Voxel-based catheter representation within an organ

Abstract

To provide a method, a device, and a system which acquire a volume of a catheter to construct a model of an anatomical structure.SOLUTION: A positioning system 26 comprises a catheter 14 and a processor 22. The processor receives a voxel grid comprising a plurality of voxels and a plurality three-dimensional coordinates of a location of the catheter and uses the three-dimensional coordinates to render the catheter on a display 29. The catheter rendering comprises a plurality of shaded pixels. The processor identifies coordinates of one or more voxels of the voxel grid which overlap with at least one shaded pixel, and marks the voxels of the voxel grid which overlap with the at least one shaded pixel. As such, a voxel trail can be created wherever the catheter moves. The voxel trail is used to define an internal volume within which the catheter is positioned, such as a chamber of a heart, a blood vessel, or a valve.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to constructing models of internal volumes, and more particularly to constructing models of anatomical structures. [Background technology]

[0002] In medical applications, it may be necessary to build a model of an anatomical structure, such as a heart chamber. In current implementations, a catheter can be moved within the heart chamber, and its position can be continuously recorded by a tracking system. Each of the recorded positions, or "points," can be added to a "point cloud" that represents the heart chamber. A volume of voxels can then be constructed from the point cloud, and a mesh model can be constructed from the volume. However, current implementations are time consuming and resource intensive. Summary of the Invention [Problem to be solved by the invention]

[0003] Therefore, it would be desirable to have a more efficient process for constructing models of anatomical structures. [Means for solving the problem]

[0004] Disclosed are methods, devices, and systems for constructing an internal volume from which a model can be created. The system may include a catheter and a processor. The processor may be configured to receive a voxel grid including a plurality of voxels and a plurality of three-dimensional coordinates of the catheter's location. The processor may use the three-dimensional coordinates to render the catheter on a display, where the catheter rendering includes a plurality of shaded pixels. The processor may identify coordinates of one or more voxels in the voxel grid that overlap with at least one shaded pixel and mark the voxels in the voxel grid that overlap with the at least one shaded pixel. In this manner, a voxel trajectory can be generated wherever the catheter moves. The voxel trajectory may be used to define an internal volume in which the catheter is located, such as a heart chamber, blood vessel, or valve. The processor may be configured to generate a mesh representing the surface of the internal volume by applying a mesh generation algorithm to the volume including the voxels marked as occupied. [Brief explanation of the drawings]

[0005] The foregoing and other features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings. [Figure 1] 1 is a schematic diagram of a system for performing a procedure on a living heart using a multi-branched cardiac catheter, according to an exemplary embodiment; [Figure 2] 2 is a detailed view of one of the branches of the catheter shown in FIG. 1 according to an exemplary embodiment. [Figure 3A] 1 is a schematic illustration of a method for generating a volume of voxels, according to an exemplary embodiment; [Figure 3B] 1 is a schematic illustration of a method for generating a volume of voxels, according to an exemplary embodiment; [Figure 4] 1 is a flowchart of a method for generating a volume of voxels, in accordance with an illustrative embodiment; [Figure 5A] 1 is an illustration of a catheter relative to a voxel grid and a pixel grid, according to an exemplary embodiment. [Figure 5B] 5B is a rendering of the catheter of FIG. 5A with occupied pixels marked, according to an exemplary embodiment. [Figure 5C] 5C is a rendering of the catheter of FIG. 5B with occupied voxels marked, according to an exemplary embodiment. [Figure 6A] 5 is a schematic diagram of various aspects of the method of FIG. 4, according to an exemplary embodiment. [Figure 6B] 5 is a schematic diagram of various aspects of the method of FIG. 4, according to an exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0006] The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates, by way of example and not by way of limitation, the principles of the invention. This description will clearly enable any person skilled in the art to make and use the invention and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is currently construed to be the best mode for carrying out the invention.

[0007] 1 is a schematic diagram of a system 10 for performing a procedure on a living heart 12, according to one embodiment. System 10 may include a catheter 14 and a control console 24. One commercially available product embodying elements of system 10 is available as the CARTO® 3 system, which is available from Biosense Webster, Inc. (3333 Diamond Canyon Road, Diamond Bar, California 91765).

