阅读说明：本技术 用于确定交互作用深度的系统和方法 (System and method for determining depth of interaction ) 是由 阿里·沙哈尔 亚龙·格雷泽 莫什·科恩-埃尔纳 阿维沙伊·奥凡 于 2019-08-13 设计创作，主要内容包括：本发明题为“用于确定交互作用深度的系统和方法”。本发明提供了一种检测器组件,其包括半导体检测器、多个像素化阳极和至少一个处理器。所述多个像素化阳极设置在所述半导体检测器的表面上。每个像素化阳极被配置成响应于接收到光子而生成主信号,并且响应于由至少一个周围阳极接收到光子引起的感应电荷而生成至少一个辅信号。所述至少一个处理器可操作地耦接到所述像素化阳极并且被配置成响应于接收到光子而从所述阳极中的一个获取主信号；从至少一个相邻像素获取至少一个辅信号；以及使用所述至少一个辅信号确定用于所述阳极中的所述一个对所述光子的所述接收的所述半导体检测器中的交互作用深度。(The invention provides a system and method for determining depth of interaction. A detector assembly includes a semiconductor detector, a plurality of pixelated anodes, and at least one processor. The plurality of pixelated anodes is disposed on a surface of the semiconductor detector. Each pixelated anode is configured to generate a primary signal in response to receiving photons and to generate at least one secondary signal in response to induced charge resulting from the receipt of photons by at least one surrounding anode. The at least one processor is operably coupled to the pixelated anodes and configured to acquire a primary signal from one of the anodes in response to receiving a photon; acquiring at least one auxiliary signal from at least one neighboring pixel; and determining a depth of interaction in the semiconductor detector for the reception of the photons by the one of the anodes using the at least one secondary signal.)

1. A radiation detector assembly comprising:

a semiconductor detector having a surface;

a plurality of pixelated anodes disposed on the surface, each pixelated anode configured to generate a primary signal in response to the pixelated anode receiving photons and to generate at least one secondary signal in response to induced charge resulting from the reception of photons by at least one surrounding anode; and

at least one processor operably coupled to the pixelated anode, the at least one processor configured to:

in response to one of the anodes receiving a photon, obtaining a primary signal from the one of the anodes;

acquiring at least one secondary signal from at least one neighboring pixel of said one of said anodes in response to an induced charge caused by said one of said anodes receiving said photons; and

determining, using the at least one secondary signal, a depth of interaction in the semiconductor detector for the reception of the photons by the one of the anodes.

2. The detector assembly of claim 1, wherein the at least one processor is configured to adjust an energy level for an event corresponding to the one of the anodes receiving the photon based on the depth of interaction.

3. The detector assembly of claim 1, wherein the at least one processor is configured to reconstruct an image using the depth of interaction.

4. The detector assembly of claim 1, wherein the at least one neighboring pixel comprises at least one neighboring anode.

5. The detector assembly of claim 1, wherein the at least one processor is configured to determine the depth of interaction using calibration information.

6. The detector assembly of claim 5, wherein the at least one processor is configured to determine the depth of interaction using a calibration based on a ratio between negative values of a single secondary signal and an amplitude of the primary signal.

7. The detector assembly of claim 5, wherein the at least one processor is configured to determine the depth of interaction using a calibration based on a ratio between a sum of negative values of a plurality of secondary signals and an amplitude of the primary signal.

8. The detector assembly of claim 1, wherein the at least one processor is configured to determine the depth of interaction without using any information from a cathode of the detector assembly.

9. The detector assembly of claim 1, wherein the at least one processor is configured to determine sub-pixel locations using the primary signal and the at least one secondary signal.

10. A method of imaging using a semiconductor detector having a surface with a plurality of pixelated anodes disposed thereon, wherein each pixelated anode is configured to generate a primary signal in response to the pixelated anode receiving photons and to generate at least one secondary signal in response to induced charge resulting from the receipt of photons by at least one surrounding anode, the method comprising:

in response to one of the anodes receiving a photon, obtaining a primary signal from the one of the anodes;

acquiring at least one secondary signal from at least one neighboring pixel of said one of said anodes in response to an induced charge caused by said one of said anodes receiving said photons; and

determining, using the at least one secondary signal, a depth of interaction in the semiconductor detector for the reception of the photons by the one of the anodes.

11. The method of claim 10, further comprising adjusting an energy level for an event corresponding to the one of the anodes receiving the photons based on the depth of interaction.

12. The method of claim 10, further comprising reconstructing an image using the depth of interaction.

13. The method of claim 10, wherein the at least one neighboring pixel comprises at least one neighboring anode.

14. The method of claim 10, further comprising using calibration information to determine the depth of interaction.

15. The method of claim 14, further comprising determining the depth of interaction using a calibration based on a ratio between negative values of a single secondary signal and an amplitude of the primary signal.

16. The method of claim 14, further comprising determining the depth of interaction using a calibration based on a ratio between a sum of negative values of a plurality of secondary signals and an amplitude of the primary signal.

17. The method of claim 10, further comprising determining the depth of interaction without using any information from a cathode of the detector assembly.

18. The method of claim 10, further comprising determining a sub-pixel location using the primary signal and the at least one secondary signal.

19. A method of providing a radiation detector assembly, comprising:

providing a semiconductor detector having a surface with a plurality of pixelated anodes disposed thereon, each pixelated anode configured to generate a primary signal in response to the pixelated anode receiving a photon and to generate at least one secondary signal in response to induced charge resulting from the receipt of a photon by at least one adjacent anode;

operably coupling the pixelated anode to at least one processor;

providing a calibrated supply of radiation at different depths along a sidewall of the semiconductor detector, wherein the pixelated anode generates primary and secondary signals in response to the calibrated supply of radiation;

obtaining, with the at least one processor, the primary signal and the secondary signal from the pixelated anode;

determining a corresponding negative value of total induced charge for each of the different depths;

determining calibration information based on the negative value of the total induced charge for each of the different depths.

20. The method of claim 19, further comprising passing the collimated supply of radiation through a pinhole collimator to the sidewalls of the semiconductor detector.

Background

The subject matter disclosed herein relates generally to apparatus and methods for diagnostic medical imaging, such as Nuclear Medicine (NM) imaging.

In NM imaging, for example, a system having multiple detectors or detector heads may be used to image a subject, such as for scanning a region of interest. For example, a detector may be positioned adjacent to a subject to acquire NM data, which is used to generate a three-dimensional (3D) image of the subject.

The imaging detector may be used to detect the reception of photons from a subject (e.g., a human patient that has been administered a radiotracer) by the imaging detector. The depth of interaction (DOI) or location along the thickness of the detector at which photons are detected can affect the strength of the signal generated by the detector in response to the photons and is used to determine the number and location of detected events. Thus, DOI can be used to correct the detector signal to improve detector energy resolution and sensitivity. However, conventional methods for determining DOI utilize signals from the cathode, requiring additional hardware and component complexity to collect and process the cathode signals using hardware. In addition, the cathode tends to be relatively large and produces a relatively noisy signal, reducing the accuracy and effectiveness of using the signal from the cathode.

Disclosure of Invention

In one embodiment, a radiation detector assembly is provided that includes a semiconductor detector, a plurality of pixelated anodes, and at least one processor. The semiconductor detector has a surface. The plurality of pixelated anodes is disposed on the surface. Each pixelated anode is configured to generate a primary signal in response to the pixelated anode receiving photons and to generate at least one secondary signal in response to induced charge resulting from the reception of photons by at least one surrounding anode. The at least one processor is operably coupled to the pixelated anodes and configured to acquire a primary signal from one of the anodes in response to the one of the anodes receiving a photon; acquiring at least one auxiliary signal from at least one neighboring pixel of one of the anodes in response to an induced charge caused by the reception of a photon by the one of the anodes; and determining a depth of interaction in the semiconductor detector for reception of photons by one of the anodes using the at least one secondary signal.

