Radiation detection method and system

Abstract

A method of detecting radiation from a target object is described that utilizes a radiation detector module that includes a collimator having a plurality of apertures having a divergence angle for emitting the radiation. The method utilizes this by associating a target object with an internal radiation source such that radiation emitted from the target object passes through a collimator to be incident on a detector; receiving a plurality of responses, each response being a response to an interaction with the incident radiation occurring within the detector; determining, for each of the plurality of responses, a location of each interaction within the probe in a three-dimensional space, the three-dimensional space comprising two area dimensions and one depth dimension; the plurality of responses are processed by simultaneously processing the location data in such a manner that information about a portion of the target object within an effective field of view that is not directly consistent with the main field of view is obtained.

Description

Technical Field

[0001] This invention relates to a method for detecting radiation from a target object or from a specific region of interest therein, and more particularly to a method suitable for detecting radiation from a target object, wherein the target object creates a low signal at the detector. In possible applications, the method relates to a method for detecting radiation from a target object in which an introduced radioactive isotope is disposed as a radiation source, and its application includes techniques for target objects being human or other animal tissues. Background Technology

[0002] There are various scenarios where more accurate information about the radiation emitted by the radiation source and received at the detection system may be required. Specifically, there are a wide range of scenarios where information may need to be resolved, for example, spatially and / or spectrally, to provide additional information about the radiation source and / or about the materials through which the radiation passes between the source and the detector.

[0003] Such scenarios include, but are not limited to, scenarios where the test object and the detector are intentionally separated, the test object is subjected to radiation, for example, from an internal or external radiation source, and the detector measures the radiation emitted from a highly active region in the test object to determine information about the test object, particularly information about the target region of interest from the test object.

[0004] These scenarios include, in particular, situations where a test object is located between two spaced detectors, is subjected to radiation from, for example, an internal or external radiation source, and the radiation emitted from highly active regions within the test object is measured on both detectors to determine information about the test object (e.g., through spatial resolution imaging).

[0005] Examples of methods suitable for such scenarios include nuclear medicine imaging methods in which radiation from a radioactive isotope source is passed through a body part including the region of interest of the subject, and in which spatial registration information about the radiation received at a remote detector is used to obtain information about the structure and / or real-time physiological function of that part of the patient's anatomy, such as constructing an image of the structure and / or physiological function.

[0006] A technique applied to the study of target objects may attempt to associate the object with a radioactive isotope as a radiation source, for example, by introducing a radioactive isotope into the object as a radiation source therein. Known applications of this technique are for target objects that are human or other animal tissues (whether tissues present in the body or tissue samples extracted from the body), and it is particularly known for its application in such medical imaging.

[0007] However, the discussion of these applications is merely illustrative, and the present invention is not limited to medical or imaging applications.

[0008] An example of an established nuclear medicine imaging technique is single-photon emission computed tomography (SPECT), a tomographic imaging technique that uses gamma rays. This technique requires delivering a radioactive isotope that emits gamma rays into the patient's body, for example, via the bloodstream. In typical applications, the radioactive isotope binds to a specific ligand, allowing it to be delivered to and bind to a region of interest within the subject's body.

[0009] The radioactive isotope emits gamma rays that penetrate the subject's tissues and can be detected by a suitable detector, such as a gamma camera. SPECT imaging using a gamma camera acquires multiple two-dimensional images, which are then used to construct a three-dimensional dataset using standard tomographic reconstruction techniques.

[0010] A similar principle is used in positron emission tomography (PET). In this case, a radioactive isotope that emits positrons (usually as part of a radioactive ligand) is introduced into the body. The emitted positrons then undergo local annihilation, and the system detects the gamma-ray pairs indirectly emitted by this annihilation event.

[0011] Both technologies are very powerful, allowing for imaging of relevant parts of the body and active functional imaging of biological processes.

[0012] One known technique for imaging breast tissue, such as detecting abnormalities that may lead to early detection of breast cancer, is mammography. Standard mammography uses X-rays to create images. These images are then analyzed to identify abnormalities, particularly characteristic dense masses that may indicate an underlying tumor. These patients are then referred for further, often more invasive, examinations. Therefore, standard mammography is a widely used first-stage screening technique.

[0013] However, the response of normal but relatively dense breast tissue to low-energy X-rays may be similar to that of a mass that may indicate the potential development of many common tumors. Therefore, the technology’s ability to differentiate patients with a high proportion of high-density breast tissue is reduced.

[0014] Molecular breast imaging (MBI) is a well-established nuclear medicine imaging technique that utilizes many principles of SPECT-type techniques. A radioactive isotope source (usually bound to a suitable ligand to localize it within breast tissue) is introduced into the patient. A suitable system using a small semiconductor-based gamma camera, roughly equivalent in configuration to more traditional mammography, is used to detect the radiation from the source as it penetrates the breast tissue. This technique is particularly effective in detecting early-stage tumors because it can distinguish between structural and physiological activity. However, this method typically results in a higher overall radiation dose to the patient, which often limits its application as a first-stage screening technique.

[0015] In all nuclear medicine imaging techniques, there is a clear requirement: to keep the radioactivity of the radiation source and the resulting radiation dose to the subject as low as possible. This results in low signal collection at the detector, presenting unique challenges in terms of data detection and resolution.

[0016] Therefore, the effective development of nuclear medicine imaging techniques (such as SPECT, PET, or MBI) requires striking a balance between: the need for effective collimation and near-perfect one-to-one registration in the x and y directions (e.g., using parallel-aperture collimators with very low diffusion angles, resulting in a reduced signal from the collimator); and the need for the lowest possible radiation dose source. A particular drawback of such systems is that multi-aperture collimators provide limited angular sampling in the direction perpendicular to the collimator, leading to limited spatial resolution in the direction perpendicular to the detector.

[0017] Possible alternatives to this problem are described in WO2021 / 176232A1 and WO2022 / 090722A1. This discloses a method for detecting radiation from a radiation source, such as for nuclear medicine imaging, which envisions the use of a porous collimator that does not have the small diffusion angle of a parallel-aperture collimator (e.g., a parallel-aperture collimator consisting of pinholes or slits). Such a porous collimator with a significant diffusion angle for the emitted radiation can allow more radiation to pass through, but tends to produce projection overlap (multiplexing), which can lead to image artifacts. This can be considered a disadvantage. However, WO2021 / 176232A1 and WO2022 / 090722A1 further utilize a detector with depth resolution to determine the location of each interaction within the detector in three-dimensional space, and thereby derive inferences about the pattern of radiation from the radiation source. This not only mitigates the effects of multiplexing but also allows these effects to be used to gather additional information.

[0018] This invention is particularly applicable to medical and / or imaging techniques such as those described above, especially nuclear medicine imaging techniques such as SPECT, PET, or MBI, and examples thereof will be discussed herein. However, this invention is not limited to medical or imaging applications.

[0019] The overall expectation is to provide alternative detection systems and methods to allow for the resolution of information about radiation from radiation source objects, particularly from low-signal source objects, such as where radiation levels are low at the desired object location.

[0020] Therefore, it is particularly desirable to collect as much information as possible from a target object subjected to a given level of radiation.

[0021] In particular, it is desirable to collect information that can improve the resolution and / or sensitivity perpendicular to the detector direction.

[0022] In particular, there is a desire to provide such alternatives that can be applied to nuclear medicine imaging and that can address these conflicting considerations in a more effective and efficient manner, thereby providing improved resolution and / or reduced radiation dose levels from the physiologically relevant data of the subjects. Summary of the Invention

[0023] According to a first aspect of the present invention, a method for detecting radiation from a target object includes:

[0024] Provides radiation detector modules, including:

[0025] The detector, having area and depth, is configured to generate a continuous response to a continuous interaction with incident radiation occurring within the detector, thereby determining the location of each interaction in a three-dimensional space, which includes two area dimensions and one depth dimension.

[0026] A collimator associated with the detector, wherein the collimator has multiple apertures having a diffusion angle for the emitted radiation;

[0027] Position the radiation detector module relative to the region of interest of the target object to define the main field of view when the area of ​​the detector module faces the target object;

[0028] Associating the target object with an internal radiation source such that radiation from the radiation source passes through at least a portion of the target object and exits therefrom, thereby causing the radiation emitted from the target object to pass through a collimator and enter the detector;

[0029] It receives multiple responses, each of which is a response to the interaction with the incident radiation that occurs within the detector;

[0030] For each of the multiple responses, determine the location of each interaction within the detector in three-dimensional space, which includes two area dimensions and one depth dimension;

[0031] The multiple responses are processed by simultaneously processing position data, thereby obtaining information about the portion of the target object within an effective field of view that is not directly congruent to the main field of view.

[0032] The method may include using a single radiation detector module positioned at appropriate intervals away from a target object with an internal radiation source, such that radiation from the radiation source passes through at least a portion of the target object to be incident on the detector module.

[0033] The method may include using two detector modules spaced apart from the target object in a suitably side-by-side configuration to collect additional information. The method may also include using three or more detector modules arranged in any suitable two-dimensional or three-dimensional manner.

[0034] In a possible embodiment, two or more detector modules may be arranged in a suitable array (such as a planar array) around the target object.

