The SBDX system uses a raster scanned focal spot, transmission target, multihole collimator, and hardware based reconstructor. Boxes with solid lines indicate the steps of image formation and image presentation in the current SBDX prototype. The proposed catheter tracking steps are shown with dashed lines.
SBDX tomographic blur. (a) A point in the patient is imaged by a patch of the source array, typically spots. Backprojecting the point to planes away from the object produce tomographic blurring that is symmetrical about the object. (b) The blurring geometry and image pixel definition are such that the central point of the blurred object falls at the same pixel row and column in all image planes (shown with a thick dark line).
Phantom demonstration of the SBDX multiplane composite display. The phantom consists of lead numbers spaced at 2 in. intervals along the source-detector axis (number “0” closest to the source). (a) SBDX single plane tomosynthetic reconstruction of a plane 4 mm above the number “4.” (b) SBDX multiplane composite image generated from single plane images with 12 mm spacing.
Overview of the SBDX tracking algorithm. [(a)–(c)] Score images are generated from the tomosynthetic images reconstructed at planes spaced throughout the volume of interest. (d) A MIP of the score data is formed and connected component labeling is applied to the MIP. (e) Each detected object (connected component) defines a cylinderlike region in the imaging volume. The row and column coordinates of an object are calculated from the MIP. (f) The -coordinate is calculated from the scores versus -plane inside the object cylindrical region.
Demonstration of SBDX tracking for an ablation catheter tip and a fiducial attached to the anterior chest surface (arrows). A total of 40 image planes were reconstructed in this example, with 12 mm spacing. (a) A fixed ROI at eight different reconstructed planes demonstrates progressive out-of-plane blurring (plane numbers 14, 17, 20, 23, 26, 29, 32, and 35 are shown). (b) Score image regions corresponding to the image regions shown in part (a). (c) Maximum intensity projection of the full score stack, with values below the object detection threshold set to zero. (d) Result of connected component labeling. [(e) and (f)] Score versus -plane distributions for the tip and fiducial, respectively, prior to subtraction of the baseline.
SBDX image of catheters A–F. Circles indicate regions that were independently tracked in 3D space.
(a) Chest phantom placed on an x-ray table and supporting foam. The SBDX x-ray source is below. (b) Cardiac phantom and catheter sheath prior to placement inside the chest phantom. (c) Tip of ablation catheter A. (d) CT images of the chest phantom showing catheter sheath.
Mean image fluence during catheter tracking studies (shaded regions) compared to the mean image fluence measured versus acrylic phantom thickness and kVp on the SBDX prototype system (lines; Ref. 11).
(a) Example tomosynthetic image during a 10 mm/s catheter pullback. [(b)–(d)] Tip tracking coordinates for all image frames (blue points) compared to the catheter sheath volume (green). The comparison is shown from three perspectives. The right-left (R-L), inferior-superior (I-S), and posterior-anteior (P-A) axes are shown for reference.
Tip tracking results for 10 (top row), 25 (middle row), and 50 mm/s (bottom row) catheter pullbacks along a fixed 3D trajectory in a chest phantom. The left column shows the tracked tip position versus image frame in the right-left (R-L), inferior-superior (I-S), and posterior-anterior (P-A) directions. The right column shows the 3D distance from catheter tip-to-sheath centerline, versus image frame.
Tip tracking in the -direction (source-detector axis) versus mean image fluence for six different catheters. Symbols indicate the mean -coordinate over 30 image frames; error bars indicate standard deviation in the individual -coordinates. The figure on the far right demonstrates simultaneous tracking of elements in catheters A–E.
Standard deviation in catheter tip -coordinate versus mean image fluence.
Standard deviation in proximal electrode -coordinate versus mean image fluence.
Cardiac electrophysiology catheters used in this study.
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