Patent Application
20220323028
This disclosure relates generally to diagnostic imaging and, more particularly, to an apparatus for a computed tomography (CT) scanner, such as a dual layer detector module for spectral CT.
Typically, in CT imaging systems, a rotatable gantry includes an x-ray tube, detector, data acquisition system (DAS), and other components that rotate about a patient that is positioned at the approximate rotational center of the gantry. X-rays emitted from the x-ray tube, are attenuated by the patient, and are received at the detector. The detector typically includes a photodiode-scintillator array of pixelated elements that convert the attenuated x-rays into photons within the scintillator, and then to electrical signals within the photodiode array. The electrical signals are digitized and then received within the DAS, processed, and the processed signals are transmitted via a slipring (from the rotational side to the stationary side) to a computer or data processor for image reconstruction, where an image is formed.
The gantry typically includes a pre-patient collimator that defines or shapes the x-ray beam emitted from the x-ray tube. X-rays passing through the patient can cause x-ray scatter to occur, which can cause image artifacts. Thus, x-ray detectors typically include an anti-scatter grid (ASG) for collimating x-rays received at the detector.
Third generation multi-slices CT scanners typically include detectors having scintillator/photodiodes arrays. These detectors are positioned in an arc where the focal spot is the center of the corresponding circle. These detectors generally have scintillation crystal/photodiode arrays, where the scintillation crystal absorbs x-rays and converts the absorbed energy into visible light. A photodiode is used to convert the light to an electric current. The reading is typically linear to the total energy absorbed in the scintillator.
Typically, CT systems obtain raw data and then reconstruct images using various known pre-processing and post-processing steps to generate a final reconstructed image. That is, CT systems may be calibrated to account for x-ray source spectral properties, detector response, and other features, to include temperature. Raw x-ray data are pre-processed using known steps that include offset correction, reference normalization, and air calibration steps, as examples.
In recent years, the development of volumetric or cone-beam CT technology has led to an increase in the number of slices used in CT detectors for computed tomography systems. The detector technology used in large coverage CT enables greater coverage in patient scanning by increasing the area exposed, by using back-illuminated photodiodes. A typical detector includes an array of 16, 32, or 64 slices. However, the need for cardiac imaging has become of greater interest to enable imaging of the heart within one rotation of the detector, substantially increasing the width of the detector in the Z-axis (e.g., along the patient length), leading to a detector having 256 or more slices. Because it is impractical to build very large modules in monolithic structure to cover this number of slices and this width in the Z-axis, due to manufacturing cost and reliability concerns, smaller modules (mini-modules) are built along the Z-axis and placed along the Z-axis to build the overall length of 256 or more slices.
In the last decade, spectral computed tomography (SCT) has been of particular interest. This technology enables the same object to be measured with different energy spectra and spectral weightings. SCT may be used to differentiate and classify material composition, by using attenuation values acquired with different energy spectra. The measurements with different spectra may be obtained in a variety of ways, for example, via a) a dual layer detector, b) fast KV switching between 80 and 140 kV from view to view, c) two KV spectra with different x-ray filter, and/or d) two x-ray sources configured to emit x-rays perpendicularly relative to one another (e.g., at 90 degrees). Each method of obtaining these measurements has advantages and disadvantages, which may include a balancing of costs and performance. In this disclosure, we describe several concepts to achieve a dual layer detector design, with appropriate electronic attachments and connections.
In examples, CT detector module may include a module frame, a first rigid flex board, a main routing substrate arranged on the first rigid flex board, a high-density scintillator-photodiode array arranged on and electrically connected to the main routing substrate, and a low-density scintillator-photodiode array electrically connected to the main routing substrate. The first rigid flex board may include a central portion, a first lateral portion, a second lateral portion, a first flexible portion extending between and connecting the central portion and the first lateral portion, and a second flexible portion extending between and connecting the central portion and the second lateral portion. The central portion may be arranged on a first surface of the mounting frame. The first lateral portion may be disposed on a second surface of the mounting frame. The second lateral portion may be disposed on a third surface of the mounting frame.
The foregoing and other potential aspects, features, details, utilities, and/or advantages of examples/embodiments of the present disclosure will be apparent from reading the following description, and from reviewing the accompanying drawings.
