Abstract: Systems, methods, and related computer program products for medical imaging and image-guided radiation treatment (IGRT) are described. In one preferred embodiment, an IGRT system provides intrafraction target tracking based on a comparison of intrafraction x-ray tomosynthesis image data with initial x-ray tomosynthesis image data acquired with the patient in an initial treatment position, the initial x-ray tomosynthesis image data having an inherent registration with co-acquired image data from a setup imaging system integral with, or having known geometry relative to, the tomosynthesis imaging system. Repeated registration of intrafraction x-ray tomosynthesis image data with pre-acquired reference image data from a different frame of reference is not required during intrafraction radiation delivery. Advantages include streamlined intrafraction computation and/or reduced treatment delivery margins.

Abstract: Treatment targets such as tumors or lesions, located within an anatomical region that undergoes motion (which may be periodic with cycle P), are dynamically tracked. A 4D mathematical model is established for the non-rigid motion and deformation of the anatomical region, from a set of CT or other 3D images. The 4D mathematical model relates the 3D locations of part(s) of the anatomical region with the targets being tracked, as a function of the position in time within P. Using fiducial-less non-rigid image registration between pre-operative DRRs and intra-operative x-ray images, the absolute position of the target and/or other part(s) of the anatomical region is determined. The cycle P is determined using motion sensors such as surface markers. The radiation beams are delivered using: 1) the results of non-rigid image registration; 2) the 4D model; and 3) the position in time within P.

Abstract: A robotic patient positioning assembly for therapeutic radiation treatment includes a robotic positioning device for moving and supporting the patient during treatment, a sensor system for detecting the position of the robotic positioning device, and a controller operatively connected with the sensor system for receiving position data of the robotic positioning device and operatively connected to the robotic positioning device for controlling the motions of the robotic positioning device. The controller is adapted for controlling the motion of the robotic positioning device in response to information representative of the position of the robotic positioning device received from the sensor system, so that the treatment target within a patient loaded on the robotic positioning device is properly aligned with a radiation source of a therapeutic radiation treatment system.

Abstract: A method and system are presented for enhancing one or more images of an object, so as to increase the visibility within the images of one or more structures within the object. The object may be an anatomical region of a patient, and may include one or more reference structures, for example skeletal structures or vertebral structures, and one or more treatment targets, for example tumors or lesions. An operator, for example a top-hat filter operator, selects at least a first neighborhood and a second neighborhood within the images. The operator selects within each neighborhood one or more pixels having an optimal pixel value, and eliminates the remaining pixels in these neighborhoods. When the operator is applied to the selected neighborhoods, only the pixels having the greatest pixel values remain in the selected neighborhoods, and the remaining pixels are eliminated in the selected neighborhoods. As a result, desired features can be located and enhanced in the images.

Abstract: A patient positioning assembly is described. The patient positioning assembly including a plate member rotatably mounted on a base member, and an arm extending between a first end and a second end, wherein the first end is rotatably attached to the plate member. The patient positioning assembly further including a support device rotatably attached to the second end of the arm to support a patient thereon, with the support device is configured to move the patient in at least five degrees of freedom.

Abstract: A method of robotic patient positioning for radiation treatment using a radiation source with an arm assembly rotatably connected to a support device is described. The method includes moving the support device with respect to the radiation source in at least five degrees of freedom to align a treatment target with respect to the radiation source. Moving the support device includes rotating the support device about first, second and third rotational axes and rotating the arm assembly about fourth and fifth rotational axes. Rotations about the fourth and fifth rotational axes translate the support device for fourth and fifth degrees of freedom of the at least five degrees of freedom.

Abstract: A method and apparatus for selectively and accurately localizing and treating a target within a patient are provided. A three dimensional mapping of a region surrounding the target is coupled to a surgical intervention. Two or more diagnostic beams at a known non-zero angle to one another may pass through the mapping region to produce images of projections within the mapping region in order to accurately localize and treat the target wherein the images are captured using one or more image recorders.

Abstract: A method and system are presented for enhancing one or more images of an object, so as to increase the visibility within the images of one or more structures within the object. The object may be an anatomical region of a patient, and may include one or more reference structures, for example skeletal structures or vertebral structures, and one or more treatment targets, for example tumors or lesions. An operator, for example a top-hat filter operator, selects at least a first neighborhood and a second neighborhood within the images. The operator selects within each neighborhood one or more pixels having an optimal pixel value, and eliminates the remaining pixels in these neighborhoods. When the operator is applied to the selected neighborhoods, only the pixels having the greatest pixel values remain in the selected neighborhoods, and the remaining pixels are eliminated in the selected neighborhoods. As a result, desired features can be located and enhanced in the images.

Abstract: A method and system are presented for enhancing one or more images of an object, so as to increase the visibility within the images of one or more structures within the object. The object may be an anatomical region of a patient, and may include one or more reference structures, for example skeletal structures or vertebral structures, and one or more treatment targets, for example tumors or lesions. An operator, for example a top-hat filter operator, selects at least a first neighborhood and a second neighborhood within the images. The operator selects within each neighborhood one or more pixels having an optimal pixel value, and eliminates the remaining pixels in these neighborhoods. When the operator is applied to the selected neighborhoods, only the pixels having the greatest pixel values remain in the selected neighborhoods, and the remaining pixels are eliminated in the selected neighborhoods. As a result, desired features can be located and enhanced in the images.

Abstract: A method and system is presented for tracking patient motion in image guided surgery, using skeletal reference structures instead of fiducial markers.

