesis with an inverse geometry x‐ray fluoroscopy system enables 3D tracking of multiple high‐contrast objects at the rate of fluoroscopic imaging. The SBDX system is capable of tracking electrodes in standard cardiac catheters with approximately 1 mm accuracy and precision.

Three‐dimensional tracking of cardiac catheters using an inverse geometry x‐ray fluoroscopy system