Adaptive data acquisition for computed tomography systems.

Abstract

To provide a computed tomography (CT) imaging system including a gantry, which includes a rotating member on a rotating side and a stationary member on a stationary side, and a data communication system.SOLUTION: The rotating member on the rotating side includes: an X-ray source configured to emit X-rays; an X-ray detector configured to generate detector data; a data storage unit configured to store the detector data; and processing circuitry configured to process at least part of the stored detector data to generate a processed data set. The stationary member on the stationary side is communicatively coupled to the rotating member on the rotating side. The data communication system is configured to transfer the processed data set from the rotating member on the rotating side to the stationary member on the stationary side.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The proposed technology relates to X-ray technology and imaging, as well as corresponding calibration, image reconstruction, and imaging tasks. In particular, the proposed technology relates to a computed tomography (CT) imaging system for improved data handling, and a method of operating such a CT imaging system. [Background technology]

[0002] Radiography, in combination with computed tomography (CT) imaging systems, has been used for many years in medical applications such as medical diagnosis and treatment.

[0003] Typically, a CT imaging system, or simply CT imaging system, includes an x-ray source and an x-ray detector array consisting of multiple detectors, each containing one or multiple detector elements for independent measurement of x-ray intensity. The x-ray source emits x-rays, which are received by the detector array after passing through the person or object being imaged. The x-ray source and the detector array are typically mounted on a rotating member of a gantry and configured to rotate about the person or object being imaged. The emitted x-rays are attenuated by the person or object as they pass through the person or object, and the resulting transmitted x-rays are measured by the detector. The measured data can then be used to reconstruct an image of the person or object being imaged.

[0004] With reference to FIG. 1(A), it may be useful to provide a brief overview of a typical illustrative x-ray imaging system according to the prior art. In this illustrative example, x-ray imaging system 1 includes an x-ray source 10, an x-ray detector system 20, and an associated image processing system or device 30. In general, x-ray detector system 20 is configured to record radiation from x-ray source 10, optionally focused by an optional x-ray optic or collimator, that passes through an imaged object, subject, or portion thereof. X-ray detector system 20 is connectable to image processing system 30 via suitable analog readout electronics that are at least partially integrated into x-ray detector system 20 to enable image processing and / or image reconstruction by image processing system 30.

[0005] By way of example, a conventional CT imaging system, or simply CT imaging system, includes an X-ray source and an X-ray detector configured in such a way that projection images of the person or object can be acquired at different viewing angles spanning at least 180 degrees. This is most commonly achieved by mounting the source and detector on a support that can be rotated around the person or object, such as a rotating member of a gantry. An image that includes projections recorded at different viewing angles on different detector elements is called a sinogram. In the following, a collection of projections recorded at different viewing angles on different detector elements is called a sinogram, even if the detector is two-dimensional and the sinogram is a three-dimensional image.

[0006] FIG. 1(B) is a schematic diagram of an example of a prior art X-ray imaging system setup, showing the projection of a ray from an X-ray source through an object to an X-ray detector.

[0007] A further development of X-ray imaging is energy-resolved X-ray imaging, also known as spectral X-ray imaging, in which X-ray transmission is measured for several different energy levels. This can be achieved either by rapidly switching the source between two different emission spectra, by using two or more X-ray sources emitting different X-ray spectra, or by using an energy-discriminating detector that measures the incident radiation at two or more energy levels. One example of such a detector is the multi-bin photon counting detector, in which each recorded photon generates a current pulse, which is compared to a set of thresholds to count the number of photons that fall into each of a given number of energy bins.

[0008] Spectral X-ray projection measurements result in a projection image for each energy level. A weighted sum of these projection images can be used to optimize the contrast-to-noise ratio (CNR) for a given imaging task. This is described in Tapiovaara and Wagner, "SNR and DQE analysis of broad spectrum X-ray imaging," Phys. Med. Biol. 30, 519.

[0009] Another technique made possible by energy-resolved x-ray imaging is basis material decomposition, which exploits the fact that all materials composed of elements with low atomic numbers, such as human tissue, have linear attenuation coefficients that are energy-dependent, and that this energy dependence can be expressed as a good approximation as a linear combination of two (or more) basis functions, i.e. μ(E)=a1f1(E)+a2f2(E) where f1 and f2 are basis functions and a1 and a2 are corresponding basis coefficients. More generally, f i are the basis functions, and a iare the corresponding basis coefficients, i=1,...,N, where N is the total number of basis functions. If one or more elements with atomic numbers large enough that their k-edges lie in the energy range used for imaging are present in the imaged volume, one basis function must be added for each such element. In the field of medical imaging, such k-edge elements might typically be iodine or gadolinium, i.e., substances used as contrast agents.

[0010] The basis material decomposition is described in Alvarez and Macovski, "Energy-selective reconstructions in X-ray computerised tomography," Phys. Med. Biol. 21, 733. In the basis material decomposition, the integral for each of the basis coefficients i=1,...,N (N is the number of basis functions) is

number

number

[0011] Here, λ i is the predicted number of energy bins i, E is the energy, and S i is a response function that depends on the spectral shape incident on the imaged object, the quantum efficiency of the detector, and the sensitivity of energy bin i to x-rays of energy E. Although the term "energy bin" is most commonly used for photon counting detectors, this equation can also describe other energy-resolving x-ray systems such as multi-layer detectors or kVp switched sources.

[0012] Then, using the maximum likelihood method, we calculate A under the assumption that the number of individuals in each bin is a random variable that follows a Poisson distribution. i can be estimated. This is accomplished by minimizing the negative log-likelihood function. See Roessl and Proksa, K-edge imaging in x-ray computed tomography using multi-bin photon counting detectors, Phys. Med. Biol. 52 (2007), 4679-4696.

number

[0013] The resulting estimated basis coefficient line integrals for each projection line

number

[0014] CT imaging systems that have a rotating part, such as the rotating member of a gantry, typically transmit all acquired data from the rotating part through a data slip ring to a stationary computer where the data is subsequently processed to reconstruct an image of the subject or object. Summary of the Invention [Problem to be solved by the invention]

[0015] Advances in the field of CT x-ray imaging have allowed for faster gantry rotation speeds and improved detector spatial resolution, thus increasing the requirements for adequate data handling.

[0016] As the amount of data generated grows, it puts increasing strain on traditional CT imaging systems that were not designed to handle the increased data flow. Thus, systems are limited by their inability to handle large amounts of data and transfer the data fast enough through slip rings, for example, creating a bottleneck effect that limits the use of CT imaging systems.

[0017] Therefore, there is a widespread need for improvements in data handling in CT imaging systems. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] U.S. Patent No. 8,183,535 [Patent Document 2] U.S. Patent No. 7,114,850

[0019] The object is to mitigate or eliminate one or more of the above mentioned deficiencies and shortcomings in the art singly or in any combination, and to solve at least the problems mentioned above.

[0020] A specific objective is to provide an improved computed tomography (CT) imaging system.

[0021] Also, one objective is to provide a method of operating a CT imaging system.

[0022] These and other objects are met by one or more embodiments of the present invention as defined by the claims.

[0023] According to a first aspect, there is provided a CT imaging system comprising a gantry including a rotating member and a stationary member. The rotating member includes an X-ray source configured to emit X-rays, an X-ray detector configured to generate detector data, a data storage unit configured to store the detector data, and a processing circuit configured to process at least a portion of the stored detector data to generate a processed data set. The stationary member is coupled in communication with the rotating member. The CT imaging system further includes a data communication system configured to transfer the processed data set from the rotating member to the stationary member.