Abstract: A method and system are presented for direct volume rendering of a deformable volume dataset that represent an object in motion. An original 3D image dataset of the object is acquired at an initial stage of the motion, and segmented. Deformed 3D image datasets of the object are acquired at subsequent stages of the motion. Deformation matrices are computed between the segmented original 3D image dataset and the deformed 3D image datasets. A plurality of deformed mesh patches are generated based on the deformation matrices. 2D textures are generated by dynamically sampling the segmented 3D image dataset, and applied to the deformed mesh patches. The textured deformed mesh patches are evaluated, blended, and composited to generate one or more volume-rendered images of the object in motion.

Abstract: A method and system is presented in image-guided radiosurgery for determining the measure of similarity of two digital images, for example a 2D x-ray image and a 2D DRR synthesized from 3D scan data. A two-dimensional array of pixel values of a difference image may be formed by subtracting each pixel value of the second image from the corresponding pixel value of the first image. The pattern intensity function may be constructed by taking the summation of functions of the gradients of the difference image. The neighborhood R may be defined so as to allow the gradients of the difference image to be considered in at least one direction.

Abstract: A method and system is presented for generating a full motion field of an object, when performing non-rigid image registration between a first and a second image of the object. A mesh grid generator generates in the first image a mesh grid having a plurality of mesh nodes, for each of a hierarchy of mesh resolution levels. A nodal motion estimator estimates, for each mesh node, at least one nodal motion vector that describes a matching of the mesh node with a corresponding mesh node in the second image. At each mesh node, multi-level block matching is performed, using a similarity measure based on pattern intensity. A smoothness constraint is imposed, in order to reconstruct the nodal motion vector for those mesh nodes at which mismatching occurs. A motion field interpolator determines a local motion vector for any desired point of interest within the first image, by interpolating from the nodal motion vectors of the surrounding mesh nodes.

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.

Abstract: DRR generation and enhancement using a dedicated graphics device are described herein. In one embodiment, an example of a process for generating DRR (digitally reconstructed radiography) images includes, but is not limited to, loading a volume rendering program into a graphics device, the volume rendering program representing a predetermined algorithm according to a non-linear attenuation model. In response to 3D scan data, the graphics device is invoked to execute the volume rendering program to perform at least a portion of volume rendering operations on at least a portion of the 3D scan data, which may include modifying the 3D scan data according to the predetermined algorithm to compensate for a difference between a first attenuation of an object with respect to a second attenuation associating a known intensity of the object. Other methods and apparatuses are also described.

Abstract: A method and system is presented for tracking patient motion in image guided surgery, using skeletal reference structures instead of fiducial markers. A non-rigid 2D/3D image registration is performed between pre-operative 3D scan data and intra-operative 2D images. The CT numbers are modified to compensate for the difference between the ratio of bone-to-tissue attenuation at the CT scan energy level, and the x-ray projection energy level. DRRs are generated from the modified CT numbers. An ROI, within which the image registration is restricted, is defined within the DRRs by calculating a modified Shannon entropy for each image, and seeking the region in which the image entropy is maximized. The DRRs and 2D images are enhanced by applying a top hat filter to increase the visibility of the skeletal structures. The 2D/3D transformation parameters are determined by generating a full motion field that accounts for non-rigid motions and deformations.

Abstract: A method and system are presented for fast generation of one or more 2D DRRs of an object. 3D scan data of the object (such as CT scan data) are generated. A 3D fast Fourier transform F(u,v,w) is computed for a 3D scan volume f(x,y,z) within the 3D scan data, the scan volume f(x,y,z) having an orientation (?, ?, ?). The 3D Fourier transform data are resampled along a surface S(?, ?, ?, u?, v?) at angles ?, ?, ? corresponding to the orientation of the scan volume. The surface S is a plane for parallel beam geometry. For cone-beam geometry, it is the surface of a sphere whose center is coincident with the imaginary origin of the X-rays for the projection. The 2D inverse Fourier transform F?1 [S(?, ?, ?, u?, v?)] of the surface is computed, thereby generating a 2D DRR reconstructed along a projection direction perpendicular to the sample surface.

Abstract: A method and system is presented for automatically selecting a region of interest (ROI) within an image of an object, for example when performing non-rigid image registration between the image and another image of the object. In this way, the need for user interaction can be minimized or eliminated during image registration. The ROI is determined by defining an entropy measure H of the image, and selecting the region within the image in which the entropy measure is maximized, In this way, the ROI is optimized to contain as much information as possible. In one embodiment, the entropy measure H is a modified Shannon entropy, defined by H=??I P(I) log P(I), where I is the value of the image intensity level, and P(I) is the probability of an image intensity value I occurring within the ROI.

Abstract: A method and system is provided for registering a 2D radiographic image of a target with previously generated 3D scan data of the target. A reconstructed 2D image is generated from the 3D scan data. The radiographic 2D image is registered with the reconstructed 2D images to determine the values of in-plane transformation parameters (x, y, ?) and out-of-plane rotational parameters (r, ?), where the parameters represent the difference in the position of the target in the radiographic image, as compared to the 2D reconstructed image. An initial estimate for the in-plane transformation parameters is made by a 3D multi-level matching process, using the sum-of-square differences similarity measure. Based on these estimated parameters, an initial 1-D search is performed for the out-of-plane rotation parameters (r, ?), using a pattern intensity similarity measure. The in-plane parameters (x, y, ?) and out-of-plane parameters (r, ?) are iteratively refined, until a desired accuracy is reached.

Abstract: A method and system is presented in image-guided radiosurgery for determining the measure of similarity of two digital images, for example a 2D x-ray image and a 2D DRR synthesized from 3D scan data. A two-dimensional array of pixel values of a difference image is formed by subtracting each pixel value of the second image from the corresponding pixel value of the first image. The pattern intensity function is constructed by taking the summation of asymptotic functions of the gradients of the difference image. The neighborhood R is defined so as to allow the gradients of the difference image to be considered in at least four directions.