[0035] In a possible embodiment, pairs of detector modules are used, each located on one side of the target object, to collect additional information.

[0036] Therefore, in this context, methods for detecting radiation from a target object include:

[0037] A first radiation detector module and a second radiation detector module are provided, each comprising:

[0038] The detector, having area and depth, is configured to generate a continuous response to a continuous interaction with incident radiation occurring within the detector, thereby determining the location of each interaction in a three-dimensional space, which includes two area dimensions and one depth dimension.

[0039] A collimator associated with the detector, wherein the collimator has multiple apertures having a diffusion angle for the emitted radiation;

[0040] Position the first radiation detector module and the second radiation detector module so that the region of interest of the target object is between the first radiation detector module and the second radiation detector module, thereby defining the position where the area of ​​the corresponding detector module overlaps with the main field of view;

[0041] Associating a target object with an internal radiation source allows radiation emitted from the target object to pass through a corresponding collimator and be incident on a corresponding detector.

[0042] It receives multiple responses, each of which is a response to the interaction with the incident radiation that occurs within one of the detectors;

[0043] For each of the multiple responses, determine the location of each interaction within the detector in a three-dimensional space, which includes two area dimensions and one depth dimension;

[0044] The multiple responses are processed by simultaneously processing location data, thereby obtaining information about the portion of the target object within an effective field of view that is not directly consistent with the main field of view.

[0045] This invention relates to obtaining information within an effective field of view that is not directly consistent with the main field of view. In particular, this invention relates to techniques and adaptive adjustments for improving resolution and sensitivity within an effective field of view that is not directly consistent with the main field of view.

[0046] This invention encompasses techniques and adaptive adjustments suitable for improving the resolution and sensitivity of an extended field of view (which extends beyond the main field of view perpendicular to the detector plane), and adaptive adjustments suitable for improving the resolution and sensitivity of a reduced field of view (which does not extend or fully utilizes the sensitivity and resolution of the main field of view perpendicular to the detector plane). The former may be advantageous when it is necessary to extend information collection beyond the main field of view. The latter may be advantageous when the entire field of view is not required. In either case, the amount of information collected for a given amount of incident radiation may be significantly enhanced compared to methods and systems with an unmodified field of view.

[0047] This document describes, by way of example, techniques and adaptive adjustments that utilize these two effects. It should be understood that, unless otherwise expressly stated to the contrary, or unless the physical characteristics of the examples necessarily render them unapplicable, the embodiments can be applied by analogy to achieve either objective.

[0048] The specific embodiments described herein include techniques and adaptive adjustments suitable for improving resolution and sensitivity within an extended field of view.

[0049] In such cases of the method, obtaining information about the portion of the target object within an effective field of view that is not directly consistent with the main field of view includes: simultaneously processing position data to obtain information about the portion of the target object within the main field of view, and further information about the portion of the target object outside the main field of view.

[0050] Therefore, more specifically, in these embodiments, the method for detecting radiation from a target object includes:

[0051] Provides radiation detector modules, including:

[0052] The detector, having area and depth, is configured to generate a continuous response to a series of interactions with incident radiation occurring within the detector, thereby determining the location of each interaction in a three-dimensional space, which includes two area dimensions and one depth dimension.

[0053] A collimator associated with the detector, wherein the collimator has multiple apertures having a diffusion angle for the emitted radiation;

[0054] The radiation detector module is positioned relative to the region of interest of the target object to define the main field of view when the area of ​​the detector module faces the target object;

[0055] The target object is associated with an internal radiation source such that radiation from the radiation source passes through at least a portion of the target object and exits therefrom, thereby causing the radiation emitted from the target object to pass through a collimator and enter the detector;

[0056] It receives multiple responses, each of which is a response to the interaction with the incident radiation that occurs within the detector;

[0057] For each of the multiple responses, determine the location of each interaction within the detector in a three-dimensional space, which includes two area dimensions and one depth dimension;

[0058] The multiple responses are processed by simultaneously processing location data, thereby obtaining information about the portion of the target object within the main field of view and further information about the portion of the target object outside the main field of view.

[0059] Similarly, more completely, when paired detectors are present, methods for detecting radiation from a target object include:

[0060] A first radiation detector module and a second radiation detector module are provided, each comprising:

[0061] The detector, having area and depth, is configured to generate a continuous response to a series of interactions with incident radiation occurring within the detector, thereby determining the location of each interaction in a three-dimensional space, which includes two area dimensions and one depth dimension.

[0062] A collimator associated with the detector, wherein the collimator has multiple apertures having a diffusion angle for the emitted radiation;

[0063] Position the first radiation detector module and the second radiation detector module so that the region of interest of the target object is between the first radiation detector module and the second radiation detector module, thereby defining the position where the area of ​​the corresponding detector module overlaps with the main field of view;

[0064] Associating a target object with an internal radiation source allows radiation emitted from the target object to pass through a corresponding collimator and be incident on a corresponding detector.

[0065] It receives multiple responses, each of which is a response to the interaction with the incident radiation that occurs within one of the detectors;

[0066] For each of the multiple responses, determine the location of each interaction within the detector in a three-dimensional space, which includes two area dimensions and one depth dimension;

[0067] The multiple responses are processed by simultaneously processing location data, thereby obtaining information about the portion of the target object within the main field of view and further information about the portion of the target object outside the main field of view.

[0068] Such techniques and adaptive adjustments can be applied when an extended field of view beyond the primary default FOV is insufficient. In an example of an operating mode explored further below, the outer portion of the detector array can be tilted off-center to improve angular sampling and sensitivity within the extended FOV.

[0069] This can take the form of a tilting detector or an angled pinhole collimator. The system may remain stationary during acquisition. Extensions of this technology allow for increasing or decreasing the field of view at each edge of the detector system, enabling increased field of view in different regions of the object being scanned or improved spatial resolution.

[0070] Other specific embodiments described herein include techniques and adaptive adjustments suitable for improving resolution and sensitivity within a reduced field of view.

[0071] In such cases of the method, obtaining information about the portion of the target object within an effective field of view that is not directly consistent with the main field of view includes: simultaneously processing position data in such a way as to obtain information about the portion of the target object within a field of view that is reduced relative to the main field of view with increased resolution and sensitivity.

[0072] Therefore, more specifically, in such embodiments, the method for detecting radiation from a target object includes:

[0073] Provides radiation detector modules, including:

[0074] The detector, having area and depth, is configured to generate a continuous response to a continuous interaction with incident radiation occurring within the detector, thereby determining the location of each interaction in a three-dimensional space, which includes two area dimensions and one depth dimension.

[0075] A collimator associated with the detector, wherein the collimator has multiple apertures having a diffusion angle for the emitted radiation;

[0076] The radiation detector module is positioned relative to the region of interest of the target object to define the main field of view when the area of ​​the detector module faces the target object;

[0077] Associating the target object with an internal radiation source such that radiation from the radiation source passes through at least a portion of the target object and exits therefrom, thereby causing the radiation emitted from the target object to pass through a collimator and enter the detector;

[0078] It receives multiple responses, each of which is a response to the interaction with the incident radiation that occurs within the detector;

[0079] For each of the multiple responses, determine the location of each interaction within the detector in a three-dimensional space, which includes two area dimensions and one depth dimension;

[0080] The multiple responses are processed by processing position data simultaneously, thereby obtaining information about the portion of the target object within a field of view that is reduced relative to the main field of view with increased resolution and sensitivity.

[0081] Similarly, more fully, when paired detectors are present, methods for detecting radiation from a target object include:

[0082] A first radiation detector module and a second radiation detector module are provided, each comprising:

[0083] The detector, having area and depth, is configured to generate a continuous response to the continuous interaction with the incident radiation occurring within the detector, thereby determining the location of each interaction in three-dimensional space, which includes two area dimensions and one depth dimension.

[0084] A collimator associated with the detector, wherein the collimator has multiple apertures having a diffusion angle for the emitted radiation;

[0085] Position the first radiation detector module and the second radiation detector module so that the region of interest of the target object is between the first radiation detector module and the second radiation detector module, thereby defining the position where the area of ​​the corresponding detector module overlaps with the main field of view;

[0086] Associating a target object with an internal radiation source allows radiation emitted from the target object to pass through a corresponding collimator and be incident on a corresponding detector.

[0087] It receives multiple responses, each of which is a response to the interaction with the incident radiation that occurs within one of the detectors;

[0088] For each of the multiple responses, determine the location of each interaction within the detector in three-dimensional space, which includes two area dimensions and one depth dimension;

[0089] The multiple responses are processed by processing position data simultaneously, thereby obtaining information about the portion of the target object within a field of view that is reduced relative to the main field of view with increased resolution and sensitivity.

[0090] Such techniques and adaptive adjustments can be applied when the entire field of view is not required. In an example of an operating mode, further explored below, the outer portion of the detector array can be tilted towards the center, thereby increasing angular sampling and sensitivity within a reduced field of view. This can take the form of a tilted detector or an angled pinhole collimator. The system may remain stationary during acquisition. Extensions of this technique allow for increasing or decreasing the field of view at each edge of the detector system, enabling increased field of view in different regions of the object being scanned or improving its spatial resolution.