[0024] According to a second aspect, there is provided a method of operating a CT imaging system. The CT imaging system includes a rotating side including an X-ray source configured to emit X-rays, an X-ray detector, a data storage unit, and a processing circuit, and a stationary side coupled in communication with the rotating side via a data communication system. The method includes generating detector data via the X-ray detector and storing the detector data in the data storage unit. The method further includes processing the stored detector data in the processing circuit to generate a processed data set. The method further includes transferring the processed data set from the rotating side to the stationary side via the data communication system.

[0025] Thus, the first and second aspects of the present invention share a common general inventive concept of providing improved handling of data processing and / or data transfer performed by a CT imaging system, i.e. by storing data at the rotating side of the CT imaging system, processing at least a portion of the stored data at the rotating side to generate a processed data set at the stationary side, and transferring or transmitting the processed data set to the stationary side, thereby enabling scan results or at least associated data to be obtained at the stationary side of the CT imaging system in a faster, more efficient and more versatile manner.

[0026] The present invention provides an adaptive procedure that allows selective adaptation of the amount of data transferred from the rotating side to the stationary side, and further allows selective and / or adaptive selection of which data should be processed on the rotating side and on the stationary side, respectively.

[0027] Other advantages will become apparent upon reading the detailed description.

[0028] Further scope of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the disclosure, are given for purposes of illustration only, since various changes and modifications within the scope of the disclosure will become apparent to those skilled in the art from this detailed description.

[0029] Thus, it is to be understood that the disclosure is not limited to the particular components of the described apparatus or steps of the described methods, as such apparatus and methods may vary. Moreover, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. When used in the specification and claims, the terms "a," "an," "the," and the like, are intended to mean that there are one or more of the elements in question, unless the context clearly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" can include several apparatus, and so forth. Furthermore, the words "comprising," "including," "containing," and similar terms do not exclude other elements or steps. [Brief description of the drawings]

[0030] [Figure 1(A)] FIG. 1 is a schematic diagram showing an example of an overall X-ray imaging system. [Figure 1(B)] FIG. 1 is a schematic diagram showing an example of an overall X-ray imaging system. [Diagram 2] FIG. 1 is a schematic diagram illustrating another example of an X-ray imaging system, such as a CT imaging system. [Diagram 3] FIG. 1 is a block schematic diagram of a CT imaging system as an illustrative example of an X-ray imaging system. [Figure 4] FIG. 2 is a schematic diagram showing another example of the relevant parts of an X-ray imaging system, such as a CT imaging system. [Diagram 5] FIG. 1 is a schematic diagram of a photon counting circuit and / or device according to the prior art. [Figure 6] FIG. 2 is a schematic diagram illustrating an example of a semiconductor detector small module according to an example embodiment. [Figure 7] FIG. 13 is a schematic diagram showing an example of a semiconductor detector small module according to another example of an embodiment. [Figure 8(A)]FIG. 13 is a schematic diagram showing an example of a semiconductor detector small module according to yet another example of an embodiment. [Figure 8(B)] FIG. 1 is a schematic diagram showing an example of a set of tiled detector sub-modules, each of which is a depth-split detector sub-module, with an ASIC or corresponding circuitry positioned below the detector element when viewed from the direction of incident X-rays. [Figure 9] 1 is a schematic diagram of a CT imaging system 100 in accordance with an exemplary embodiment. [Figure 10] 1 is a schematic diagram of a CT imaging system 100 in accordance with an exemplary embodiment. [Figure 11] 1 is a schematic diagram of a CT imaging system 100 in accordance with an exemplary embodiment. [Figure 12] 1 is a schematic diagram of a CT imaging system 100 in accordance with an exemplary embodiment. [Figure 13] FIG. 1 is a schematic diagram illustrating an example of a method of operating a CT imaging system according to one embodiment. [Figure 14] FIG. 1 is a schematic diagram illustrating an example of a method of operating a CT imaging system according to one embodiment. [Figure 15] FIG. 1 is a schematic diagram illustrating an example of a method of operating a CT imaging system according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] For a more thorough understanding, it may be useful to follow with an introductory description of a non-limiting example of an overall X-ray imaging system in which data processing and transfer according to the concepts of the present invention may be implemented.

[0032] 2 is a schematic diagram showing an example of a CT imaging system 1, which includes an X-ray source 10 that emits X-rays, an X-ray detector system 20 with an X-ray detector that detects the X-rays after passing through an object, an analog processing circuit 25 that processes and digitizes raw electrical signals from the X-ray detector, a digital processing circuit 40 that may perform further processing operations on the measurement data, such as applying corrections to the measurement data, temporarily storing the measurement data, or performing filtering, and a computer 50 that may store the processed data and perform further post-processing and / or image reconstruction. According to an example of an embodiment, all or part of the analog processing circuit 25 may be implemented in the X-ray detector system 20. The X-ray source and the X-ray detector may be coupled to a rotating member of a gantry 15 of the CT imaging system 1.

[0033] The entire X-ray detector may be considered as the X-ray detector system 20, or the X-ray detector system 20 may be combined with associated analog processing circuitry 25.

[0034] An image processing system 30 is in communication with and electrically coupled to the analog processing circuitry 25, and may include a digital processing circuitry 40 and / or a computer 50, which may be configured to perform image reconstruction based on image data from the x-ray detector. As such, the image processing system 30 may be considered as the computer 50, or as the combined system of the digital processing circuitry 40 and the computer 50, or possibly as the digital processing circuitry 40 itself if the digital processing circuitry is further dedicated to image processing and / or image reconstruction.

[0035] One example of a commonly used x-ray imaging system is the CT imaging system, which may include an x-ray source or tube that produces a fan or cone beam of x-rays and an opposing x-ray detector array that measures the portion of the x-rays that pass through the patient or object. The x-ray source or tube and detector array are mounted on a gantry that rotates around the object being imaged.

[0036] FIG. 3 shows a schematic of a CT imaging system 1 as an illustrative example of an X-ray imaging system. The CT imaging system includes a computer 50 that receives commands and scanning parameters from an operator via an operator console 60, which may have a display 62 and some form of operator interface, such as a keyboard, mouse, joystick, touch screen, or other input device. The operator-supplied commands and parameters are then used by the computer 50 to provide control signals to the X-ray controller 41, the gantry controller 42, and the table controller 43. In particular, the X-ray controller 41 provides power and timing signals to the X-ray source 10 to control the emission of X-rays to an object or patient located on the table 12. The gantry controller 42 controls the rotational speed and position of the gantry 11, which includes the X-ray source 10 and the X-ray detector 20. By way of example, the X-ray detector may be a photon-counting X-ray detector. The table controller 43 controls and determines the position of the patient table 12 and the scan range of the patient. There is also a detector controller 44 configured to control and / or receive data from the X-ray detector 20 .

[0037] In one embodiment, computer 50 also performs image reconstruction and post-processing of image data output from the x-ray detector, thereby corresponding to image processing system 30 as shown in Figures 1 and 2. An associated display 62 allows an operator to observe the reconstructed image and other data from computer 50.

[0038] An X-ray source 10 disposed on a gantry 11 emits X-rays. An X-ray detector 20, which may be in the form of a photon-counting X-ray detector, detects the X-rays after passing through an object or patient. The X-ray detector 20 may be formed, for example, by a number of pixels, also called sensors or detector elements, and associated processing circuitry, such as an application specific integrated circuit (ASIC), disposed on a detector module. Part of the analog processing may be implemented in the pixels, while any remaining processing is implemented, for example, in the ASIC. In one embodiment, the processing circuitry (ASIC) digitizes the analog signals from the pixels. The processing circuitry (ASIC) may also include a digital processing unit that may perform further processing operations on the measurement data, such as applying corrections to the measurement data, temporarily storing the measurement data, and / or filtering. During a scan to acquire X-ray projection data, the gantry and the components mounted on the gantry rotate about an isocenter 13.

