DRR generation using a non-linear attenuation model
First Claim
1. A method of generating a DRR (digitally reconstructed radiograph) from 3D scan data of an object so as to increase the visibility within the DRR of one or more structures in the object, the DRRs representing a radiographic projection image of the object that would be obtained with an imaging beam of a known intensity, origination position, and angle if the object were positioned as shown in the 3D scan data, the method comprising:
- providing 3D scan data of the object, the 3D scan data resulting from a 3D scan conducted at a 3D scan energy level;
modifying the 3D scan data to compensate for a difference between the attenuation of the one or more structures at the scan energy level and the attenuation of the one or more structures at the known intensity of the imaging beam;
casting a plurality of hypothetical rays through the modified 3D scan data from the known intensity, the known origination position, and angle; and
integrating the 3D scan data along each hypothetical ray, and projecting the integrated value of the 3D scan data onto an imaging plane.
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Abstract
A method and system are presented for generating a DRR of an anatomical region so that the visibility within the DRR of one or more skeletal reference structures is enhanced. 3D scan data, which have been obtained from a 3D scan of the object conducted at a 3D scan energy level, are provided. The 3D scan data are modified to compensated for a difference between the ratio of bone-to-tissue attenuation at the 3D scan energy level, and the ratio of bone-to-tissue attenuation at the intensity of the imaging beam which the DRR emulates. The modified 3D scan data are related to the raw 3D scan data by a non-linear, exponential relationship. A plurality of hypothetical rays are cast through the modified 3D scan data, from the known geometry of the imaging beam. The 3D scan data are integrated along each hypothetical ray, and the integrated values are projected onto an imaging plane.
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Citations
34 Claims
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1. A method of generating a DRR (digitally reconstructed radiograph) from 3D scan data of an object so as to increase the visibility within the DRR of one or more structures in the object, the DRRs representing a radiographic projection image of the object that would be obtained with an imaging beam of a known intensity, origination position, and angle if the object were positioned as shown in the 3D scan data, the method comprising:
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providing 3D scan data of the object, the 3D scan data resulting from a 3D scan conducted at a 3D scan energy level;
modifying the 3D scan data to compensate for a difference between the attenuation of the one or more structures at the scan energy level and the attenuation of the one or more structures at the known intensity of the imaging beam;
casting a plurality of hypothetical rays through the modified 3D scan data from the known intensity, the known origination position, and angle; and
integrating the 3D scan data along each hypothetical ray, and projecting the integrated value of the 3D scan data onto an imaging plane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for generating a DRR (digitally reconstructed radiograph) from 3D scan data of an object so as to increase the visibility within the DRR of one or more structures in the object, the DRRs representing a radiographic projection image of the object that would be obtained with an imaging beam of a known intensity, origination position, and angle if the object were positioned as shown in the 3D scan data, the method comprising:
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means for providing 3D scan data of the object, wherein the 3D scan data are obtained from a 3D scan conducted at a 3D scan energy level;
a scan data modifier configured to compensate for a difference between the attenuation of the one or more structures at the 3D scan energy level, and the attenuation of the one or more structures at the known intensity of the imaging beam; and
a DRR generator configured to generate at least one DRR of the object from the 3D scan data, the DRR generator comprising;
a ray casting subsystem configured to cast a plurality of hypothetical rays through the modified 3D scan data at the known intensity and from the known origination position and angle of the imaging beam;
a CT number integrator configured to integrate the 3D scan data along each hypothetical ray; and
a projector configured to project the integrated values of the 3D scan data onto an imaging plane. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. An image registration system for registering at least one 2D image of an anatomical region with previously generated 3D scan data of the anatomical region, the anatomical region including at least one treatment target and at least one reference structure, wherein the 2D image is generated in near real time by detecting one or more radiographic imaging beams after the imaging beams have traversed at least a portion of the anatomical region, the imaging beams having known intensities and known positions and angles relative to the anatomical region, the system comprising:
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means for providing the 3D scan data of the anatomical region;
a scan data modifier configured to modify the 3D scan data so as to compensate for a difference between the ratio of bone-to-tissue attenuation at the energy level of the 3D scan, and the ratio of bone-to-tissue attenuation at the energy level of the imaging beam used for the near real-time 2D image;
a DRR generator configured to generate at least one DRR (digitally reconstructed radiograph) of the anatomical region, using the 3D scan data and the known locations, angles, and intensities of the imaging beams;
a motion field generator configured to generate a 3D full motion field within the DRR by estimating a plurality of local motion fields within the DRR; and
a parameter determiner configured to determine from the 3D full motion field a set of non-rigid transformation parameters that represent the difference in the position and orientation of the treatment target as shown in the 2D image, as compared to the position and orientation of the treatment target as shown in the DRR. - View Dependent Claims (23, 24, 25, 26)
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27. A method of registering a near real-time 2D x-ray image of an anatomical region with 3D scan data representative of a preoperative image of the anatomical region, the anatomical region including at least one reference structure and at least one treatment target, the method comprising:
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modifying the 3D scan data, and reconstructing from the modified 3D scan data at least one DRR;
generating a 3D motion field by estimating one or more 2D local motion fields within the DRR, and constructing a full 3D motion field from the local motion fields; and
determining from the full 3D motion field a set of non-rigid transformation parameters that represent the difference in the position and orientation of the reference structure and the treatment target, as shown in the 2D x-ray image, as compared to the position and orientation of the reference structure and the treatment target, as shown in the DRR. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34)
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Specification