In another embodiment, a method of imaging using a semiconductor detector is provided. The semiconductor detector has a surface on which a plurality of pixelated anodes are disposed. Each pixelated anode is configured to generate a primary signal in response to the pixelated anode receiving photons and to generate at least one secondary signal in response to induced charge resulting from the reception of photons by at least one surrounding anode. The method includes acquiring a primary signal from one of the anodes in response to the one of the anodes receiving a photon, and acquiring at least one secondary signal from at least one neighboring pixel of the one of the anodes in response to an induced charge caused by the one of the anodes receiving the photon. The method also includes determining a depth of interaction in the semiconductor detector for reception of photons by one of the anodes using the at least one secondary signal.

In another embodiment, a method includes providing a semiconductor detector having a surface with a plurality of pixelated anodes disposed thereon. Each pixelated anode is configured to generate a primary signal in response to the pixelated anode receiving a photon and to generate at least one secondary signal in response to induced charge resulting from the receipt of a photon by at least one adjacent anode. The method also includes operatively coupling the pixelated anode to at least one processor. In addition, the method includes providing a calibrated supply of radiation at different depths along a sidewall of the semiconductor detector, wherein the pixelated anode generates primary and secondary signals in response to the calibrated supply of radiation. Additionally, the method includes acquiring, with the at least one processor, a primary signal and a secondary signal from the pixelated anode. The method also includes determining a corresponding negative value of the total induced charge for each of the different depths, and determining calibration information based on the negative value of the total induced charge for each of the different depths.

Drawings

Fig. 1 depicts a representation of weighted potentials of a detector having pixels biased by voltage potentials.

Fig. 2 depicts four events within the detector of fig. 1.

Fig. 3 depicts the corresponding induced charges for the four events of fig. 2.

Fig. 4 depicts five sets of events under a primary or collection pixel at five different DOIs.

FIG. 5 depicts Z located in FIG. 4₀The resulting non-collected or secondary signal of the event(s).

FIG. 6 depicts Z located in FIG. 4₁The resulting non-collected or secondary signal of the event(s).

FIG. 7 depicts Z located in FIG. 4₂The resulting non-collected or secondary signal of the event(s).

FIG. 8 depicts Z located in FIG. 4₃The resulting non-collected or secondary signal of the event(s).

FIG. 9 depicts Z located in FIG. 4₄The resulting non-collected or secondary signal of the event(s).

Fig. 10 depicts a calibration system according to various embodiments.

Fig. 11 provides a schematic illustration of a radiation detector assembly according to various embodiments.

Fig. 12 provides a flow diagram of a method according to various embodiments.

Fig. 13 provides a flow diagram of a method according to various embodiments.

Fig. 14 provides a schematic illustration of an imaging system according to various embodiments.

Fig. 15 provides a schematic illustration of an imaging system according to various embodiments.

Detailed Description

The following detailed description of certain embodiments will be better understood when read in conjunction with the appended drawings. To the extent that the figures illustrate diagrams of the functional blocks of various embodiments, the functional blocks are not necessarily indicative of the division between hardware circuitry. For example, one or more of the functional blocks (e.g., processors or memories) may be implemented in a single piece of hardware (e.g., a general purpose signal processor or a block of random access memory, hard disk, or the like) or multiple pieces of hardware. Similarly, the programs may be stand alone programs, may be incorporated as subroutines in an operating system, may be functions in an installed software package, and the like. It should be understood that the various embodiments are not limited to the arrangements and instrumentality shown in the drawings.

As used herein, the terms "system," "unit," or "module" may include a hardware and/or software system that operates to perform one or more functions. For example, a module, unit or system may include a computer processor, controller or other logic-based device that performs operations based on instructions stored on a tangible and non-transitory computer-readable storage medium (such as a computer memory). Alternatively, a module, unit or system may comprise a hardwired device that performs operations based on hardwired logic of the device. The various modules or units illustrated in the figures may represent hardware that operates based on software or hardwired instructions, software that instructs the hardware to perform operations, or a combination thereof.

A "system," "unit" or "module" may include or represent hardware and associated instructions (e.g., software stored on a tangible and non-transitory computer-readable storage medium such as a computer hard drive, ROM, RAM, etc.) to perform one or more operations described herein. Hardware may include electronic circuitry that includes and/or is connected to one or more logic-based devices, such as microprocessors, processors, controllers, and the like. These devices may be off-the-shelf devices that are suitably programmed or instructed to perform the operations described herein in accordance with the instructions described above. Additionally or alternatively, one or more of the devices may be hardwired with logic circuitry to perform these operations.

As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural said elements or steps, unless such exclusion is explicitly recited. Furthermore, references to "one embodiment" are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments "comprising" or "having" an element or a plurality of elements having a particular property may include additional elements not having that property.

Various embodiments provide systems and methods for improving the sensitivity and/or energy resolution of image acquisition, for example in Nuclear Medicine (NM) imaging applications. In various implementations, measurements of non-collected (or sensed) adjacent transient signals are utilized to determine the depth of interaction (DOI) of a corresponding event in a detector. It may be noted that the same measurements of non-collected neighboring transient signals may also be used to determine the corresponding sub-pixel locations of the event.

In general, various embodiments provide methods and/or systems for measuring negative values of sensing signals and deriving or determining corresponding DOIs based on the negative values. For certain values of DOI (e.g., DOI is not located near the anode), all events with the same DOI yield approximately the same negative value for the non-collected induced signal regardless of their lateral position (where lateral position is defined as the x, y coordinate of the DOI measured along the z-axis). Thus, various embodiments use measurements of the sense signals (e.g., measured negative values of non-collected sense signals, which may also be used for sub-pixel position determination) to derive or determine DOI, as well as to provide 3D localization of events that result in non-collected sense signals.

Technical effects provided by various embodiments include increased sensitivity and/or energy resolution of detector systems, such as NM imaging detector systems. Technical effects of various embodiments include improved image quality. Technical effects of various embodiments include reducing processing and/or hardware complexity associated with determining DOI by eliminating the use of signals from the cathode.

Before addressing certain aspects of certain embodiments, certain aspects of detector operation are discussed. Fig. 1 depicts a representation 10 of the weighted potential of a detector 11 having a pixelated anode 12 biased by a 1 volt potential. The adjacent pixelated anode 13 is not biased or is at ground potential of 0 volts. It may be noted that for clarity of illustration and ease of description, a description of a given pixelated anode at voltage is provided, while adjacent pixelated anodes are not biased in connection with the various examples herein; however, in practice, each pixelated anode of the detector may be biased by a similar voltage. In the example shown in fig. 1, the cathode 14 is grounded at 0 volts. The solid lines 15 represent electric field lines and the dashed lines 16 represent equipotential lines. The equipotential lines are perpendicular to the electric field lines at the line intersections.

The weighted potentials of FIG. 1 are described according to the Shockley-Ramo theorem. Under this theorem, the induced current generated by the weighted potential is described by i ═ qE × V × cos (a), where i is the induced current, q is the electron charge, E × V is the scalar product between the electric field E of the weighted potential and the velocity V of the electrons, and a is the angle between vectors E and V.

Fig. 2 and 3 depict events occurring in various locations of the detector 11 and the induced charge resulting therefrom. Fig. 2 depicts four events within the detector 11 of fig. 1, and fig. 3 depicts the corresponding induced charges.

FIG. 2 depicts four events-from Z₀Event 21 starting from depth, from Z₁Event 22 starting at depth, from Z₂Event 23 starting at depth and from Z₃Event 24 of the beginning of the depth. Each event edge starts at X₁And terminates in a trajectory movement of the anode of the main or collection pixel 25 (anode of the collection event). The non-collected induced charge on the adjacent pixel (or non-collecting pixel, in this case pixel 12, in the example shown immediately adjacent collecting pixel 25) is the integral of the current over time (or over distance) given by the above relationship (i qE V qE cos (a)). E is the field that does not collect the weighted potentials of the neighboring pixels (pixel 12 in this example). Two ranges are shown for the depth D of the detector-a first range I and a second range II.

