Photon interaction characteristics from a subset of pixels

Abstract

One embodiment provides a method comprising: receiving a photon interaction occurring within a photon detector pixel array, wherein the photon detector pixel array comprises a plurality of pixels; determining a photoelectron cloud generated by the photon interaction, wherein the photon detector pixel array comprises an electric field, wherein electrostatic repulsive forces cause the photon to disperse into the photoelectron cloud; identifying a plurality of subsets of the plurality of pixels associated with the photon interaction, wherein each of the plurality of subsets of the plurality of pixels corresponds to a pixel activated by the photoelectron cloud, wherein the plurality of subsets of the plurality of pixels comprises a center pixel and a plurality of neighboring pixels, wherein the center pixel comprises a pixel having a highest amplitude response to the photon interaction; and determining a characteristic of the photon interaction from the photoelectron cloud, wherein the characteristic comprises at least one of: a time, a location, and an energy of the interaction. Other aspects are described and claimed.

Description

Technical Field

[0001] This application relates generally to imaging, and more specifically to determining the properties of photon interactions at sub-pixelation resolution. Background Technology

[0002] Imaging devices perform many different functions, such as medical imaging, security screening, and image capture. The imaging source can be a radiation source, visible light, invisible light, or any type of source that the imaging device can detect. For example, in a medical setting, a patient may be injected with a radiopharmaceutical tracer, and the imaging device can capture the gamma photon radiation emitted from the patient's body for diagnostic analysis. Imaging devices can include gamma cameras sensitive to emission sources, such as cameras that include specific substances or objects that are sensitive to or react to emission sources. The camera can contain individual pixels that allow the image to determine the location, energy, time, and intensity of the emitted signal. Summary of the Invention

[0003] In summary, one aspect provides a method comprising: receiving photonic interactions occurring within a photonic detector pixel array, wherein the photonic detector pixel array comprises a plurality of pixels; determining a photoelectron cloud generated by the photonic interactions, wherein the photonic detector pixel array comprises an electric field, wherein electrostatic repulsion disperses photons into the photoelectron cloud; identifying a subset of the plurality of pixels associated with the photonic interactions, wherein each subset of the plurality of pixels corresponds to a pixel activated by the photoelectron cloud, wherein the subset of the plurality of pixels comprises a central pixel and a plurality of neighboring pixels, wherein the central pixel comprises a pixel having the highest amplitude response to the photonic interactions; and determining characteristics of the photonic interactions based on the photoelectron cloud, wherein the characteristics include at least one of the following: the time, location, and energy of the interaction.

[0004] Another aspect provides an apparatus comprising: a photon detector pixel array including a plurality of pixels; a processor operatively coupled to the photon detector pixel array; and a storage device storing instructions executed by the processor to: receive photon interactions occurring within the photon detector pixel array, wherein the photon detector pixel array includes a plurality of pixels; determine a photoelectron cloud generated by the photon interactions, wherein the photon detector pixel array includes an electric field, wherein electrostatic repulsion disperses photons into the photoelectron cloud; identify a subset of a plurality of pixels associated with the photon interactions, wherein each subset of the plurality of pixels corresponds to a pixel activated by the photoelectron cloud, wherein the subset of pixels includes a central pixel and a plurality of neighboring pixels, wherein the central pixel includes a pixel having the highest amplitude response to the photon interactions; and determine characteristics of the photon interactions based on the photoelectron cloud, wherein the characteristics include at least one of the following: the time, location, and energy of the interaction.

[0005] Another aspect provides a product comprising: a storage device storing code executed by a processor and comprising: receiving code for photon interactions occurring within a photon detector pixel array, wherein the photon detector pixel array comprises a plurality of pixels; determining code for a photoelectron cloud generated by the photon interactions, wherein the photon detector pixel array comprises an electric field, wherein electrostatic repulsion disperses photons into the photoelectron cloud; identifying a subset of a plurality of pixels associated with the photon interactions, wherein each subset of the plurality of pixels corresponds to a pixel activated by the photoelectron cloud, wherein the subset of pixels comprises a central pixel and a plurality of neighboring pixels, wherein the central pixel comprises a pixel having the highest amplitude response to the photon interactions; and determining, based on the photoelectron cloud, characteristics of the photon interactions, wherein the characteristics include at least one of the following: the time, location, and energy of the interaction.

[0006] The foregoing is an overview and may therefore contain simplifications, generalizations and omissions of details; therefore, those skilled in the art will understand that the overview is merely illustrative and not intended to be limiting.

[0007] To better understand the embodiments, as well as other and further features and advantages of the embodiments, reference is made to the following description in conjunction with the accompanying drawings. The scope of the invention will be set forth in the appended claims. Attached Figure Description

[0008] Figure 1 A flowchart of an example embodiment is shown.

[0009] Figure 2 An example embodiment of the generation of an electronic cloud is shown.

[0010] Figure 3 An example embodiment of subpixelation correction is shown.

[0011] Figure 4 Example count data from three consecutive pixels is shown.

[0012] Figure 5 Example data for a 2×2 subpixelation factor is shown.

[0013] Figure 6 Example data for the center pixel and its eight surrounding neighboring pixels is shown.

[0014] Figure 7 An example of an information processing device circuit is shown. Detailed Implementation

[0015] It will be readily understood that the components of the embodiments generally described and illustrated in the accompanying drawings can be arranged and designed in various different configurations beyond the exemplary embodiments described herein. Therefore, as shown in the drawings, the following more detailed description of the exemplary embodiments is not intended to limit the scope of the claimed embodiments, but is merely representative of exemplary embodiments.

[0016] Throughout this specification, references to "an embodiment" or "an embodiment" (or similar expressions) mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Therefore, phrases such as "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment.

