![]() These projections are directed at a small high-speed photon-counting detector. 7, 8 In inverse geometry beam scanning, a scanning x-ray source with an electromagnetically deflected focal spot and large area target is used to generate thousands of narrow overlapping x-ray projections of the patient in every frame period. SBDX is a cardiac x-ray fluoroscopy system designed to reduce x-ray dose by up to 84% through scatter rejection, detector efficiency, and inverse geometry beam scanning. We present a novel stereoscopic imaging technique using Scanning Beam Digital X-ray (SBDX) technology that provides simultaneous stereo projection images at fluoroscopic frame rates using a single gantry. Stereoscopic XRF methods can be adapted from conventional XRF geometries (A) by using two complete gantries (B) or a special dual-anode x-ray tube with a common detector (C), but both methods have drawbacks. It is possible for a device in the heart to move between the two exposures, which may be distracting to the user or possibly misrepresent an object’s depth. Special XRF tubes with two anodes produce image pairs suitable for stereoscopic visualization, 3, 4 however they use a common detector and must make alternating x-ray exposures ( Figure 1C). 6 In addition, there is a limited area of overlap between the two views where an object can be imaged stereoscopically ( Figure 1B). Using the two gantries of a conventional biplane XRF system does not allow the x-ray sources to be positioned close enough to each other to create the stereoscopic effect the parallax is too great for the operator to fuse the two images into a single 3D scene. 5 The single, 3D display can convey depth information to the user in way that is as intuitive as normal binocular human vision.Įxisting methods for stereoscopic imaging using conventional XRF geometries have several drawbacks. 3, 4 Each eye sees a different view, and the brain interprets the disparity between object positions, or parallax, in the two views as depth. If the two views are only slightly different instead of orthogonal, they can be presented as a single, 3D stereoscopic image. Biplane XRF typically uses two orthogonal views from which the operator can mentally reconstruct a 3D representation of the field of view. ![]() Visualization of device depth and orientation may improve the accuracy and efficiency of these procedures.Īn additional x-ray view allows the operator to better determine the depth or orientation of an object. ![]() Recent interventional therapies such as RF ablation for cardiac arrhythmias 1 and transendocardial therapeutic injections 2 require precise device guidance within cardiac chambers, where they can be freely manipulated in 3D. However the projection process of XRF compresses all of the features in the 3D imaging volume into a single 2D image, eliminating information about the relative position of anatomy and devices along the direction of the projection (i.e. X-ray fluoroscopy (XRF) is the primary image guidance method for cardiovascular interventions due to its high spatial and temporal resolution and ease of use. This stereoscopic imaging method could be implemented in real time to provide live 3D visualization and device guidance for cardiovascular interventions using a single gantry and data acquired through normal, low-dose SBDX imaging. away) could be resolved, whereas the device orientation was ambiguous in conventional 2D projection images. When viewed as a stereoscopic red/cyan anaglyph, the true orientation (towards vs. To demonstrate visualization capabilities, a cardiac RF ablation catheter was imaged with the tip oriented towards the detector. After registering the localized spheres to the phantom geometry, the 3D residual RMS errors were between 0.81 and 1.93 mm, depending on the stereoscopic geometry. To confirm the accuracy of the 3D information contained in the stereoscopic projections, a phantom of known geometry containing high contrast steel spheres was imaged, and the spheres were localized in 3D using a previously described stereoscopic localization method. We present a novel method of stereoscopic imaging using SBDX, in which two slightly offset projection-like images are reconstructed from the same scan data by utilizing raw data from two different detector regions. The system performs x-ray tomosynthesis at multiple planes in each frame period and combines the tomosynthetic images into a projection-like composite image for fluoroscopic display. Scanning Beam Digital X-ray (SBDX) is a low-dose inverse geometry fluoroscopic system for cardiac interventional procedures.
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