In range I, the vector of the field has a component pointing downwards. Thus, the induced charge is over range IIs positive. Over range II, the vector of the field has an upwardly directed component. Thus, the induced charge is negative over range II. Depth Z₀The event 21 starts at the cathode 14 and the relevant charge therefore propagates over the entire length of the ranges I and II. Other events start at the cathode and thus the associated charge does not propagate over the entire depth of range I. In addition, the depth Z₃The event 24 at (a) starts within the boundary of range II, closer to the pixelated anode than the boundary of range II. Thus, with the depth Z₃The charge associated with event 24 does not propagate over the entire depth of range II.

Fig. 3 depicts the resulting signals corresponding to the events of fig. 2. That is, the signal 32 depicts the collection signal or main signal that results in the collection pixel 25. Signal 34 depicts a start from Z₀Event 21, signal 35 depicts a non-collected signal from the pixelated anode 12 starting at Z₁Event 22, signal 36 depicts the non-collected signal from the pixelated anode 12 starting at Z₂Event 23, and signal 37 depicts a non-collected signal from the pixelated anode 12 starting at Z₃Event 24 results in a non-collected signal of the pixelated anode 12.

As shown in FIG. 3, the pair starts at Z₀The total induced charge in ranges I and II is zero because the positive induced charge in range I and the negative induced charge in range II are equal and cancel each other out over the entire depth (e.g., at the anode at Z ═ D, where D is the thickness of the detector 11).

For starting from Z₁Is negative because the charge from event 22 does not traverse the entire depth of range I, so the positive induced charge in range I is less than the induced charge from event 21. Similarly, the total induced charge from event 23 is more negative than the total induced charge from event 22, and the total induced charge from event 24 is more negative than the total induced charge from event 23. This can be expressed as [ Q ]₀＝0]>[Q₁<0]>[Q₂<0]>[Q₃<0]Wherein Q is₀Is started from Z₀The total induced charge of event 21, wherein Q₁Is started from Z₁The total induced charge of event 22, wherein Q₂Is started from Z₂And wherein Q is the total induced charge of event 23, and₃is started from Z₃The total induced charge of event 24. Thus, as shown in FIG. 3, the closer an event is to the pixelated anode (or the farther away from the cathode), the more negative the signal from the non-collecting anode will tend to be.

Fig. 4 depicts five sets of events under a primary pixel 42 (the collection pixel that generates the primary signal) at five different DOIs: z₀、Z₁、Z₂、Z₃、Z₄. Each group includes a different X coordinate (i.e., X) at a particular depth₁、X₂And X₃) Three events at (c). The trajectory of each event moving towards the primary anode 42 (e.g., anode 25 of fig. 2) is schematically shown in fig. 4. These events move in the weighted potentials and electric fields of adjacent non-collecting pixels 44 (e.g., anodes 12 of fig. 1 and 2), inducing non-collecting charges on the weighted potentials and electric fields, thereby producing secondary signals generated by the adjacent non-collecting pixels 44.

Fig. 5-9 depict the resulting sensed non-collected or secondary signals resulting from each event. FIG. 5 includes a graph 50 depicting a plot at Z₀The resulting non-collected or secondary signal of the event(s). As shown in fig. 5, despite the fact that Z is₀Having different lateral positions X₁、X₂And X₃But they all produce the same total non-collected induced charge signal equal to zero. It may be noted that Z₀All events at (a) start from the cathode. The curve 51 in fig. 5 is the primary collected signal at the primary anode 42 and is shown in fig. 5 to help illustrate the difference in amplitude and shape of the primary and secondary sense signals.

FIG. 6 includes a graph 60 depicting a plot at Z₁The resulting non-collected or secondary signal of the event(s). As shown in fig. 6, despite the fact that Z is₁Having different lateral positions X₁、X₂And X₃However, they all haveProducing the same (or nearly the same) and negative total non-collected induced charge signal. It may be noted that Z₁All events at (a) start at a small distance from the cathode and thus have a relatively small magnitude of negative induced charge.

FIG. 7 includes a graph 70 depicting a plot at Z₂The resulting non-collected or secondary signal of the event(s). As shown in fig. 7, despite the fact that Z is₂Having different lateral positions X₁、X₂And X₃But they all produce the same and negative total non-collected induced charge signal (e.g., in range 72). It may be noted that Z₂All events at start with ratio Z₁The event at (a) is a greater distance from the cathode and therefore has a relatively more negative induced charge of a relatively small magnitude.

FIG. 8 includes a graph 80 depicting a position at Z₃The resulting non-collected or secondary signal of the event(s). As shown in fig. 8, despite the fact that Z is₃Having different lateral positions X₁、X₂And X₃But they all produce the same and negative total non-collected induced charge signal (e.g., in range 82). It may be noted that Z₃All events at start with ratio Z₂(and Z₁) The event at (a) is a greater distance from the cathode and therefore has a relatively more negative induced charge of a relatively small magnitude. It may be noted that the difference between the upper and lower values of range 82 and range 72 (see fig. 7) is small enough to be ignored in various embodiments, such that the DOI is considered independent of the lateral position.

FIG. 9 includes a graph 90 depicting a position at Z₄The resulting non-collected or secondary signal of the event(s). Due to Z₄Proximity to the anode, derived from Z₄The negative charges of events at depth are significantly different from each other. Generally, in the illustrated example, as the depth of the event moves closer to the anode, the variability of the negative induced charge based on lateral position increases, with the variability only becoming significant at depths very close to the anode.

As described above, except for events that begin very close to the collecting anode, the events produce total non-collected induced charge in one or more adjacent anodes of the collecting anode that is related to the DOI of the event and substantially independent of lateral position. Thus, a total induced charge that is zero or negative due to an event on an adjacent pixelated anode (or pixelated anode) may be used to derive or determine the DOI for a particular event. It should also be noted that because of the high absorption of the detector, there are few events that begin near the anode, and therefore such events can have a negligible effect on the use of negative induced charge to determine DOI. Accordingly, various embodiments and methods disclosed herein determine a magnitude of a negative sense non-collected signal (also referred to herein as a secondary signal) and use the determined negative signal magnitude to determine or derive a DOI.

As described above, in various embodiments, the DOI of an event may be derived from a correlation between the DOI of the event and total non-collected induced charges on one or more neighboring pixels that are zero or negative, wherein the correlation between the DOI and the total non-collected induced charges is substantially independent of lateral position, such that lateral position may be ignored in deriving the DOI. However, it may be noted that, for example, different photons may have different energies that may yield different values than the total non-collected induced charge. Thus, in various embodiments, the detector system may be calibrated to account for different photon energies, such as normalizing non-collected induced charge values to photon energies. Such a calibration procedure may be performed to provide calibration information for determining the DOI. The calibration information may be in the form of a look-up table, as one example, or a formula or mathematical expression based on curve fitting, as another example.

Fig. 10 depicts a calibration system 92 according to one embodiment. The depicted calibration system 92 is used to calibrate a detector 93 having a sidewall 94 extending between an anode surface 95 and a cathode surface 96. The calibration system 92 comprises a radiation source 97 and a pinhole collimator 98. The pinhole collimator 98 defines a scanning aperture that is movable in the Z direction, as shown in fig. 10, to illuminate the side walls 94 of the detector 93 at different DOIs (different Z coordinates). In this way, events with known DOI and known photon energies are created with different lateral positions that depend on the absorption statistics of the illumination through the sidewall. By measuring the resulting induced negative charges of different DOIs, the negative values of the total induced charge of non-collected neighboring signals can be used to create a look-up table or other relationship for deriving DOIs from the induced non-collected charges.

