The following generally relates to imaging and more particularly to generating one or more 2D planning projection images based on 3D pre-scan image data, and is described with particular application to computed tomography (CT). However, the following is also amenable to other imaging modalities.
A CT scanner includes an x-ray tube that emits radiation that traverses an examination region and an object therein. A detector array located opposite the examination region across from the x-ray tube detects radiation that traverses the examination region and the object therein and generates projection data indicative of the examination region and the object therein. A reconstructor processes the projection data and reconstructs volumetric image data indicative of the examination region and the object therein.
Planning a volume scan has included performing a two-dimensional (2D) pre-scan, which produces a 2D projection image.
The user defines a bounding box 102, which defines a field of view, which is the region that will be scanned during the volume scan. The bounding box 102 identifies a start scan position 104 and an end scan position 106. In the illustrated example, start and end 108 and 110 support positions are shown next to the start scan position 104 in the 2D projection image. Once a plan is created, the plan is used by the imaging system to perform a volume scan from the start scan position 104 to the end scan position 106.
With a 2D pre-scan, the 3D anatomical information is projected on a 2D display. As such, a pixel in the 2D projection image has an intensity value that represents a summation of the individual intensity values of the individual voxels corresponding to the pixel. As a result, anatomy in front of and/or behind tissue of interest may obscure the boundaries of the tissue of interest. A margin can be added to bounding box 102 to ensure adequate coverage.
A similar approach can be used with three-dimensional (3D) pre-scans. However, with a 3D pre-scan, the user scrolls through the slices of the pre-scan volume and creates the bounding box on one of the slices. This allows the user to find a slice in which less tissue obscures the boundaries of the tissue of interest, which facilitates optimizing the size of the bounding box to the tissue of interest and dose. Unfortunately, this approach consumes more user time since the user scrolls through the pre-scan volume.
The 3D pre-scan image data also allows the user to select one or more planning directions. For example, the coronal plane can be shown to provide a view similar to that shown in
Aspects described herein address the above-referenced problems and others.
The following describes an approach for generating one or more 2D volume scan planning images from 3D pre-scan image data. This includes, in one instance, locating tissue(s) of interest in the volume of the 3D pre-scan image data and then selecting a sub-volume of the 3D pre-scan image data that includes the located tissue(s) of interest. The one or more 2D volume scan planning images are generated based on the sub-volume. The one or more 2D volume scan planning images may have improved image quality with respect to identifying the perimeter and/or boundaries associated with the tissue of interest, relative to a configuration in which the entire 3D pre-scan image data is used to generate the one or more 2D volume scan planning images where structure in front of and/or behind the tissue of interest visually obscures the perimeter and/or boundaries of the tissue of interest.
In one aspect, a method includes obtaining 3D pre-scan image data generated from a scan of a subject. The 3D pre-scan image data includes voxels that represent a tissue of interest. The method further includes generating a 2D planning projection image showing the tissue of interest based on the 3D pre-scan image data.
In another aspect, an imaging system includes a 2D planning projection image from 3D pre-scan image data generator. The 2D planning projection image from 3D pre-scan image data generator obtains 3D pre-scan image data generated from a scan of a subject. The 3D pre-scan image data includes voxels that represent a tissue of interest. The 2D planning projection image from 3D pre-scan image data generator further generates a 2D planning projection image showing the tissue of interest based on the 3D pre-scan image data.
In another aspect, computer readable instructions are encoded on computer readable storage medium, which, when executed by a processor of a computing system, cause the processor to: obtain 3D pre-scan image data generated from a scan of a subject, wherein the 3D pre-scan image data includes voxels that represent a tissue of interest, detect the tissue of interest in the 3D pre-scan image data, generate at least one region of interest in the 3D pre-scan image data, select a sub-volume of the 3D pre-scan image data based on the at least one region of interest, wherein the sub-volume bounds the region of interest, generate at least one 2D planning projection image for the tissue of interest based on the sub-volume of the 3D pre-scan and a view direction, plan a volume scan for the tissue of interest based on the 2D planning project image, and perform a scan of the subject based on the volume scan.
The invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention.
