Method and apparatus for calibrating an intra-operative X-ray system
First Claim
1. A method for calibrating an intra-operative X-ray system having an X-ray source and a detector, said method comprising the steps of:
- (1) performing an off-line process comprising;
(a) initializing said X-ray system into an arbitrary position,(b) placing into a position an X-ray phantom,(c) placing into a first position an optical phantom,(d) taking an off-line X-ray image,(e) taking an optical image by a camera associated with said X-ray source,(f) taking an off-line optical image by a camera associated with said detector; and
(2) performing an on-line process comprising;
(A) initializing said X-ray system into a position,(B) placing into a second position said optical phantom,(C) taking an on-line X-ray image,(D) taking an on-line optical image by a camera associated with said X-ray source, and(E) taking an optical image by a camera associated with said detector; and
(3) combining information from said off-line optical images and said off-line X-ray image and the on-line optical images so as to derive a projection matrix for use in an image reconstruction process using said on-line X-ray image.
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Accused Products
Abstract
Apparatus for calibrating an intra-operative X-ray system having an X-ray source and a detector includes an optical camera associated with the X-ray source; an optical camera associated with the detector; an X-ray phantom placed within a field of view of the X-ray system during an off-line process; an optical phantom placed within a field of view of the optical cameras during the off-line process as well as the on-line process (called the patient run); and apparatus for computing a respective projection matrix from an image provided by any of the X-ray source and detector, and the optical cameras. A method to obtain the projection matrices characterizing the X-ray imaging geometry during the patient run, using the projection matrices associated to X-ray geometry as well as the optical cameras computed during an off-line process, and the projection matrices associated to the optical cameras during the patient run. The relative motion of the apparatus between the off-line and on-line process is computed using the projection matrices characterizing the imaging geometry of the optical cameras. This information leads us to the modification of the off-line estimation of X-ray imaging geometry and to the characterization of its on line imaging geometry.
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Citations
30 Claims
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1. A method for calibrating an intra-operative X-ray system having an X-ray source and a detector, said method comprising the steps of:
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(1) performing an off-line process comprising; (a) initializing said X-ray system into an arbitrary position, (b) placing into a position an X-ray phantom, (c) placing into a first position an optical phantom, (d) taking an off-line X-ray image, (e) taking an optical image by a camera associated with said X-ray source, (f) taking an off-line optical image by a camera associated with said detector; and (2) performing an on-line process comprising; (A) initializing said X-ray system into a position, (B) placing into a second position said optical phantom, (C) taking an on-line X-ray image, (D) taking an on-line optical image by a camera associated with said X-ray source, and (E) taking an optical image by a camera associated with said detector; and (3) combining information from said off-line optical images and said off-line X-ray image and the on-line optical images so as to derive a projection matrix for use in an image reconstruction process using said on-line X-ray image. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for calibrating an intra-operative X-ray having an X-ray source and a detector system, said method comprising the steps of:
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(A) performing an off-line process comprising; (a) initializing said X-ray system into an initial position, as closely as possible to its position when a patient is present, (b) placing into position an X-ray phantom, (c) placing into position an optical phantom, (d) taking off-line, a radiographic image, (e) computing and storing a projection matrix Px (f) taking off-line, an optical image by a camera associated with said X-ray source, (g) computing from said optical image and storing a projection matrix Psc (h) taking off-line, an optical image by a camera associated with said detector, and (i) computing from said optical image and storing a projection matrix Pdc ; and (B) performing an on-line process comprising; (1) placing into position an optical phantom, (2) taking on-line, a radiographic image, (3) taking on-line, an optical image by a camera associated with said X-ray source, (4) computing from said optical image and storing a projection matrix psc (5) taking on-line, an optical image by a camera associated with said detector, (7) computing from said optical image and storing a projection matrix pdc, and (8) calculating an X-ray projection matrix Px from said foregoing matrices Px, Psc, Pdc, psc, pdc.
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8. A method for calibrating an intra-operative X-ray having an X-ray source and a detector system during a rotational run around the patient, said method comprising the steps of:
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(A) performing an off-line process comprising; (a) initializing said X-ray system into a starting position (i), (b) placing into position an X-ray phantom, (c) placing into position an optical phantom, (d) taking off-line, a radiographic image, (e) computing and storing a projection matrix Pxi (f) taking off-line, an optical image by a camera associated with said X-ray source, (g) computing from said optical image and storing a projection matrix Psci (h) taking off-line, an optical image by a camera associated with said detector, (i) computing from said optical image and storing a projection matrix Pdci (j) rotating said X-ray system to the next position (i+1) (k) repeating steps (d) through (j) unless the end position is reached; and (B) performing an on-line process comprising; (1) initializing said X-ray system into said starting position (i), (2) placing into position an optical phantom, (3) taking on-line, a radiographic image, (4) taking on-line, an optical image by a camera associated with said X-ray source, (5) computing from said optical image and storing a projection matrix psci (6) taking on-line, an optical image by a camera associated with said detector, (7) computing from said optical image and storing a projection matrix pdci (8) calculating an X-ray projection matrix Pxi from said foregoing matrices Pxi, Psci, Pdci, psci, pdci ; (9) rotating said X-ray system tp the next position (i+1), (10) repeating (3) through (9) unless the end position is reached, and (11) applying said projection matrices Pxi to an image reconstruction process. - View Dependent Claims (10, 12, 14)
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9. Apparatus for calibrating an intra-operative X-ray system having an X-ray source and a detector, said apparatus comprising:
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an optical camera associated with said X-ray source; an optical camera associated with said detector; an X-ray phantom placed within a field of view of said X-ray system; an optical phantom placed within a field of view of said optical cameras; and means for computing a respective projection matrix from an image provided by any of said X-ray source and detector, and said optical cameras. - View Dependent Claims (11, 13)
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15. A method for calibrating an intra-operative X-ray having an X-ray source and a detector system during a rotational run around a patient, said method comprising the steps of:
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beginning at a starting position and taking a radiographic image of an X-ray phantom from a first spatial position and taking respective optical images of an optical phantom from respective second and third spatial positions, said first and second spatial positions being in fixed relationship relative to said first spatial position, wherein said optical and X-ray phantoms are in fixed spatial relationship to one another; and deriving and storing respective projection matrices from said images. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. A method for calibrating an intra-operative X-ray having an X-ray source and a detector system during a rotational run around a patient, said method comprising the steps of:
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beginning at a starting position and taking a radiographic image of an X-ray phantom from a first spatial position and taking respective optical images of an optical phantom from respective second and third spatial positions, said first and second spatial positions being in known relationship relative to said first spatial position, wherein said optical and X-ray phantoms are in known spatial relationship to one another; and deriving and storing respective projection matrices from said images. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30)
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Specification