[0091] To achieve one or both of the objectives of expanding or narrowing the field of view, according to this method, each radiation detector module is further modified by one or more of the following modifications:

[0092] Orientation of the detector or its components

[0093] Orientation of the collimator or its components,

[0094] The orientation, shape, or configuration of some apertures of the collimator; at least toward the edge of the detector module, in order to further increase the angular acceptance range at the edge of the detector module.

[0095] In practical applications, this method may include:

[0096] The radiation detector module and collimator are positioned relative to the region of interest of the target object such that the distance between the radiation detector module and the collimator is less than the distance between the collimator and the region of interest.

[0097] In a preferred embodiment, when the first radiation detector module and the second radiation detector module are located on both sides of the target object, the method includes:

[0098] Each radiation detector module and its corresponding collimator are positioned relative to the region of interest of the target object such that the distance between the radiation detector module and the collimator is less than the distance between the collimator and the region of interest.

[0099] The principles utilized in this invention are embodied in systems such as those described in WO2021 / 176232A1 and WO2022 / 090722A1, in which a combination of a detector with significant depth and a porous collimator (such as a pinhole collimator) with significant diffusion angle is used to derive additional inferences about the pattern of radiation from a target object, for example, to construct an image of the target object. Using this detector, the response to the continuous interaction with the incident radiation occurring within the detector can be localized in three-dimensional space, comprising two area dimensions and one depth dimension, and the collimator introduces complexity into the emitted radiation pattern through divergence and overlap.

[0100] In other words, the system is characterized by: using a collimator with an array of multiple apertures, which is inherently configured to produce divergence and overlap between modes of radiation from different apertures; using a detector with significant depth to capture information about this divergence and overlap by determining the location and depth of the interaction within the detector; and using the detected complexity in the processing stage to derive additional useful inferences.

[0101] Therefore, this method can utilize the features of the methods described in WO2021 / 176232A1 and WO2022 / 090722A1. For example, the method may include: receiving a plurality of responses, each response being a response to an interaction with incident radiation occurring within the detector; for each of the plurality of responses, determining a characteristic of the interaction, wherein the characteristic includes at least the location and depth of the interaction within the detector; and processing the plurality of responses by simultaneously processing the location and depth data of the interaction in such a way as to accommodate the effect of multiplicity on the detection location on the detector due to the overlap of projected radiation paths of multiple apertures in the collimator at the detector.

[0102] The method may further include: determining an input dataset (including the determined position and depth of each interaction within the detector), and processing the input dataset to generate a modified dataset, which includes at least the modified position data of each interaction, in a manner adapted to the multiplicity effects caused by the overlap of projected radiation paths from multiple apertures. The method may also include processing data of consecutive particle interactions to generate an image dataset, wherein, for example, the image dataset is generated by tomographic reconstruction, and the method includes processing the position and depth data of the interactions in a manner adapted to the effect of multiplicity on the reconstructed tomographic image dataset, thereby reducing multiplicity artifacts in the reconstructed tomographic images.

[0103] However, in this example, the principle is used to change the effective field of view, and in the embodiment, at least the effective field of view of the detector module is extended. In a preferred case, the system is arranged such that the distance between each radiation detector module and its collimator is less than the distance between the collimator and the region of interest. The principle is further used to extract information that utilizes the reduction effect rather than the magnification effect inherent in conventional methods.

[0104] This invention solves the problem of imaging outside the standard field of view (FOV) of conventional detectors, such as conventional imaging cameras. In parallel aperture collimation systems, the FOV is limited to the area directly above a single detector array or the area between pairs of detector arrays. Therefore, portions of the object outside this area cannot be imaged. In the non-parallel aperture collimation system used in this invention, data from the detectors is collected within a certain angular acceptance range. The portion of the angular acceptance range that extends beyond the FOV defined by the detector area can provide additional area that can be imaged without extending the detector coverage directly above it.

[0105] One arrangement produces the effect that a single detector module (including a detector or detector array and a collimator) or a pair of opposing detector modules (including a corresponding detector array and a corresponding collimator) is arranged in a simple planar configuration, and in parallel for the case of paired modules. In this arrangement, the portion of the angular receiving range that extends beyond the FOV defined by the detector area essentially provides additional area capable of imaging without extending the detector coverage directly above it. However, the invention can be further modified in alternative embodiments by further modifying each radiation detector module by altering one or more of the orientation of the detector or a portion thereof, the orientation of the collimator or a portion thereof, the orientation, shape, or configuration of some apertures of the collimator. This modification is made at least towards the edge of the detector module. This modification is made to further increase the angular receiving range at the edge of the detector module and to obtain further information about the target object outside the main field of view.

[0106] Therefore, for example, a method for detecting radiation from a target object includes: providing a first radiation detector module and a second radiation detector module, each comprising:

[0107] The detector, having area and depth, is configured to generate a continuous response to a continuous interaction with incident radiation occurring within the detector, thereby determining the location of each interaction in a three-dimensional space, which includes two area dimensions and one depth dimension.

[0108] A collimator associated with the detector, wherein the collimator has multiple apertures having a diffusion angle for the emitted radiation;

[0109] Position the first radiation detector module and the second radiation detector module so that the region of interest of the target object is between the first radiation detector module and the second radiation detector module, thereby defining the position where the area of ​​the corresponding detector module overlaps with the main field of view;

[0110] Associating a target object with an internal radiation source allows radiation emitted from the target object to pass through a corresponding collimator and be incident on a corresponding detector.

[0111] It receives multiple responses, each of which is a response to the interaction with the incident radiation that occurs within one of the detectors;

[0112] For each of the multiple responses, determine the location of each interaction within the detector in three-dimensional space, which includes two area dimensions and one depth dimension;

[0113] The multiple responses are processed by simultaneously processing location data, thereby obtaining information about the portion of the target object within the main field of view and further information about the portion of the target object outside the main field of view;

[0114] Each radiation detector module is further modified by one or more of the following modifications:

[0115] Orientation of the detector or a part thereof,

[0116] Orientation of the collimator or a portion thereof,

[0117] The orientation, shape, or configuration of some apertures of the collimator; at least toward the edge of the detector module, in order to further increase the angular acceptable range at the edge of the detector module.

[0118] As described herein, the concept of modifying the orientation, shape, or configuration characteristics of detector module elements to increase the angular acceptance range at the detector edges should be understood as modifying the simple planar conformance of the detector and collimator, as well as the uniform shape and configuration of the aperture, in order to increase the angular acceptance range at the detector edges and further extend the field of view (FOV) to complement the extension of the FOV inherent in apertures with divergent diffusion angles, even in simple planar and parallel systems.

[0119] Given the known extension of FOV provided by the diverging diffusion angle of the aperture, and the foregoing discussion of further extending the field of view by seeing modifications to the orientation, shape, or configuration of the detector module elements to increase the angular acceptance range at the detector edge, particularly in a non-uniform manner toward the detector edge, those skilled in the art will consider the options described below.

[0120] For example, in some embodiments, it may be useful to tilt the entire detector or collimator relative to the collimator or detector (as the case may be) or relative to the target object, or to tilt one of a collimator, or one of a pair of detectors or a pair of detector modules, relative to its counterpart. The effect of this tilting is to provide a greater extended field of view coverage, now including not only the contribution of the additional angular acceptance range from the diverging geometry of the aperture, but also the further extension contribution caused by the tilt angle.

[0121] Tilt a single planar collimator, detector, or detector module as a whole may not be suitable. In embodiments (as discussed further below), the components of the system can be modular. In this case, alternatively, only modules near the edge of the main field of view are tilted to provide a greater angular acceptance range at the detector edge. For example, the detector may comprise multiple discrete detector formations arranged in a two-dimensional array. In this case, an embodiment of the method may be to change the orientation of only some of these detector formations (e.g., including detector formations located at or towards the detector edge of the array, which is most effective for extending the field of view) relative to a common detector plane.

[0122] Additionally or alternatively, the orientation, shape, or configuration of some apertures of the collimator can be modified to increase the angular acceptance range at the detector edges and further expand the field of view (FOV). Specifically, the apertures of the collimator can be configured non-uniformly toward the edge of the detector module, for example, more divergent and / or pointing outward toward the edge.

[0123] In a particular preferred embodiment, the method includes at least configuring a collimator such that the shape of a plurality of apertures having a diffusion angle for outgoing radiation is modified in the area of ​​the collimator near the edge of the main field of view to be more divergent and to provide a larger angular acceptance range at the edge of the detector.

[0124] The method of the present invention in a preferred embodiment includes modifying the orientation, shape, or configuration features of elements of a detector module to increase the angular acceptance range at the detector edges and supplementing the extended FOV even in simple planar and parallel systems through an aperture with a diverging diffusion angle. It should be understood that this can be implemented as a fixed structural feature, the method comprising: providing a detector module with such modifications as a fixed structural feature, for example by providing a detector module or a portion thereof or a specific element of a detector array with a built-in tilt angle, or by providing an array of apertures with non-uniform orientation or divergence, thereby providing a greater angular acceptance range at the detector edges. It is understood that this can be provided as an operatively modifiable feature, for example by providing a means for changing the orientation and, for example, the tilt angle of a detector module or a portion thereof or a specific element of a detector array, the method comprising operating the means to achieve an orientation change, for example, tilting the detector module or a portion thereof or a specific element of a detector array. Both of the above may be provided in a single implementation of a single system and method.