A radiation sensitive detector array 210 is located opposite the radiation source 208 across the examination region 206. The radiation sensitive detector array 210 detects radiation traversing the examination region 206 and generates a signal indicative thereof. A support 212 supports an object or subject in the examination region 206. A computer serves as an operator console 214 and includes an output device such as a display and an input device such as a keyboard, mouse, etc. Software resident on the console 214 allows the operator to control an operation of the imaging system 200 such as data acquisition.
Examples of suitable data acquisition include two-dimensional (2D) and/or three-dimensional (3D) pre-scans and include volumetric scans. An example of a 2D pre-scan is a 2D scout (also referred to as pilot or surview) scan. Generally, this type of pre-scan is a 2D projection image, similar to an x-ray. An example of a 3D pre-scan is a lower dose volumetric scan, which, generally, is not used for diagnostic purposes due to the lower image quality (e.g., lower contrast resolution). An example of lower dose image data is shown in
An example of the volumetric scan is a helical or spiral scan with scan setting (e.g., electrical current and voltage, pitch, slice thickness, etc.), which result in an image quality at which the image data can be used for diagnostic purposes. Again,
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A 2D planning projection image from 3D pre-scan image data generator 218 generates one or more 2D planning projection images from the 3D pre-scan image data. As described in greater detail below, in one instance this includes locating tissue(s) of interest in the volume of the 3D pre-scan image data, selecting a sub-volume of the 3D pre-scan image data that includes the located tissue(s) of interest, and generating the one or more 2D planning projection images based on the sub-volume. Using the sub-volume instead of the entire volume may remove structure in front of and/or behind the tissue of interest in the chosen view direction, which would otherwise visually obscure the tissue of interest in the 2D planning projection images. Using the sub-volume instead of the entire volume may also reduce planning time as there are less image slices to scroll through.
A scan planner 220 plans, with or without user interaction, a volumetric scan based the one or more 2D planning projection images. In one instance, this includes visually displaying the one or more 2D planning projection images and allowing a user to create a volume scan bounding box, which identifies at least a start position of the volumetric scan and a stop location or a length of the volumetric scan, which can be used to derive a stop location. The start and end locations define a field of view (or an extent at least along the z-axis). The field of view represents the sub-portion of the object or subject that will be scanned during the volumetric scan.
In another instance, the bounding box is automatically created and presented superimposed over one or more 2D planning projection images. In this instance, the clinician can accept, reject and/or modify the bounding box. In either instance, the one or more 2D planning projection images can be displayed with pre-set and/or optimized window/level (contrast/brightness) settings. For instance, since the thickness of the sub-volume is known and the intensity of each voxel in the sub-volume is known, an average Hounsfield unit (HU) can be computed along each of a plurality of rays through the volume, and the level can be automatically set (and accepted, rejected or modified by authorized personnel) based on the average HU value. This can be considered normalizing the intensity based on the depth of the sub-volume.
The 2D planning projection image from 3D pre-scan image data generator 218 and/or the volume scan planner 220 can be implemented via one or more computer processors (e.g., a central processing unit (CPU), a microprocessor, a controller, etc.) executing one or more computer executable instructions embedded or encoded on computer readable storage medium, which excludes transitory medium, such as physical memory. However, at least one of the computer executable instructions can alternatively be carried by a carrier wave, signal, and other transitory medium and implemented via the one or more computer processors.
The volume scan plan is provided to the console 214, which controls data acquisition based on the volume scan plan.
The 2D planning projection image from 3D pre-scan image data determiner 218 receives, as an input, 3D pre-scan image data. The 3D pre-scan image data can be from the imaging system 200 (
The 2D planning projection image from 3D pre-scan image data determiner 218 also receives, as an input, a signal indicating one or more tissues of interest. The signal can be from the console 214 (
An atlas memory 502 stores one or more anatomical atlases of one or more tissues of interest. Examples of tissues of interest include an organ such as the heart, the kidneys, etc., an anatomical region such as the chest, the pelvis, the head, etc., and/or other tissue of interest.
A tissue(s) of interest detector 504 obtains one or more anatomical atlases from the atlas memory 502 based on the signal indicating the one or more tissues of interest. The tissue(s) of interest detector 504 detects the one or more tissues of interest in the 3D pre-scan image data and registers obtained one or more anatomical atlases to the corresponding detected one or more tissues of interest in the 3D pre-scan image data. The tissue(s) of interest detector 504 can employ elastic and/or rigid registration algorithms.