[0017] Furthermore, in one or more embodiments, the described features, structures, or characteristics can be combined in any suitable manner. Numerous specific details are provided in the following description to provide a thorough understanding of the embodiments. However, those skilled in the art will recognize that various embodiments can be practiced without one or more of these specific details, or using other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid confusion.

[0018] Users of imaging equipment often desire image outputs with high spatial, temporal, and energy resolution. For example, medical images with high spatial, temporal, and energy resolution can influence patient treatment by guiding doctors to locations of interest within the patient's body. Many imaging devices utilize cameras that are sensitive to the type of emission being imaged in order to capture images precisely. To capture an image, the camera image is divided into discrete regions or picture elements (pixels), where each pixel can represent a position and intensity within the captured image.

[0019] As an example, in a nuclear medicine (molecular imaging) setting, a patient can be injected with a radiopharmaceutical tracer, and an imaging device (gamma camera) can capture the emission of gamma photon radiation from the patient's body for diagnostic analysis. The detector in the gamma camera can include semiconductor direct conversion materials such as CdZnTe, CdTe, HgI, and Si. Gamma photon detector pixel arrays that include semiconductor direct conversion detector materials have advantages over scintillator photon detector gamma cameras, including superior energy and spatial resolution. However, a drawback of such pixelated semiconductor detector arrays is the energy spectral distortion of individual pixels, where some counts are recorded at energies lower than the light peak due to hole carrier trapping or charge sharing with adjacent pixels. Since image formation may typically only require accepting counts within an energy range closely surrounding the light peak, counts in the lower energy spectral tails are not included in the image. This means that even if the thickness of each camera provides the same stopping power for gamma photons, the efficiency of a gamma camera is clearly lower than that of a scintillator camera. This invention provides a novel solution to the problems of charge sharing and hole trapping spectral tails.

[0020] The principles of this invention depend on a profound and specific understanding of photon interactions in CdZnTe detectors and signal formation in pixelated CdZnTe detectors. However, the invention can be understood at a high level. When gamma photons (preferably from the cathode side) are incident on a pixelated CdZnTe detector, they may undergo zero or more Compton scatterings before depositing their remaining energy in a photoelectric manner. These interactions can occur within a single pixel or multiple pixels. These interactions directly translate into a charge cloud of electrons and holes. The detector is typically operating under an electric field of approximately 100 volts per millimeter, with the pixelated anode at ground potential and the typical bulk cathode at a high negative voltage. Therefore, holes are accelerated towards the cathode, and electrons towards the pixelated anode. Since hole mobility is typically much lower than electron mobility, it takes longer to sweep out holes than electrons, and holes are more likely to be trapped in crystal defects. When the pixel is smaller than the detector thickness, the device is much more sensitive to electrons than to holes due to the "small pixel effect."

[0021] When an electron cloud approaches the anode, an induced voltage is detected on multiple anodes and / or pixels. When a charge cloud reaches the anode plane, the charge accumulates on one or several pixels. Then, any adjacent pixel where the induced voltage is detected will detect a voltage of opposite polarity, such that the integral over time for any non-charge-accumulated pixel will be zero. Therefore, there are multiple ways a signal can be shared among multiple pixels: charge can be shared when electron charge clouds overlap with multiple pixels, photon interactions may have occurred in multiple pixels due to Compton scattering or k-escape X-rays, and transient induced voltages can be detected on multiple adjacent pixels. Of course, hole charges accumulate on the cathode, and this information can be used to estimate the interaction depth of incident photons. However, this invention explicitly does not use any cathode signal to determine the characteristics of photon interactions. Furthermore, this invention uses only the positive and negative peak amplitudes of the anode pixel signals. This is a significant simplification, making the determination of interaction characteristics a relatively straightforward matter of combining information from the peak signal amplitudes of multiple anode pixels.

[0022] As with any device, there is the problem of determining the location and energy of the signal on the detector. Photons or particles can enter the receiving imaging unit, causing the interaction between the incident photons or particles and the imaging unit material to generate signals at multiple pixels or detection areas. This problem may arise in the case of photons entering the imaging unit with an angled trajectory. A photon entering the detection unit may strike one or more pixels. In other words, a photon can enter the detector at an angle and pass through one or more pixel detection areas before its trajectory terminates.

[0023] Current systems may struggle to attribute detected charges to the correct interactions on pixels or subsets of pixels, resulting in images with lower accuracy. Currently, many imaging devices rely on one or more signals from a single pixel to identify the location of interactions. Imaging techniques acquire signals from individual pixels from the detection unit of the imaging device. In this way, the imaging unit receives a “pixelated” image of the received signals. Thus, a central pixel may have a high value, while neighboring pixels may have lower values. However, data about how neighboring pixel values ​​relate to the central pixel value can be lost in imaging techniques. For example, when a photon enters the imaging detection unit, it can interact with multiple pixels, generating signals from all the pixels it interacts with. For instance, the pixel with the primary interaction can provide a signal indicating that it received the maximum energy from the photon, and neighboring pixels may have lower energy values. However, it can be difficult to pinpoint exactly where the photon struck within the pixel region. Data loss from neighboring pixels, or even resolution within the pixel itself, reduces the resolution of the imaging unit. Lower resolution in the imaging unit can lead to reduced treatment efficiency. For example, patients may require further imaging, diagnoses may be missed, imaging times may be longer, costs may increase, and so on.