It may also be noted that since the negative value of the induced charge also depends on the energy of the absorbed photon, the calibration may also take into account the photon energy. For example, the DOI may be calibrated based on a ratio between a negative value of the sensed non-collected signal and an amplitude of the main or collected signal. In various embodiments, such a ratio may be expressed as follows:

since the negative value of the sensing signal is independent (or substantially independent as discussed herein) of the lateral position (or X, Y coordinates), all adjacent or neighboring pixels will produce similar negative signals. Thus, the signal-to-noise ratio can be improved by adding negative signals from a plurality of adjacent or neighboring pixels. In various embodiments, such a ratio may be expressed as:

it may be noted that in various embodiments, the negative induced charge or signal and the main signal of adjacent pixels are measured after a shaper configured to shape the received or acquired signal. In various embodiments, both signals have a generally stepped shape and generally similar peaking and shaping times. Thus, the ratio between the signals may be substantially the same after the shaper or immediately after the amplifier from which the shaper receives the signal.

Fig. 11 provides a schematic illustration of a radiation detector assembly 100 according to various embodiments. As shown in fig. 11, the radiation detector assembly 100 includes a semiconductor detector 110 and a processing unit 120. The semiconductor detector 110 has a surface 112 on which a plurality of pixelated anodes 114 are disposed. In the depicted embodiment, the cathode 142 is disposed on a surface opposite the surface 112 on which the pixelated anode 114 is disposed. For example, a single cathode may be deposited on one surface with a pixelated anode disposed on the opposite surface. In general, when radiation (e.g., one or more photons) strikes the pixelated anode 114, the semiconductor detector 110 generates an electrical signal corresponding to the radiation that passes through the surface of the cathode 142 and is absorbed by the volume of the detector 110 below the surface 112. In the illustrated embodiment, the pixelated anodes 114 are shown in a 5 x 5 array, for a total of 25 pixelated anodes 114; however, it may be noted that other numbers or arrangements of pixelated anodes may be used in various embodiments. For example, each pixelated anode 114 may have a surface area of 2.5 square millimeters; however, other sizes and/or shapes may be employed in various embodiments.

In various embodiments, the semiconductor detector 110 may be constructed using different materials, such as semiconductor materials, including cadmium zinc telluride (CdZnTe), commonly referred to as CZT, cadmium telluride (CdTe), silicon (Si), and the like. The detector 110 may be configured for use in, for example, a Nuclear Medicine (NM) imaging system, a Positron Emission Tomography (PET) imaging system, and/or a Single Photon Emission Computed Tomography (SPECT) imaging system.

In the illustrated embodiment, each pixelated anode 114 generates a different signal depending on the lateral position (e.g., in the X, Y directions) at which photons are absorbed in the volume of detector 110 below surface 112. For example, each pixelated anode 114 generates a primary or collected signal in response to the absorption of a photon in the volume of the detector 110 below the particular pixelated anode 114 through which the photon entered the detector volume. The volume of detector 110 below pixelated anode 114 is defined as a voxel (not shown). For each pixelated anode 114, the detector 110 has a corresponding voxel. The absorption of a photon by a certain voxel corresponding to a particular pixelated anode 114a also results in an induced charge that can be detected by the pixels 114b near or around the particular pixelated anode 114a that receives the photon. The charge detected by the neighboring or surrounding pixels may be referred to herein as non-collected charge and produce a non-collected or secondary signal. The primary signal may include information about the photon energy (e.g., distribution across a range of energy levels) as well as location information corresponding to a particular pixelated anode 114 where photons pass through the surface of the cathode 142 and are absorbed by corresponding voxels.

For example, in fig. 1, a photon 116 is shown impinging on the pixelated anode 114a to be absorbed in the corresponding voxel. Thus, the pixelated anode 114a generates a primary signal in response to receipt of the photons 116. As also shown in fig. 1, the pixelated anode 114b is adjacent to the pixelated anode 114 a. The pixelated anode 114a has 8 adjacent pixelated anodes 114 b. When the pixelated anode 114a is struck by photons 116, an electrical charge is induced in the pixelated anode 114a and collected to produce a main signal. One or more of the adjacent pixelated anodes 114b generates an auxiliary signal in response to induced charge generated and collected in the pixelated anode 114a that produces the main signal. The auxiliary signal has an amplitude less than the main signal. For any given photon, the corresponding primary signal (from the impacted pixel) and secondary signal (from one or more pixels adjacent to the impacted pixel) may be used to locate the photon's point of receipt at a particular location within the pixel (e.g., identify a particular sub-pixel location within the pixel).

As shown in fig. 11, sidewall 140 extends in the Z-direction along a depth 150 between surface 112 and cathode 142. The position along the absorption depth 150 and along the Z-direction at which the photon 116 is absorbed is the DOI of the corresponding event. As discussed herein, in the illustrated embodiment, negatively induced non-collected charge on one or more adjacent pixelated anodes 114b is used to determine the DOI of an event corresponding to the impact of a photon 116.

Each pixelated anode 114 may have one or more electronic channels associated therewith that are configured to provide primary and secondary signals to one or more aspects of the processing unit 120 in cooperation with the pixelated anode. In some embodiments, all or a portion of each electron channel may be disposed on detector 110. Alternatively or in addition, all or a portion of each electronic channel may be housed outside of the detector 110, for example as part of a processing unit 120, which may be or include an Application Specific Integrated Circuit (ASIC). The electronic channels may be configured to provide the primary and secondary signals to one or more aspects of the processing unit 120 while discarding other signals. For example, in some embodiments, each electronic channel includes a threshold discriminator. The threshold discriminator may allow transmission of signals that exceed the threshold level while preventing or inhibiting transmission of signals that do not exceed the threshold level. Generally, the threshold level is set low enough to reliably capture the secondary signal while still being set high enough to exclude lower intensity signals, e.g., due to noise. It may be noted that since the strength of the secondary signal may be relatively low, the electronics utilized are preferably low noise electronics to reduce or eliminate noise that is not eliminated by the threshold level. In some embodiments, each electronic channel includes a peak-hold unit for storing electrical signal energy, and may also include a readout mechanism. For example, the electronic channels may include a request-acknowledge mechanism that allows the peak hold energy and pixel location of each channel to be read out individually. Further, in some embodiments, the processing unit 120 or other processor may control the signal threshold level and request acknowledgement mechanism.

In the illustrated embodiment, the processing unit 120 is operatively coupled to the pixelated anode 114 and is configured to acquire a primary signal (for collected charge) and a secondary signal (for non-collected charge). For example, in various embodiments, the processing unit 120 acquires a primary signal from one of the anodes in response to the anodes receiving photons. For example, the primary signal may be acquired from the pixelated anode 114a in response to receiving the photons 116. The processing unit 120 also acquires at least one secondary signal from at least one neighboring pixel (e.g., at least one neighboring anode 114b) in response to the induced charge caused by the received photons. For example, the secondary signal may be acquired from one or more of the neighboring pixels 114b in response to receiving the photon 116. It may be noted that the secondary signal(s) and the primary signal generated in response to receiving the photons 116 may be associated with each other based on the timing and location of the detection of the corresponding charges.