[0039] Modern X-ray detectors usually require the conversion of incident X-rays into electrons, which typically occurs through the photoelectric effect or Compton interaction, and the resulting electrons usually generate secondary visible light until they lose energy, which is then detected by a photosensitive material. Semiconductor-based detectors also exist, where the electrons generated by the X-rays create charge as electron-hole pairs, which are collected through an applied electric field.

[0040] There are also detectors that operate in an energy integration mode, meaning that they give an integrated signal from many x-rays: the output signal is proportional to the total energy deposited by the x-rays detected.

[0041] X-ray detectors with photon-counting and energy-resolving capabilities are becoming common for medical x-ray applications. Photon-counting detectors are advantageous because they can, in principle, measure the energy of each x-ray, providing additional information about the composition of the object. This information can be used to improve image quality and / or reduce radiation dose.

[0042] Typically, photon-counting X-ray detectors determine the energy of a photon by comparing the height of the electrical pulse generated by the photon's interaction with the detector material to a set of comparator voltages. These comparator voltages are also called energy thresholds. Typically, the analog voltages of the comparators are set by a digital-to-analog converter (DAC). The DAC converts the digital settings sent by the controller into analog voltages against which the height of the photon pulse can be compared.

[0043] Photon counting detectors count the number of photons that interact with the detector during a measurement time. A new photon is typically identified by an electrical pulse whose height exceeds the comparator voltage of at least one comparator. Once a photon has been identified, this event is recorded by incrementing a digital counter associated with the channel.

[0044] Using several different thresholds, so-called energy discriminating photon counting detectors are obtained, in which the detected photons can be sorted into energy bins corresponding to the various thresholds. This type of photon counting detector is sometimes called a multi-bin detector. In general, the energy information allows to create a new kind of image, in which new information is available and image artifacts inherent in the prior art can be eliminated. In other words, for an energy discriminating photon counting detector, the pulse height is compared in a comparator with a predefined number of programmable thresholds (T1 to T N ) and classified according to the pulse height, which is in turn proportional to the energy. In other words, a photon counting detector that includes more than one comparator is referred to herein as a multi-bin photon counting detector. In the case of a multi-bin photon counting detector, the number of photons is stored in a set of counters, typically one for each energy threshold. For example, a counter may be assigned to correspond to the highest energy threshold that the photon pulse crossed. In another example, a counter records the number of times that the photon pulse crosses each energy threshold.

[0045] As an example, edge-on (vertical orientation) is a special, non-limiting design of a photon-counting detector in which the x-ray sensors, such as x-ray detector elements or pixels, are oriented edge-on with respect to the incident x-rays.

[0046] For example, such photon counting detectors can have pixels in at least two directions, one of which for edge-on photon counting detectors has a component in the direction of the X-rays. Such edge-on photon counting detectors are also called depth-segmented photon counting detectors, and have pixels in two or more depth segments in the direction of the incident X-rays.

[0047] Alternatively, the pixels can be arranged in an array (non-depth-resolved) in a direction substantially perpendicular to the direction of the incident x-rays, with each of the pixels oriented edge-on with respect to the incident x-rays. In other words, the photon-counting detector is said to be non-depth-resolved while still being arranged edge-on with respect to the incident x-rays.

[0048] The absorption efficiency can be increased by arranging the edge-on photon counting detectors in a vertical orientation, in which case the absorption depth can be chosen to be any length and the edge-on photon counting detector can still be fully depleted without reaching extremely high voltages.

[0049] The conventional mechanism for detecting X-ray photons through a direct semiconductor detector basically works as follows: the energy of the X-ray interaction with the detector material is converted into electron-hole pairs inside the semiconductor detector, where the number of electron-hole pairs is generally proportional to the photon energy. The electrons and holes travel backwards (or away) towards the detector electrode. During this travel, the electrons and holes induce a current in the electrode, which can be measured.

[0050] As shown in FIG. 4, signals flow from the detector elements 21 of the X-ray detector to the input of a parallel processing circuit (e.g., ASIC) 25 via a path referenced 26. It should be understood that the term application specific integrated circuit (ASIC) should be broadly interpreted as any general circuit used and configured for a specific application. The ASIC processes and converts the charge generated from each X-ray into digital data that can be used to obtain measurement data such as photon counts and / or estimated energy. The ASIC is configured for connection to a digital data processing circuit so that the digital data can be sent to further digital data processing 40 and / or one or more memory circuits or components 45, and finally the data becomes an input for image processing 30 / 50 to form a reconstructed image.

[0051] Since the number of electrons and holes from an X-ray event is proportional to the energy of the X-ray photon, the total charge in one induced current pulse is proportional to this energy. After a filtering stage in the ASIC, the pulse amplitude is proportional to the total charge of the current pulse and therefore to the X-ray energy. The pulse amplitude can then be measured by comparing the value with one or several thresholds (THR) in one or more comparators (COMP), and a counter is introduced that can record the number of times the pulse is greater than the threshold. In this way, it is possible to count and / or record the number of X-ray photons detected within some time frame with energies exceeding the energy corresponding to the respective thresholds (THR).

[0052] The ASIC typically samples the analog photon pulse once per clock period and records the output of a comparator. The comparator (threshold) outputs a 1 or 0 depending on whether the analog signal is above or below the comparator voltage. The information available in each sample is, for example, a 1 or 0 for each comparator, representing whether the comparator was triggered (the photon pulse was above the threshold) or not.

[0053] In a photon counting detector, there is typically a photon counting logic that determines if a new photon has been recorded and records the photon in a counter. In the case of a multi-bin photon counting detector, there are typically several counters, e.g. one for each comparator, and the number of photons is recorded in the counter according to an estimate of the photon energy. This logic can be implemented in several different ways. Two of the most common categories of photon counting logic are the so-called non-paralyzed counting mode and paralyzed counting mode. Other photon counting logic is, for example, maximum detection, which counts maxima detected in the voltage pulse and possibly records the pulse height of the maxima.

[0054] There are many advantages of photon counting detectors, including but not limited to high spatial resolution, low sensitivity to electronic noise, good energy resolution, and material separation capabilities (spectral imaging capabilities). However, energy integrating detectors have the advantage of allowing high count rates. This count rate allowance comes from the fact / realization that since the total energy of the photons is measured, adding one additional photon will always increase the output signal (within reasonable limits) regardless of the amount of photons currently registered by the detector. This advantage is one of the main reasons why energy integrating detectors are standard in medical CT today.

[0055] FIG. 5 shows a schematic diagram of a photon counting circuit and / or device according to the prior art.

[0056] When photons interact in the semiconductor material, a cloud of electron-hole pairs is generated. By applying an electric field to the detector material, the charge carriers are collected by electrodes attached to the detector material. The signal flows from the detector elements to the input of a parallel processing circuit, e.g., an ASIC. It should be understood that the term application specific integrated circuit (ASIC) should be broadly interpreted as any general circuit used and configured for a specific application. The ASIC processes and converts the charge generated from each X-ray into digital data, which can be used to obtain measurement data such as the number of photons and / or estimated energy. In one example, the ASIC can process the charge such that a voltage pulse is generated having a maximum height proportional to the amount of energy deposited in the detector material by the photon.