[0008] The catheter 14 can be used for any suitable therapeutic and / or diagnostic purpose, such as anatomical mapping of the chambers of the heart 12. The catheter 14 may be a multi-electrode catheter having an elongated body with multiple branches 37, each with mapping and position sensing capabilities. The catheter 14 may further include a handle 20 having controls that allow an operator 16, typically a physician, to steer the distal end of the catheter 14 and position and direct the position and orientation of the branches 37 as needed. The five-branch catheter described in U.S. Patent No. 6,961,602 is suitable for use as the catheter 14. This catheter is available from Biosense Webster as the Pentaray™ catheter or probe.

[0009] In some embodiments, the catheter 14 includes an elongate body having a proximal end, a distal end, and at least one lumen extending longitudinally therethrough, and a mapping assembly attached to the distal end of the catheter body and including at least two branches 37. Each branch 37 has a proximal end attached to the distal end of the catheter body and a free distal end. Each branch 37 includes a support arm having shape memory, a non-conductive cover surrounding the support arm, at least one position sensor 41 ( FIG. 2 ) attached to the distal end of the branch 37, one or more electrodes attached to the distal end of the branch 37 and electrically insulated from the support arm, and one or more electrode lead wires extending within the non-conductive cover, each electrode wire attached to a corresponding electrode. In some embodiments, an additional position sensor (not shown) can be positioned on the shaft of the catheter 14 proximal to the branches 37.

[0010] The catheter 14 may be percutaneously inserted by an operator 16 through the patient's vascular system into a cavity or vasculature of the heart 12. The operator 16 may bring the distal tip 18 of the catheter into contact with the heart wall at a desired mapping site. The distal end of the catheter 18 may then collect measurements. The collected measurements may be referred to as "points." Each point includes a three-dimensional coordinate on the tissue of the cavity and a respective measurement of several physiological characteristics measured at that coordinate.

[0011] Additionally or alternatively, ablation energy and electrical signals can be transmitted to and from heart 12 through one or more optional ablation electrodes located at or near distal tip 18 via a cable to console 24. Pacing and other control signals can be transmitted from console 24 to heart 12 via cable 38 and one or more ablation electrodes.

[0012] Wiring connections 35 may connect the console 24 with the body surface electrodes 30 and other components of the positioning subsystem. A temperature sensor 43 (FIG. 2), such as a thermocouple or thermistor, may be mounted on or near the distal tip 18.

[0013] Console 24 may include one or more ablation generators 25. Catheter 14 may be adapted to deliver ablation energy to the heart using any known ablation technique, including, but not limited to, radiofrequency energy, ultrasound energy, and laser-generated light energy. Such methods are disclosed in commonly assigned U.S. Patent Nos. 6,814,733, 6,997,924, and 7,156,816, which are incorporated herein by reference.

[0014] The processor 22 may be a component of a positioning system 26 of the system 10 that measures the position and orientation coordinates of the catheter 14 .

[0015] In some embodiments, the positioning system 26 may include a magnetic position tracker that determines the position and orientation of the catheter 14 by generating magnetic fields within a predetermined working volume nearby and sensing these fields at the catheter using field generating coils 28, and may also include impedance measurements, for example, as taught in U.S. Patent No. 7,756,576, which is incorporated herein by reference. The positioning system 26 may be augmented by position measurements using impedance measurements as described in U.S. Patent No. 7,536,218, which is incorporated herein by reference.

[0016] As mentioned above, catheter 14 is coupled to console 24, which allows operator 16 to observe and adjust the functions of catheter 14. Console 24 includes processor 22, which may be coupled to display 29. Signal processing circuitry may receive, amplify, filter, and digitize signals from catheter 14, including signals generated by the sensors described above and by a plurality of position-sensing electrodes (not shown) disposed on catheter 14. The digitized signals may be received and used by console 24 and positioning system 26 to calculate the position and orientation of catheter 14 and to analyze electrical signals from the electrodes.