[0125] The combination of the above methods with each other, as well as their combination with other methods that further increase the angular acceptance range at the edge of the detector module, are all within the scope of this invention.

[0126] The present invention also provides the ability to utilize reduction, which can further improve the flexibility / utility of imaging information obtained from the region of interest.

[0127] Therefore, this method provides additional capabilities not previously proposed or provided in the prior art. These additional capabilities may enable the operator of the method to gather more information from the target subject for any given treatment and radiation level. In nuclear medicine imaging, this could offer particular advantages, namely improved resolution and / or reduced radiation dose levels, enabling the provision of physiologically relevant data from the subject.

[0128] It should be understood that the detectors mentioned herein apply to any detector that effectively receives radiation from a radiation source and has a resolution capable of determining the location and depth of the interaction within the detector for each of multiple responses. In particular, the singular form includes the plural form. This invention is applicable to detectors comprising multiple discrete detector structures, and / or to a single detector structure defining multiple discrete detection regions, and / or to a single detector structure defining a single continuous detection region (which is actually subdivided into individually addressed sub-regions). Multiple responses can be received from multiple detectors.

[0129] In some applications of the present invention, the detector is typically positioned perpendicular to the direction of radiation incidence to define the x and y incident planes perpendicular to the direction of radiation incidence and the z direction corresponding to the depth of the detector. It should be understood that the positions of the interactions within the detector can constitute the position of the linear detector in the x direction and the position of the area detector in the x and y directions, and the depth of the interactions within the detector can constitute the depth in the z direction.

[0130] In some applications of this invention, the detector may be pixelated, meaning it can be divided into a one-dimensional or two-dimensional array of discrete addressable sub-cells. These sub-cells are discrete elements and / or discrete addressable regions, for example defined on a surface generally perpendicular to the direction of radiation incidence. It should be understood that the locations of interactions within the detector can constitute the localization of a particular discrete addressable sub-cell, and the depth of interactions within the detector can constitute the depth below the surface of said sub-cell. The sub-cells can be discrete physical entities or can be virtually defined digitally, and can be virtually subdivided in terms of the detection area, with positions determined in x and y, and interactions assigned to the sub-cells using these determined positions.

[0131] Unless the context explicitly states otherwise, the term "pixel" or similar subunits as used herein should be understood to include physically discrete pixel subunits, their clusters, and subunits that are virtually defined digitally as described above.

[0132] The detector can be planar, meaning that a planar detection surface can be defined during use, facing the test object and receiving incident radiation from it. In cases where the detector comprises multiple discrete detector structures, these discrete detector structures can therefore lie on a single common plane, such as a detection surface that collectively defines the plane. In this case, the main field of view (FOV) can be defined, for example, by projecting the detection plane along the normal direction of the detector.

[0133] In some embodiments of this method, static scanning is performed. That is, one or more detector modules are held in a fixed position relative to the target object, and the method includes receiving a plurality of responses, each response being a response to an interaction with incident radiation occurring within the detector while the detector is in a fixed position relative to the target object.

[0134] In some embodiments of the method, a moving scan is performed, wherein during the scan, one or more detector modules move relative to the target object around the main field of view, for example, around the imaging axis which serves as the axis of symmetry of the field of view.

[0135] In other words, one or more detector modules move relative to a target object, and the method includes receiving multiple responses, wherein a continuous response is a response to a continuous interaction with incident radiation occurring within the detector as the detector moves relative to the target object.

[0136] In each case, the present invention has the potential to expand or shrink the axial field of view (i.e., the field of view parallel to the imaging axis).

[0137] However, it should be understood that the operation of the method of the present invention does not require, and does not necessarily require, a strictly planar detector. The detector may be generally planar, but not strictly planar. For example, in the case where the detector comprises multiple discrete detector structures, some of these configurations may be angled to the general planar orientation of the detector. Additionally or alternatively, non-planar surfaces may be provided. Even with such a detector provided, those skilled in the art can still effortlessly determine the overall primary FOV provided by the detector and its associated collimator combination in a conventional manner, and determine the expanded or reduced FOV according to the principles of the method.

[0138] In possible embodiments, paired detector modules are used, with each module positioned on either side of the target object during use. In a simple embodiment, the method includes providing a first detector module and a second detector module spaced apart on either side of the target object, and the paired detectors are typically parallel. That is, if each detector is generally planar, the plane defined by the detection surface of each detector is generally parallel.

[0139] However, embodiments of paired detectors are not limited to the method of providing parallel planar detectors. Specifically, in some embodiments, to provide additional information, one or both of the detectors may be tilted, wholly or partially, relative to the target object in use, deviating from a parallel configuration. This tilting effect provides a greater extension to the expanded field of view coverage, now including not only the contribution of the additional angular acceptance range from the diverging geometry of the aperture, but also the contribution of a further extension caused by the tilt angle.

[0140] In some embodiments of the method, a simple planar detector with a single-plane detection surface is provided, and the entire detector is tilted.

[0141] For example, in some embodiments, the detector may include multiple discrete detector structures arranged in a two-dimensional array. In such embodiments, an alternative implementation of the method may be to change only the orientation and tilt of some of these detector structures relative to a common detector plane, for example, specifically changing only the orientation and tilt of some detector structures that comprise the array located at or toward the detector edge, which is most effective for extending the field of view.

[0142] The orientation of the detector structure can be adopted in any suitable combination and can be configured to be fixed, variable during a single inspection operation, and variable between inspection operations to suit the requirements of a specific inspection. In the apparatus used to implement the method, and in the implementation of the method, the orientation of the detector, or the orientation of the individual detector structures constituting the detector (as the case may be), can be fixed during scanning or can be adaptively tilted from a fixed direction during scanning.

[0143] In a preferred embodiment, the method includes processing the plurality of responses to generate an image of the target object.

[0144] More fully, the method includes processing the multiple responses by simultaneously processing position data to obtain imaging information about the portion of the target object within the modified effective FOV (e.g., obtaining imaging information about the portion of the target object within the main FOV by simultaneously processing position data), further obtaining imaging information about the portion of the target object outside the main FOV, and co-processing the imaging information to generate an image of the target object beyond that generated from the main FOV.

[0145] In a possible embodiment, the method includes arranging the system such that the distance between each radiation detector module and its collimator is less than the distance between the collimator and the region of interest. In this case, the method involves downscaling rather than upscaling the imaging information.

[0146] Therefore, the method preferably includes such an imaging system that processes the multiple responses by simultaneously processing position data, thereby obtaining reduced imaging information from the target object, and co-processing the imaging information to generate a reduced image of the target object.

[0147] In this way, the present invention provides additional functionality for image generation of the target object, particularly allowing imaging of portions of the target object that extend beyond the main field of view (FOV). This can be useful in situations where these portions are difficult to access, or where attempting to approach them would require more complex moving scanning devices. It also provides additional functionality by generating scaled-down images.

[0148] Preferably, the image is a reconstructed tomographic image.

[0149] The particular advantages of the invention have been discussed, relating to nuclear medicine imaging techniques such as SPECT, PET, or MBI. In a preferred embodiment, the method includes a method for generating nuclear medicine images, such as using SPECT, PET, or MBI, practiced on a target object comprising biological tissue. The biological tissue may include a sample or part of a living body. Specifically, the method may allow for examination of processes within the organism. Applicable organisms include human and non-human organisms, and the invention can be practiced on human bodies or tissues, non-human animal bodies or tissues, or non-animal bodies or tissues. The method can provide images for use in subsequent review stages, such as determining whether further testing or intervention is needed, or for performing or assisting subsequent diagnostic steps. The method can provide images as part of a diagnostic approach to determine conditional states.

[0150] However, the present invention is not limited to medical imaging, but has been found to be advantageous in applications with any additional field of view.

[0151] The method involves associating a target object with a radiation source such that radiation from the source exits through at least a portion of the target object (including at least one region of interest) and is detectable by a suitably positioned radiation detector. In some embodiments, the radiation source may be placed near the target object, or the target object may be otherwise irradiated from a remote radiation source. In other embodiments, the method may include inserting the radiation source into the target object, particularly distributing the radiation source within the target object, at least near the region of interest. This last approach may be particularly suitable for studying target objects including biological tissue, for example, for imaging, whether as discrete samples or as part of a living or dead organism. A suitable radioactive source may be introduced into the tissue and allowed to diffuse through portions of the tissue, at least near the region of interest.

[0152] An example of an established nuclear medicine imaging technique is single-photon emission computed tomography (SPECT), a nuclear medicine tomographic imaging technique that uses gamma rays. This technique requires delivering a radioactive isotope that emits gamma rays into the patient's body, for example, via the bloodstream. In typical applications, the radioactive isotope binds to a specific ligand, allowing it to be carried and bound to the region of interest within the organism being studied.

[0153] According to the invention, the method includes using a collimator with multiple apertures, which do not have a minimum diffusion angle. The collimator with apertures is not a parallel-aperture collimator. Instead, in the collimator with apertures, the apertures are structured such that each aperture defines a radiation projection region outside the aperture, which exhibits non-zero angular diffusion. For example, in the case of a multi-aperture collimator, each aperture is configured such that it defines a radiation projection cone with positive angular diffusion outside the aperture. Therefore, the collimator is configured such that the radiation projection region outside the aperture at the outer edge of the resulting collimator (corresponding to the edge of the main FOV) extends beyond the main FOV. Preferably, the collimator is further configured such that the resulting radiation projection regions outside the apertures can overlap, producing a multiplicity effect at the detector.