[0057] The ASIC may include a set of comparators 302, each of which compares the magnitude of the voltage pulse with a reference voltage. The comparator output is typically 0 or 1 (0 / 1) depending on which of the two compared voltages is the greater. Assume here that the comparator output is 1 when the voltage pulse is greater than the reference voltage and 0 when the reference voltage is greater than the voltage pulse. A digital-to-analog converter (DAC) 301 may be used to convert a digital setting, which may be provided by a user or a control program, into a reference voltage that may be used by the comparators 302. When the height of the voltage pulse exceeds the reference voltage of a particular comparator, that comparator is said to be "triggered." Each comparator is typically associated with a digital counter 303, which is incremented based on the comparator output according to photon counting logic.

[0058] As previously mentioned, the resulting estimated basis coefficient line integrals for each projection line are

number

[0059] It will be appreciated that the mechanisms and configurations described herein can be implemented, combined, and rearranged in a variety of ways.

[0060] For example, the embodiments may be implemented in hardware, or at least partly in software for execution by suitable processing circuitry, or a combination of both.

[0061] The steps, functions, procedures, and / or blocks described herein may be implemented in hardware using any conventional technology such as discrete or integrated circuit technology, including both general purpose electronic circuits and application specific circuits.

[0062] Alternatively, or as a supplement, at least some of the steps, functions, procedures and / or blocks described herein may be implemented in software, such as a computer program, for execution by suitable processing circuitry, such as one or more processors or processing units.

[0063] In the following description, non-limiting examples of specific detector module implementations are discussed. More specifically, the examples refer to edge-on oriented detector modules and depth-segmented detector modules. Other types of detectors and detector modules are also possible.

[0064] 6 is a schematic diagram of an example of a semiconductor detector sub-module according to an embodiment, in which a semiconductor sensor 21 is divided into detector elements or pixels 22, each of which is typically based on a diode having a charge collection electrode as its main component. X-rays enter through the edge of the semiconductor sensor.

[0065] 7 is a schematic diagram showing an example of a semiconductor detector sub-module according to another example of the embodiment. In this example, the semiconductor sensor 21 is also divided in the depth direction as a plurality of so-called depth sections or detector elements 22, and it is also assumed that X-rays enter through the edge in this case.

[0066] Typically, a detector element is a discrete X-ray sensitive subelement of the detector. In general, photon interactions occur at the detector element and the charge thus generated is collected by a corresponding electrode of the detector element.

[0067] Each detector element typically measures the incident x-ray flux as a series of frames, where a frame is a set of measured data over a given time interval called the frame time.

[0068] Depending on the topological configuration of the detector, a detector element may correspond to a pixel, particularly when the detector is a flat panel detector. A depth-segmented detector may be considered to have a number of detector strips, each having a number of depth sections. In the case of such a depth-segmented detector, each depth section may be considered to be a separate detector element, particularly when each depth section is provided with its own separate charge collection electrode.

[0069] The detector strips of a depth-segmented detector usually correspond to the pixels of a conventional flat panel detector and are therefore also called pixel strips, however, a depth-segmented detector can also be viewed as a three-dimensional pixel array, where each pixel (also called a voxel) corresponds to an individual depth section / detector element.

[0070] The semiconductor sensor can be implemented as a so-called multi-chip module (MCM), in the sense that the semiconductor sensor is used as a substrate for electrical wiring and also for a certain number of ASICs, which are preferably attached through the so-called flip-chip method. The wiring includes connections for the signals from each pixel or detector element to the ASIC inputs and connections from the ASIC to external memories and / or digital data processing. Power to the ASIC can be provided through similar wiring, taking into account the increased cross-section required for the high currents in these connections, but the power may also be provided through a separate connection. The ASIC can be arranged at the side of the active sensor, which means that the ASIC can be protected from incident X-rays by placing an absorbing cover on top and also from scattered X-rays from the side by placing an absorber in this direction as well.

[0071] FIG. 8(A) is a schematic diagram showing a semiconductor detector submodule embodied as an MCM similar to the embodiment of US Pat. No. 8,183,535. In this example, it is shown how a semiconductor sensor 21 can also have a substrate function in an MCM. Signals flow by signal paths 23 from the detector elements or pixels 22 to the inputs of parallel processing circuits 24 (e.g., ASICs) located adjacent to the active sensor areas. It should be understood that the term application specific integrated circuit (ASIC) should be broadly interpreted as any general circuit used and configured for a specific application. The ASIC processes and converts the charge generated from each X-ray into digital data, which can be used to detect photons and / or estimate the energy of the photons. The ASIC can have its own digital processing circuitry and memory for small tasks. The ASIC can also be configured for connection to digital processing and / or memory circuits or components located outside the MCM, and the data is finally used as input to reconstruct an image.

[0072] However, the adoption of depth sectioning also introduces two significant problems for silicon-based photon counting detectors. First, a large number of ASIC channels must be used to process the data provided by the associated detector section. In addition to the increased number of channels due to the smaller pixel size and depth sectioning, the amount of data increases further due to multiple energy bins. Second, because a given number of incoming x-rays is distributed over smaller pixels, sections, and energy bins, the signal in each bin is much smaller, and therefore detector calibration / correction requires orders of magnitude more calibration data to minimize statistical uncertainties.

[0073] Naturally, as data volumes increase by orders of magnitude, both data handling and preprocessing slow down, in addition to the need for larger computational resources, hard disks, memory, and central processing units (CPUs) / graphics processing units (GPUs). If data volumes are, say, 10 gigabytes instead of 10 megabytes, data handling times, i.e., reading and writing, can take 1000 times longer. For pile-up (Radiation Detection and Measurement, Glenn F. Knoll, 3rd edition, John Wiley & Sons Inc, pp. 632-pp. 642) calibration vector generation, pile-up calibration data needs to be preprocessed for spit correction. For material decomposition vector generation, material decomposition data needs to be preprocessed for both spit correction and pile-up correction. For patient scan data, the data needs to be preprocessed for spit, pile-up, and material decomposition before image reconstruction begins. These processes are simplified examples to illustrate "preprocessing." Since the actual pre-processing step may optionally include several other calibration steps such as standard normalization and air calibration, the term "processing" may sometimes refer only to the final step in each calibration vector generation or patient scan, but is sometimes used interchangeably.

[0074] Figure 8(B) is a schematic diagram showing an example of a set of tiled detector modules, each of which is a depth-splitting detector module, in which an ASIC or corresponding circuit 24 is positioned below the detector element 22 when viewed from the direction of the incident X-rays, and a passage path from the detector element 22 to the ASIC 23 is projected in the space between the detector elements.

[0075] The present invention relates to a system design having improved data handling capabilities with respect to data processing and / or data transfer.

[0076] According to a first aspect, there is provided a CT imaging system comprising a gantry including a rotating member and a stationary member. The rotating member includes an X-ray source configured to emit X-rays, an X-ray detector configured to generate detector data, a data storage unit configured to store the detector data, and a processing circuit configured to process at least a portion of the stored detector data to generate a processed data set. The stationary member is coupled in communication with the rotating member. The CT imaging system further includes a data communication system configured to transfer the processed data set from the rotating member to the stationary member.

[0077] By way of example, the rotating member may be a rotating part / section / segment / portion of a gantry configured to rotate around a subject / imaged object, etc. The stationary member may be defined as a stationary part / section / segment / portion of a gantry configured in a stationary manner on a stationary side, and the rotating and stationary members may be communicatively connected via a data communication system, e.g., slip rings.