[0017] In some embodiments, the processor 22 may be a computer and may be programmed with software to perform the functions described herein. For example, in some embodiments, the processor 22 is a programmed digital computing device that includes a central processing unit (CPU), a graphics processing unit (GPU), random access memory (RAM), non-volatile secondary storage such as a hard drive or CD-ROM drive, a network interface, and / or peripherals. As is known in the art, program code and / or data, including software programs, are loaded into RAM for execution and processing by the CPU and / or GPU, generating results for display, output, transmission, or storage. The software code may be downloaded to the computer in electronic form over a network, or may be provided to and / or stored on a non-transitory tangible medium, such as magnetic, optical, or electronic memory.

[0018] FIG. 2 is a detailed view of one of the branches 37 of FIG. 1 showing the electrode configuration, according to one embodiment. The electrode configuration may include a tip electrode 39, two ring electrodes 41, and a temperature sensor 43. The tip electrode 39 may be configured for both sensing and ablation. The temperature sensor 43 may be used when the catheter 14 is in ablation mode. The two ring electrodes 41 may be configured as sensing electrodes for detecting electrophysiological signals in the heart. However, as will be appreciated by those skilled in the art, the number, configuration, and distribution of sensing and ablation electrodes may vary in many combinations. One or more cables 45 may carry signals between the electrodes, sensors, and the console 24. With multiple electrodes distributed among several branches 37, signals can be collected from multiple locations simultaneously.

[0019] In the current system, a catheter, such as catheter 14 described above, is moved within the chamber or adjacent blood vessel, and the position of catheter 14 is continuously recorded. Processor 22 can receive coordinates for each of a plurality of locations within the heart chamber. For example, as described above with respect to FIG. 1, the CPU can receive the coordinates from a location verification routine that verifies the location of the distal end of catheter 14 as the distal end moves within the chamber. Each coordinate may be referred to as a "point," and a collection of coordinates may be referred to as a "point cloud." A point cloud may include hundreds, thousands, or tens of thousands of points, with gaps where no points exist.

[0020] The CPU can provide the GPU with a catheter tree. The catheter tree can include a collection of splines, each of which includes a continuous curve formed to pass through multiple points. The points forming the spline can be points (recorded locations) along a physical portion of the catheter 14. Thus, each spline can represent a physical portion, such as a branch 37 of the catheter 14. In some embodiments, the points of a spline are spaced 1-2 mm apart from one another. As used herein, a voxel grid is a regularly spaced three-dimensional grid, and a voxel represents a data point on the voxel grid. In the current implementation, the processor 22 can use the catheter tree to determine volumetric acquisition by using a voxel-to-cylinder collision test and / or a voxel-to-sphere collision test, as briefly described in the following paragraphs.

[0021] In the current implementation, each spline can be associated with a branch radius. The branch radius can correspond to the radius of a branch 37 of the catheter 14. Using the branch radius and multiple points of the spline, the processor 22 can create a cylinder. The processor 22 can create a cylinder for each spline. The processor 22 can overlay the cylinder representing the branch 37 of the catheter 14 on a voxel grid and perform collision tests between the cylinder and voxels of the voxel grid. In other words, the processor 22 can determine which voxels overlap or are inside the cylinder. If a voxel overlaps or is inside the cylinder, the processor 22 marks the voxel as occupied.

[0022] In the current implementation, each spline tip can be associated with a tip radius. The tip radius can correspond to the radius of the tip of the branch 37. Using the tip radius and one or more points of the spline tip, processor 22 can create a sphere. Processor 22 can create a sphere for each spline. Processor 22 can overlay the spheres representing the branch tips on a voxel grid and perform collision tests between the spheres and voxels of the voxel grid. In other words, processor 22 can determine which voxels overlap or are inside the sphere. If a voxel overlaps or is inside the sphere, processor 22 marks the voxel as occupied.

[0023] This process can be used to determine the voxels that correspond to the current position of the catheter. The catheter can be moved throughout the interior volume to define the interior volume. The interior volume can be an anatomical cavity, such as a heart chamber. The processor 22 can be configured to generate a mesh representing a surface of the volume by applying a mesh generation algorithm to the volume including the first voxels and the subset of second voxels. The processor 22 can be further configured to display the mesh on a display.