[0024] Therefore, embodiments provide a system and method for determining photonic interactions with a pixel array at the sub-pixelation level. In one embodiment, photonic interactions can be received within a photonic detector pixel array. The photonic pixel array may include multiple pixels. A photoelectron cloud can be generated. Using an electric field (E-field), the photoelectron cloud can drift on a detector or a CdZnTe (CZT) crystal. The photoelectron cloud can drift toward an electron sensor within the E-field. Along the drift path, electrostatic repulsion may cause photoelectron diffusion. The electrostatic repulsion may be due to photoelectrons having the same charge as other photoelectrons. Diffusion may be primarily perpendicular to the direction of motion of the photoelectron cloud. This diffusion may cause the photoelectron cloud to disperse before reaching the electron sensor region. The E-field may be between an anode and a cathode. The photoelectron cloud can be determined by the photonic detector pixel array. In one embodiment, the method or system can identify a subset of multiple pixels associated with photonic interactions. Each subset of the multiple pixels may correspond to a pixel activated by the photoelectron cloud. In one embodiment, the subset of multiple pixels may include a central pixel and multiple neighboring pixels. In one embodiment, the central pixel may be the pixel with the highest amplitude response to the photonic interaction. In one embodiment, the method or system can determine the characteristics of photon interactions based on the photoelectron cloud. These characteristics may include the timing, location, and energy of the interaction.

[0025] Such systems and methods offer a technological improvement to current imaging techniques. Instead of signals from both the cathode and anode of the detector, the embodiments described herein capture information from both the central anode pixel and adjacent anode pixels. Using these values, the system can identify subpixel resolution, thus providing a system and method that delivers higher-resolution images by being able to more accurately identify characteristics related to interactions without requiring potentially difficult-to-obtain cathode signals. The system can use signals from adjacent anodes, which can interpret the shared charge between the central pixel and adjacent pixels. Typically, these shared events may not be counted. It is possible to recombine this information and correct for characteristics related to interactions. By correcting for characteristics related to interactions, energy resolution can be improved. These improvements may be important for medical imaging, reducing patient imaging reagent dosages, and reducing examination / procedure times.

[0026] The illustrated exemplary embodiments will be best understood by referring to the accompanying drawings. The following description is intended only by way of example and only shows certain exemplary embodiments.

[0027] Pixelated detectors, gamma cameras, and / or pixelated arrays in various embodiments can be configured as part of different types of imaging systems, such as nuclear medicine (NM) imaging systems like positron emission tomography (PET) imaging systems, single-photon emission computed tomography (SPECT) imaging systems, and / or X-ray imaging systems, and X-ray computed tomography (CT) imaging systems, etc. The system can be fixed to an integrated gantry that further includes a rotor oriented about a central bore of the gantry. The rotor is configured to support one or more pixelated cameras, such as, but not limited to, gamma cameras, SPECT detectors, multi-slice pixelated cameras (e.g., Compton cameras), and / or PET detectors. It should be noted that when the medical imaging system includes a CT camera or an X-ray camera, the medical imaging system also includes an X-ray tube for emitting X-ray radiation to the detector. In various embodiments, as described in more detail herein, the camera is formed by a pixelated detector. The rotor is also configured to rotate axially about an examination axis. Operation and control of the imaging system can be performed in any manner known in the art. It should be noted that various embodiments can be implemented by combining imaging systems including rotating or fixed gantry systems.

[0028] In one embodiment, the imaging device can be mounted at a location used for security scanning. For example, the device could be at an airport security checkpoint, baggage handling area, etc. The device may include multiple X-ray sources and multiple pixelated photon detector arrays. In one embodiment, the imaging device may be permanently anchored, mobile, or entirely portable. For example, the imaging device could be a handheld device used by a first responder, security, or assessment team. Other uses beyond secure environments are contemplated and disclosed. As those skilled in the art will understand, healthcare imaging and security screening are merely examples. Other possible applications of the techniques described herein are also possible and contemplated.

[0029] In one embodiment, the receiving device may include sensors sensitive to radioactive particles or photons. The receiving device may record communication events (also referred to as interactions) on an array of sensors located within the receiving device. Each sensor in the array can be represented as a pixel in the final image. During imaging, photons or particles may strike one or more pixel detection units. In one embodiment, signals received from one or more pixel detection units can be used to determine the characteristics of the photon interactions. In a healthcare setting, this can allow healthcare professionals to achieve better imaging in less time and provide patients with less radioactive labeling, which can lead to better treatment planning and reduced healthcare costs, for example, by achieving better resolution and reducing the duration of the imaging process.

[0030] Embodiments of the imaging device can be in healthcare settings, security screenings, manufacturing processes, or any application where the imaging device can be used. For example, the imaging device can be a radiographic imaging device in which radioactive material (composed of particles or photons) passes through or is injected into and emitted from a patient. Another example could include an airport or port of entry for scanning radiation or other materials of interest for security purposes. Another example of the imaging device could be used by a first responder to determine the safety of environmental conditions and / or location. Other uses are contemplated and disclosed.

[0031] refer to Figure 1 At position 101, the embodiment can receive or capture photon interactions or interactions occurring within the photon detector pixel array. Photons can travel towards the cathode and enter the device from the cathode side of the cell (see...). Figure 2Receiving or capturing interactions can include receiving one or more signals from one or more pixel detection units indicating that an interaction has occurred with one or more pixel detection units. For readability, this discussion will refer to the photon as the object that causes the interaction and generates the signal. However, it should be understood that the object can include photons, light of any spectrum, radioactive particles, or any type of energy that the detection unit can detect. The photon detector pixel array can be one or more pixel detector units. The photon detector pixel array can be organized in any configuration (e.g., grid, brick pattern, scattering pattern, etc.). The photon detector pixel array can be oriented in a flat plane, a curved plane, etc. In other words, the photon detector pixel array can be arranged in a manner suitable for detecting interactions from the emission source, and can be different for different applications. For example, photons from the emission source can interact with one or more pixels on a photon pixel array that is part of an imaging unit in a medical environment.