[0078] By storing data on the rotating side of the CT imaging system, processing at least a portion of the data to generate a processed data set on the rotating side, and transferring or sending the processed data set to the stationary side, the relevant data can be obtained on the stationary side in a fast, efficient and versatile manner. Processing at least a portion of the detector data on the rotating side can reduce the amount of data transferred via a data communication system, e.g., via a slip ring, by a factor of 2 to 20,000, allowing many calibration and / or imaging steps to send data within the existing slip ring bandwidth, thus speeding up the overall imaging and / or calibration process. The data storage unit can include a dedicated mass memory, e.g., Non-Volatile Memory Express (NVMe). The data storage unit on the rotating side can additionally or alternatively include temporary memory required during continuous data processing, e.g., ASIC, field programmable gate array (FPGA) registers or memory. The data storage unit can additionally or alternatively include a RAM (random access memory). Processing the stored data on the rotating side can include one or more operations. By way of example, the calculations may be, but are not limited to, Spitz correction, data integration, and pile-up correction for an X-ray source or X-ray tube.

[0079] X-ray tube "spits" refer to temporary electrical shorts that sometimes occur inside the X-ray tube. Typically, when a tube spit occurs, power to the X-ray tube is temporarily cut off to prevent electrical arcing, resulting in no X-ray output. Spits can be corrected and are currently applied on the stationary side. See U.S. Pat. No. 7,114,850. Corrections are made on the rotating side, allowing frame integration of detector data, e.g., calibration data, on the rotating side as well. As mentioned above, for a given X-ray input, with smaller pixels, multiple depth segments, and multiple energy bins, the number of X-rays in each bin is reduced by an order of magnitude (number of input X-rays / (pixel size ratio x number of segments x number of energy bins)). To generate statistically meaningful calibration vectors, for example pile-up (each X-ray incidence generates an electrical signal of some length. The signal pulse has a finite length, so it may overlap with the next incoming X-ray pulse. This overlap is called "pile-up". Both the number and the energy distribution are distorted due to pile-up and need to be corrected.) and material decomposition require accumulating or averaging many frames, i.e., 100 to 10000 frames. Due to the large amount of data, even with modern computing power on the stationary side, relatively simple Spitz and accumulation tasks take an impractical amount of time. By distributing electronic circuits per small detector on the rotating side, i.e., ASIC / FPGA / CPU (references 40 / 45 in Fig. 4, 114 / 118 / 116 in Fig. 9), and utilizing these circuits in parallel, the same goal can be achieved without any delay or within a negligible time.

[0080] As frames are accumulated, the amount of data becomes smaller, allowing faster data transfer through a data communication system, e.g., a slip ring, and faster processing of detector data, e.g., calibration data, to generate pile-up and material decomposition calibration vectors on the stationary side.

[0081] Additionally, to increase the efficiency of data acquisition, pile-up and material decomposition calibration vectors / algorithms can be loaded into a register / memory, e.g., data storage unit, and applied simultaneously to the data being collected, thus eliminating the slow stationary side calibration pre-processing by using parallel detector electronics.

[0082] Once the data is corrected on the rotational side, the pixels and segments can be combined to support various patient scan modes such as ultra-high resolution scans, high resolution scans, cardiac specific scans, and axial scans. One patient scan mode requires ultra-high spatial resolution, while another scan mode requires better material contrast, which can be achieved by combining pixels to increase statistics. The combined data can be immediately transferred to the stationary side and reconstructed for patient diagnosis.

[0083] As an example, X-ray tube spit correction can be implemented as follows: While the ASIC energy bin counts for one frame are being read out to the ASIC register / memory, the X-ray tube spit information for this frame is notified to all detector elements through the data acquisition board. The length of one frame is typically longer than 25 microseconds to integrate the X-ray counts, and the spit notification from the X-ray tube can be done in less than 1 microsecond. During the time to acquire the next frame, if spits have occurred in the current frame, the spit correction is applied to the current frame, and the corrected current frame is moved to the next register / memory of the ASIC. This allows the first register / memory space to be used for the next frame seamlessly while the spit correction is being applied.

[0084] The Spitz corrected views can be accumulated as needed. As an example, if one wishes to accumulate 1000 frames, the counts from each frame can be added together. After the 1000th frame, the added counts are transferred to a data communications unit, e.g., 130-1 in FIG. 9, and the registers / memories are reset for the next 1000 frames.

[0085] Since modern FPGAs have a large amount of computational resources, processing circuits can be implemented in the FPGA to perform more complex algorithms. A simple example is performing view average and standard deviation calculations. A more complex algorithm would be applying a pileup algorithm to the data stream.

[0086] For example, this system design invention can speed up the process of retrieving results using a CT imaging system by allowing data to be processed and transferred simultaneously. The invention can further speed up the process of retrieving results by allowing data to be processed quickly at the rotational side and converted into a format that is faster and / or more efficient in terms of information sent per unit time for transfer through a data communication system.

[0087] Moreover, the present invention is advantageous in that it allows the CT imaging system to be more versatile with regard to the selection and timing of data for processing and transfer. In particular, such improved versatility is achieved by storing the detector data in the rotating side data storage unit without any pre-processing or compression. For example, the system offers the option of which data should be processed and transferred and when, so that the system can be used on the one hand for a quick patient scan and on the other hand for a more detailed examination of the imaged person / object. For the quick patient scan, the system can process the detector data of a full scan, for example by merging on the rotating side with respect to views and / or pixels, and transfer the processed data to the stationary side, where the final steps of forming an image are performed, for example. This allows the user of the CT imaging system to retrieve sufficiently good results in a faster way. In case of a detailed examination, the CT imaging system can transfer the complete raw detector data as generated by the X-ray detector to the stationary side.

[0088] According to one embodiment, the processed data set includes a reduced data set. The term "reduced data set" is used herein without limitation to mean a data set resulting from an operation that reduces the amount of data on a conventional data set, such as generated detector data. As mentioned above, because of the small pixels, depth partitions, and multiple energy bins, detector calibration requires multiple same view / frame data to reduce statistical errors. Examples of operations performed on the same view data include averaging the data per each energy bin and / or accumulating the frame data per each energy bin, where a detector element may include at least one energy bin. The input may be, for example, 1000 views, and the output is an accumulated or averaged view. These operations may be accomplished simultaneously in the ASIC while each view data is being read out from the detector. Alternatively, the counts may be transferred to a separate other memory for accumulating.

[0089] The "output mode" of the processing circuitry is described below with respect to a number of optional features, it being understood that any combination of these features is contemplated by the inventors.

[0090] According to one embodiment, the processing circuitry is configured to operate in a plurality of output modes, each of which generates a respective processed data set. For example, the plurality of output modes may include an output mode for calibration and an output mode for patient imaging. The plurality of output modes may include a plurality of different calibration modes for the CT imaging system and a plurality of output modes for patient imaging.

[0091] Multiple output modes can generate respective processed data sets, each differing from the other output modes with respect to the amount of data in the respective generated processed data sets.

[0092] According to one embodiment, an output mode is selected on demand and a corresponding processed data set is generated using the selected output mode. This embodiment allows a user of the CT imaging system to request the output mode via a user interface. Thus, the user can at least partially determine how the CT imaging system is operated in terms of how the data is handled. The user interface may be, for example, a display on a rotating or stationary computer.

[0093] According to one embodiment, the processing circuitry is configured to select a predetermined output mode and generate a corresponding processed data set using the predetermined output mode, allowing the CT imaging system to perform one or more output modes without a user having to request any output mode. For example, the CT imaging system may have one or more predetermined default modes.

