CN213240527U - Device for determining the depth of interaction of a PET detector - Google Patents

Device for determining the depth of interaction of a PET detector Download PDF

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CN213240527U
CN213240527U CN202021116983.2U CN202021116983U CN213240527U CN 213240527 U CN213240527 U CN 213240527U CN 202021116983 U CN202021116983 U CN 202021116983U CN 213240527 U CN213240527 U CN 213240527U
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crystal
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李弘棣
安少辉
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Shanghai United Imaging Healthcare Co Ltd
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Shanghai United Imaging Healthcare Co Ltd
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Abstract

Apparatus for determining the depth of interaction of a PET detector. For example, the apparatus includes a crystal array including a plurality of crystal elements arranged at least along a first direction and a second direction, the plurality of crystal elements extending along a third direction between a first end and a second end, the plurality of crystal elements configured to receive radiation entering from the second end; wherein the plurality of crystal elements are arranged in a plurality of crystal pairs, each of the plurality of crystal pairs optically coupled at a first end to an optical bridge extending along a first direction and bridging light; each crystal pair of the plurality of crystal pairs is optically coupled to at least adjacent crystal pairs in the second direction only through two optical channels.

Description

Device for determining the depth of interaction of a PET detector
Technical Field
The present disclosure relates generally to Positron Emission Tomography (PET), and more particularly, to an apparatus for determining depth of interaction (DOI) in a PET detector.
Background
PET is generally an imaging technique that produces three-dimensional images of functional processes in a subject or part of a subject to monitor bioactive molecules labeled with radiotracers in vivo. The tracer may undergo positron emission decay and emit positrons. The positrons can be annihilated by electrons, producing a pair of annihilation photons (e.g., gamma photons) that move in substantially opposite directions. The annihilation photon may be absorbed by a plurality of crystal elements (e.g., arranged in one or more rings) that generate bursts (bursts) of optical photons (e.g., visible light photons), which in turn may be detected by photodetectors. A three-dimensional image of the object may then be generated based on the coincident photon detection. Since the detected pair of annihilation photons can travel along an almost straight line, called a line of response (LOR), the location of the tracer can be determined by identifying the LOR.
In conventional devices, PET scanners exhibit a gradual decrease in spatial resolution as the distance from the center of their field of view (FOV) increases. This loss of resolution is caused at least in part by the uncertainty in assigning the LOR to the detected coincidence event (coincident event). Uncertainty in LOR assignment may be relatively small for a pair of detector modules located near a central axis of the scanner (i.e., an axis passing through the center of the FOV in the axial direction of the scanner) compared to a pair of detector modules located away from the central axis. Furthermore, a pair of detector modules disposed close to each other along the axial direction of the scanner may have a relatively smaller uncertainty in LOR assignment than a pair of detector modules disposed further away from each other. For example, as shown in fig. 2a, a pair of detector modules 201 and 202 are closer to the central axis of the scanner than a pair of detector modules 203 and 204. As shown in fig. 2b, the distance between the detector module 201 and the detector module 202 in the axial direction of the scanner is smaller than the distance between a pair of detector modules 202 and 205. Dashed lines A and B define the range of possible LORs assigned to the detector modules 201 and 202, dashed lines C and D define the range of possible LORs assigned to the detector modules 203 and 204, and dashed lines E and F define the range of possible LORs assigned to the detector modules 202 and 205. The difference Δ r1 between A and B is less than the difference Δ r2 between C and D, indicating that the resolution loss in detector module 201 and detector module 202 is relatively small compared to detector module 203 and detector module 204. Similarly, the difference Δ r1 is less than the difference Δ r3 between E and F, indicating that the resolution loss in the detector module 201 and the detector module 202 is relatively small compared to the detector module 202 and the detector module 205.
Therefore, to increase imaging resolution, it is desirable to determine the location or depth of gamma photon interactions occurring within the PET detectors. A PET imaging device that provides depth of interaction (DOI) information can more accurately assign LORs to coincident events, resulting in more uniform resolution throughout the FOV. Various techniques have been proposed for extracting DOI information from PET detectors. One possible way is to optically couple the photon sensor to both ends of the crystal element of the PET detector. For example, as shown in FIG. 3a, photonic sensor 301a and photonic sensor 301b are optically coupled to two ends of crystal element 302, respectively. DOI information for gamma photon interactions (e.g., gamma photon interaction 1) within crystal element 302 may be determined based on a ratio of output energies from photon sensor 301a and photon sensor 301 b.
Another exemplary approach employs a photonic sensor array coupled to a monolithic crystal. For example, as shown in fig. 3b, a photonic sensor array 303 comprising a plurality of photonic sensors 301c is optically coupled to a crystal element 304. DOI information for gamma photon interactions (e.g., gamma photon interaction 2 or gamma photon interaction 3) may be determined based on the distribution of the output of photon sensor 301 c. For example, when a gamma photon interaction excites one or more photons detected by more photon sensors 301c, it may occur at a location that is remote from the photon sensor array 303.