[0032] At position 102, in one embodiment, the system or method can determine a photoelectron cloud generated by photon interactions. In one embodiment, the device may have a cathode and an anode (see example device configuration). Figure 2 Photons or photon interactions can enter the device at the cathode end. In one embodiment, the cathode or anode can be a single plane spanning the device or module. This plane can be flat or have curvature suitable for imaging applications. The cathode can be held at a negative high voltage and / or AC-coupled. The anode can have pixelated detection elements, be electrically grounded, and / or DC-coupled. In one embodiment, a CdZnTe (CZT) crystal or other type of semiconductor material is between the cathode and anode. For ease of readability, reference will be made to CZT crystals herein, but the described system is not limited thereto, as any type of semiconductor material or imaging material can be utilized and can be based on the application of the imaging device.

[0033] In one embodiment, photonic interaction with CZT or other semiconductor materials can generate or create electron clouds and hole clouds. As the electron cloud drifts toward the anode channel, its size may increase due to electrostatic repulsion. The initial creation of the photoelectron cloud can be represented by the quantity eγ ≈ Eγ / 4.64 eV. In one embodiment, the electron cloud can resist an electric field (E-field) drifting through the CZT crystal toward the anode and pixel detection array. The electron cloud can generate a negative charge signal toward one or more pixels and / or associated ASIC channels. One or more pixels can be connected to charge-sensitive preamplifiers and / or shaping amplifiers. When a charge is detected, the pixels and associated electronics can be triggered for data collection.

[0034] In embodiments with semiconductor detector materials, the photon detector pixel array may have metal electrodes deposited on the semiconductor detector crystal on both sides. The first side may include multiple pixels arranged in a grid pattern, also referred to as the pixelated side. This side may be coupled to a readout electronics capable of capturing signals from the pixelated side. In the case of CdZnTe or CdTe where the electron mobility is much greater than the hole mobility, the pixelated side may be the anode side of the array and provide an anode signal. In some configurations, this side may be connected to ground potential. In one embodiment, a second side of the detector pixel array may be substantially opposite to the first side; for example, in the case of a sheet-like detector, the first side may be the bottom side, and the second side may be the top side, typically the side from which gamma photons can incident on the detector. This second side of the detector pixel array may be a cathode and may be connected to a negative voltage bias.

[0035] In one embodiment, the center pixel, defined as the pixel receiving the maximum count, can receive a negative charge sensing signal. Conversely, neighboring pixels surrounding the center pixel can receive a positive charge sensing signal. Figure 2 The example shows the electron cloud on the left that has a greater impact on the central pixel. As an example, Figure 2 The illustration shows an example of charge induction measured by a center pixel and two adjacent pixels. The center pixel receives the largest pulse height or count (as shown by the solid line) and negative charge induction. Both adjacent pixels receive positive charge induction. For example, the left pixel has a higher amplitude and shorter delay compared to the right pixel. Such data can indicate that the center pixel receives the charge cloud closer to the left than the right. This is example data, and more complex scenarios are discussed herein. For example, the center pixel could have eight adjacent pixels surrounding it to further pinpoint the location of the induced charge.

[0036] At 103, in one embodiment, the method or system can identify a subset of multiple pixels associated with photon interactions. In one embodiment, pixels (see...) Figure 3 A pixel () refers to a discrete location on the surface of the imaging hardware, which may be only a subset of the imaging region. A subset of pixels can correspond to pixels activated by a photoelectron cloud. A subset of pixels can include a central pixel and multiple neighboring pixels. The central pixel can be defined as the pixel with the highest amplitude response or count to photon interactions. Data or communication from one or more pixels can be used to form an image synthesized from one or more pixels.

[0037] In one embodiment, the system and method can identify multiple pixels associated with an interaction with a photon. For example, when a photon interacts with a detector, one or more pixels generate a signal corresponding to that interaction. As an example, as a photon moves through an array of pixels, it interacts with different pixels. Each of these pixels then generates a signal indicating some form of interaction or contact. In one embodiment, a central pixel can be identified. This central pixel can be associated with the photon's "resting" location (e.g., the location of photoelectric interaction). In other words, the photon has stopped moving through the pixel array. One or more characteristics can be used to perform the identification of the central pixel. For example, the central pixel can be identified as the pixel with the highest energy detected based on a photon event. However, the central pixel may not necessarily represent the pixel with the highest energy detected by photon interaction. As an example, if two pixels share the same level of interaction, they can provide the same highest energy value. In this case, one pixel can simply be characterized as the central pixel.

[0038] In addition to the central pixel, the system can also identify one or more neighboring pixels. In one embodiment, the identified one or more neighboring pixels can be located in any physical position relative to the central pixel. In other words, neighboring pixels do not necessarily have to be direct neighbors of the central pixel or directly adjacent to the central pixel. Rather, one or more neighboring pixels can be identified as pixels that receive less energy from photons than those received by the central pixel. In other words, as a photon moves through the pixel array, it may interact with pixels other than the central pixel, for example, through Compton scattering. These pixels can be identified as neighboring pixels. One or more neighboring pixels can be in any type of configuration relative to the central pixel. For example, neighboring pixels can be in a “ring” or “box” configuration around the central pixel. As another example, one or more neighboring pixels can be located on one or more sides of the central pixel. As a final example, a neighboring pixel can be a single pixel adjacent to the central pixel. Each of the neighboring pixels can have a different signal relative to each other and / or the central pixel. In other words, each signal from a neighboring pixel can be the same, different, or a combination thereof relative to other neighboring pixels and / or the central pixel.