[0094] According to one embodiment, the processing circuitry is configured to process the stored data to generate respective processed data sets using a set of successive output modes, and the data communication system is configured to transfer these respective processed data sets one after the other. This embodiment is advantageous in that the CT imaging system can operate in multiple steps that can be predefined. For example, this allows the CT imaging system to optimize how the detector data is stored, processed and transferred to first form an initial image for a quick diagnosis, followed by a more detailed image for a final diagnosis. Furthermore, this embodiment allows the CT imaging system to process the data and transfer one or more processed data sets without requiring input from the user, thus reducing the overall process downtime by avoiding interruption times between each step.

[0095] According to one embodiment, portions of the first processed data set are transferred via the data communications system while other portions of the first processed data set are being generated, and the processing of the detector data and the transfer of the processed data set from the rotating member to the stationary member are at least partially simultaneous. This embodiment allows for a faster and more efficient use of the CT imaging system, essentially shortening the time it takes between performing a scan of the subject / object and forming an image reconstructed from the detector data.

[0096] According to one embodiment, the data communication system includes a first data communication unit provided on a rotating member on a rotating side, and a second data communication unit provided on a stationary member on a stationary side.

[0097] According to one embodiment, a data communication system includes one or more slip rings.

[0098] According to one embodiment, the X-ray detector is configured to send the detector data to a data storage unit, which is configured to store the generated detector data in its entirety. This embodiment is advantageous in that all information from a scan with the CT imaging system can be stored and processed or transferred, allowing a more versatile way of handling the detector data.

[0099] According to one embodiment, the data storage unit is a non-volatile memory, NVMe, and / or a random access memory RAM, allowing the CT imaging system to store detector data and / or processed data on the rotating side to optimize data handling. NVMe can provide a more reliable storage of data, e.g., minimizing the impact of power loss.

[0100] According to one embodiment, the data storage unit is a set of temporary registers that are part of the data processing circuit.

[0101] According to one embodiment, the X-ray detector is a photon counting detector.The present invention is particularly useful for detector technologies that generate large amounts of data, such as photon counting detectors.

[0102] According to one embodiment, the X-ray detector is an energy discriminating detector, such as a detector with multiple energy bins.

[0103] According to one embodiment, processing the detector data includes combining the detector data to generate a processed data set.

[0104] According to one embodiment, the processing circuitry is configured to process at least a portion of the generated detector data before this portion is stored in the data storage unit in order to further optimize data handling. Spitz or pile-up corrections or other corrections can be applied before storage. After storage, the data can be transferred directly through a data communication unit, e.g. a slip ring, or the sections, pixels and views can be combined according to a patient data prescription. Filter corrections can also be applied to smooth statistical variations.

[0105] According to one embodiment, the system includes a second data storage unit configured to receive a processed data set from the rotating member of the rotating side, and a second set of processing circuits configured to process the received processed data set, both of which are disposed on the stationary member of the stationary side.

[0106] For a better understanding, the proposed technique is explained in more detail below with reference to figures 9 to 13, which show non-limiting examples of data processing and transfer according to the invention.

[0107] FIG. 9 is a schematic diagram of a CT imaging system 100 according to an exemplary embodiment of the present invention. In FIG. 9, the CT imaging system 100 includes a rotating side 110 and a stationary side 120. The rotating side 110 may include a gantry including a rotating member disposed on the rotating side 110, which can rotate around the subject / object as described, for example, in FIG. 3, and an X-ray source 112 disposed on one side of the gantry and an X-ray detector 114 disposed on the other side such that X-rays emitted by the X-ray source 112 can pass through the subject / object and be received and detected at the X-ray detector 114. The X-ray detector 114 may be a photon counting detector, and may optionally be an energy discriminating type detector with multiple energy bins, for example, as described in FIGS. 3 to 7, 8(A), and 8(B). The X-ray detector may alternatively be an energy integrating detector (EID), in which the detected signal does not have specific information about individual photons or their energies, but is proportional to the total energy deposited by all photons. The CT imaging system 100 further includes a data storage unit 116 that allows for storing detector data from the X-ray detector 114 on the rotating side 110. The data storage unit 116 may be a non-volatile memory. The CT imaging system 100 further includes a processing circuit 118 that may receive and process data, such as detector data. The term "processing circuit" as used herein means a circuit, such as a processor, that may perform functions such as mathematical operations to process and transfer data. The processing circuit may be a digital processing circuit. The processing circuit 118 and the data storage unit 116 may be communicatively connected such that data may be transferred between them. It is to be understood that the processing circuit 118 may process the detector data and / or already processed data to obtain a resultant processed data set that may be transferred to the stationary side 120. The processed data set may be a reduced data set with a reduced amount of data.

[0108] The processing performed by the processing circuitry 118 may include one or more operations, such as, for example, changing the format or reducing the amount of data. For example, at least a portion of the detector data may be averaged or multiplied to generate a reduced data set having a reduced amount of data. The reduction in the amount of data may be achieved through lossy and / or lossless compression. The CT imaging system 100 further includes a data communications system 130 through which raw and / or processed detector data may be transferred from the rotating side 110 to, for example, a computer at the stationary side 120.

[0109] By way of example, the data communication system 130 may include a first data communication unit 130-1 on the rotating side and a second data communication unit 130-2 on the stationary side. For example, the data communication system 130 may be a slip ring typically used with rotating members of a gantry in a CT imaging system. "Slip ring" as used herein means, but is not limited to, an electromechanical device that allows for the transfer of power and electrical signals, such as the transfer of power and data between a rotating structure and a stationary structure. The CT imaging system 100 of FIG. 9 may also include a display 132 coupled to the second data communication unit 130-2 and configured to receive and display the processed data set.

[0110] Figure 10 illustrates a schematic of a CT imaging system 100 similar to the CT imaging system 100 of Figure 9. Much of the configuration and operation of the CT imaging system 100 is substantially similar to that described in Figure 9, and therefore a detailed description of the features common to the embodiment shown in Figure 9 will be omitted to avoid unnecessary clutter and for the sake of brevity.

[0111] In FIG. 10, the CT imaging system 100 includes a second data storage unit 126 and a second set of processing circuits 128 disposed on the stationary side 120. The second data storage unit 126 is configured to receive the processed data set from the rotating side 110 via a data communication system 130. The second set of processing circuits 120 may be configured to process the data received in the data storage unit 126 to construct a final image of the scan of the object / imaged person. By way of example, the CT imaging system 100 may store the detector data in its entirety. The CT imaging system 100 may process portions of the detector data stored in the data storage unit 116 by the processing circuits 118 at the rotating side 110 to generate the processed data set. The CT imaging system may also process all of the stored detector data at the rotating side 110 to generate the processed data set. The detector data being processed may be a copy of the stored detector data and / or the processed data set may be a new data set generated from the detector data set, thus allowing the same detector data to be processed multiple times in different ways.

[0112] The CT imaging system 100 can transfer the processed datasets and / or detector data to the stationary side 120 via the data communication system 130. The transferred processed datasets and / or detector data can be received by and stored in the data storage unit 126. For example, any processed datasets and / or detector data can be processed at the stationary side 120, for example to complete an image reconstruction of the detector data. Thus, the detector data can be processed once at the rotating side 110 to generate a processed dataset, and then the processed dataset can be processed again at the stationary side 120. Furthermore, the detector data can be transferred in its entirety from the rotating side 110 to the stationary side 120, even if a processed dataset was generated using parts of the detector data and already transferred to the stationary side 120. This can be useful in scenarios where a processed dataset based on the detector data from a patient scan is determined in a simpler manner to allow for a simpler diagnosis, and a more precise examination is later determined based on the complete detector data.

[0113] The CT imaging system 100 may store any portion of the detector data and / or the processed data in the data storage unit 116 and / or the second data storage unit 126.

