Digital image remapping
The present invention relates to production of 2D digital images suitable for use in medical imaging. The invention particularly relates to remapping X-ray images taken from a first viewpoint so that they present the same image as seen from a second viewpoint. Remapping is achieved by registering separate 2D images taken from the first and second viewpoints of an area with a 3D scan volume of the same region to ascertain their relative viewpoints with respect to the 3D scan volume. The image taken with respect to the first viewpoint is then remapped to yield the image as seen from the second viewpoint.
1. An image generation method comprising:
a) obtaining single first and single second 2D images through an object to be imaged, wherein the images are from different viewpoints with respect to the object;
b) providing a 3D image data set of the object to be imaged;
c) defining a remapping surface within the 3D image data set;
d) registering the first and second 2D images with the 3D image data set and determining a viewpoint of the first and second 2D images with respect to the 3D image data set; and
e) remapping pixels of the first 2D image to generate a remapped 2D image from the viewpoint of the second 2D image by:
i. back projecting rays from the pixels of the first 2D image and determining the points of intersection of the back projected rays with the remapping surface; and
ii. remapping the pixels of the first 2D image corresponding to the points of intersection to generate the 2D remapped image, whereby the pixels of the first 2D image are remapped according to the direction of rays projected from the viewpoint of the second 2D image via the intersection points corresponding to each pixel.
2. The image generation method of claim 1 , comprising:
f) obtaining a third 2D image through an object to be imaged, wherein the third image shares the viewpoint of the first image and is aligned with the first image;
g) providing a 3D image data set of the object to be imaged;
h) defining a remapping surface within the 3D image data set;
i) registering the first and second 2D images with the 3D image data set and determining the viewpoint of the first and second 2D images with respect to the 3D image data set;
j) remapping pixels of the third 2D image to generate the remapped 2D image from the viewpoint of the second 2D image by:
i. determining which pixels of the third 2D image correspond to the pixels of the first 2D image;
ii. back projecting rays from the pixels of the first 2D image and determining the points of intersection of the back projected rays with the remapping surface; and
iii. remapping the pixels of the third 2D image that correspond with the pixels of the first 2D image to generate the 2D remapped image, whereby the pixels are remapped according to the direction of rays projected from the viewpoint of the second 2D image via the intersection points corresponding to each pixel.
3. The method according to claim 1 , wherein the first or second 2D image is a fluoroscopy image.
4. The method according claim 1 , wherein the 3D image data set is obtained from a computerised tomography (CT) or magnetic resonance (MR) or cone beam computerised tomography (CBCT) scan.
5. The method according to claim 1 , wherein the remapping surface is any of:
i. angled planar or multi-planar;
ii. curved; and/or
iii. discontinuous;
or any combination thereof.
6. The method according to claim 1 , wherein the remapping surface is shaped to follow a feature of the object to be imaged.
7. The method according to claim 6 , wherein the feature of the object to be imaged within the 3D image data set of the object to be imaged is enhanced by the use of contrast medium.
8. The method according to claim 1 , wherein the origin of the pixels is marked.
9. The method according to claim 1 wherein the object is a patient and wherein the image generated by the remapping is used to carry out a surgical procedure on the patient.
10. The method of claim 1 , further comprising administering contrast medium to the object to be imaged and thus defining a remapping surface within a 3D image data set in relation to the location of the contrast medium.
11. An imaging system, comprising:
a 2D imaging system arranged in use to obtain 2D images; and
a processor, arranged in use to:
a) obtain single first and single second 2D images through an object to be imaged, wherein the images are from different viewpoints with respect to the object;
b) obtain a 3D image data set of the object to be imaged;
c) define a remapping surface within the 3D image data set;
d) register the first and second 2D images with the 3D image data set and determine the viewpoint of the first and second 2D images with respect to the 3D image data set; and
e) remap pixels of the first 2D image to generate a remapped 2D image from a viewpoint of the second 2D image by:
i. back projecting rays from the pixels of the first 2D image and determining the points of intersection of the back projected rays with the remapping surface; and
ii. remapping the pixels of the first 2D image corresponding to the points of intersection to generate the 2D remapped image, whereby the pixels of the first 2D image are remapped according to the direction of rays projected from the viewpoint of the second 2D image via the intersection points corresponding to each pixel.
12. The imaging system according to claim 11 ,
wherein the 2D imaging system is arranged to obtain 2D images to be registered with a 3D image data set; and further comprising
a processor, arranged to:
f) obtain single first and single second 2D images through an object to be imaged, wherein the images are from different viewpoints with respect to the object;
g) obtain a third 2D image through an object to be imaged, wherein the third image shares the viewpoint of the first image and is aligned with the first image;
h) define a remapping surface within the 3D image data set;
i) register the first and second 2D images with the 3D image data set and determining the viewpoint of the first and second 2D images with respect to the 3D image data set;
j) remap pixels of the third 2D image to generate the remapped 2D image from the viewpoint of the second 2D image by:
i. determining which pixels of the third 2D image correspond to the pixels of the first 2D image;
ii. back projecting rays from the pixels of the first 2D image and determining the points of intersection of the back projected rays with the remapping surface; and
iii. remapping the pixels of the third 2D image that correspond with the pixels of the first 2D image to generate the 2D remapped image, whereby the pixels are remapped according to the direction of rays projected from the viewpoint of the second 2D image via the intersection points corresponding to each pixel.