Spool distortion correction method for an x-ray radiograph diagnosis device

Claim 2

A distortion correction method for determining a distortion center of an X-ray image obtain by an X-ray imaging device, said distortion correction method comprising the steps of: (a) preparing a plate-shaped object having an X-ray imageable marker pattern therein, said marker pattern including a marker center and at least three sample points positioned at an equal distance from said marker center; (b) positioning said object upon said X-ray imaging device; (c) displaying an X-ray image of said object by means of said X-ray imaging device; and (d) inferring a distortion center of said X-ray imaging device on the basis of displayed distances from said marker center of said sample points.

Claim 3

A distortion correction method as claimed in claim 1, wherein said distortion is a spool distortion of said X-ray imaging device.

Claim 4

A distortion correction method for determining a distortion center of an X-ray image obtained by an X-ray imaging device, said distortion correction method comprising the steps of: (a) preparing a plate-shaped object having an x-ray imageable marker pattern therein, said marker pattern including a marker center and a plurality of sample points position at distinct distance from said marker center upon respective axes of an orthogonal coordinate system; (b) positioning said object upon said X-ray imaging device; (c) displaying an X-ray image of said object by means of said X-ray imaging device; and (d) inferring a distortion center of said X-ray imaging device on the basis of displayed distances from said marker center of said sample points.

Claim 5

A distortion correction method for determining a distortion center of an X-ray image obtained by an X-ray imaging device, said distortion correction method comprising the steps of: (a) preparing a plate-shaped object having an x-ray imageable marker pattern therein, said marker pattern including a marker center and a plurality of sample points position at distinct distance from said marker center upon respective axes of an orthogonal coordinate system; (b) positioning said object upon said X-ray imaging device; (c) displaying an X-ray image of said object by means of said X-ray imaging device; and (d) inferring a distortion center of said X-ray imaging device on the basis of displayed distances from said marker center of said sample points.

Claim 6

A distortion correction method as claimed in claim 3, wherein said distortion is a spool distortion of said X-ray imaging device.

Claim 7

A distortion correction method as claimed in claim 1, further comprising the step of: (e) judging whether or not a difference between said marker center and said inferred distortion center is within a predetermined allowable limit; and (f) repeating said steps (b) through (e) until judgment at step (e) is affirmative; and (g) determining as a distortion center inferred at said step (d) preceding step (e) at which said judgement is affirmative.

Claim 8

A distortion correction method as claimed in claim 3, further comprising the step of: (e) judging whether or not a difference between said marker center and said inferred distortion center is within a predetermined allowable limit; and (f) repeating steps (b) through (e) until judgment at step (e) is affirmative; and (g) determining as a distortion center inferred at said step (d) preceding step (e) at which said judgement is affirmative.

Claim 9

A distortion correction method as claimed in claim 1, wherein said X-ray imaging device comprises an X-ray image intensifier upon which the imaged body is positioned, said distortion correction method further comprising the steps of: (h) marking a position of said distortion center inferred at step (d) upon said X-ray image intensifier of said X-ray imaging device; and (i) aligning an axis of an imaging X-ray of said X-ray imaging device with said mark upon said X-ray image multiplier.

Claim 10

A distortion correction method as claimed in claim 3, wherein said X-ray imaging device comprises an X-ray image intensifier upon which the imaged body is positioned, said distortion correction method further comprising the steps of: (h) marking a position of said distortion center inferred at step (d) upon said X-ray image intensifier of said X-ray imaging device; and (i) aligning an axis of an imaging X-ray of said X-ray imaging device with said mark upon said X-ray image intensifier.

Claim 11

A distortion correction method for correcting a distortion of an X-ray image obtained by an X-ray imaging device, wherein a distortion center of said X-ray image is determined beforehand, said distortion correction method comprising the steps of: (a) preparing a plate-shaped object having an x-ray imageable marker pattern therein, said marker pattern including a marker center and a plurality of groups of sample points positioned at distinct distances from said marker center upon respective axes of an orthogonal coordinate system; (b) positioning said object upon said X-ray imaging device; (c) displaying an X-ray image of said object by means of said X-ray imaging device; (d) determining physical and displayed distances from said marker center to respective groups of said sample points; (e) determining a relationship between said physical and displayed distances determined at step (d); (f) determining distortion coefficients at respective distances from said distortion center on the basis of said relationship determined at step (e); (g) determining correction coefficients at respective distances from said distortion center on the basis of said distortion coefficients determined at step (f); and (h) correcting said X-ray image on the basis of said correction coefficients determined at step (g).

Claim 12

A distortion correction method for correcting a distortion of an X-ray image obtained by an X-ray imaging device, wherein a distortion center of said X-ray image is determined beforehand, said distortion correction method comprising the steps of: (a) preparing a plate-shaped object having an x-ray imageable marker pattern therein, said marker pattern including a marker center and a plurality of groups of sample points positioned at distinct distances from said marker center upon respective axes of an orthogonal coordinate system; (b) positioning said object upon said X-ray imaging device; (c) displaying an X-ray image of said object by means of said X-ray imaging device; (d) determining physical and displayed distances from said marker center to respective groups of said sample points; (e) determining a relationship between said physical and displayed distances determined at step (d); (f) determining distortion coefficients at respective distances from said distortion center on the basis of said relationship determined at step (e); (g) determining correction coefficients at respective distances from said distortion center on the basis of said distortion coefficients determined at step (f); and (h) correcting said X-ray image on the basis of said correction coefficients determined at step (g).

Claim 13

A distortion correction method as claimed in claim 9, wherein in said step (b), said marker center is positioned substantially at said distortion center.

Claim 14

A distortion correction method as claimed in claim 9 wherein in said step (e) said relationship is approximated by means of a polynomial.

Claim 15

A distortion correction method as claimed in claim 9, wherein in said step (a), said marker pattern includes a plurality of lattice points arranged in a form of matrix, said groups of sample points consisting of said lattice points.

Claim 16

A distortion correction method as claimed in claim 9, wherein said X-ray imaging device includes a digital display device, said X-ray image being displayed on said display device in said step (c); and said distances from said marker center to said sample points are determined on the basis of number of pixels between respective points on said display device.