[0114] Figure 11 illustrates a schematic of a CT imaging system 100 similar to the CT imaging system 100 of Figures 9 and 10. Much of the configuration and operation of the CT imaging system 100 is substantially similar to that described in Figures 9 and 10, and therefore a detailed description of the features common to the embodiment shown in Figures 9 and 10 will be omitted to avoid unnecessary clutter and for the sake of brevity.

[0115] In FIG. 11, the x-ray detector 114 is an energy discriminating detector including individual detector elements 114a / 114b / 114c / 114d. The CT imaging system 100 can discriminate detector data coming from a particular detector element 114a / 114b / 114c / 114d and store the detector data without losing information about which detector element the data comes from. The stored detector data can be processed by the processing circuitry 118 by performing one or more operations. For example, one operation can be averaging detector data from different detector elements 114a / 114b / 114c / 114d or integrating together data from several elements, e.g., adjacent elements. The CT imaging system can provide the option to individually store, process, and / or transfer detector data and / or processed data sets from one or more detector elements 114a / 114b / 114c / 114d between the rotating side and the stationary side. The CT imaging system 100 of FIG. 11 may also include a display 132 coupled to the second data communications unit 130-2 and configured to receive and display the processed data set.

[0116] Figure 12 illustrates a schematic of a CT imaging system 100 similar to the CT imaging system 100 of Figures 9, 10, and 11. Much of the configuration and operation of the CT imaging system 100 is substantially similar to that described in Figures 9, 10, and 11, and therefore a detailed description of the features common to the embodiment illustrated in Figures 9, 10, and 11 will be omitted to avoid unnecessary clutter and for the sake of brevity.

[0117] In FIG. 12, the processing circuitry 118 is configured to operate in multiple output modes, each of which generates a respective processed data set. One or more of the output modes may relate to calibration of the CT imaging system 100, and one or more of the modes may relate to patient imaging. Calibrating the CT imaging system 100 may include generating correction factors that are used in the reconstruction of subsequent scans. The purpose of the calibration may be to characterize system-specific behavior, either before, during, or after the scan, that can be compensated for later. The calibration may be performed by scanning a phantom, which may be an object that mimics the human body in terms of composition, for example, to provide a reference so that a more accurate quantitative representation of the scanned subject / person can be provided by the CT imaging system 100. Alternatively, the calibration may be performed by scanning air, for example, to normalize the detector response at different positions on the detector. Another alternative is to calibrate by acquiring data with the x-ray source off, for example, to characterize and compensate for phenomena due to the detector electronics.

[0118] Calibration of the CT imaging system 100 may involve taking multiple detector measurements to obtain multiple sets of detector data and processing these data together to calculate the calibration coefficients. For example, multiple consecutive scans / views may be averaged together with corresponding detector data taken at the same angle to reduce the effects of noise in the measurements and generate better statistics in the correction coefficients. One alternative is to transfer the detector data to the stationary side 120 and process it there, which can be very slow when the bandwidth of the data communication system 130 becomes a bottleneck for the amount of detector data. Another alternative is to generate one or more processed data sets from the detector data at the rotating side 110 and transfer the processed data sets, which may be smaller in volume than the detector data, allowing for even faster transfer over the data communication system 130.

[0119] The CT imaging system 100 may provide the option to operate in many different patient imaging modes, such as a primary patient scan mode, which may allow for a faster but less detailed process of forming a reconstructed image. The CT imaging system 100 may, for example, form images faster because it allows for specification of which detector data stored in the data storage unit 116 should be processed by the processing circuitry 118 and how the detector data is to be processed. Additionally, the CT imaging system 100 may allow for a specified processed data set to be transferred to the stationary side 120 via the data communication system 130, for example, allowing for processing and / or transferring a majority of the detector data after processing and / or transferring the most important or most desired portion of the detector data to the stationary side 120. Another exemplary output mode is a secondary patient scan mode, which may, for example, provide more detail in the reconstructed image but take longer to form. These different output modes may also be used when scanning an object.

[0120] In some sense, the output mode may also be considered as a data processing mode in which respective processed data sets are generated and output for further use and / or transfer.

[0121] Each processed data set generated by each output mode may differ in terms of data amount. For example, a first output mode may generate a first processed data set from a first portion of the detector data, and a second output mode may generate a second processed data set from a second portion of the detector data, where the first processed data set may have a smaller amount of data compared to the second processed data set. The detector data may be received from a storage portion of the data storage unit 116 or directly from the X-ray detector 114 or the individual detector elements 114a / 114b / 114c / 114d. The processing circuitry 118 may perform different operations on the data depending on which output mode is being performed. The first portion of the detector data may be the same as or a part of the second portion of the detector data. Depending on which output mode is being performed, the amount of detector data being processed on the rotating side 110 and the stationary side 120 may vary, and the detector data and / or the processed data set may vary for the stationary side 120 at any point in time.

[0122] CT imaging system 100 may be configured in a first output mode, for example for patient imaging, to first form a relatively less detailed image based on detector data from a scan of the imaged person / object, followed by a more detailed image of the scan. This may be done by initially forming a first processed data set from a first portion of the detector data, and then transferring the first processed data set to stationary side 120 via data communication system 130. CT imaging system 100 may then be configured in the first output mode to transfer the remaining detector data to stationary side 120 via data communication system 130 without processing by processing circuitry 118. In this manner, the first output mode of the CT imaging system allows an initial, simpler scan to be performed and presented to a user of the system, with the remaining detector data being processed and / or transferred at a later time.

[0123] For example, in a second output mode, the CT imaging system 100 may be configured to first process a second portion of the detector data to generate a second processed data set, and transfer the second processed data set to the stationary side 120 via the data communication system 130 to form an image based on the second processed data set. The CT imaging system 100 may then be configured to process a third portion of the detector data to generate a third processed data set, and then transfer the third processed data set to the stationary side 120 via the data communication system 130 to form a secondary image having information not present in the second processed data set, e.g., to complete a more detailed image. The CT imaging system 100 of FIG. 12 may include a display 132 coupled to the second data communication unit 130-2 and configured to receive and display the processed data sets.

[0124] FIG. 13 is a schematic diagram illustrating an example of a method of operating a CT imaging system in accordance with one embodiment.

[0125] According to a second aspect, there is provided a method of operating a CT imaging system including a rotating side including an X-ray source configured to emit X-rays, an X-ray detector, a data storage unit, and processing circuitry, and a stationary side coupled in communication with the rotating side via a data communication system.

[0126] The method basically comprises a step 310 of generating detector data via the X-ray detector and a step 320 of storing the detector data in a data storage unit. The method further comprises a step 330 of processing the stored detector data in a processing circuit to generate a processed data set. The method further comprises a step 340 of transferring the processed data set from the rotating side to the stationary side via a data communication system. The step of "storing data" may be performed by a dedicated memory and / or a relay register / memory of the processing circuit. For example, when the step 310 of generating detector data is being processed simultaneously through a relay register, steps 320 and 330 may be reversed or step 320 may be omitted.

[0127] According to one embodiment, the processing in the processing circuitry includes selecting one of a plurality of output modes, each of which generates a respective processed data set. This embodiment is advantageous in that the CT imaging system is more versatile since the data may be stored and processed as needed or desired by a user.

[0128] According to one embodiment, the processing in the processing circuitry includes selecting one of a plurality of output modes, each of which produces a respective processed data set, each of which differs from the other in terms of the amount of data in the processed data set. This embodiment has the advantage that data handling is customised for different time frames and requirements for the resulting images.