[0154] In embodiments, the collimator may have multiple apertures in a one-dimensional or two-dimensional array, which do not have a minimum diffusion angle. The apertures may be configured, for example, such that each aperture defines a portion of the radiation emitted, which is configured (e.g., with reference to a short length and / or divergence profile along the direction of emitted radiation) to tend to give the radiation passing through the aperture a non-zero diffusion angle upon emission. A suitable diffusion angle may be at least 15 degrees.

[0155] In some embodiments, the method includes using a collimator with an array of slits, such as a slit-slat arrangement. In other embodiments, the method includes using a collimator with an array of one-dimensional or two-dimensional pinholes. In this case, the slits or pinholes may have equivalent or different configurations and may be uniformly or non-uniformly spaced. Arrangements and configurations of other plurality of holes are also conceivable.

[0156] Multiple apertures constituting an array of apertures (e.g., multiple pinholes in a two-dimensional pinhole array) do not need to have the same conformity. In particular, considering that the device is adapted to the method of the first aspect of the invention, as a means of extending the effective field beyond the main field of view area, additional angular coverage can be provided by changing the shape of the apertures (such as pinholes) in the area of ​​the collimator near the edge of the main field of view to make them more divergent, thereby providing a greater angular acceptance range at the edge of the detector or detector array.

[0157] According to the invention, the method includes receiving multiple responses to corresponding multiple interactions with incident radiation occurring within the detector, and for each such response, determining the location of the interaction within the detector in three-dimensional space.

[0158] For example, the method of the present invention includes using a detector that is adjusted or configured such that an interaction occurring within the detector with incident radiation can be localized to an interaction location in three-dimensional space within the detector. In this case, the method includes the steps of incidenting radiation from a radiation source onto such a detector and accordingly performing receiving and determination steps.

[0159] In some embodiments, for example, the present invention includes using a detector comprising a three-dimensional voxel array, wherein, for each of a plurality of responses, determining the characteristics of the interaction (which at least includes the location of the interaction in three-dimensional space) includes locating the interaction to a specific voxel.

[0160] In a preferred embodiment, the detector includes means for positioning interactions within the detector to each of the x and y directions in a plane substantially perpendicular to the direction of incident radiation, and to the z direction, which includes a depth within the detector along a direction substantially perpendicular to the x, y plane.

[0161] For example, a radiation detector includes a detection surface divided into multiple individually addressable detection sections, each of which is positionally defined on the detection surface along two orthogonal directions (hereinafter referred to as the x-direction and y-direction), whereby the interaction of radiation-incident particles from the radiation source at the detection module can be positionally located at the detection section; and at a depth in a third orthogonal direction (hereinafter referred to as the z-direction), the radiation detector is configured such that the interaction of radiation-incident particles from the radiation source at the detection module can be further positionally located at the depth in the z-direction.

[0162] The method also includes (e.g., in a suitable processing module for data communication with the radiation detector) receiving and processing radiation data from the interaction of multiple consecutive particles on the detector, thereby locating each position to a specific voxel and / or x, y, and z coordinates.

[0163] An embodiment of the invention is characterized in that the detector locates each interaction not only in the x and y planes of the detector, but also in the interaction depth or z direction. This dataset, including the interaction depth and the position in the x and y directions, can also be additionally used to reconstruct a radiation pattern image from the radiation source in a manner that can adapt to and, for example, mitigate the effects of multiplicity. In this case, the method of the invention is preferably further characterized by using a collimator with multiple apertures having overlapping projected radiation regions, accepting the multiplicity effects generated in the original data of the interaction positions in the x and y directions, but using the interaction depth in the z direction to adapt to and, for example, mitigate the contribution of such multiplicity effects, and preferably further using the multiplicity to derive additional useful inferences.

[0164] In some embodiments, the method includes processing a collected dataset that includes the determined location and depth of each interaction within the detector, thereby generating a modified dataset that includes at least data on the modified location of each interaction, for example, including data locating each interaction in pixels and / or in the x, y directions as defined above, in such a way as to accommodate the effect of multiplicity arising from the overlap of projected radiation paths from multiple apertures in the collimator at the detector on the apparent location of the interaction in the input dataset.

[0165] In some embodiments, the method includes reducing the effects of multiplicity, for example, substantially eliminating the effects of multiplicity from the modified dataset.

[0166] In a preferred embodiment, the data can be used to reconstruct one or more images. The invention may also include using the depth of interaction to adapt to the multiplicity effects in one or more reconstructed images, such as improving image quality and reducing artifacts in one or more reconstructed images.

[0167] According to a further aspect of the present invention, a radiation detection system for detecting radiation from a target object is provided, the system comprising:

[0168] Radiation source;

[0169] The radiation detector module includes:

[0170] The detector, having depth and an area defining the main field of view, is configured to generate a continuous response to a series of interactions with the incident radiation occurring within the detector, thereby determining the position of each interaction in a three-dimensional space, which includes two area dimensions and one depth dimension.

[0171] A collimator associated with the detector, wherein the collimator has multiple apertures having a diffusion angle for the emitted radiation;

[0172] A device for positioning a radiation source inside a target object, such that during use, radiation from the radiation source passes through at least a portion of the target object and exits therefrom, thereby causing the radiation emitted from the target object to pass through a collimator and be incident on a detector.

[0173] The processing module is operable for:

[0174] It receives multiple responses, each of which is a response to the interaction with the incident radiation that occurs within the detector;

[0175] For each of the multiple responses, determine the location of each interaction within the detector in three-dimensional space, which includes two area dimensions and one depth dimension;

[0176] The multiple responses are processed by simultaneously processing position data, thereby obtaining information about the portion of the target object within an effective field of view that is not directly consistent with the main field of view. The effective field of view is, for example, the extended or reduced field of view described above with respect to this method.

[0177] The radiation detection system may include a single radiation detection module spaced appropriately away from a target object locator configured to locate a target object with an internal radiation source such that radiation from the radiation source passes through at least a portion of the target object to be incident on the detector module.

[0178] A radiation detection system may include two detector modules spaced apart from the target locator in any suitable side-by-side configuration to collect additional information. A radiation detection system may also include three or more detector modules arranged in any suitable two-dimensional or three-dimensional configuration.

[0179] In a possible embodiment, two or more detector modules may be arranged in a suitable array (such as a planar array) around the target object locator.

[0180] In a possible embodiment, pairs of detector modules are used, each located on one side of the target object, to collect additional information.

[0181] Therefore, in this context, a radiation detection system for detecting radiation from a target object is provided, the system comprising:

[0182] Radiation source;

[0183] The first radiation detector module and the second radiation detector module each include:

[0184] The detector, having depth and an area defining the main field of view, is configured to generate a continuous response to a series of interactions with the incident radiation occurring within the detector, thereby determining the position of each interaction in a three-dimensional space, which includes two area dimensions and one depth dimension.

[0185] A collimator associated with the detector, wherein the collimator has multiple apertures having a diffusion angle for the emitted radiation;

[0186] The detector and collimator together define a detection area with means for positioning the radiation source inside the target object, so that the radiation emitted from the target object passes through the collimator and is incident on each detector.

[0187] The processing module is operable for:

[0188] It receives multiple responses, each of which is a response to an interaction with the incident radiation that occurs within one of the detectors;

[0189] For each of the multiple responses, determine the location of each interaction within the detector in a three-dimensional space, which includes two area dimensions and one depth dimension;

[0190] The multiple responses are processed by simultaneously processing location data, thereby obtaining information about the portion of the target object within the main field of view and information about the portion of the target object outside the main field of view.

[0191] In one embodiment, a radiation detection system for detecting radiation from a target object is provided, the system comprising:

[0192] Radiation source;

[0193] The radiation detector module includes:

[0194] The detector, having depth and an area that defines the main field of view, is configured to generate a continuous response to the continuous interactions with the incident radiation occurring within the detector, thereby determining the position of each interaction in three-dimensional space, which includes two area dimensions and one depth dimension.

[0195] A device for positioning a radiation source inside a target object, such that during use, radiation from the radiation source passes through at least a portion of the target object and exits therefrom, thereby causing the radiation emitted from the target object to pass through a collimator and be incident on a detector.

[0196] The processing module is operable for:

[0197] It receives multiple responses, each of which is a response to the interaction with the incident radiation that occurs within the detector;

[0198] For each of the multiple responses, determine the location of each interaction within the detector in a three-dimensional space, which includes two area dimensions and one depth dimension;

[0199] The multiple responses are processed by processing position data simultaneously, thereby obtaining information about the portion of the target object within an effective field of view that is not directly consistent with the main field of view. For example, information within the main field of view and further information about the portion of the target object outside the main field of view are obtained.

[0200] Each radiation detector module includes structural modifications to one or more of the following and / or operable changes to one or more of the following in use:

[0201] Orientation of the detector or a part thereof

[0202] Orientation of the collimator or a portion thereof,

[0203] The orientation, shape, or configuration of some apertures of the collimator; at least toward the edge of the detector module, in order to further increase the angular acceptable range at the edge of the detector module.