While the claims are not limited to a specific illustration, an appreciation of various aspects may be gained through a discussion of various examples. The drawings are not necessarily to scale, and certain features may be exaggerated or hidden to better illustrate and explain an innovative aspect of an example. Further, the exemplary illustrations described herein are not exhaustive or otherwise limiting, and embodiments are not restricted to the precise form and configuration shown in the drawings or disclosed in the following detailed description. Exemplary illustrations are described in detail by referring to the drawings as follows:
Reference will now be made in detail to embodiments of the present disclosure, examples of which are described herein and illustrated in the accompanying drawings. While the present disclosure will be described in conjunction with embodiments and/or examples, they do not limit the present disclosure to these embodiments and/or examples. On the contrary, the present disclosure covers alternatives, modifications, and equivalents.
The operating environment of disclosed embodiments is described with respect to a multi-slice computed tomography (CT) system. Embodiments are described with respect to a “third generation” CT scanner, however it is contemplated that the disclosed embodiments are applicable to other imaging systems as well.
Referring to
Gantry 102 includes a rotatable base 120, on which is mounted x-ray tube 114, a heat exchanger 122, a data acquisition system (DAS) 124, an inverter 126, a generator 128, and a detector assembly 130, as examples. System 100 is operated with commands entered by a user into computer 110. Gantry 102 may include gantry controls 132 located thereon, for convenient user operation of some of the commands for system 100. Detector assembly 130 includes a plurality of detector modules (e.g., a dual layer detector module 400), which include an anti-scatter grid (ASG; e.g., ASG 440), scintillators (e.g., a low-density scintillator 452, a high-density scintillator 462, etc.), photodiodes (e.g., a front-illuminated photodiode 454, a back-illuminated photodiode 464, etc.), and the like, which detect x-rays and convert the x-rays to electrical signals, from which imaging data is generated. Gantry 102 includes a pre-patient collimator 134 that is positioned to define or shape an x-ray beam 136 emitted from x-ray tube 114. Although not shown, a shape filter may be positioned for instance between x-ray tube 114 and pre-patient collimator 134.
In operation, rotatable base 120 is caused to rotate about the patient up to typically a few Hz in rotational speed, and table 106 is caused to move the patient axially within opening 104. When a desired imaging location of the patient is proximate an axial location where x-ray beam 136 will be caused to emit, x-ray tube 114 is energized and x-ray beam 136 is generated from a focal spot within x-ray tube 114. The detectors receive x-rays, some of which have passed through the patient, yielding analog electrical signals are digitized and passed to DAS 124, and then to computer 110 where the data is further processed to generate an image. The imaging data may be stored on computer system 100 and images may be viewed. An X-Y-Z triad 138, corresponding to a local reference frame for components that rotate on rotatable base 120, defines a local directional coordinate system in a gantry circumferential direction X, a gantry radial direction Y, and gantry axial direction Z. Accordingly, and referring to triad 138, the patient passes parallel to the Z-axis, the x-rays pass along the Y axis, and the rotational components (such as detector assembly 130) rotate in a circumferential direction and in the X direction, and about an isocenter 140 (which is a centerpoint about which rotatable base rotates, and is an approximate position of the patient for imaging purposes). A focal spot 142 is illustrated within x-ray tube 114, which corresponds to a spot from which x-ray beam 136 emits.
X-ray detection 306 occurs when x-rays having emitted from x-ray tube 114 pass to detector assembly 130. An anti-scatter grid (e.g., ASG 440) prevents x-ray scatter (emitting for example from the patient as secondary x-rays and in a direction that is oblique to x-ray beam 136), by generally passing x-rays that emit from x-ray tube 114. DAS 124 processes signals received from detector assembly 130. Image generation 308 occurs after the digitized signals are passed from a rotating side of gantry 102 (on rotatable base 120) to a stationary side, via for instance a slipring.
Image generation 308 occurs in computer system 110, or in a separate processing module that is in communication with computer system 110. The data is pre-processed, and image views or projections are used to reconstruct images using known techniques such as a filtered backprojection (FBP). Image post-processing also occurs, after which the images may be displayed 310, or otherwise made available for display elsewhere (such as in a remote computing device).