[0024] This current implementation is time-consuming and resource-intensive. For example, the Pentaray™ catheter contains five branches, each approximately 10 mm long. A voxel-cylinder collision detection test requires approximately 100 floating-point operations, potentially resulting in a total of 5,000 floating-point operations. Furthermore, as the catheter moves frequently (e.g., every 16 ms), the CPU must provide updated points to the GPU, which must then convert the points to voxel space.

[0025] 3A and 3B are schematic diagrams 300A and 300B, respectively, of a catheter voxel trajectory generated according to a current implementation, which, as noted above, is time-consuming, resource-intensive, and introduces a time delay between the rendering of the catheter 301 and the voxel trajectory 302.

[0026] 4 is a method for generating a volume of a catheter 400, according to one embodiment. The method 400 may be executed on the system 10, as described above, to perform a procedure on the living heart 12. However, as will be appreciated by those skilled in the art, the method 400 described herein may also be implemented on a computer system utilized for a variety of purposes.

[0027] At 401, the processor 22 defines a voxel grid for the volume. The voxel grid may have any suitable shape. In some embodiments, the voxel grid may be a three-dimensional grid shape, such as a cubic shape. In some embodiments, the voxel grid may be defined by a CPU. For example, the CPU may determine the voxel grid using an algorithm, such as a fast anatomical mapping (FAM) algorithm. The CPU may define the volume as a discrete number of voxels. The CPU may further define the dimensions of each voxel. By way of example only, the voxel grid may include 256 x 256 x 256 voxels, with each voxel having dimensions of 0.8 x 0.8 x 0.8 mm. Defining the voxel grid and voxel dimensions may be a one-time operation that does not need to be repeated later during the procedure, as in the current implementation. After defining the voxel grid and the dimensions of each voxel, the CPU may send this information to the GPU. The CPU may also send catheter tree information to the GPU at 401. Alternatively, the CPU can provide the catheter tree information to the GPU before the process begins.

[0028] At 402, after the catheter is inserted into the patient, processor 22 receives a plurality of three-dimensional coordinates of catheter 14. For example, as described above with reference to FIG. 1, the coordinates may be determined from a position determination routine that determines the position of the distal end of catheter 26 as the distal end moves within the lumen.

[0029] At 403, the processor 22 renders the catheter 14 on the display 29 using coordinates corresponding to the position of the catheter 14 and the known catheter tree information. The GPU of the processor 22 may be used to render the catheter 14. In some embodiments, the GPU may utilize one or more programs, including but not limited to a vertex shader, a rasterizer, and a pixel shader, to render the catheter 14 on the display 29. The vertex shader may receive the original three-dimensional coordinates of the catheter 14 and convert the three-dimensional coordinates into two-dimensional coordinates that appear on the screen and depth values ​​in a Z-buffer. The vertex shader may manipulate properties such as position, color, and texture coordinates. The output of the vertex shader may be passed to a rasterizer. The rasterizer may determine the pixels covered by a primitive (e.g., a triangle) and interpolate the output parameters of the vertex shader for each covered pixel. For each sample of a pixel covered by a primitive, a "fragment" is generated. The output of the rasterizer may then be provided to a pixel shader, also known as a fragment shader. The pixel shader may shade multiple pixels in a pixel grid to generate a two-dimensional rendering of the catheter 14 that corresponds to the three-dimensional position of the catheter on the screen. Specifically, the pixel shader may determine the color, brightness, contrast, and other characteristics of the pixels. However, as will be appreciated by those skilled in the art, rendering of the catheter may involve a variety of different methods.

[0030] At 404, processor 22 determines the coordinates of each voxel that overlaps with a shaded pixel of the catheter rendering. In some embodiments, processor 22 determines the coordinates of voxels that overlap with a shaded pixel of the catheter rendering using Equation 1, where:

[0031]

number

[0032]

number

[0033] At 405, processor 22 marks one or more voxels that overlap with pixels of the catheter rendering and designates such voxels as occupied. In this manner, as catheter 14 moves throughout the cavity, the marked voxels can represent a subvolume of the cavity.