[0039] Imaging devices can use numerous methods to detect communication events from pixels. For example, in a consumer camera, a pixel represents the intensity and wavelength of visible light detected by that pixel. As another example, radiographic imaging devices, radiation detectors, etc., used in cancer screening utilize a type of atomic particle or photon emitted from a source and measurable by a sensor associated with circuitry to provide the location and intensity (or count density) of the detected radioactive particle or photon. Using communication events from pixels, an image can be created based on the location, intensity, energy, or wavelength of the communication events from the pixels. In other words, embodiments can create an image during imaging using signals transmitted from pixels based on information contained within the signals. Data can be collected from multiple pixels to create an image of a larger area.

[0040] refer to Figure 3 In one embodiment, each pixel can be divided into subpixels or subpixelated regions. In one embodiment, pixels can be labeled as a grid structure with rows and columns. For ease of illustration, a square pixel is shown; however, different geometries and interlocking shapes can be used. For row and column naming conventions, a column can be defined as i, and a row can be defined as j. For example, the center pixel can be given a position identifier of "i, j", the pixel to its left as "i-1, j", and the pixel above it as "i, j+1". Alternatively, columns and rows can be simply assigned numeric identifiers. For example, columns and rows can be identified by numerical order from left to right and from bottom to top.

[0041] For example, the center pixel can be the location of the interaction that indicates the 2D position where the photon is "resting". The center pixel is the pixel that provides the highest energy signal relative to the photon interaction. Adjacent pixels represent pixels that provide energy signals but whose energy signals are not as large as those of the center pixel. For example, the center pixel (also called the trigger pixel) can be defined as "i, j", the adjacent pixels to the left of the center pixel in the box or ring are "i-1, j", and the adjacent pixels above it are "i, j+1".

[0042] Pixels can be further subdivided or subpixelated. For example, a single pixel can be divided into 2×2 subpixelated regions (see [link to documentation]). Figure 3 For example, a processing method can be used to convert a regular 3×3 pixel region into a “virtual” 6×6 subpixelated region. For this particular example, a single pixel will have four subpixels within the pixel boundary. In other words, a single pixel can be divided into subpixelated regions of four areas. Other divisions are anticipated and disclosed; 2×2 subpixelation is an illustrative example. As another example, subpixelated regions with a factor of 3×3 or larger can be used. Subpixelation provides higher resolution with lower electrical noise and / or production costs.

[0043] At 104, in one embodiment, the system and method can determine the characteristics of photon interactions based on the photoelectron cloud. These characteristics may include time, location, energy, etc. In one embodiment, the method or system can receive a trigger signal as described above. For example, the system can receive a trigger at the center pixel, such as pixel (i, j). The system can then obtain negative energy or negative charge sensing for adjacent pixels (e.g., NE(i-1, j) and (i+1, j)). The system can perform a calibration step. The calibration can be represented by NE'(i, j) = (NE(i, j) - baseLineNoise(i, j)) * gain(i, j). Furthermore, a correction factor can be used. The correction may be under-range cut. The correction can be expressed as: (NE'(i+1, j) - NE'(i-1, j)) / (NE'(i-1, j) + NE'(i+1, j)). In an embodiment, a correction factor can be added to the trigger pixel (i, j).

[0044] refer to Figure 4 The example data illustrates sample data from the center pixel and two adjacent pixels. For example, at a peak count of 59.0 keV, the bottom adjacent pixel, center pixel, and top adjacent pixel are shown. The example data demonstrates the light peak data and pixel gaps. For example, the actual physical gap between pixels can be 75 μm. The example data shows apparent gaps up to ~200 μm, likely due to the dominant role of charge sharing when the photon beam illuminates the region between the gaps. In some cases, most electron clouds split into two (and thus registered to two or more pixels), each with significantly lower energy. Such signals are not collected because the y-axis is a peak count from a specific energy window. The width of the pixel gap can be determined using an X-ray tube source for high-throughput cleaning of the desired spectrum and a moving fixture for moving the pixel array along the x, y, and z axes. For example, the X-ray tube can be fixed, and the detector system can be moved in small increments (e.g., 20 μm–40 μm). Alternatively, a static detector system can be used to move the X-rays. This method can be used to apply subpixelation techniques to the final data to examine the accuracy or fine-tune the method. (Reference) Figure 5 In one embodiment, the system and method may use a 2×2 subpixelation technique. Figure 5This is an example embodiment of statistically significant 2×2 subpixelation. For instance, if photons and the resulting photon cloud appear on the side closer to the center pixel, the system and method can identify the location with sub-millimeter accuracy. The technique can also be used in conjunction with a collimator and a photon source to achieve this level of resolution and accuracy. In the example shown, the photon source is moving across the array along the direction from row 33 to row 34. For each pixel using the 2×2 subpixelation technique, a count can be drawn at a certain distance. In this example, the peak count is at 59.0 keV. However, other peak counts, such as 67.2 keV, can be used.

[0045] refer to Figure 6 This technique allows the amount of induced charge to be plotted over a certain distance (measured in μm). In this example, the center pixel is located at the center of the graph, and data from eight adjacent pixels are shown. The trigger pixel (center pixel) is labeled #126. The center pixel receives the largest signal from the photon cloud. Referring to pixel #127, there is more induced charge compared to pixel #125, indicating that the photon interaction occurs closer to #127 compared to #125. This technique allows for better spatial resolution of the hardware on the pixel array.

[0046] In one embodiment, the system or method can identify whether the characteristics of an interaction can be determined. The system can determine many different characteristics for an interaction, such as time, location (potentially including depth), energy, intensity, etc. To determine a characteristic, the system can receive signals from one or more pixels (e.g., a center pixel and neighboring pixels). For example, a photon may not enter the detector pixel array at a right angle. Therefore, as a photon travels through the detector, it can interact with more than one pixel. In other words, as a photon enters the detector pixel plane, the interaction can “share” characteristics (i.e., energy) with one or more neighboring pixels. Different characteristics can be determined not only using signals received from the center pixel but also using signals received from neighboring pixels. The system can use these signals to directly identify the characteristics or attribute these signals to signals from other pixels. The system can determine one or more characteristics simultaneously or at different times.