As generally shown in
The first rigid flex board 410 includes one or more conductors disposed on, connected to, and/or integrated therein via which a first rigid flex board 410 may facilitate transmission of and/or convey electrical signals and/or currents between two or more components, elements, structures, etc. The first rigid flex board 410 includes one or more electronic components for signal processing, wherein analog electrical signals (e.g., from one or more scintillator-photodiode arrays 450, 460) are digitized and then passed to DAS 124. The first rigid flex board 410 includes a central portion 412, a first lateral portion 414, a second lateral portion 416, a first connector portion 418, and a second connector portion 420. The central portion 412, the first lateral portion 414, and the second lateral portion 416 are each configured as a circuit board (e.g., a printed circuit board). The first lateral portion 414 and the second lateral portion 416 of the first rigid flex board 410 are disposed on opposite sides of the central portion 412 relative to one another. The first lateral portion 414 and the second lateral portion 416 are connected to the central portion 412 via the first connector portion 418 and the second connector portion 420, respectively. The first connector portion 418 and the second connector portion 420 are configured to transmit and/or convey electrical signals and/or currents between the central portion 412 and the associated lateral portion 414, 416.
The first connector portion 418 and the second connector portion 420 are each configured as a flexible portion (e.g., a first flexible portion, a second flexible portion), which may allow a position and/or orientation of the lateral portion(s) 414, 416 to be adjusted relative to the central portion 412. The first flexible portion 418 and the second flexible portion 420 are each configured as a high-density flex portion.
Additionally and/or alternatively, the first connector portion 418 and/or the second connector portion 420 may be configured as a curved and/or bent portion (e.g., a first bent portion, a second bent portion). The first bent portion and/or the second bent portion may be bent and/or curved such that the associated lateral portion 414, 416 is disposed transversely, obliquely, and/or perpendicularly relative to the central portion 412 (e.g., at a 90° angle).
One or more electrical connectors, circuit boards, electronics packages, processors, analog to digital ASICs (application-specific integrated circuit) or FPGA (field-programmable gate array), and/or other associated electronic components may be disposed on and connected to the first rigid flex board 410. For example, as illustrated in
The first rigid flex board 410 is disposed and/or mounted on and connected to the module frame 430. The central portion 412 of the first rigid flex board 410 is disposed on and/or aligned with a first surface 430a of the module frame 430. The module frame 430 includes a receptacle 432 (e.g., a recess, depression, notch, etc.), a bottom surface of which may be the first surface 430a. The central portion 412 of the first rigid flex board 412 is configured to be received at least partially within the receptacle 432. The first and/or second lateral portions 414, 416 of the first rigid flex board 410 are disposed on and connected to one or more surfaces 430b, 430c of the module frame 430. For example, the first lateral portion 414 is disposed on a second surface 430b of the module frame 430 (e.g., a first lateral surface 430b extending transversely to the first surface 430a), and the second lateral portion 416 is disposed on a third surface 430c of the module frame 430 (e.g., a second lateral surface 430c extending transversely to the first surface 430a and/or parallel to the second surface 430b). The connector portions 418, 420 enable such an arrangement. For example, the first flexible portion and the second flexible portion flex and/or deform to conform the first rigid flex board 410 to the shape of the module frame 430 when mounting the first rigid flex board 410. The first rigid flex board 410 and/or one or more portions thereof (e.g., portions 412, 414, 416) are connected to the module frame 430 via screws, but may be connected in a variety of manners such as with connectors, fasteners, pins, adhesive, chemical bonding, molding, etc.
The main routing substrate 436 is disposed on and connected to the first rigid flex board 410 (e.g., the central portion 412) and/or the module frame 430. The main routing substrate may include a multi-layer ceramic routing substrate. The main routing substrate 436 is to receive, gather, collect, assemble, merge, etc. one or more signals and/or currents from the low-density scintillator-photodiode array 450 and the high-density scintillator-photodiode array 460 (e.g., directly and/or via a thru-via substrate 502, one or more rigid flex boards 480, 490, 610, a high-density flex, etc.), which signals may convey information and/or data collected via the received x-rays. The main routing substrate 436 may be further configured to route the signals, currents, information, etc. to the first rigid flex board 410.
The ASG 440 has a plurality of plates 442 and two end blocks 444a, 444b. The two end blocks 444a, 444b are disposed on and connected to opposite sides of the plates 442. The plates 442 are oriented approximately parallel to a Y-Z plane of the detector assembly 130. The two end blocks 444a, 444b are each connected to the main routing substrate 436 such that the plates 442 are disposed above and aligned with the low-density scintillator-photodiode array 450 and the high-density scintillator-photodiode array 460. The ASG 440 and the main routing substrate 436 are connected to the module frame 430 via mounting screws 434a, 434b that engage the module frame 430 and the two end blocks 444a, 444b.