[0034] If updated three-dimensional coordinates of catheter 14 are received by processor 22 at 406, the process returns to 403. If updated three-dimensional coordinates of catheter 14 are not received, the process ends at 407.

[0035] 5A is a two-dimensional view 500 of a catheter branch 37 in relation to a voxel grid (a three-dimensional grid made up of voxels 502) and a pixel grid (a two-dimensional grid made up of pixels 501). As discussed above, the voxel grid includes a plurality of voxels 502, indicated by thick lines, and the pixel grid includes a plurality of pixels 501, indicated by thin lines. In the illustrated embodiment, the size of the pixels 501 that make up the pixel grid is smaller than the size of the voxels 502 that make up the voxel grid. However, as will be appreciated by those skilled in the art, the size of the pixels 501 and the size of the voxels 502 may be the same, or the size of the voxels 502 may be smaller than the size of the pixels 501.

[0036] Figure 5B is a two-dimensional view 510 of branch 37 of Figure 5A, where the pixels occupied by the catheter are marked 501A, as described above with respect to 403 above. In the embodiment shown in Figure 5B, the marked pixels 501A comprise the same color, brightness, and contrast. However, as will be appreciated by those skilled in the art, each of the marked pixels 501A may comprise a different color, brightness, contrast, etc.

[0037] FIG. 5C is a two-dimensional view 520 of the branch 37 of FIG. 5A, in which voxels 502A of the plurality of voxels 502 that overlap with at least one shaded pixel 501A of FIG. 5B are marked as described above with respect to 404 and 405.

[0038] The processor 22 can optionally apply one or more algorithms to optimize the volume acquisition of the catheter 14. For example, if a voxel is surrounded on all sides by marked voxels, the algorithm can identify and mark the voxel as occupied. Additionally or alternatively, known cavity walls can be used to determine that readings of voxels identified outside the cavity walls are not accurate readings.

[0039] The disclosed method 400 is less time- and resource-intensive than current implementations. For example, in a Pentaray™ catheter containing six splines, each approximately 10 mm long, the points on the splines are approximately 0.5 mm apart. Therefore, approximately 20 points are required per spline, resulting in 120 distinct pixels. The voxel-pixel collision test requires three floating-point operations. Thus, a total of approximately 360 floating-point operations are required, far fewer than the thousands typically required in current implementations. Furthermore, the disclosed method 400 can be implemented entirely using the GPU of the processor 22. By operating solely on the GPU, the entire method does not require multiple uploads and downloads of information during CPU and GPU execution.

[0040] Figures 6A and 6B are schematic diagrams 600A and 600B, respectively, of a catheter voxel trajectory generated according to the method of Figure 4, according to one embodiment. As shown in Figures 6A and 6B, voxels are marked wherever the catheter is rendered, and a voxel trajectory 602 is created behind the catheter rendering 601. There is no time delay in creating the voxel trajectory 602, as there is no "real" calculation to find the voxels.

[0041] The voxel trajectory 602 may be used to define an interior volume in which the catheter 14 is positioned, such as a heart chamber, blood vessel, or valve. For example, the interior volume may be obtained by contacting the catheter 14 within multiple points on the interior surface of a wall defining the interior volume. A volume outside the interior volume may be an exterior volume corresponding to an additional anatomical structure, such as a second heart chamber of a body organ. The processor 22 may be configured to generate a mesh representing the surface of the interior volume by applying a mesh generation algorithm to the volume containing the voxels marked as occupied. The processor 22 may further be configured to display the mesh on a display.

[0042] The methods described herein may also include algorithms that may be utilized by a skilled software engineer to generate the step-by-step computer code required to implement the overall method in a computer system (e.g., a general-purpose computer or a dedicated computer such as a Carto system).

[0043] It should be noted that although this disclosure is primarily directed to heart chambers, the techniques described herein can also be used to model any other anatomical or non-anatomical structure. For example, the techniques described herein may be used in depth sensing applications.