[0204] As in the method of the first aspect, and by analogy, the present invention first solves the problem of imaging with different effective fields of view (FOV), such as imaging outside the standard FOV of conventional detectors, through the non-parallel aperture collimation system used in the present invention, so that data in the detector can be collected within a certain angular acceptance range. The portion of the angular acceptance range that exceeds the FOV defined by the detector area can provide additional area capable of imaging without extending the detector coverage area directly above it. A further feature of the present invention is that each radiation detector module includes: structural modifications to one or more aspects of the orientation or shape or configuration of one or more elements of the detector module relative to the simple planar conformal of the detector and collimator and the uniform shape and configuration of the aperture, and / or, operable to change one or more of the above aspects in use, thereby increasing the angular acceptance range at the detector edge and further extending the FOV to supplement the extension of the FOV inherent in the aperture with a divergent diffusion angle, even in simple planar and parallel systems.

[0205] The example implementations discussed in this article can be understood, in the context of the method, as being analogously applicable to this system, and vice versa.

[0206] For example, in some embodiments, it may be useful to tilt the entire detector or collimator relative to the collimator or detector (as the case may be) or relative to the target object, or to tilt one of a collimator, a pair of detectors, or a pair of detector modules relative to its counterpart. Alternatively, the elements of the system may be modular, and optionally only those modules or portions near the edge of the main field of view may be tilted to provide a greater angular acceptance range at the detector edges. Additionally or alternatively, the orientation, shape, or configuration of some apertures of the collimator may be modified in this manner to increase the angular acceptance range at the detector edges and further expand the FOV. Specifically, the apertures of the collimator may be configured to be non-uniformly oriented toward the edge of the detector module, for example, more divergent and / or outwardly pointing toward the edge.

[0207] It should be understood that this can be achieved through fixed structural features, such as by providing a detector module or a portion thereof or a specific element of the detector array with a built-in tilt angle, or by providing an array of apertures with non-uniform orientation or divergence, in order to provide a greater angular acceptance range at the detector edges. It should also be understood that this can be achieved through operable, modifiable functionality, for example by providing means operable in use to change the orientation and tilt angle of the detector module or a portion thereof or a specific element of the detector array.

[0208] The combination of the above-mentioned elements, as well as combinations with other methods to further increase the angular acceptance range at the edge of the detector module, are all within the scope of this invention.

[0209] In a preferred embodiment, the system is configured such that the radiation detector module and the collimator are arranged relative to each other to define a scanning area, such that the distance between the radiation detector module and the collimator is less than the distance between the collimator and the scanning area.

[0210] In a preferred embodiment, the first radiation detector module and the second radiation detector module are disposed on both sides of the target object, and the corresponding radiation detector modules and collimators are configured relative to each other to define a scanning area between them, such that the distance between each radiation detector module and its collimator is less than the distance between the collimator and the scanning area.

[0211] In some embodiments, the system is configured to perform a static scan as described above. That is, one or more detector modules are held in a fixed position relative to the target object.

[0212] In some embodiments, the system is configured to perform a moving scan as described above. That is, one or more detector modules are configured to be movable relative to a target object around the main field of view, for example, around an imaging axis that serves as the axis of symmetry of the field of view. In the example described above, where the field of view is defined as the volume projected by projecting the detector plane along the normal direction of the detector, such an imaging axis can be defined as perpendicular to the detector plane.

[0213] In each case, the present invention has the potential to extend the axial field of view (i.e., the field of view is parallel to the imaging axis).

[0214] In use, the target object is positioned such that the region of interest is within the main field of view of the scanned region in order to take advantage of the extended FOV and reduction effect discussed herein with respect to the first aspect of the invention.

[0215] Therefore, the system is particularly preferred to be a system suitable for carrying out the method of the first aspect of the present invention.

[0216] Therefore, in embodiments, the processing module may also be operated to perform one or more of the determining or processing steps of the method of the present invention in any suitable combination, as defined herein.

[0217] In an embodiment, the detector itself is adjusted or configured such that the interaction with the incident radiation occurring within the detector can be located at at least one position and depth within the detector where the interaction occurs.

[0218] This system is particularly a system that is suitable for the method of the first aspect, and the preferred features of each aspect will be understood to be applicable to the other aspects.

[0219] Specifically, the system's processing module may be operable for, and / or the system may further include additional modules, such as an imaging module, operable to perform any step of the method of the first aspect of the invention.

[0220] In an embodiment, the detector is adjusted or configured such that the interaction with the incident radiation occurring within the detector can be located at the interaction position in the three-dimensional space within the detector.

[0221] In an embodiment, the detector has detector x and y planes and a detector z direction orthogonal to them; and the processing module is operable to locate each interaction at a position in the detector x and y planes and at a depth of the interaction in the detector z direction. In some embodiments, the detector is adjusted or configured such that interactions with incident radiation occurring within the detector can be located in this way.

[0222] In some embodiments, the detector is pixelated into a plurality of individually addressable detector sub-units as described above; and the processing module is operable to locate each interaction to a specific sub-unit and the depth of its interaction. In some embodiments, the detector is adjusted or configured such that interactions with incident radiation occurring within the detector can be located in this way.

[0223] In embodiments, the collimator may have multiple apertures in a one-dimensional or two-dimensional array. The apertures are configured, for example, with reference to a short length and / or divergence profile along the direction of emitted radiation, to tend to give radiation passing through the aperture a non-zero diffusion angle upon emission. A suitable diffusion angle may be at least 15 degrees.

[0224] In some embodiments, the collimator includes a plurality of slits, such as a slit-slab arrangement. In other embodiments, the collimator includes a two-dimensional pinhole array. Other arrangements of multiple diverging apertures are also conceivable.

[0225] For example, in some embodiments, the detector is a voxel detector, comprising a three-dimensional voxel array. In this case, for each of the plurality of responses, determining the characteristics of the interaction (which at least includes the location of the interaction in three-dimensional space) includes localizing the interaction to a specific voxel.

[0226] In some embodiments, the detector includes means for positioning interactions within the detector to each of the x and y directions in a plane substantially perpendicular to the direction of incident radiation, and to the z direction, which includes a depth within the detector along a direction substantially perpendicular to the x, y plane.

[0227] For example, the detector includes a detection surface divided into multiple individually addressable detection sections, each of which is positionally defined on the detection surface along one of two orthogonal directions (hereinafter referred to as the x-direction and y-direction), whereby the interaction of radiated particles from the radiation source at the detection module can be positionally located at the detection section; and at a depth in a third orthogonal direction (hereinafter referred to as the z-direction), the radiation detector is configured such that the interaction of radiated particles from the radiation source at the detection module can be further positionally located at the depth in the z-direction.

[0228] Therefore, the detector is configured to determine the interaction depth (i.e., the dimension in the z-direction) at which each photon interaction occurs. This can be achieved in any suitable manner through a combination of materials, structural features, and processing electronics.

[0229] For example, the detector can be made of a material that inherently allows for the extraction of depth information about interactions, such as a bulk crystalline cadmium telluride-type solid-state semiconductor detector. Materials constituting the semiconductor detector are selected from, for example, cadmium telluride, cadmium zinc telluride (CZT), cadmium manganese telluride (CMT), and their alloys, including crystalline Cd. 1-(a+b) Mn a Zn b Te, where a+b<1, and a and / or b can be zero. Bulk single-crystal detectors may be particularly preferred.

[0230] Additionally or alternatively, the detector may comprise multiple discrete layers in the z-direction made of suitable detector materials. For example, a multilayer scintillator detector may be suitable for implementation of the present invention.

[0231] In some embodiments, the method further includes generating an image and optionally further displaying the image. The system may also include an image generation module and an image display for generating the image. The method may also include generating successive images for tomographic reconstruction. The system may also include a tomographic reconstruction module to achieve the same purpose.

[0232] In some embodiments, the image is a tomographic image, and the image generation module includes a tomographic image reconstruction module for generating a continuous image as a tomographic reconstruction, for example, using the 3D location of the detected event to explain the uncertainty of the radioactive source.

[0233] Alternatively, this can be done directly during the reconstruction process or as a previous processing step. Alternatively, a hybrid approach can be used, such as the hybrid approach discussed below.

[0234] Other preferred features of the second aspect of the system can be understood by analogy to the discussion of the method in the first aspect, and vice versa. Attached Figure Description

[0235] The following will only refer to the appendix Figures 1 to 10 The invention is described by way of example, wherein:

[0236] Figure 1 The principle of multi-pinhole multiplicity is illustrated, and a pinhole collimator is shown as an example of a multiplicity filter used in the system and method of the present invention.

[0237] Figure 2 The principle of a pair of detectors in a first possible configuration with an extended field of view (FOV) is illustrated schematically according to the principles of the invention, for example, applicable to tomographic imaging;

[0238] Figure 3 The principle of a pair of detectors in an alternative configuration with an extended field of view (FOV) according to the invention is illustrated, for example, for tomographic imaging.