The low-density scintillator-photodiode array 450 is configured to collect low-energy data from received x-rays and the high-density scintillator-photodiode array 460 is configured to collect high-energy data from received x-rays. The low-density scintillator-photodiode array 450 is disposed above and aligned with the high-density scintillator-photodiode array 460 such that, during operation, x-rays interact with the low-density scintillator-photodiode array 450 prior to interacting with the high-density scintillator-photodiode array 460. The low-density scintillator-photodiode array 450 and the high-density scintillator-photodiode array 460 may collectively form/define a stack of multiple scintillator-photodiode arrays. The scintillator-photodiode arrays 450, 460 may each be arranged on a respective base substrate that may include a ceramic or other solid base material. The low-density scintillator-photodiode array 450 includes a low-density scintillator 452 (e.g., an Yttrium Aluminum Garnet or YAG scintillator) disposed on a front-illuminated first photodiode 454. The low-density scintillator 452 is disposed on a side of the first photodiode 454 opposite the main routing substrate 436. The high-density scintillator-photodiode array 460 includes a high-density scintillator 462 (e.g., Gadolinium OxySulfide or GOS scintillator) disposed on a back-illuminated second photodiode 464. The high-density scintillator 462 is disposed on a side of the second photodiode 464 opposite the main routing substrate 436. The first and second photodiodes 454, 464 are each optically coupled via an optical coupler to the associated scintillator 452, 462. The first and second scintillators 452, 462 may be pixelated scintillators. The first and second scintillators 452, 462 each include a plurality of pixels (e.g., an array of pixels), which may extend generally in the X-direction. The first and second photodiodes 454, 464 may be pixelated photodiodes. The first and second photodiodes 454, 464 each include a plurality of photodiode pixels (e.g., an array of pixels), which correspond with the pixels of the associated scintillator 452, 462.
The scintillator-photodiode arrays 450, 460 are physically, electrically, and/or communicatively connected to the main routing substrate 436. The scintillator-photodiode arrays 450, 460 may be connected to the main routing substrate 436 in a variety of different manners illustrative examples of which are shown in
In the illustrative example generally shown in
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In the illustrative example generally shown in
During use of the dual layer detector module 400 (e.g., during operation of the CT scanner), the low-density scintillator-photodiode array 450 receives and absorbs low-energy photons of the received x-rays to collect low-energy data, while allowing high-energy photons of the received x-rays to pass therethrough and reach the high-density scintillator-photodiode array 460, which receives and absorbs the high-energy photons of the received x-rays to collect high-energy data. The low-density scintillator-photodiode array 450 sends one or more signals and/or currents to the main routing substrate 436 via the second and third rigid flex boards 480, 490 (e.g.,
In examples, the scintillator-photodiode arrays 450, 460 may each have a 16×64 pixel array (i.e., 1024 pixels). In such a case, the connector portions 486, 496, 618, 620 may each be configured as 512 high-density flex to provide 1024 channels (i.e., one channel for each pixel) from the low-density scintillator-photodiode array 450 to the main routing substrate 436. Similarly, 1024 channels (i.e., one channel for each pixel) may also be provided from the high-density scintillator-photodiode array 460 to the main routing substrate 436 and, thus, a total of 2048 channels routed from the main routing substrate 436 to the first rigid flex board 410. Each ASIC 422a-422h may have 256 channels and, thus, 1024 channels are provided on each lateral portion 414, 416 of the first rigid flex board 410.
When introducing elements of various embodiments of the disclosed materials, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Furthermore, any numerical examples in the following discussion are intended to be non-limiting, and thus additional numerical values, ranges, and percentages are within the scope of the disclosed embodiments.
While the preceding discussion is generally provided in the context of medical imaging, it should be appreciated that the present techniques and processes are not limited to such medical contexts. The provision of examples and explanations in such a medical context is to facilitate explanation by providing instances of implementations and applications. The disclosed approaches may also be utilized in other contexts, such as the non-destructive inspection of manufactured parts or goods (i.e., quality control or quality review applications), and/or the non-invasive inspection or imaging techniques.
While the disclosed materials have been described in detail in connection with only a limited number of embodiments, it should be readily understood that the embodiments are not limited to such disclosed embodiments. Rather, that disclosed can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the disclosed materials. Additionally, while various embodiments have been described, it is to be understood that disclosed aspects may include only some of the described embodiments. Accordingly, that disclosed is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
This application claims priority to U.S. Provisional Patent Application No. 63/173,563, filed on Apr. 12, 2021, the contents of which are incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63173563 | Apr 2021 | US |