The depicted processing unit 120 is further configured to determine a depth of interaction (DOI) in the semiconductor detector 110 for reception of photons using (e.g., based on) the at least one secondary signal. For example, the DOI along a depth 150 where photons 116 are absorbed may be determined. In some embodiments, the total negative induced non-collected charge of the at least one secondary signal may be determined and used to determine the DOI as discussed herein. In various embodiments, a look-up table or other correlation may be used to determine the DOI from the determined total negative induced non-collected charge of the at least one secondary signal. It may be noted that in various embodiments, the processing unit 120 only uses the signal generated based on the information from the pixelated anode 114 to determine the DOI, and does not use any information from the cathode 142. Accordingly, the construction and/or assembly of detector assembly 100 may avoid or eliminate any hardware or electrical connections that would otherwise be necessary to acquire a signal from cathode 142 for determination of DOI. Furthermore, by using the same information (primary and secondary signals) as discussed herein to determine both DOI and sub-pixel position, the complexity or requirements of acquisition and/or processing may be further reduced.

The determined DOI may be used to improve image quality. For example, the determined DOI may be used to correct or adjust the acquired imaging information. In some embodiments, the processing unit 120 is configured to adjust an energy level for an event corresponding to the anode receiving a photon based on the DOI. It may be noted that the charge loss of a detected event depends on the absorption distance of the event from the anode. Thus, the DOI of multiple events can be used to adjust the charge loss to make the energy level of the events more uniform and/or closer to the light peak, thereby accurately identifying the events and accurately counting the events.

Alternatively or additionally, the processing unit 120 may be configured to reconstruct an image using DOI. For example, the reconstruction technique may directly use DOIs of multiple events to reconstruct with 3D localization of events in the detector. As another example, DOI may be used indirectly by reconstruction techniques by using DOI to correct energy levels and then using the corrected energy levels for image reconstruction.

As discussed herein, calibration information is utilized in various embodiments. In various embodiments, the processing unit 120 is configured to use the calibration information (see, e.g., fig. 10 and related discussion) to determine the DOI. The calibration may be in the form of a lookup table or other relationship stored by the processing unit 120 or otherwise associated with or accessible by the processing unit (e.g., stored in the memory 130). In some embodiments, the processing unit 120 is configured to determine the DOI using a calibration based on a ratio between negative values of the single secondary signal and the amplitude of the primary signal. (see fig. 10 and related discussion.) as another example, in some embodiments, the processing unit 120 is configured to determine the DOI using a calibration based on a sum or ratio of a combination of negative values of a plurality of secondary signals (e.g., signals from a plurality of neighboring pixels 114b) and an amplitude of the primary signal. (see FIG. 10 and related discussion.)

In various embodiments, in addition to determining the DOI, the processing unit 120 may be configured to determine a sub-pixel position (e.g., lateral position) of the event using the primary signal and the at least one secondary signal. The sub-pixel positions and DOIs can be determined using the same primary signal and at least one secondary signal, providing an efficient determination of both. For example, the depicted exemplary processing unit 120 is configured to define a sub-pixel for each pixelated anode. It may be noted that the sub-pixels (depicted as being separated by dashed lines) in the illustrated embodiment are not physically separated, but rather are virtual entities defined by the processing unit 120. Generally, using more and more sub-pixels per pixel increases resolution, while also increasing computational or processing requirements. The particular number of sub-pixels defined or employed in a given application may be selected based on a balance between improved resolution and increased processing requirements. In various embodiments, the use of virtual sub-pixels as discussed herein provides improved resolution while avoiding or reducing the costs associated with increasingly larger numbers of progressively smaller pixelated anodes.

In the illustrated embodiment, the pixelated anode 114a is shown as being divided into four sub-pixels, namely sub-pixel 150, sub-pixel 152, sub-pixel 154, and sub-pixel 156. Although only the subpixels are shown for the pixelated anode 114a in FIG. 11 for clarity and ease of illustration, it may be noted that the processing unit 120 in the illustrated embodiment also defines corresponding subpixels for each of the remaining pixelated anodes 114. As shown in fig. 11, the photon 116 strikes a portion of the pixelated anode 114a defined by the virtual sub-pixel 150.

In the illustrated embodiment, the processing unit 120 acquires a primary signal for a given acquisition event (e.g., an impact of a photon) from the pixelated anode 114a, along with timing (e.g., timestamp) information corresponding to the time of generation of the primary signal and location information identifying the pixelated anode 114a as the pixelated anode corresponding to the primary signal. For example, an acquisition event such as a photon striking the pixelated anode 114 may result in multiple counts occurring over an energy range or spectrum, where the primary signal includes information describing a distribution of counts within the energy range or spectrum. The processing unit 120 also acquires one or more secondary signals for the acquisition event from the pixelated anode 114b, along with timestamp information and location information for the one or more secondary signals. The processing unit 120 then determines the location of a given acquisition event that identifies the pixelated anode 114a as an impacted pixelated anode 114a, and then determines which of the sub-pixels 150, 152, 154, 156 defines the location of impact for that acquisition event. Using conventional methods, the locations of the sub-pixels 150, 152, 154, 156 may be derived based on the location (e.g., the associated pixelated anode) and the relationship between the intensity of the primary signal in the associated pixelated anode 114a and the one or more secondary signals in the adjacent pixelated anode 114b for the acquisition event. The processing unit 120 may use the timestamp information and the location information to correlate the primary and secondary signals generated in response to a given acquisition event and to distinguish the primary and secondary signals for a given acquisition event from signals for other acquisition events that occur during collection or acquisition using the timestamp and location information. Thus, the use of timestamp information helps to distinguish random coincidences that may occur between a primary signal and its corresponding secondary signal and a primary signal of an adjacent pixel, as timestamps from the primary signal and its corresponding secondary signal are correlated for a particular acquisition event.

U.S. patent application serial No. 14/724,022 entitled "Systems and methods for Charge-damping identification and Correction Using a Single Pixel" filed on day 2015 5, 28 (the "022 application"); U.S. patent application Ser. No. 15/280,640 entitled "Systems and Methods for Sub-Pixel Location Determination," filed on 9/29 2016 ("the 640 application"); and U.S. patent application Ser. No. 14/627,436 entitled "Systems and Methods for Improving Energy Resolution by sub-Pixel Energy Call" filed on 20/2/2015 ("the' 436 application"). The subject matter of each of the 022 application, the 640 application, and the 436 application is incorporated by reference in its entirety.

In various embodiments, processing unit 120 includes processing circuitry configured to perform one or more tasks, functions, or steps discussed herein. It may be noted that a "processing unit" as used herein is not necessarily limited to a single processor or computer. For example, processing unit 120 may include multiple processors, ASICs, FPGAs, and/or computers, which may be integrated in a common housing or unit or may be distributed among various units or housings. It may be noted that the operations performed by processing unit 120 (e.g., the operations corresponding to the process flows or methods discussed herein, or aspects thereof) may be sufficiently complex that a human may not be able to perform the operations within a reasonable period of time. For example, determining the values of collected and non-collected charge based on collected and/or non-collected charge within the time constraints associated with these signals, and/or determining DOI and/or sub-pixel locations may rely on or utilize calculations that may not be possible to accomplish by a human in a reasonable period of time.

The depicted processing unit 120 includes a memory 130. Memory 130 may include one or more computer-readable storage media. For example, memory 130 may store mapping information describing sub-pixel locations, acquired emission information, image data corresponding to generated images, results of intermediate processing steps, calibration parameters or calibration information (e.g., a look-up table correlating negative induced charge values to DOIs), and the like. Additionally, the process flows and/or flow diagrams (or aspects thereof) discussed herein may represent one or more sets of instructions stored in the memory 130 for directing the operation of the radiation detection assembly 100.

Fig. 12 provides a flow diagram of a method 200 (e.g., for determining DOI) according to various embodiments. For example, the method 200 may employ or be performed by structures or aspects of various embodiments (e.g., systems and/or methods and/or process flows) discussed herein. In various embodiments, certain steps may be omitted or added, certain steps may be combined, certain steps may be performed simultaneously, certain steps may be split into multiple steps, certain steps may be performed in a different order, or certain steps or series of steps may be re-performed in an iterative fashion. In various embodiments, portions, aspects, and/or variations of method 200 may be capable of being used as one or more algorithms to direct hardware (e.g., one or more aspects of processing unit 120) to perform one or more operations described herein.