In one non-limiting example, the tissue(s) of interest detector 504 detects the one or more tissues of interest in the 3D pre-scan image data and registers obtained one or more anatomical atlases to the detected one or more tissues of interest based on the approach in application Ser. No. 61/773,429, filed on Mar. 6, 2013, and entitled “Scan region determining apparatus,” the entirety of which is incorporated by reference herein.
A region of interest (ROI) generator 506 generates one or more regions of interest (ROI's) in the 3D pre-scan image data for each of the registered one or more anatomical atlases.
Examples of view directions include, but are not limited to, coronal, axial, sagittal, oblique, etc. Note that the shape of the ROI 606 is provided for explanatory purposes and is not limiting, and that square, rectangular, irregular, and/or other shapes are contemplated herein. Furthermore, the region of interest (ROI) generator 506 can generate one or more other ROI's for one or more other tissues of interest in the same and/or other view direction.
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By way of non-limiting example, in
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The output of the 2D projection image rendering engine 510 is a 2D projection image, which, in the illustrated embodiment, represents a 2D planning projection image. By processing the sub-volume to generate the 2D projection image rather than the entire 3D pre-scan image data volume, sub-portions of the 3D pre-scan image data volume that do not include a tissue of interest and/or visually obscure tissue of interest (e.g., the perimeter of a tissue of interest) are not used to generate the 2D projection image. As a result, the 2D planning projection image may have improved image quality with respect to the tissue of interest and/or allow for more accurate and/or optimal planning of a volume scan.
For example, it may be easier to visually identify the perimeter of tissue of interest and/or a boundary between the tissue of interest and other tissue. This may allow the user to define the bounding box to ensure the entire tissue of interest (or the entirety of a sub-portion of interest of the tissue of interest) is scanned, while mitigating irradiating and dosing tissue outside of the tissue of interest. This may include tissue in a margin defined around the tissue of interest in a configuration in which the entire 3D pre-scan image data is used to generate the 2D planning projection image and structure in front of and/or behind the tissue of interest visually obscures the tissue of interest in the 2D planning projection image.
For example, for a cardiac scan, a sub-portion of the 3D pre-scan image data that includes voxels that represent the rib cage and none of the heart are excluded from or not included in the sub-volume. In this instance, this may include extracting the sub-volume and discarding the remaining volume such that the sub-volume is an actual smaller volume of data. In another instance, the voxels representing the rib cage are either visually masked, set to an intensity value of the background, and/or given a window/level and/or opacity setting that renders them visually translucent. Other approaches are also contemplated herein. Furthermore, scrolling through the sub-volume to find an image slice to plan from may consume less time relative to scrolling through the entire volume.
In
It is to be appreciated that the ordering of the acts of these methods is not limiting. As such, other orderings are contemplated herein. In addition, one or more acts may be omitted and/or one or more additional acts may be included.
At 1002, obtain 3D pre-scan image data that includes voxels representing at least one tissue of interest. This may include performing a 3D pre-scan, which includes scanning the at least one tissue of interest, to generate the 3D pre-scan image data or obtaining 3D pre-scan image data from a data repository.
At 1004, the tissue of interest is located in the 3D pre-scan image data.
At 1006, the located 3D pre-scan image data is registered with an anatomical atlas or a geometric model.
At 1008, an ROI is created for the tissue of interest in the 3D pre-scan image data. As described herein, one or more ROI's can be created in one or more different reformatted view directions.
At 1010, a sub-volume of the 3D pre-scan image data that bounds or includes the tissue of interest is selected.
At 1012, a 2D planning projection image is generated based on the sub-volume. As disclosed herein, a volume rendering or other approach can be employed.
At 1014, a volume scan of the tissue of interest is created using the 2D planning projection image.
At 1016, the volume scan of the tissue of interest is performed based on the volume scan plan.
The above acts may be implemented by way of computer readable instructions, encoded or embedded on computer readable storage medium, which, when executed by a computer processor cause the processor to carry out the described acts. Additionally or alternatively, at least one of the computer readable instructions is carried by a signal, carrier wave and other transitory medium and implemented by the computer processor.
The invention has been described with reference to the preferred embodiments. Modifications and alterations may occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be constructed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Filing Document | Filing Date | Country | Kind |
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PCT/IB2014/065729 | 10/31/2014 | WO | 00 |
Number | Date | Country | |
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61905550 | Nov 2013 | US |