TRANS-AXIAL TRUNCATION COMPENSATION FOR CT IMAGING
Imaging apparatuses described herein include a radiation source configured for imaging radiation, a radiation detector positioned to receive radiation from the radiation source, and an image processing system. The image processing system is configured to: receive projection data from the radiation detector, the projection data corresponding to a scan field-of-view (scanFOV), the image being trans-axially truncated; identify a final reconstruction field-of-view (reconFOV) that is larger than the scanFOV; reconstruct an image having a reconstruction field-of-view (reconFOV n ), wherein reconFOV n is less than reconFOV; generate a progressive refinement for the image; reproject the image with the progressive refinement thereby generating a virtual scan vscanFOV n ; refine the virtual scan vscanFOV n data; and repeat the reconstruction, generation of the progressive refinement, and reprojection for one or more subsequent reconstructions until reconFOV is reached.
1 . An imaging apparatus, comprising:
a rotatable gantry system positioned at least partially around a patient support;
a radiation source coupled to the rotatable gantry system, the radiation source configured for imaging radiation;
a radiation detector coupled to the rotatable gantry system and positioned to receive radiation from the radiation source; and
an image processing system configured to:
receive projection data from the radiation detector, the projection data corresponding to a scan field-of-view (scanFOV), wherein an image reconstructed from the projection data has a reconstruction field-of-view reconFOV 0 that is the same as scanFOV, and the image is trans-axially truncated;
identify a final reconstruction field-of-view (reconFOV) that is larger than the scanFOV;
reconstruct an image having a reconstruction field-of-view (reconFOV n ) using projection data from a virtual scan that precedes the reconstruction (vscanFOV n-1 ) and estimated data between the vscanFOV n-1 and vscanFOV n , wherein reconFOV n is less than reconFOV;
generate a progressive refinement for the image;
reproject the image with the progressive refinement thereby generating a virtual scan vscanFOV n ;
refine the virtual scan vscanFOV n data; and
repeat the reconstruction, generation of the progressive refinement, and reprojection for one or more subsequent reconstructions until reconFOV is reached.
2 . The imaging apparatus according to claim 1 , wherein the image processing system is configured to generate the progressive refinement for the image by adjusting pixel values of the estimated data using information regarding a subject of the imaging.
3 . The imaging apparatus according to claim 2 , wherein the information regarding the subject of the imaging comprises information regarding estimated pixel values corresponding to bone, soft tissue, the patient support, and metal.
4 . The imaging apparatus according to claim 1 , wherein the imaging processing system is configured to generate the progressive refinement for the image reconFOV n by adjusting pixel values using the reconstructed image from a preceding reconstruction reconFOV n-1 .
5 . The imaging apparatus according to claim 1 , wherein the image processing system is further configured to:
determine a number of progressive refinements based on the difference between reconFOV and scanFOV.
6 . The imaging apparatus according to claim 5 , wherein the number of progressive refinements is greater than one.
7 . The imaging apparatus according to claim 1 , wherein the image processing system is further configured to:
reconstruct a first progressive image over a first reconstruction field-of-view (reconFOV 1 ) from the projection data corresponding to the scanFOV, wherein a difference between vscanFOV 1 and scanFOV corresponds to a first refinement segment of the image.
8 . The imaging apparatus according to claim 1 , wherein the image processing system is further configured to:
reconstruct a final image having reconFOV, wherein the final image is not trans-axially truncated.
9 . The imaging apparatus according to claim 1 , refining the virtual scan vscanFOV n data comprises using curvature of a sinogram of projection data from a virtual scan that precedes the reconstruction (vscanFOV n-1 ) to adjust a shape of estimated projection data for vscanFOV n .
10 . A multimodal imaging apparatus comprising the imaging apparatus of claim 1 .
11 . An image processing method comprising:
receiving projection data from a radiation detector, the projection data corresponding to a scan field-of-view (scanFOV), wherein an image reconstructed from the projection data has a reconstruction field-of-view (reconFOV 0 ) that is the same as scanFOV, and the image is trans-axially truncated;
identifying a final reconstruction field-of-view (reconFOV) that is larger than the scanFOV;
reconstructing an image having a reconstruction field-of-view (reconFOV n ) using projection data from a virtual scan that precedes the reconstruction (vscanFOV n-1 ) and estimated data between the vscanFOV n-1 and vscanFOV n , wherein reconFOV n is less than reconFOV, and reconFOV n is equal to vscanFOV n ;
generating a progressive refinement for the image;
reprojecting the image with the progressive refinement thereby generating a virtual scan vscanFOV n ;
refining the virtual scan vscanFOV n data; and
repeating the reconstructing, generating the progressive refinement, and reprojecting for one or more subsequent reconstructions until reconFOV is reached.
12 . The image processing method of claim 11 , wherein generating the progressive refinement for the image comprises adjusting pixel values of the estimated data using information regarding a subject of the imaging.
13 . The image processing method of claim 12 , wherein the information regarding the subject of the imaging comprises information regarding estimated pixel values corresponding to bone, soft tissue, the patient support, and metal.
14 . The image processing method of claim 11 , wherein generating the progressive refinement for the image reconFOV n by adjusting pixel values using the reconstructed image from a preceding reconstruction reconFOV n-1 .
15 . The image processing method of claim 11 , wherein generating the progressive refinement for the image reconFOV n comprises adjusting a shape of an object recovered in the image using body surface curvature information from vscanFOV n-1 .
16 . The image processing method of claim 11 , wherein the image processing method further comprises:
determining a number of progressive refinements based on the difference between reconFOV and scanFOV.
17 . The image processing method of claim 16 , wherein the number of progressive refinements is greater than one.
18 . The image processing method of claim 11 , wherein the image processing method further comprises:
reconstructing a first progressive image over a first reconstruction field-of-view (reconFOV 1 ) from the projection data corresponding to the scanFOV, wherein a difference between vscanFOV 1 and scanFOV corresponds to a first refinement segment.
19 . The image processing method of claim 11 , wherein the image processing method further comprises:
reconstructing a final image having reconFOV, wherein the final image is not trans-axially truncated.
20 . The image processing method of claim 11 , wherein refining the virtual scan vscanFOV n data comprises using curvature of a sinogram of projection data from a virtual scan that precedes the reconstruction (vscanFOV n-1 ) to adjust a shape of estimated projection data for vscanFOV n .