At 202, a primary signal and a secondary signal are acquired corresponding to an acquisition event (e.g., an event corresponding to the receipt of a photon). The primary and secondary signals are generated in response to the semiconductor detector receiving photons, and are received from a pixelated anode (e.g., an anode of a semiconductor device of an imaging system such as assembly 100). For example, a patient to whom at least one radiopharmaceutical has been administered may be placed within a field of view of one or more detectors, and radiation (e.g., photons) emitted from the patient may impinge a pixelated anode disposed on a receiving surface of the one or more detectors, resulting in an acquisition event (e.g., photon impingement). For a given photon strike in the depicted exemplary embodiment, the struck pixelated anode (or collecting anode) generates a primary signal (in response to the collected charge) and the pixelated anodes (or non-collecting anodes) adjacent to the struck pixelated anode generate one or more secondary signals (in response to the non-collected charge).

At 204, a depth of interaction (DOI) in the semiconductor device is determined for the acquisition event that resulted in the acquisition of the primary and secondary signals at 202. In various embodiments, at least one secondary signal for a particular event is used to determine the DOI for that given event. For example, as discussed herein, DOI in various embodiments is determined based on total negative induced non-collected charge values from one or more adjacent or non-collected pixels (e.g., at least one adjacent pixelated anode). It may be noted that DOI in various embodiments is determined without using any information (e.g., detected charge or corresponding signal) from the cathode of the detector assembly.

In various embodiments, the total negative non-collected induced charge may be adjusted or corrected to account for variations in semiconductor configuration and/or photon energy. For example, in the depicted embodiment, at 206, the DOI is determined using the calibration information. As described herein, in some embodiments, the DOI may be determined using a calibration based on the ratio between the negative values of a single secondary signal and the amplitude of the primary signal, and in some embodiments, the DOI may be determined using a calibration based on the ratio between the sum or combination of the negative values of multiple secondary signals and the amplitude of the primary signal. (see FIG. 10 and related discussion.)

At 208, a sub-pixel location is determined using the primary signal and the at least one secondary signal. For each event, a corresponding sub-pixel location may be determined. It may be noted that the same information (primary and secondary signals) used to determine the DOI of events may also be used to determine the sub-pixel locations of those events.

At 210, the energy level for the event is adjusted based on the DOI. For example, because the detected energy may vary based on the DOI, the DOI for each acquired event may be used to adjust the corresponding energy level based on the corresponding DOI to make the energy levels for a set of events more consistent and/or closer to a target or other predetermined energy level.

At 212, an image is reconstructed using the DOI. For example, the corrected energy level from 210 may be used for reconstruction of an image. As another example, the DOI of events can be used to determine 3D localization information for those events within the detector, where the 3D localization information is used to reconstruct the image.

As described herein, a radiation detector system (e.g., a system configured to determine DOI using secondary signals corresponding to non-collected induced charges) can be calibrated. Fig. 13 provides a flow diagram of a method 300 (e.g., for providing and calibrating a radiation detector assembly) according to various embodiments. For example, the method 300 may employ or be performed by structures or aspects of various embodiments (e.g., systems and/or methods and/or process flows) discussed herein. In various embodiments, certain steps may be omitted or added, certain steps may be combined, certain steps may be performed simultaneously, certain steps may be split into multiple steps, certain steps may be performed in a different order, or certain steps or series of steps may be re-performed in an iterative fashion. In various embodiments, portions, aspects, and/or variations of method 300 may be capable of being used as one or more algorithms to direct hardware (e.g., one or more aspects of processing unit 120) to perform one or more operations described herein.

At 302, a semiconductor detector (e.g., semiconductor detector 110 of radiation imaging assembly 100) is provided. The semiconductor detector of the illustrated example has a surface on which a plurality of pixelated anodes are disposed. Each pixelated anode is configured to generate a primary signal in response to the pixelated anode receiving photons and to generate at least one secondary signal in response to induced charge resulting from at least one adjacent anode receiving photons. At 304, the pixelated anode is operably coupled to at least one processor (e.g., processing unit 120).

At 306, a supply of calibrated radiation (e.g., having a known photon energy) is provided at different depths along the sidewalls of the semiconductor detector. In response to receiving the calibrated supply of radiation, the pixelated anode generates a primary signal and a secondary signal. For example, the collimated radiation supply may be delivered to the sidewalls of the semiconductor detector through a pinhole collimator. The position of a given pinhole (e.g., in the Z direction) through which radiation passes may be used to determine the DOI of the corresponding radiation as it passes from the collimator and is received by the semiconductor detector. At 308, the at least one processor acquires a primary signal and a secondary signal from the pixelated anode.

At 310, the corresponding negative value of the total induced charge for each of the different depths at which the radiation is supplied is determined. At 312, calibration information (e.g., a look-up table or other correlation between DOI and negative induced non-collected charge values) is determined.

FIG. 14 is a schematic diagram of an NM imaging system 1000 having multiple imaging detector head assemblies (which may be mounted, for example, in rows, in iris shapes, or other configurations, such as a configuration in which a movable detector carrier 1016 is radially aligned toward a patient's body 1010) mounted on a gantry. Specifically, a plurality of imaging detectors 1002 are mounted to a gantry 1004. In the illustrated embodiment, the imaging detector 1002 is configured as two separate detector arrays 1006 and 1008 that are coupled to the gantry 1004 above and below a subject 1010 (e.g., a patient), as shown in fig. 14. The detector arrays 1006 and 1008 may be directly coupled to the gantry 1004, or may be coupled to the gantry 1004 via support members 1012 to allow movement of the entire array 1006 and/or 1008 relative to the gantry 1004 (e.g., lateral translational movement in a leftward or rightward direction, as indicated by arrow T in fig. 14). In addition, each imaging detector 1002 includes detector units 1014, at least some of which are mounted to a movable detector carrier 1016 (e.g., a support arm or actuator that can be driven by a motor to cause movement thereof) that extends from the gantry 1004. In some embodiments, the detector carrier 1016 allows the detector unit 1014 to move, such as linearly move, toward and away from the subject 1010. Thus, in the illustrated embodiment, the detector arrays 1006 and 1008 are mounted in parallel above and below the subject 1010 and allow the detector unit 1014 to move linearly in one direction (indicated by arrow L), shown perpendicular to the support member 1012 (coupled generally horizontally on the gantry 1004). However, other configurations and orientations are possible, as described herein. It should be noted that the movable detector carrier 1016 may be any type of support that allows the detector unit 1014 to move relative to the support member 1012 and/or the gantry 1004, which in various embodiments allows the detector unit 1014 to move linearly toward and away from the support member 1012.

Each imaging detector 1002 in the various embodiments is smaller than conventional whole-body or general-purpose imaging detectors. Conventional imaging detectors may be large enough to image most or all of the width of a patient's body at once, and may have dimensions of about 50cm or more in diameter or larger. In contrast, each imaging detector 1002 may include one or more detector cells 1014 coupled to a respective detector carrier 1016 and having a size of, for example, 4cm to 20cm, and may be formed from a Cadmium Zinc Telluride (CZT) tile or module. For example, each detector cell 1014 may be 8 x 8cm in size and may be comprised of a plurality of CZT pixelation modules (not shown). For example, each module may be 4 × 4cm in size and have 16 × 16 ═ 256 pixels. In some embodiments, each detector unit 1014 includes a plurality of modules, such as an array of 1 x 7 modules. However, different configurations and array sizes are contemplated, including, for example, detector cells 1014 with multiple rows of modules.

It should be understood that the imaging detectors 1002 may have different sizes and/or shapes relative to each other, such as square, rectangular, circular, or other shapes. The actual field of view (FOV) of each imaging detector 1002 may be proportional to the size and shape of the respective imaging detector.

