Method for representing a patient's treatment site as data for use with a CAD or CAM device

• US 5,452,407 A
• Filed: 11/29/1993
• Issued: 09/19/1995
• Est. Priority Date: 06/10/1992
• Status: Expired due to Term

• Current Assignee: AMER Technology Limited (AMER International Group Company Limited)
• Original Assignee: AMER Technology Limited (AMER International Group Company Limited)
• Inventors: Crook, David F.
• Primary Examiner(s): Herndon, Heather R.
• Assistant Examiner(s): Smith, Michael
• Application Number:
  US08/158,732
• Time in Patent Office: 659 Days
• Field of Search: 395/121, 395/124, 395/128, 395/129, 364/413.16, 364/413.13, 364/413.14, 364/413.19, 364/413.25, 364/474.24, 540/730
• US Class Current: 345/421
• CPC Class Codes: A61B 17/7059 Cortical plates A61B17/7007, A61B17/7058 take precedence
• CPC Class Codes: A61F 2/30942 for designing or making customized prostheses, e.g. using templates, CT or NMR scans, finite-element analysis or CAD-CAM techniques
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2002/2825 Femur
• CPC Class Codes: A61F 2002/30943 using mathematical models
• CPC Class Codes: A61F 2002/30948 using computerized tomography, i.e. CT scans
• CPC Class Codes: A61F 2002/30952 using CAD-CAM techniques or NC-techniques
• CPC Class Codes: A61F 2002/30957 using a positive or a negative model, e.g. moulds
• CPC Class Codes: A61F 2002/30962 using stereolithography
• CPC Class Codes: B33Y 50/00 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: G05B 19/4099 Surface or curve machining, making 3D objects, e.g. desktop manufacturing
• CPC Class Codes: G05B 2219/35043 Tool, fixture design
• CPC Class Codes: G06T 9/20 Contour coding, e.g. using detection of edges
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]
• CPC Class Codes: Y10S 623/901 Method of manufacturing prosthetic device

Abstract

A method is described for representing a treatment site (10) of a patient as data suitable for use with a computer-aided design device (46). The method includes scanning the treatment site(10) with a scanning apparatus (40), such as a CT scanner, to produce image data; determining the image data that represents the surface of the item; generating vectors from the determined data; and associating the vectors with poles of a non-uniform rational B-spline so that a polynomial equation may be generated, which is a data form suitable for use with CAD devices.

Claims

1. A method for representing a treatment site on a patient, the treatment site containing a surface, as data suitable for use with a computer-aided design device, the method comprising the steps of:

scanning the treatment site with a scanning apparatus to produce image data for a plurality of voxels;

identifying a plurality of boundary voxels representative of the surface of the treatment site;

generating a vector representing the location of each boundary voxel; and

converting the vectors into a form of data suitable for use with a computer-aided design device by associating each of the vectors with a pole of a control polygon of a non-uniform rational B-spline.

2. The method of claim 1 wherein the step of converting the vectors into a form of data suitable for use with a computer-aided design device further comprises the step of generating a polynomial equation from the non-uniform rational B-spline.

3. The method of claim 1 wherein said step of scanning the treatment site with a scanning apparatus to produce image data comprises scanning the treatment site with a CT scanner.

4. The method of claim 1 wherein said step of scanning the treatment site With a scanning apparatus to produce image data comprises scanning the treatment site with a MRI scanner.

5. A method for modelling an image of a surface of a treatment site on a patient, the method comprising the steps of:

generating a plurality of sets of data values for a plurality of voxels defining a three dimensional object, the data values within each set corresponding to a property of a three-dimensional object along the first and a second dimension, the object defining the treatment site, each set of data values corresponding to the property at one of a plurality of predetermined positions along a third dimension;

identifying the voxels that define the surface;

measuring a magnitude of each identified voxel;

using the magnitude of each identified voxel to generate a corresponding vector;

converting the vectors into computer-aided-design data suitable for use with a computer-aided design device by associating each vector with a pole of a control polygon of a non-uniform rational B-spline;

converting the computer-aided-design data into slice data suitable for use with a stereolithography system; and

forming a model of the image with the stereolithography system.

6. The method of claim 5 wherein the step of identifying comprises the steps of:

converting the data value into binary data values; and

surface tracking the binary data values to identify the data values that define the surface.

7. The method of claim 5 wherein the step of generating the plurality of sets of data values comprises the step of:

generating the plurality of sets Of data values tomographically.

8. The method of claim 7 wherein the step of generating the plurality of sets of data values tomographically comprises the step of:

scanning the treatment site with a CT scanner.

9. The method of claim 7 wherein the step of generating the plurality of sets of data values tomographically comprises the step of:

scanning the treatment site with an MRI scanner.

10. The method of claim 5 wherein the step of converting the plurality of vectors into the computer-aided-design data comprises the step of:

generating a polynomial equation from the non-uniform rational B-spline.