[0044] It should be understood that many variations are possible based on the disclosure herein, and although features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements, or in various combinations with or without the other features and elements.

[0045] [Embodiment] (1) A method executed on a processor, comprising: receiving a voxel grid including a plurality of voxels; receiving a plurality of three-dimensional coordinates of the location of the catheter; rendering the catheter on a display using the three-dimensional coordinates, the catheter rendering including a plurality of shaded pixels; identifying coordinates of one or more voxels of the voxel grid that overlap at least one shaded pixel; and marking the voxels of the voxel grid that overlap with at least one shaded pixel. (2) The method described in embodiment 1, wherein the coordinates (i, j, k) of the voxel that overlaps with a pixel of the catheter rendering are determined by dividing the three-dimensional coordinate associated with a shadow pixel by the size of the voxel in the voxel grid. (3) The method of embodiment 1, wherein the voxel grid is defined by a central processing unit (CPU) of the processor. (4) The method of embodiment 3, wherein the CPU determines the voxel grid using a fast anatomical mapping (FAM) algorithm. (5) The method of embodiment 1, wherein each time the catheter moves, the processor performs the steps of receiving the plurality of three-dimensional coordinates, rendering the catheter on the display, identifying the three-dimensional coordinates of one or more voxels that overlap with at least one shaded pixel, and marking the one or more voxels identified as overlapping with at least one shaded pixel.

[0046] (6) The method of embodiment 1, wherein the method is implemented using a graphics processing unit (GPU) of the processor. (7) The method of embodiment 1, wherein the catheter is brought into contact with a plurality of points on a wall defining an internal volume, and the marked voxels define the internal volume. (8) The method of embodiment 7, wherein the internal volume defines an anatomical structure. (9) The method of embodiment 8, wherein the anatomical structure is a cardiac chamber. (10) The method of embodiment 7, further comprising generating a mesh representing the surface of the internal volume by applying a mesh generation algorithm to the marked voxels.

[0047] (11) A system comprising: 1. A processor, comprising: receiving a voxel grid including a plurality of voxels; receiving a plurality of three-dimensional coordinates of the location of the catheter; rendering the catheter on a display using the three-dimensional coordinates, the catheter rendering including a plurality of shaded pixels; identifying coordinates of one or more voxels of the voxel grid that overlap at least one shaded pixel; marking the voxels of the voxel grid that overlap with at least one shaded pixel; and a display device connected to the processor for displaying the catheter rendering and the marked voxels. (12) The system of embodiment 11, wherein the processor includes a central processing unit (CPU) and a graphics processing unit (GPU). (13) The system described in embodiment 12, wherein the voxel grid is defined by the CPU of the processor. (14) The system of embodiment 13, wherein the CPU determines the voxel grid using a fast anatomical mapping (FAM) algorithm. (15) The system of embodiment 11, wherein each time the catheter moves, the processor is configured to receive the plurality of three-dimensional coordinates, render the catheter on the display, identify the three-dimensional coordinates of one or more voxels that overlap with at least one shaded pixel, and mark the one or more voxels identified as overlapping with at least one shaded pixel.

[0048] (16) The system of embodiment 11, wherein the GPU is configured to receive the voxel grid, receive the plurality of three-dimensional coordinates, render the catheter, identify coordinates of one or more voxels in the voxel grid, and mark the voxels in the voxel grid. (17) The system of embodiment 11, wherein the marked voxels define an internal volume. (18) The system of embodiment 17, wherein the internal volume defines an anatomical structure. (19) The system of embodiment 17, wherein the processor is further configured to apply a mesh generation algorithm to the marked voxels to generate a mesh representing a surface of the internal volume. (20) A tangible, non-transitory computer-readable medium, When read by a processor, the processor: receiving a voxel grid including a plurality of voxels; receiving a plurality of three-dimensional coordinates of the location of the catheter; rendering the catheter on a display using the three-dimensional coordinates, the catheter rendering including a plurality of shaded pixels; identifying coordinates of one or more voxels of the voxel grid that overlap at least one shaded pixel; and marking the voxels of the voxel grid that overlap with at least one shaded pixel.