The frame 1004 may be formed with a hole 1018 (e.g., an opening or aperture) therethrough, as shown. A patient table 1020, such as a patient bed, is configured with a support mechanism (not shown) to support and carry the subject 1010 within the bore 1018 and at one or more of a plurality of viewing positions relative to the imaging detector 1002. Alternatively, the gantry 1004 may include multiple gantry segments (not shown), each of which may independently move the support member 1012 or one or more imaging detectors 1002.

Gantry 1004 can also be configured in other shapes, such as "C," "H," and "L," for example, and can rotate around subject 1010. For example, the gantry 1004 may be formed as a closed loop or circle, or as an open arc or arch that allows easy access to the subject 1010 and facilitates loading and unloading of the subject 1010 while imaging, as well as mitigating claustrophobia of some subjects 1010.

Other imaging detectors (not shown) may be positioned to form multiple rows of detector arrays or arcs or rings around subject 1010. By positioning the plurality of imaging detectors 1002 at multiple positions relative to the subject 1010, such as along an imaging axis (e.g., a head-to-foot direction of the subject 1010), image data specific to a larger FOV may be acquired more quickly.

Each imaging detector 1002 has a radiation detection face that is directed toward the subject 1010 or a region of interest within the subject.

In various embodiments, the porous collimator may be configured to register with pixels of detector units 1014, which in one embodiment are CZT detectors. However, other materials may be used. The collimation of the registration may improve the spatial resolution by forcing photons passing through one aperture to be collected mainly by one pixel. In addition, the alignment of the registration may improve the sensitivity and energy response of the pixelated detector, as the detector area near the pixel edge or between two adjacent pixels may have reduced sensitivity or reduced energy resolution or other performance degradation. Having the collimator baffles directly above the edges of the pixels reduces the chance of photons striking these performance degrading locations without reducing the overall probability of photons passing through the collimator.

Controller unit 1030 may control the movement and positioning of patient table 1020, imaging detector 1002 (which may be configured as one or more arms), gantry 1004, and/or collimator 1022 (which in various embodiments moves with, is coupled to, imaging detector 1002). A series of motions, either before or during acquisition or between different image acquisitions, is set to maintain the actual FOV of each imaging detector 1002, e.g., toward or "aimed" at a particular region or zone of the subject 1010 or along the entire subject 1010. As described in more detail herein, the motion may be a combination or complex motion in multiple directions simultaneously, concurrently, or sequentially.

The controller unit 1030 may have a gantry motor controller 1032, an examination table controller 1034, a detector controller 1036, a pivot controller 1038, and a collimator controller 1040. The controllers 1030, 1032, 1034, 1036, 1038, 1040 may be automatically commanded by the processing unit 1050, manually controlled by an operator, or a combination of the two. The gantry motor controller 1032 can move the imaging detector 1002 relative to the subject 1010, e.g., individually, in segments or subsets, or simultaneously in a fixed relationship to each other. For example, in some embodiments, the gantry controller 1032 may move or rotate the imaging detector 1002 and/or the support member 1012 relative to the subject 1010 around the subject, which may include less than or up to 180 degrees (or more) of motion.

A table controller 1034 may move the patient table 1020 to position the subject 1010 with respect to the imaging detector 1002. For example, the patient table 1020 may be movable in the up-down direction, the in-out direction, and the left-right direction. Detector controller 1036 may control the movement of each imaging detector 1002 to move together as a group or individually, as described in more detail herein. In some embodiments, the detector controller 1036 can also control movement of the imaging detector 1002 to move it closer to or away from the surface of the subject 1010, such as by controlling translational motion (e.g., sliding or telescoping movement) of the detector carrier 1016 linearly toward or away from the subject 1010. Optionally, the detector controller 1036 can control movement of the detector support 1016 to allow movement of the detector array 1006 or 1008. For example, the detector controller 1036 can control lateral movement of the detector carrier 1016 shown by the T arrow (and to the left and right as shown in fig. 14). In various embodiments, the detector controller 1036 can control movement of the detector carrier 1016 or support member 1012 in different lateral directions. The detector controller 1036 may control the rotational movement of the detector 1002 with its collimator 1022.

The pivot controller 1038 may control a pivoting or rotational movement of the detector unit 1014 at an end of the detector carrier 1016 and/or a pivoting or rotational movement of the detector carrier 1016. For example, one or more of the detector cells 1014 or the detector carrier 1016 may be rotated about at least one axis to view the subject 1010 from multiple angular orientations to acquire 3D image data in, for example, a 3D SPECT or 3D imaging mode of operation. Collimator controller 1040 may adjust the position of an adjustable collimator, such as a collimator having adjustable bands (or leaves) or adjustable pinholes.

It should be noted that the movement of one or more imaging detectors 1002 may be in directions other than strictly axial or radial, and that movement in several directions of movement may be used in various embodiments. Thus, the term "motion controller" may be used to indicate the collective name of all motion controllers. It should be noted that the various controllers may be combined, for example, detector controller 1036 and pivot controller 1038 may be combined to provide the different movements described herein.

Prior to acquiring images of subject 1010 or a portion of subject 1010, imaging detector 1002, gantry 1004, patient table 1020, and/or collimator 1022 may be adjusted, such as to a first or initial imaging position and a subsequent imaging position. The imaging detectors 1002 may each be positioned to image a portion of the subject 1010. Alternatively, for example in the case of a small-sized subject 1010, one or more of the imaging detectors 1002 may not be used to acquire data, such as the imaging detectors 1002 at the ends of the detector arrays 1006 and 1008, which are in a retracted position away from the subject 1010, as shown in fig. 14. The positioning may be done manually by an operator and/or automatically, which may include using, for example, image information, such as other images acquired prior to the current acquisition, such as acquired by another imaging modality, such as X-ray Computed Tomography (CT), MRI, X-ray, PET, or ultrasound. In some embodiments, additional information for localization, such as other images, may be acquired by the same system, such as in a hybrid system (e.g., a SPECT/CT system). Additionally, detector unit 1014 may be configured to acquire non-NM data, such as x-ray CT data. In some embodiments, a multi-modality imaging system may be provided, for example, to allow NM or SPECT imaging to be performed, as well as x-ray CT imaging, which may include a dual-modality or gantry design as described in more detail herein.

After the imaging detectors 1002, the gantry 1004, the patient table 1020, and/or the collimator 1022 are positioned, one or more images, such as three-dimensional (3D) SPECT images, are acquired using one or more of the imaging detectors 1002, which may include using a combined motion that reduces or minimizes the spacing between the detector cells 1014. In various embodiments, the image data acquired by each imaging detector 1002 may be combined and reconstructed into a composite image or 3D image.

In one embodiment, at least one of detector array 1006 and/or 1008, gantry 1004, patient table 1020, and/or collimator 1022 is moved after initial positioning, which includes individual movement (e.g., combined lateral and pivotal movement) of one or more of detector units 1014 along with rotational movement of detectors 1002. For example, at least one of the detector arrays 1006 and/or 1008 may move laterally when pivoted. Thus, in various embodiments, a plurality of small size detectors, such as detector unit 1014, may be used for 3D imaging, such as when moving or sweeping detector unit 1014 in conjunction with other movements.

In various embodiments, a Data Acquisition System (DAS)1060 receives electrical signal data generated by imaging detectors 1002 and converts the data to digital signals for subsequent processing. However, in various embodiments, the digital signal is generated by the imaging detector 1002. In addition to the processing unit 1050, an image reconstruction device 1062 (which may be a processing device or a computer) and a data storage device 1064 may also be provided. It should be noted that one or more functions related to one or more of data acquisition, motion control, data processing, and image reconstruction may be accomplished by hardware, software, and/or shared processing resources, which may be located within or near the imaging system 1000, or may be remotely located. In addition, a user input device 1066 may be provided for receiving user input (e.g., control commands), and a display 1068 for displaying images. DAS1060 receives acquired images from detectors 1002 and corresponding lateral, vertical, rotational, and rotational coordinates of gantry 1004, support member 1012, detector units 1014, detector carrier 1016, and detectors 1002 for accurate reconstruction of images, including 3D images and slices thereof.