[0239] Figure 4 An extended FOV tomography scan using such a system is shown;

[0240] Figure 5 A possible rotating embodiment of the dual-detector system is shown;

[0241] Figure 6 A more complex moving scanning system was shown;

[0242] Figure 7 The principle of a pair of detectors in a second possible configuration with a reduced FOV, according to the principles of the invention, is illustrated, for example, suitable for tomographic imaging;

[0243] Figure 8 Reconstructed images of three line sources with low background activity concentrations are shown at detector angles of 0°(a), 10°(b), 20°(c), and 30°(d).

[0244] Figure 9The estimated resolution (FWHM) of three line sources at distances of 0 mm, 25 mm, and 50 mm from the center is shown as a function of the detector angle in both x-dimension (a) and y-dimension (b).

[0245] Figure 10 The relationship between relative system sensitivity and detector angle is shown under different configurations. Detailed Implementation

[0246] Figure 1 The illustration depicts the principle commonly referred to as multi-pinhole imaging multiplicity, showing the projection of an image from a radiation source onto a detection plane using a pinhole collimator. This principle is generally described, for example, in WO2021 / 176232A1. For instance, the radiation source is part of a biological system under study in which radioactive material is introduced and diffused.

[0247] Data from photons incident on the detectors is collected within a certain angular receiving range around the detector array. This principle can be utilized in a familiar manner for tomographic imaging, for example, in a modified MBI system.

[0248] Figure 2 and Figure 3 The general principle is illustrated in the diagram. Figure 2 and Figure 3 Possible systems are shown that can be used for tomographic imaging, such as MBI systems, whose FOV is extended according to the principles of the present invention. For example, when applied to tomographic imaging for medical purposes (e.g., in such modified MBI systems), those skilled in the art will be able to readily deduce the necessary structures and methods for their implementation.

[0249] In applications where MBI is used in this way, this principle is well-suited for imaging tissues near the chest wall that are outside the field of view (FOV) of a conventional MBI camera.

[0250] In a parallel-aperture collimated MBI system, the field of view (FOV) is limited to the area directly above the detector array. Therefore, any tissue outside this area cannot be imaged.

[0251] In a (multi) pinhole collimation system, data from the detectors is collected within a certain angular receiving range around the detector array. The portion of this angular receiving range that extends beyond the main field of view (FOV) conventionally defined by the detector area can provide additional imageable area without extending the detector coverage directly above it. The general principle is as follows: Figure 2 As shown.

[0252] The detector plane can be like Figure 2 As shown, they can be parallel to each other, or one or both planes can be tilted to provide a greater extended coverage area, such as... Figure 3 As shown.

[0253] As can be seen in the illustrated embodiment, the distance between each detector array and its corresponding collimator will be less than the distance between the collimator and the extended field of view (FOV) of the region of interest (ROI) of the imaging object. Therefore, this method typically involves downscaling rather than upscaling as in known methods.

[0254] Therefore, the following two principles are utilized to provide additional functionality: the portion of the angular receiving range beyond the main FOV can be imaged without extending the detector coverage directly above it, and the generated reduced-size image can be used in conjunction with this to collect and present more information from the target object in tomographic scans or other images for use in any given process and radiation level. In embodiments as MBI systems, a particular advantage may arise from this: providing improved physiologically relevant images of the patient's breast and / or a reduced radiation dose level for a given image.

[0255] like Figure 4 As shown, a basic simulation of the dual-detector head system has been performed. Additional information is provided regarding the operation of the method according to the present invention.

[0256] There is no need to tilt the entire detector plane. This plane may consist of multiple detectors arranged in a specific array. Changing the orientation of some detectors, especially those near the edge of the array, may suffice to achieve similar results. The orientation of individual detectors can be fixed or potentially adjusted according to the requirements of a specific inspection, and they do not need to be identical.

[0257] Compared to existing technologies, the proposed method does not rely on detector movement during scanning. Due to the unique design of the collimator-detector system, stationary acquisition is possible, which in turn is made possible by a detector technology that, in addition to collecting data on interactions in the x and y planes of the probe surface, also collects depth data on interactions in the z-direction of the detector. Detectors with this inherent capability are preferred.

[0258] In a particular embodiment, a bulk zinc cadmium telluride (CZT) semiconductor detector is used. This detector essentially allows for the determination of the depth of photon interaction in the z-direction, and the position of a specific pixel in the x and y directions. However, the invention is not limited to this type of detector. This semiconductor detector can be replaced by any "depth sensing" or "3D position sensing" detector structure, for example, including a scintillator detector module composed of several layers to provide some depth sensing.

[0259] In some operational embodiments, the system can be used to obtain static scans. The detector module remains in a fixed position relative to the target object while collecting continuous responses to successive interactions.

[0260] The invention can also provide an extended field of view (FOV) in the case of one or more rotating camera arrangements, but in practice this may be limited to the axial direction (i.e., along the axis of rotation). The detectors (one, two, or more) move within the field of view. In most cases, this movement is a simple rotation about the imaging axis.

[0261] For example, Figure 5 Two alternative configurations of the dual-module system are shown.

[0262] In other cases, such as Figure 6 As shown, the detector performs a flipping motion around its own axis.

[0263] In all such cases, the present invention has the potential to extend the axial field of view (i.e., parallel to the imaging axis).

[0264] In a further alternative, multiple static detectors are arranged in a ring. Again, our invention extends the axial field of view (the axis is perpendicular to the detector ring).

[0265] Figures 7 to 10 An alternative arrangement is shown that reduces the effective field of view but achieves increased resolution within the reduced FOV.

[0266] Figure 7 The principle of a pair of detectors in a second possible configuration with a reduced field of view (FOV), according to the invention, is schematically illustrated. This invention relates to a technique for improving resolution and sensitivity within a reduced FOV by introducing some flexibility in detector orientation. For cases where the entire FOV is not required, the outer portions of the detector array can be tilted towards the center, thereby improving angular sampling and sensitivity within the reduced FOV. This can be in the form of tilted detectors or angled pinholes. The system may remain stationary during acquisition. Extensions of this technique allow for increasing or decreasing the field of view at each edge of the detector system to allow for increased field of view or improved spatial resolution in different regions of the object being scanned. One specific application of this technique can be suitably used for tomosynthesis, for example, to improve the resolution of the depth of interaction.

[0267] This technology is particularly suitable for applications requiring collimation using densely packed multi-pinhole arrays. We conducted computer simulations assuming a detector array 198 mm wide, divided into three sections, with the first and last sections capable of tilting at different angles.

[0268] Simulation results are as follows Figures 8 to 10 As shown. Each detector array is 198 mm wide and can be divided into three sections. Figure 1 As shown, the first and last sections can be tilted at different angles. The pinhole spacing is 11 mm, and the detector spacing is 70 mm. The active distribution consists of elliptical cylinders with low background density and three line sources located on the midplane between the detectors at different horizontal distances from the center (x = 0 mm, -25 mm, and 50 mm). Noise-free projection data is generated through forward projection. Assuming ideal de-MX, MX is not applied. This is reasonable in this case, as we are only interested in comparing different detector geometries. Data is generated for detector angles of 0°, 10°, 20°, and 30°. Images are reconstructed using 20 iterations of MLEM. The images are integrated along the axial dimensions, and each source is fitted with a 2D Gaussian function to estimate the FWHM in the x and y dimensions. The relative system sensitivity of different configurations is estimated based on the total counts in the projection data. All data processing and analysis are performed in MATLAB.

[0269] Figure 8 Reconstructed images of three line sources with low background activity concentrations are shown at detector angles of 0°(a), 10°(b), 20°(c), and 30°(d). The image corresponding to the standard configuration (a) shows slightly better resolution for the source with x = 50 mm. This is because it is closer to the edge of the elliptical background region, which speeds up convergence. It can also be seen that the resolution improves with increasing detector angle (bd).

[0270] Figure 9 The estimated resolution (FWHM) of three line sources at distances of 0 mm, 25 mm, and 50 mm from the center are shown as a function of the detector angle in both the x-axis (a) and y-axis (b). In most cases, the resolution increases (FWHM decreases) as the angle increases. The improvement is more pronounced in the y-axis (perpendicular to the detector).

[0271] Figure 10 The relationship between relative system sensitivity and detector angle is shown for different configurations. Sensitivity increases approximately linearly with increasing angle.

[0272] For the three line sources, with detector tilt angles of 10°, 20°, and 30°, the average resolution in the x-direction improved by 0.92, 0.81, and 0.76 times (with reduced FWHM), respectively, and the average resolution in the y-direction improved by 0.88, 0.72, and 0.64 times, respectively. At the same angles, the sensitivity improved by 1.19, 1.45, and 1.72 times, respectively. These improvements are attributed to increased angular sampling and reduced detector distance. The largest resolution improvement (nearly 3-fold) was observed in the y-axis at the source furthest from the center (x = 50 mm).

[0273] Our simulations show that spatial resolution and sensitivity can be improved by sacrificing some FOV by introducing some flexibility in the detector configuration. However, the standard configuration remains with two opposing parallel-plane detectors.

[0274] Therefore, solutions are provided in MBI and other nuclear medicine imaging systems / methods, particularly by utilizing the FOV expansion or reduction and / or shrinkage capabilities discussed herein, to allow for the resolution and imaging of information about radiation from the target ROI when low levels of body radiation are ideal, and to provide increased resolution and / or reduced radiation dose levels from physiologically relevant data of the subject.