[0129] According to one embodiment, one of a plurality of output modes may be selected on demand, and a corresponding processed data set may be generated using the selected output mode.

[0130] According to one embodiment, the transferring includes transferring portions of the first processed data set via the data communication system while other portions of the first processed data set are being generated, such that the processing of the detector data and the transfer of the processed data set from the rotating side to the stationary side are performed at least partially simultaneously.

[0131] According to one embodiment, the detector data is sent to a data storage unit, which is adapted to store the generated detector data in its entirety.

[0132] According to one embodiment, the processing circuitry is configured to process at least a portion of the generated detector data before said portion is stored in the data storage unit.

[0133] According to one embodiment, the processed data from the rotating side can be received at a second data storage unit at the stationary side, and the processed data received at the second data storage unit can be received at a second set of processing circuits at the stationary side.

[0134] Fig. 14 illustrates a schematic, non-limiting example of a CT imaging system 100 according to an embodiment. In Fig. 14, the CT imaging system 100 includes an X-ray detector 114 arranged on a rotating member of a gantry at the rotating side of the CT imaging system 100, a data storage unit 116, and a processing circuit 118. Here, at least a portion of the generated detector data from the X-ray detector 114 is pre-processed by a pre-processing circuit 115 before being stored in the data storage unit 116 and / or processed by the processing circuit 118. The processing circuit 118 can include logic box 118-1 and / or processing box 118-2, where the processing box 118-2 can be configured to perform computationally intensive calculations compared to the logic box 118-1. The processing circuitry 118 can process at least a portion of the detector data in the data storage unit 116, and the data collector 119 can collect and send processed or unprocessed data from all channels or a subset thereof to the data communication system 130, which can then transfer the data from the rotating member of the gantry to a stationary member of the gantry disposed on the stationary side of the CT imaging system 100. By way of example, a selected subset of the generated detector data from the X-ray detector 114 can be pre-processed by the pre-processing circuitry 115 prior to storage in the data storage unit 116 and / or prior to primary processing by the processing circuitry 118. As a specific example, the same subset of the detector data or at least partially different or completely different subsets of the detector data can be processed by the processing circuitry 118.

[0135] 15 is a schematic diagram illustrating another non-limiting example of a CT imaging system 100 according to an embodiment. In FIG. 15, the CT imaging system 100 includes an X-ray detector 114 arranged on a rotating member of a gantry, for example, at the rotating side of the CT imaging system 100, a data storage unit 116, and a processing circuit 118. Here, the generated detector data from the X-ray detector 114 is stored in the data storage unit 116 and / or by the processing circuit 118 without pre-processing. The processing circuit 118 can include logic box 118-1 and / or processing box 118-2, and the processing box 118-2 can be configured to perform computationally intensive calculations compared to the logic box 118-1. The processing circuitry 118 can process at least a portion of the detector data in the data storage unit 116, and the data collector 119 can collect and send processed or unprocessed data from all or a subset of the channels to the data communication system 130, which can then transfer the data from the rotating member of the gantry to a stationary member of the gantry disposed on the stationary side of the CT imaging system 100. This embodiment has several technical advantages as described above. The effects and features of the second aspect are largely similar to those described above in relation to the first aspect. The embodiments mentioned in relation to the first aspect are largely compatible with the second aspect. It is further noted that the inventive concept relates to all possible combinations of each feature, unless otherwise stated. [Explanation of symbols]

[0136] 1. X-ray Imaging System 21 Detector element (semiconductor sensor) 22 Detector element or pixel 23 Signal Path 24 Parallel Processing Circuit 26 Signal Flow 62, 132 display 100 CT Imaging System 114a, 114b, 114c, 114d detector elements 118 Processing Circuit

Claims

1. A gantry including a rotating member on a rotating side (110) and a stationary member on a stationary side (120), The rotating member on the rotating side is an X-ray source (112) configured to emit X-rays; a depth-resolved X-ray detector (114) configured to generate detector data; a data storage unit (116) configured to store said detector data; a processing circuit (118) configured to process at least a portion of the stored detector data to generate a processed data set; Contains a gantry, the stationary member of the stationary side being coupled to communicate with the rotating member of the rotating side; a data communication system (130) configured to transfer the processed data set from the rotating members of the rotating side to the stationary members of the stationary side; Equipped with the processing circuitry is configured to operate in a plurality of output modes, each of which generates a respective processed data set; an output mode is selected in response to the request, and a corresponding processed data set is generated using the selected output mode; the processed data set includes a Spitz-corrected and / or pile-up corrected data set of the X-ray source (112); A computed tomography (CT) imaging system (100), wherein the x-ray detector is an energy discriminating photon counting detector having multiple energy bins.

2. The CT imaging system of claim 1 , wherein the processed data set comprises a reduced data set.

3. The CT imaging system of claim 1 , wherein the plurality of power modes includes a power mode for calibration and a power mode for patient imaging.

4. The processing circuitry includes: generating correction factors for use in reconstructing the scan in said calibration output mode; 4. The CT imaging system of claim 3, wherein in said output mode for patient imaging, a relatively low detailed image is formed based on detector data from a scan of the imaged subject.

5. 2. The CT imaging system of claim 1, wherein the plurality of output modes generate respective processed data sets, each differing from the others with respect to the amount of data in the processed data set.

6. The CT imaging system of claim 1 , wherein the x-ray detector (114) operates in an energy integration mode to generate the detector data.

7. The CT imaging system of claim 1 , wherein the processing circuitry is configured to select a predetermined output mode and generate a corresponding processed data set using the predetermined output mode.

8. 2. The CT imaging system of claim 1, wherein the processing circuitry is configured to process the stored data using a set of successive output modes to generate respective processed data sets, and the data communication system is configured to transfer the respective processed data sets in succession.

9. 2. The CT imaging system of claim 1, wherein a portion of a first processed data set is transferred via the data communications system while another portion of the first processed data set is being generated, such that the processing of the detector data and the transfer of the processed data set from the rotating member on the rotating side to the stationary member on the stationary side occur at least partially simultaneously.

10. 2. The CT imaging system of claim 1 , wherein the X-ray detector is configured to send the detector data to the data storage unit, and the data storage unit is configured to store the generated detector data in its entirety.

11. The CT imaging system of claim 1 , wherein the processing circuitry is configured to process at least a portion of the generated detector data prior to storing the data in the data storage unit.

12. In the stationary member on the stationary side, a second data storage unit (126) configured to receive the processed data set from the rotating member of the rotating side; a second set of processing circuits (128) configured to process the received processed data set; Including, 5. The CT imaging system of claim 4, wherein the second set of processing circuits (128) in an output mode for patient imaging produces a more detailed image of the scan of the imaged subject.

13. 1. A method of operating a CT imaging system, the CT imaging system comprising: an x-ray source configured to emit x-rays; Depth-resolved X-ray detector, A data storage unit, and Processing Circuit A rotating side including a stationary side coupled to communicate with said rotating side via a data communication system; Contains generating detector data via the X-ray detector (310); storing (320) the detector data in the data storage unit; processing (330) the stored detector data in the processing circuitry to generate a processed data set; transferring (340) the processed data set from the rotating side to the stationary side via the data communication system; Equipped with said step of processing (330) in said processing circuitry includes selecting an output mode from a plurality of output modes, each output mode producing a respective processed data set; an output mode is selected in response to the request, and a corresponding processed data set is generated using the selected output mode; the processed data set includes a Spitz-corrected and / or pile-up corrected data set of the X-ray source (112); The method, wherein the x-ray detector is an energy discriminating photon counting detector having multiple energy bins.

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