It may be noted that the embodiment of fig. 14 may be understood as a linear arrangement of detector heads (e.g. with detector units arranged in rows and extending parallel to each other). In other embodiments, a radial design may be employed. For example, a radial design may provide additional advantages in effectively imaging smaller objects (such as limbs, the head, or an infant). Fig. 15 provides a schematic diagram of a Nuclear Medicine (NM) multi-head imaging system 1100, according to various embodiments. Generally, the imaging system 1100 is configured to acquire imaging information (e.g., photon counts) from a subject to be imaged (e.g., a human patient) to which a radiopharmaceutical has been administered. The illustrated imaging system 1100 includes a gantry 1110 having an aperture 1112 therethrough, a plurality of radiation detector head assemblies 1115, and a processing unit 1120.

The frame 1110 defines an aperture 1112. The aperture 1112 is configured to receive an object to be imaged (e.g., a human patient or portion thereof). As shown in fig. 15, a plurality of radiation detector head assemblies 1115 are mounted to the gantry 1110. In the illustrated embodiment, each radiation detector head assembly 1115 includes an arm 1114 and a head 1116. The arm 1114 is configured to radially articulate the head 1116 toward and/or away from the center of the aperture 1112 (and/or in other directions), and the head 1116 includes at least one detector, wherein the head 1116 is disposed at a radially inward end of the arm 1114 and is configured to pivot to provide a range of positions from which imaging information is acquired.

The detector of the head 1116 may be, for example, a semiconductor detector. For example, various embodiments of the semiconductor detector may be constructed using different materials, such as semiconductor materials, including cadmium zinc telluride (CdZnTe), commonly referred to as CZT, cadmium telluride (CdTe), and silicon (Si), among others. The detector may be configured for use with, for example, a Nuclear Medicine (NM) imaging system, a Positron Emission Tomography (PET) imaging system, and/or a Single Photon Emission Computed Tomography (SPECT) imaging system.

In various embodiments, the detector may include a pixelated array of anodes, and may generate different signals depending on where in the volume of the detector below the detector surface photons are absorbed. The volume of the detector below the pixelated anode is defined as the voxel. For each pixelated anode, the detector has a corresponding voxel. Absorption of photons by certain voxels corresponding to a particular pixelated anode results in the generation of countable charges. The counts may be correlated to specific locations and used to reconstruct the image.

In various embodiments, each detector head assembly 1115 may define a corresponding view oriented toward the center of aperture 1112. In the illustrated embodiment, each detector head assembly 1115 is configured to acquire imaging information within a scan range corresponding to a view of a given detector unit. Additional details regarding an example of a system having detector units radially disposed about an aperture can be found in U.S. patent application serial No. 14/788,180 entitled "Systems and Methods for dynamic Scanning With Multi-Head Camera," filed on 30.6.2015, the subject matter of which is incorporated herein by reference in its entirety.

Processing unit 1120 includes memory 1122. The imaging system 1100 is shown as including a single processing unit 1120; however, blocks for processing unit 1120 may be understood to represent one or more processors that may be distributed or located remotely from each other. The illustrated processing unit 1120 includes processing circuitry configured to perform one or more tasks, functions, or steps discussed herein. It may be noted that a "processing unit" as used herein is not necessarily limited to a single processor or computer. For example, processing unit 1120 may include multiple processors and/or computers, which may be integrated in a common housing or unit or may be distributed among various units or housings.

In general, various aspects of the processing unit 1120 (e.g., programming modules) are executed alone or in conjunction with other aspects to perform one or more aspects of a method, step, or process discussed herein. In the illustrated embodiment, the memory 1122 includes a tangible, non-transitory computer-readable medium that stores instructions thereon for performing one or more aspects of the methods, steps, or processes discussed herein.

It should be noted that the various embodiments may be implemented in hardware, software, or a combination thereof. Various embodiments and/or components (e.g., modules or components and controllers therein) may also be implemented as part of one or more computers or processors. The computer or processor may include a computing device, an input device, a display unit, and an interface, for example, for accessing the internet. The computer or processor may include a microprocessor. The microprocessor may be connected to a communication bus. The computer or processor may also include memory. The memory may include Random Access Memory (RAM) and Read Only Memory (ROM). The computer or processor may also include a storage device, which may be a hard disk drive or a removable storage drive such as a solid state drive, optical disk drive, or the like. The storage device may also be other similar means for loading computer programs or other instructions into the computer or processor.

As used herein, the term "computer" or "module" may include any processor-based or microprocessor-based system including systems using microcontrollers, Reduced Instruction Set Computers (RISC), ASICs, logic circuits, and any other circuit or processor capable of executing the functions described herein. The above examples are exemplary only, and are thus not intended to limit in any way the definition and/or meaning of the term "computer".

The computer or processor executes a set of instructions stored in one or more storage elements in order to process input data. The storage elements may also store data or other information as desired or needed. The storage elements may be in the form of information sources or physical memory elements within the processor.

The set of instructions may include various commands that instruct the computer or processor as a processor to perform specific operations, such as the methods and processes of the various embodiments. The set of instructions may be in the form of a software program. The software may be in various forms, such as system software or application software, and may be embodied as tangible and non-transitory computer readable media. Further, the software may be in the form of a collection of separate programs or modules, a program module within a larger program or a portion of a program module. The software may also include modular programming in the form of object-oriented programming. The processing of input data by a processing machine may be in response to an operator command, or in response to the results of a previous process, or in response to a request made by another processing machine.

As used herein, a structure, limitation, or element that is "configured to" perform a task or operation is formed, constructed, or adjusted on a particular structure in a manner that corresponds to the task or operation. For the purposes of clarity and avoidance of doubt, an object that can only be modified to perform a task or operation is not "configured to" perform the task or operation as used herein. Rather, as used herein, the use of "configured to" refers to structural adaptations or characteristics and to structural requirements of any structure, limitation, or element described as "configured to" perform a task or operation. For example, a processor unit, processor, or computer "configured to" perform a task or operation may be understood as being specifically configured to perform the task or operation (e.g., having one or more programs or instructions stored thereon or used therewith that are customized or intended to perform the task or operation, and/or having an arrangement of processing circuits that are customized or intended to perform the task or operation). For the purposes of clarity and avoidance of doubt, a general purpose computer (which may be "configured to" perform a task or operation, if appropriately programmed) is not "configured to" perform the task or operation unless or until specifically programmed or structurally modified to perform the task or operation.

As used herein, the terms "software" and "firmware" are interchangeable, and include any computer program stored in memory for execution by a computer, including RAM memory, ROM memory, EPROM memory, EEPROM memory, and non-volatile RAM (NVRAM) memory. The above memory types are exemplary only, and are thus not limiting as to the types of memory usable for storage of a computer program.

It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments without departing from the scope thereof. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments, they are by no means limiting and are exemplary only. Many other embodiments will be apparent to those of skill in the art upon reading the above description. The scope of various embodiments should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms "including" and "in … … are used as the plain-chinese equivalents of the respective terms" comprising "and" wherein ". Furthermore, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Furthermore, the limitations of the following claims are not written in a device-plus-function format, and are not intended to be interpreted based on 35u.s.c. § 112(f), unless and until such claim limitations explicitly use the phrase "device for … …," followed by a functional statement without other structure.

This written description uses examples to disclose various embodiments, including the best mode, and also to enable any person skilled in the art to practice various embodiments, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the various embodiments is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.