Claims

1. A method for detecting radiation from a target object, comprising: Provides radiation detector modules, including: A detector having area and depth is configured to generate a continuous response to a continuous interaction with incident radiation occurring within the detector, thereby determining the location of each interaction in a three-dimensional space, which includes two area dimensions and one depth dimension. A collimator associated with the detector, wherein the collimator has multiple apertures having a diffusion angle for emitted radiation; The radiation detector module is positioned relative to the region of interest of the target object to define the main field of view when the area of ​​the detector module faces the target object; The target object is associated with an internal radiation source, so that radiation emitted from the target object passes through the collimator and is incident on the detector; Receive multiple responses, each of which is a response to an interaction with the incident radiation occurring within the detector; For each of the plurality of responses, determine the location of each interaction within the detector in a three-dimensional space, the three-dimensional space comprising two area dimensions and one depth dimension; The multiple responses are processed by simultaneously processing location data, thereby obtaining information about the portion of the target object within an effective field of view that is not directly consistent with the main field of view.

2. The method according to claim 1, comprising: A pair of detector modules are provided, with each detector module located on one side of the target object.

3. The method according to claim 1 or 2, comprising: A first radiation detector module and a second radiation detector module are provided, each comprising: A detector having area and depth is configured to generate a continuous response to a continuous interaction with incident radiation occurring within the detector, thereby determining the location of each interaction in a three-dimensional space, which includes two area dimensions and one depth dimension. A collimator associated with the detector, wherein the collimator has multiple apertures having a diffusion angle for emitted radiation; Position the first radiation detector module and the second radiation detector module so that the region of interest of the target object is between the first radiation detector module and the second radiation detector module, thereby defining the position where the area of ​​the corresponding detector module overlaps with the main field of view; The target object is associated with an internal radiation source, so that the radiation emitted from the target object passes through the corresponding collimator and is incident on the corresponding detector; Receive multiple responses, each of which is a response to an interaction with incident radiation that occurs within one of the detectors; For each of the plurality of responses, determine the location of each interaction within the detector in a three-dimensional space, the three-dimensional space comprising two area dimensions and one depth dimension; The multiple responses are processed by simultaneously processing location data, thereby obtaining information about the portion of the target object within an effective field of view that is not directly consistent with the main field of view.

4. The method according to any of the preceding claims, wherein, Obtaining information about a portion of the target object within an effective field of view that is not directly aligned with the main field of view includes: simultaneously processing position data to obtain information about the portion of the target object within the main field of view, and further information about the portion of the target object outside the main field of view.

5. The method according to any one of claims 1 to 3, wherein, Obtaining information about a portion of the target object within an effective field of view that is not directly consistent with the main field of view includes: simultaneously processing position data to obtain information about a portion of the target object within a field of view that is reduced relative to the main field of view.

6. The method according to any of the preceding claims, wherein, Each radiation detector module is further modified by one or more of the following modifications: Orientation of the detector or a part thereof Orientation of the collimator or a portion thereof, The orientation, shape, or configuration of some of the apertures of the collimator; at least toward the edge of the detector module, in order to further increase the angular acceptance range at the edge of the detector module.

7. The method according to any preceding claim, comprising: The radiation detector module and the collimator are positioned relative to the region of interest of the target object such that the distance between the radiation detector module and the collimator is less than the distance between the collimator and the region of interest.

8. The method of claim 7, comprising: A first radiation detector module and a second radiation detector module are respectively installed on both sides of the target object; Each radiation detector module and its corresponding collimator are positioned relative to the region of interest of the target object, such that the distance between the radiation detector module and the collimator is less than the distance between the collimator and the region of interest.

9. The method according to any of the preceding claims, wherein, The detector, or each detector, defines a generally planar detection surface when in use, which faces the test object and receives incident radiation from the test object.

10. The method according to claim 9, wherein, The main field of view is defined by projecting the probe surface along the normal direction of the plane.

11. The method according to any of the preceding claims, wherein, The detector comprises multiple discrete detector structures arranged in a two-dimensional array.

12. The method according to claim 9, wherein, The method includes altering the orientation and tilt of some of the detector structures relative to the detector plane.

13. The method according to any of the preceding claims, wherein, Performing a static scan, i.e., keeping one or more of the detector modules in a fixed position relative to the target object, and the method includes receiving a plurality of responses, each of which is a response to an interaction with incident radiation occurring within the detector while the detector is in a fixed position relative to the target object.

14. The method according to any one of claims 1 to 12, wherein, Performing a moving scan, i.e., moving one or more of the detector modules relative to the target object around the main field of view, and the method includes receiving a plurality of responses, the continuous responses being responses to continuous interactions with incident radiation occurring within the detector as the detector moves relative to the target object.

15. The method according to claim 14, wherein, During scanning, one or more of the detector modules move relative to the target object about an imaging axis that is the axis of symmetry of the main field of view.

16. The method according to claim 14 or 15, wherein, The method includes changing only the orientation and tilt of some of the detector structures that constitute part of the array and are located or toward the edge of the detector relative to the universal detector plane.

17. The method according to any of the preceding claims, further comprising: The multiple responses are processed to generate an image of the target object.

18. The method of claim 17, comprising: The multiple responses are processed by simultaneously processing position data to obtain imaging information about the portion of the target object within the main field of view, and further to obtain imaging information about the portion of the target object outside the main field of view. The imaging information is then processed collaboratively to generate an image of the target object that extends beyond the main field of view.

19. The method of claim 17 or 18, further comprising arranging the system such that the distance between each radiation detector module and its collimator is less than the distance between the collimator and the region of interest; and processing the plurality of responses by simultaneously processing position data in such a manner as to obtain reduced imaging information from the target object, and co-processing the imaging information to produce a reduced image of the target object.

20. The method according to any one of claims 15 to 19, wherein, The image is a reconstructed tomographic image.

21. The method according to any of the preceding claims, wherein, The collimator comprises multiple apertures in a one-dimensional or two-dimensional array, wherein the multiple apertures do not have a minimum diffusion angle.

22. The method according to claim 21, wherein, The aperture has a diffusion angle of at least 15 degrees.

23. The method according to any of the preceding claims, further comprising: The collimator is configured such that the shape of the plurality of apertures having a diffusion angle for emitted radiation is modified in the area of ​​the collimator near the edge of the main field of view to be more divergent and to provide a larger angular acceptance range at the edge of the detector.

24. A radiation detection system for detecting radiation from a target object, comprising: Radiation source; The radiation detector module includes: The detector has depth and an area defining a main field of view, and is configured to generate a continuous response to a continuous interaction with incident radiation occurring within the detector, thereby determining the position of each interaction in a three-dimensional space, which includes two area dimensions and one depth dimension. A collimator associated with the detector, wherein the collimator has multiple apertures having a diffusion angle for emitted radiation; A device for positioning the radiation source inside a target object, so that radiation emitted from the target object passes through the collimator and is incident on the detector; The processing module is operable for: Receive multiple responses, each of which is a response to an interaction with the incident radiation occurring within the detector; For each of the plurality of responses, determine the position of each interaction within the detector in a three-dimensional space, the three-dimensional space comprising two area dimensions and one depth dimension; The multiple responses are processed by simultaneously processing location data, thereby obtaining information about the portion of the target object within an effective field of view that is not directly consistent with the main field of view.

25. The radiation detection system of claim 24, comprising a pair of detector modules, wherein each detector module is located on one side of the target object during use.

26. The radiation detection system according to claim 24 or 25, comprising: Radiation source; The first radiation detector module and the second radiation detector module each include: The detector has depth and an area defining a main field of view, and is configured to generate a continuous response to a continuous interaction with incident radiation occurring within the detector, thereby determining the position of each interaction in a three-dimensional space, which includes two area dimensions and one depth dimension. A collimator associated with the detector, wherein the collimator has multiple apertures having a diffusion angle for emitted radiation; The detector and the collimator together define a detection area, which has means for positioning the radiation source inside the target object, so that radiation emitted from the target object passes through the collimator to be incident on each detector; The processing module is operable for: Receive multiple responses, each of which is a response to an interaction with incident radiation that occurs within one of the detectors; For each of the plurality of responses, determine the position of each interaction within the detector in a three-dimensional space, the three-dimensional space comprising two area dimensions and one depth dimension; The multiple responses are processed by simultaneously processing location data, thereby obtaining information about the portion of the target object within an effective field of view that is not directly consistent with the main field of view.

27. The radiation detection system according to any one of claims 24 to 26, wherein, The radiation detector module and the collimator are configured relative to each other to define a scanning area such that the distance between the radiation detector module and the collimator is less than the distance between the collimator and the scanning area.

28. The radiation detection system according to any one of claims 24 to 27, wherein, The collimator comprises multiple apertures in a one-dimensional or two-dimensional array, wherein the multiple apertures do not have a minimum diffusion angle.

29. The radiation detection system according to claim 28, wherein, The aperture has a diffusion angle of at least 15 degrees.

30. The radiation detection system according to any one of claims 24 to 29, wherein, The processing module is operable to perform one or more steps of the determining or processing steps of the method according to any one of claims 1 to 23 in any suitable combination.

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