[0047] In one embodiment, the determined characteristics may include the depth of the interaction. In one embodiment, the depth of the interaction can be determined by first identifying a multidimensional space comprising two or more dimensions, including peak signal amplitude responses along multiple axes: 1) the positive polarity of the center pixel, 2) the positive polarity of neighboring pixels, and optionally, 3) the negative polarity of neighboring pixels. The next step is to identify one or more clusters within this multidimensional space, which represent one or more mechanisms of inter-pixel charge sharing or hole trapping that depend on the depth.

[0048] Each of these pixel signals and subpixelated signals can also have an associated amplitude, which represents, for example, the interaction energy of the signals. Therefore, the signals from the pixels can include signals with peak amplitudes of both positive and negative polarity signals. Using these signals from the center pixel and neighboring pixels, the system can determine the timing, location, energy, and depth of the interaction, for example, by clustering these signals in a multidimensional space. As described above, the system and method described herein capture only the peak amplitude signal from the anode portion of the detector. Therefore, by analyzing and correlating the peak amplitudes of the positive and negative polarity signals from all pixels (e.g., the center pixel and neighboring pixels), the system can determine at what depth the interaction occurred. Thus, the system can determine location characteristics, including the depth of the interaction.

[0049] In addition to the signal from the center pixel, the system can also use signals from one or more neighboring pixels to determine other characteristics. For example, using signals from one or more neighboring pixels in addition to the signal from the center pixel can allow for better resolution of characteristics such as time, position, and energy. The determination of some of these characteristics can be accomplished using conventional techniques, except by considering the signals from neighboring pixels together with the signal from the center pixel (which provides a more precise or accurate determination of the characteristics).

[0050] For example, the system can determine the position of an interaction relative to a two-dimensional location with greater precision than conventional systems and methods. For instance, the interaction of a photon with neighboring pixels can be tailored to the photon's position at sub-pixel resolution, rather than just pixel resolution. As an example, see [reference]. Figure 2Relative to an imaginary center line of a pixel, the interaction occurs to the left of the central pixel. Using information from neighboring pixels, the system can identify that the interaction occurs to the left of the central pixel, rather than simply at the central pixel. For example, by identifying signals from neighboring pixels, the system can determine which neighboring pixels have higher signals compared to other neighboring pixels. Since pixels closer to the interacting pixel will have higher signals, if the interaction occurs off-center, neighboring pixels closer to the interacting pixel will provide higher signals compared to pixels farther away from the interacting pixel. Therefore, by identifying which pixels have higher signals, the system can determine on which side of the pixel the interaction occurred.

[0051] For example, the system can use a weighted average to identify sub-pixel location information. As an illustrative example, if the detector pixel array receives photon interactions, with one neighboring pixel receiving 2 / 3 of the interactions occurring outside the center pixel and another neighboring pixel receiving 1 / 3 of the interactions outside the center pixel, the system can determine the location of the event along the center line of the two pixels by weighting these two interactions along the center pixel. In other words, the interaction may not fall at the center of the pixel region, and neighboring pixels allow for a more precise determination of the interacting photon's location.

[0052] As another example of more accurate or precise characteristic determination, the system can determine a more precise energy of the interaction. When a photon interacts with a pixel, neighboring pixels may receive a portion of the interaction. This is called shared charge. Therefore, the system can attribute the charge received by neighboring pixels to the center pixel to provide a more accurate representation of the actual energy of the interaction. To provide this more accurate representation, the system can correct the energy value received from the center pixel. This correction can include adding the shared charge of one or more neighboring pixels to the response of the center pixel. In other words, if the pixel array detects the interaction of a photon, the charge detected by neighboring pixels can be added to the charge value of the center pixel. As an example, if a photon interacts with a detector pixel array, and 80% of the charge is received at the center pixel and 20% of the charge is received at neighboring pixels, then the 20% charge of the neighboring pixels can be allocated to the center pixel.

[0053] If one or more properties cannot be determined for an interaction at point 104, the system can ignore the interaction and receive information related to the new interaction at point 101. Conversely, if the system can determine one or more properties at point 104, the system can record data related to the interaction at point 105. The recorded data can be analyzed in real time or saved for later analysis. Furthermore, the recorded data can be used by a system as described herein to generate one or more images of the object being scanned using an imaging device.

[0054] Therefore, the various embodiments described herein represent technological improvements to imaging devices that may require high sensitivity and resolution to the material being imaged. One embodiment allows for the use of subpixelation to determine the characteristics of photon interactions. Using the techniques described herein, more complete images can be obtained with shorter imaging durations and / or lower radiation doses, eliminating the need for longer imaging processes and / or higher radiation doses. Such systems achieve more accurate imaging, less equipment downtime, and lower costs associated with the imaging process.

[0055] Although any of the various embodiments described herein pertains to an instrument for determining the characteristics of the electron cloud on a subset of pixels, various other circuits, circuit systems, or components may be used in information processing devices. Figure 7 An example is shown. Device circuitry 10' may include a measurement system on a chip design fabric (e.g., a specific computing platform, such as mobile computing, desktop computing, etc.). Software and processor are combined in a single chip 11'. As is known in the art, the processor includes an internal arithmetic unit, registers, cache memory, buses, I / O ports, etc. Internal buses, etc., vary depending on the vendor, but essentially all peripherals (12') can be attached to a single chip 11'. Circuitry 10' combines the processor, memory control, and I / O controller hub all into a single chip 11'. Similarly, this type of system 10' typically does not use SATA, PCI, or LPC. Common interfaces include SDIO and I2C, for example.

