| 主权项 |
1. A method for reconstructing a 3D image from 2D X-ray images acquired with an X-ray imaging system, said method comprising the steps of:
a) receiving a set of 2D X-ray images of a region of a patient with said X-ray imaging system, wherein a calibration phantom comprising at least one radiopaque marker having a known 3D position in a coordinate system of said calibration phantom is placed on said patient during the acquisition of the set of 2D X-ray images, such that said acquired set comprises:
at least two 2D X-ray images containing each at least one detectable radiopaque marker of the calibration phantom; andat least one 2D X-ray image wherein no radiopaque marker of the calibration phantom is automatically detectable; a1) selecting, from said set of 2D X-ray images, reference images in which at least one radiopaque marker of the calibration phantom is detected automatically, and determining the 2D position of each detected marker in each of said reference images, all remaining images being classified as non-reference images; a2) computing an optimal rigid transformation between a coordinate system of the X-ray imaging system and the coordinate system of the calibration phantom by optimizing the registration between the known 3D position of at least one marker of the calibration phantom and the corresponding 2D position of said marker detected in at least two different reference images using nominal projective geometry data of said X-ray imaging system, such that the distance between the projections of the 3D position of the marker in each reference image and the corresponding 2D position in said reference images is minimized; a3) applying said optimal rigid transformation to the 3D position of said at least one marker of the calibration phantom to determine its respective transformed 3D position in the coordinate system of the X-ray imaging system; a4) for each of said reference images, computing adjusted projective geometry data from the 2D position of the at least one marker detected in said reference image and said transformed 3D phantom marker position, such that the projection of said transformed 3D position using the adjusted projective geometry data fits optimally with the 2D position of corresponding marker; a5) calculating a reconstructability criterion that characterizes the ability to reconstruct a 3D image with sufficient quality from the reference images only; b) computing an initial 3D image within the coordinate system of the X-ray imaging system by using at least part of said 2D X-ray images with their respective projective geometry data; said computation being implemented by using:
if the reconstructability criterion calculated in step (a5) is met, the reference images with their respective adjusted projective geometry data; orif the reconstructability criterion calculated in step (a5) is not met, the reference images with their respective adjusted projective geometry data and the non-reference images with their respective nominal projective geometry data c) projecting said initial 3D image on the non-reference images and adjusting the respective projective geometry data of said non-reference images by registration of said non-reference images with the projection of the initial 3D image using an image-to-image registration technique; d) computing an updated 3D image using the complete set of 2D X-ray images with their respective adjusted projective geometry data. |