Claims

1. 1. A system comprising:

1. A processor, comprising: receiving a voxel grid including a plurality of voxels; receiving a plurality of three-dimensional coordinates of the position of the catheter; rendering the catheter on a display using the three-dimensional coordinates, the rendering using a plurality of shaded pixels to generate a two-dimensional rendering of the physical portion of the catheter; identifying coordinates of one or more voxels of the voxel grid that overlap at least one shaded pixel; marking the voxels of the voxel grid that overlap with at least one shaded pixel; and a display device connected to the processor for displaying the rendering of the catheter and the marked voxels.

2. The system of claim 1 , wherein the processor includes a central processing unit (CPU) and a graphics processing unit (GPU).

3. The system of claim 2 , wherein the voxel grid is defined by the CPU of the processor.

4. The system of claim 3 , wherein the CPU utilizes a fast anatomical mapping (FAM) algorithm to determine the voxel grid.

5. 2. The system of claim 1, wherein each time the catheter moves, the processor is configured to receive the plurality of three-dimensional coordinates, render the catheter on the display, identify the three-dimensional coordinates of one or more voxels that overlap with at least one shaded pixel, and mark the one or more voxels identified as overlapping with at least one shaded pixel.

6. 3. The system of claim 2, wherein the GPU is configured to receive the voxel grid, receive the plurality of three-dimensional coordinates, render the catheter, identify coordinates of one or more voxels in the voxel grid, and mark the voxels in the voxel grid.

7. The system of claim 1 , wherein the marked voxels define an interior volume.

8. The system of claim 7 , wherein the interior volume defines an anatomical structure.

9. The system of claim 7 , wherein the processor is further configured to apply a mesh generation algorithm to the marked voxels to generate a mesh representing a surface of the internal volume.

10. A tangible, non-transitory computer-readable medium, comprising: When read by a processor, the processor: receiving a voxel grid including a plurality of voxels; receiving a plurality of three-dimensional coordinates of the position of the catheter; rendering the catheter on a display using the three-dimensional coordinates, the rendering using a plurality of shaded pixels to generate a two-dimensional rendering of the physical portion of the catheter; identifying coordinates of one or more voxels of the voxel grid that overlap at least one shaded pixel; and marking the voxels of the voxel grid that overlap with at least one shaded pixel.

11. 1. A method executed on a processor, comprising: receiving a voxel grid including a plurality of voxels; receiving a plurality of three-dimensional coordinates of the position of the catheter; rendering the catheter on a display using the three-dimensional coordinates, the rendering using a plurality of shaded pixels to generate a two-dimensional rendering of the physical portion of the catheter; identifying coordinates of one or more voxels of the voxel grid that overlap at least one shaded pixel; and marking the voxels of the voxel grid that overlap with at least one shaded pixel.

12. 12. The method of claim 11, wherein the coordinates (i, j, k) of the voxels that overlap with pixels of the catheter rendering are determined by dividing the three-dimensional coordinates associated with a shaded pixel by the size of the voxel in the voxel grid.

13. The method of claim 11 , wherein the voxel grid is defined by a central processing unit (CPU) of the processor.

14. The method of claim 13 , wherein the CPU utilizes a fast anatomical mapping (FAM) algorithm to determine the voxel grid.

15. 12. The method of claim 11, wherein, each time the catheter moves, the processor performs the steps of receiving the plurality of three-dimensional coordinates, rendering the catheter on the display, identifying the three-dimensional coordinates of one or more voxels that overlap with at least one shaded pixel, and marking the one or more voxels identified as overlapping with at least one shaded pixel.

16. The method of claim 11 , wherein the method is performed using a graphics processing unit (GPU) of the processor.

17. The method of claim 11 , wherein the catheter is brought into contact with a plurality of points on a wall defining an interior volume, and the marked voxels define the interior volume.

18. The method of claim 17 , wherein the interior volume defines an anatomical structure.

19. 20. The method of claim 18, wherein the anatomical structure is a cardiac chamber.

20. The method of claim 17 , further comprising generating a mesh representing a surface of the internal volume by applying a mesh generation algorithm to the marked voxels.

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