[0056] A power management chip 13', such as a battery management unit (BMU), is present, which manages power supplied, for example, via a rechargeable battery 14', which can be charged by connection to a power source (not shown). In at least one design, a single chip (e.g., 11') is used to provide functions such as BIOS and DRAM memory.

[0057] System 10' typically includes one or more of a WWAN transceiver 15' and a WLAN transceiver 16' for connecting to various networks, such as telecommunications networks and wireless internet devices (e.g., access points). Additionally, device 12' typically includes, for example, transmit and receive antennas, oscillators, PLLs, etc. System 10' includes input / output devices 17' for data input and display / rendering (e.g., computing locations located away from single-beam systems that are easily accessible to users). System 10' also typically includes various storage devices, such as flash memory 18' and SDRAM 19'.

[0058] As can be understood from the foregoing, the electronic components of one or more systems or devices may include, but are not limited to, at least one processing unit, memory, and a communication bus or communication device coupling the various components (including memory) to the processing unit. The system or device may include or have access to various device-readable media. System memory may include device-readable storage media in the form of volatile and / or non-volatile memory, such as read-only memory (ROM) and / or random access memory (RAM). By way of example and not limitation, system memory may also include an operating system, application programs, other program modules, and program data. The disclosed system may be used in embodiments of instruments used to determine the characteristics of an electron cloud over a subset of pixels.

[0059] As those skilled in the art will understand, the aspects may be embodied as a system, method, or device program product. Therefore, the aspects may take the form of a completely hardware embodiment or an embodiment including software, which may generally be referred to herein as a “circuit,” “module,” or “system.” Furthermore, the aspects may take the form of a device program product embodied in one or more device-readable media having device-readable program code embodied therewith.

[0060] As those skilled in the art will understand, the aspects may be embodied as a system, method, or device program product. Therefore, the aspects may take the form of a completely hardware embodiment or an embodiment including software, which may generally be referred to herein as a “circuit,” “module,” or “system.” Furthermore, the aspects may take the form of a device program product embodied in one or more device-readable media having device-readable program code embodied therewith.

[0061] It should be noted that the various functions described herein can be implemented using instructions stored on a device-readable storage medium, such as a non-signal storage device, wherein the instructions are executed by a processor. In the context of this document, a storage device is not a signal, and "non-transitory" includes all media other than signal media.

[0062] The program code used to perform the operation can be written in any combination of one or more programming languages. The program code can execute entirely on a single device, partially on a single device, as a standalone software package, partially on a single device and partially on another device, or entirely on other devices. In some cases, the device can be connected via any type of connection or network (including a local area network (LAN) or a wide area network (WAN)), or via other devices (e.g., via the Internet through an Internet service provider), via wireless connections (e.g., near-field communication), or via hard-wired connections (e.g., via USB).

[0063] It should be noted that the various functions described herein can be implemented using instructions stored on a device-readable storage medium, such as a non-signal storage device, and executed by a processor. A storage device can be, for example, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or any suitable combination thereof. More specific examples of storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable optical disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In the context of this document, a storage device is not a signal, and "non-transitory" includes all media other than signal media.

[0064] The program code embodied on the storage medium can be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, RF, or any suitable combination thereof.

[0065] The program code used to perform the operation can be written in any combination of one or more programming languages. The program code can execute entirely on a single device, partially on a single device, as a standalone software package, partially on a single device and partially on another device, or entirely on another device. In some cases, the device can be connected via any type of connection or network (including a local area network (LAN) or a wide area network (WAN)), or via other devices (e.g., via the internet through an internet service provider), via wireless connections (e.g., near-field communication), or via hard-wired connections (e.g., via USB).

[0066] This document describes exemplary embodiments with reference to the accompanying drawings, which illustrate exemplary methods, apparatuses, and program products according to various exemplary embodiments. It will be understood that actions and functions can be implemented at least in part by program instructions. These program instructions can be provided to a processor of a device, a special-purpose information processing device, or other programmable data processing device to create a machine, such that the instructions, which execute via the processor of the device, perform the specified function / action.

[0067] Note that the values ​​provided herein should be interpreted to include equivalent values ​​indicated by the use of the term "about". Equivalent values ​​will be apparent to those skilled in the art, but at least include values ​​obtained by ordinary rounding to the last significant digit.

[0068] It is important to note that although specific boxes are used in the accompanying drawings and a particular order of the boxes has been shown, these are non-limiting examples. In some cases, two or more boxes may be combined, a box may be split into two or more boxes, or certain boxes may be appropriately reordered or reorganized, because the explicitly illustrated examples are for descriptive purposes only and should not be construed as restrictive.

[0069] As used herein, the singular "one" and "a" can be interpreted to include the plural "one or more" unless otherwise clearly indicated.

[0070] This disclosure has been presented for purposes of illustration and description, but it is not intended to be exhaustive or limiting. Many modifications and variations will be apparent to those skilled in the art. Example embodiments have been chosen and described to explain the principles and practical applications, and to enable others skilled in the art to understand the disclosure of various embodiments with various modifications suitable for the intended particular purpose.

[0071] Therefore, although illustrative exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the description is not limiting and that various other changes and modifications can be made therein by those skilled in the art without departing from the scope or spirit of this disclosure.