11. The method of claim 5 wherein the step of forming comprises the step of:

forming a model of the inverse image of the surface of the treatment site.

12. The method of claim 5 wherein the step of forming comprises the step of:

forming a model of direct image of the surface of the treatment site.

13. The method of claim 5 further comprising the step of:

generating a replica of the treatment site.

14. The method of claim 5 further comprising the step of:

generating a fixation device having a treatment-site mating surface with a contour substantially conforming to the inverse image of the surface of the treatment site.

15. A method for producing a visual representation of at least a portion of an image of an object comprising the steps of:

generating an image of an object including a structure of interest using a non-intrusive image generating device which produces a set of image data;

filtering the image data to distinguish between image data points corresponding to a structure of interest and image data points corresponding to other structures;

generating a surface representation of the structure of interest using the filtered image data;

generating a set of vectors from the surface representation defining the boundary of the structure of interest;

associating each vector with a pole of a non-uniform rational B-spline to create a series of such B-splines;

generating one or more polynomial equations from one or more nonuniform rational B-splines; and

displaying a visual representation of the structure of interest utilizing a display device which displays images utilizing polynomials generated from non-uniform rational B-splines.

16. The method of claim 15, wherein the step of generating an image of an object is performed by a CT scanner.

17. The method of claim 15, wherein the step of generating an image of an object is performed by a MRI scanner.

18. The method of claim 15, wherein the step of generating an image of an object is performed by an X-ray scanner.

19. The method of claim 15, wherein the step of generating an image of an object is performed by a PET scanner.

20. The method of claim 15, wherein the step of generating a surface representation of the structure of interest is performed using surface tracking.

21. The method of claim 15, wherein the step of filtering the image data is performed according to a binary density filtering method.

22. The method of claim 21, wherein the step of generating a surface representation of the structure of interest is performed using surface tracking.

23. The method of claim 15, wherein the step of filtering the image data is performed according to a boundary-based approach based on the density gradient of the set of image data points.

24. The method of claim 23, wherein the step of generating a surface representation of the structure of interest is performed using surface tracking.

25. The method of claim 15, wherein the step of displaying a visual representation of the structure of interest is performed by a CAD system.

26. The method of claim 15, wherein:

the step of generating an image of an object is performed by a CT scanner;

the step of generating a surface representation of the structure of interest is performed using surface tracking; and

the step of filtering the image data is performed according to a binary density filtering method.

27. The method of claim 26, wherein the step of displaying a visual representation of the structure of interest is performed by a CAD system.

28. The method of claim 15, wherein:

the step of generating an image of an object is performed by a CT scanner;

the step of generating a surface representation of the structure of interest is performed using surface tracking; and

the step of filtering the image data is performed according to a boundary-based approach based on the density gradient of the set of image data points.

29. The method of claim 28, wherein the step of displaying a visual representation of the structure of interest is performed by a CAD system.

30. The method of claim 15, wherein:

the step of generating an image of an object is performed by a MRI scanner;

the step of generating a surface representation of the structure of interest is performed using surface tracking; and

the step of filtering the image data is performed according to a binary density filtering method.

31. The method of claim 30, wherein the step of displaying a visual representation of the structure of interest is performed by a CAD system.

32. The method of claim 15, wherein:

the step of generating an image of an object is performed by a MRI scanner;

the step of generating a surface representation of the structure of interest is performed using surface tracking; and

the step of filtering the image data is performed according to a boundary-based approach based on the density gradient of the set of image data points.

33. The method of claim 32, wherein the step of displaying a visual representation of the structure of interest is performed by a CAD system.

34. A method for physically modelling an image of a surface of a structure of interest, the method comprising the steps of:

generating an image of an object including the structure of interest using a non-intrusive image generating device which produces a set of image data;

filtering the image data to distinguish between image data points corresponding to the structure of interest and image data points corresponding to other structures;

generating a surface representation of the structure of interest using the filtered image data;

generating a set of vectors from the surface representation defining the boundary of the structure of interest;

associating each vector with a pole of a non-uniform rational B-spline to create a series of such B-splines;

generating one or more polynomial equations from one or more nonuniform rational B-splines;

converting the polynomial equations into slice data suitable for use with a stereolithography system; and

forming a model of the image of the surface of the structure of interest with the stereolithography system.

35. The method of claim 34 wherein the step of forming comprises the step of:

forming a model of the inverse image of the surface.

36. The method of claim 35 further comprising the step of:

using the model of the inverse image as a mold to form a model of a direct image of the surface.

37. The method of claim 34 wherein the step of forming comprises the step of:

forming a model of a direct image of the surface.

38. The method of claim 37 further comprising the step of:

using the model of the direct image as a mold to form a model of the inverse image of the surface.

39. The method of claim 34 further comprising the step of:

generating a replica of the structure of interest.

40. The method of claim 34 further comprising the step of:

generating a device having a mating surface for closely mating with the surface of the structure of interest, the mating surface having a contour substantially conforming to the inverse image of the surface.