Claims

1. An imaging method, comprising: Receive photon interactions occurring within a photon detector pixel array, wherein the photon detector pixel array comprises a plurality of pixels; A photoelectron cloud generated by the photon interaction is determined, wherein the photon detector pixel array includes an electric field, wherein electrostatic repulsion forces disperse photons into the photoelectron cloud; Identify subsets of the plurality of pixels associated with the photon interaction, wherein each subset of the plurality of pixels corresponds to a pixel activated by the photoelectron cloud, wherein the subset of the plurality of pixels includes a central pixel and a plurality of neighboring pixels, wherein the central pixel includes the pixel having the highest amplitude response to the photon interaction; and The characteristics of the photon interaction are determined based on the photoelectron cloud, wherein the characteristics include at least one of the following: the time, location, and energy of the photon interaction. The determination includes adding a correction factor to the response of the center pixel to improve energy resolution and compensate for charge sharing and hole trapping. The correction factor is determined based on the ratio of the negative energy or negative charge induction of each of the plurality of neighboring pixels to that of the center pixel. The determination utilizes the positive peak amplitude and negative peak amplitude of the anode pixel signal.

2. The imaging method according to claim 1, wherein the photon detector array includes an anode and a cathode that generate electrostatic repulsion within the photons.

3. The imaging method according to claim 1, wherein the central pixel receives negative charge current sensing.

4. The imaging method according to claim 1, wherein each of the plurality of adjacent pixels receives positive charge current sensing.

5. The imaging method according to claim 4, wherein the positive charge current sensing is proportional to the sub-integration ratio of the photoelectron cloud.

6. The imaging method according to claim 1, wherein the characteristic includes the location of the photon interaction, wherein determining the location of the photon interaction includes: Compare the pulse heights from at least two adjacent pixels.

7. The imaging method of claim 1, wherein the characteristic includes the intensity of the photon interaction, wherein the intensity is based on the summation of the responses to the center pixel and the plurality of neighboring pixels.

8. The imaging method according to claim 1, wherein the characteristic includes the location of the photon interaction, wherein determining the location of the photon interaction includes: Compare the time delays from at least two adjacent pixels.

9. The imaging method of claim 1, wherein a plurality of responses do not correspond to responses from the cathode of the photon detector pixel array.

10. The imaging method according to claim 1, wherein the photon detector pixel array comprises a pixelated semiconductor detector array, and the pixelated semiconductor detector comprises CdZnTe.

11. An imaging device, comprising: A photon detector pixel array, comprising multiple pixels; A processor is operatively coupled to the photon detector pixel array; Storage device, storage instructions, said instructions executed by said processor to: Receives photon interactions occurring within the pixel array of the photon detector; Determine the photoelectron cloud generated by the photon interaction, wherein the photon detector pixel array includes an electric field, wherein electrostatic repulsion forces disperse photons into the photoelectron cloud; Identify subsets of the plurality of pixels associated with the photon interaction, wherein each subset of the plurality of pixels corresponds to a pixel activated by the photoelectron cloud, wherein the subset of the plurality of pixels includes a central pixel and a plurality of neighboring pixels, wherein the central pixel includes the pixel having the highest amplitude response to the photon interaction; and The characteristics of the photon interaction are determined based on the photoelectron cloud, wherein the characteristics include at least one of the following: the time, location, and energy of the photon interaction. The determination includes adding a correction factor to the response of the center pixel to improve energy resolution and compensate for charge sharing and hole trapping. The correction factor is determined based on the ratio of the negative energy or negative charge induction of each of the plurality of neighboring pixels to that of the center pixel. The determination utilizes the positive peak amplitude and negative peak amplitude of the anode pixel signal.

12. The imaging apparatus of claim 11, wherein the photon detector array includes an anode and a cathode that generate electrostatic repulsion within the photons.

13. The imaging apparatus of claim 11, wherein the central pixel receives a negative charge current sensing.

14. The imaging apparatus of claim 11, wherein each of the plurality of adjacent pixels receives a positive charge current sensing.

15. The imaging apparatus of claim 14, wherein the positive charge current sensing is sub-integrated with the photoelectron cloud.

16. The imaging apparatus of claim 11, wherein the characteristic includes the location of the photon interaction, wherein determining the location of the photon interaction includes: Compare the pulse heights from at least two adjacent pixels.

17. The imaging apparatus of claim 11, wherein the characteristic includes the intensity of the photon interaction, wherein the intensity is based on the summation of the responses to the center pixel and the plurality of neighboring pixels.

18. The imaging apparatus of claim 11, wherein the characteristic includes the location of the photon interaction, wherein determining the location of the photon interaction includes: Compare the time delays from at least two adjacent pixels.

19. The imaging apparatus of claim 11, wherein a plurality of responses do not correspond to responses from the cathode of the photon detector pixel array.

20. An imaging product, comprising: A storage device for storing code, which is executed by a processor, and includes: Receives code for photon interactions occurring within a photon detector pixel array, wherein the photon detector pixel array comprises a plurality of pixels; The code for determining the photoelectron cloud generated by the photon interaction, wherein the photon detector pixel array includes an electric field, wherein electrostatic repulsion forces disperse photons into the photoelectron cloud; A code that identifies a subset of the plurality of pixels associated with the photon interaction, wherein each subset of the plurality of pixels corresponds to a pixel activated by the photoelectron cloud, wherein the subset of the plurality of pixels includes a central pixel and a plurality of neighboring pixels, wherein the central pixel includes the pixel having the highest amplitude response to the photon interaction; and A code that determines the characteristics of the photon interaction based on the photoelectron cloud, wherein the characteristics include at least one of the following: the time, location, and energy of the photon interaction. The determination includes adding a correction factor to the response of the center pixel to improve energy resolution and compensate for charge sharing and hole trapping. The correction factor is determined based on the ratio of the negative energy or negative charge induction of each of the plurality of neighboring pixels to that of the center pixel. The determination utilizes the positive peak amplitude and negative peak amplitude of the anode pixel signal.

Images