Another exemplary way is based on a multilayer crystal optically coupled to the photonic sensor array and determining DOI information based on characteristics of the signal detected by the photonic sensor array. For example, as shown in FIG. 3c, the PET detector includes a first crystal layer 305, a second crystal layer 306, and a photon sensor array 307 optically coupled to the second crystal layer 306. The nature of the crystals in the different layers may be different. The above techniques are applicable to DOI determination, however, most of them rely on additional detector electronics, requiring much more complex hardware and possibly introducing other problems. Accordingly, it is desirable to provide a device for efficiently and accurately determining DOI in a PET device.
SUMMERY OF THE UTILITY MODEL
According to one aspect of the present disclosure, a PET detector may include a crystal array and a single-ended read-out structure. The crystal array may include a plurality of crystal elements. The plurality of crystal elements may be arranged along a first direction and a second direction to define a plurality of crystal groups along the first direction. Each of the plurality of crystal groups may include at least two crystal elements of the plurality of crystal elements. Each of the plurality of crystal elements may include a first end and a second end, and may extend from the first end to the second end along a third direction. The photonic sensor array is optically coupled to the crystal array. At least one pair of crystals in adjacent crystal groups of the plurality of crystal groups may include a first optical isolator and a second optical isolator. A first optical isolator of a first length can be positioned between the crystal groups of at least one pair of adjacent crystal groups, the first length along the third direction. A second optical isolator of a second length can be located between two adjacent crystal elements of the crystal group of at least one pair of the adjacent crystal groups, the second length being along the third direction. The first length of the first optical isolator may be equal to or greater than the second length of the second optical isolator.
In some embodiments, the photonic sensor forms a single-ended readout structure, and the photonic sensor array may include a plurality of photonic sensors configured to receive photons emitted from the first ends of the plurality of crystal elements.
In some embodiments, each photonic sensor in the photonic sensor array may be optically coupled with one or more crystal elements of the plurality of crystal elements.
In some embodiments, the detector may include one or more third optical isolators. Each of the one or more third optical isolators may be positioned between adjacent crystal elements along the second direction.
In some embodiments, at least one of the first optical isolator, the second optical isolator, or the one or more third optical isolators can include at least one of a reflective film, a reflective foil, or a reflective coating.
In some embodiments, the first optical isolator extends from a first end of one of the plurality of crystal elements to a second end of the one of the plurality of crystal elements.
In some embodiments, the second length of the second optical isolator can be equal to or greater than half the length of at least one of the two adjacent crystal elements between which the second optical isolator is located, the length of the crystal element being along the third direction.
In some embodiments, at least one of the first optical isolator or the second optical isolator may extend from the first end of at least one of the two adjacent crystal elements in the third direction, the at least one of the first optical isolator or the second optical isolator being located between the two adjacent crystal elements.
In some embodiments, at least one crystal group of the plurality of crystal groups, two ends of at least two crystal elements may be integrated into a single end.
In some embodiments, the first optical isolator extends from a first end of one of the plurality of crystal elements to a second end of the one of the plurality of crystal elements.
According to another aspect of the disclosure, a computer-implemented method may include one or more of the following operations performed by at least one processor. The method may include acquiring output information of at least two photonic sensors. At least two photon sensors may be optically coupled to one crystal group of the PET detector. The output information may correspond to gamma photon interactions in the crystal group. The method may also include determining a location of the gamma photon interaction within the crystal group based on the output information.
In some embodiments, the method may further include identifying a target crystal element in the crystal group in which the gamma photon interaction occurred based on the output information.
In some embodiments, the method may further include determining a depth of gamma photon interaction within the target crystal element based on the output information.
In some embodiments, the output information of the at least two photon sensors may include the energy detected by each of the at least two photon sensors. The method may also include determining a total energy detected by the at least two photon sensors based on the energy detected by each of the at least two photon sensors. The method may further include determining a location of a gamma photon interaction within the crystal group based on the energy detected by each of the at least two photon sensors and the total energy.
According to another aspect of the disclosure, a computer-implemented method may include one or more of the following operations performed by at least one processor. The method may include obtaining output information for a plurality of photon sensor groups. Each of the plurality of photon sensor groups may include at least two photon sensors and is optically coupled with the crystal group of the PET detector. The output information may correspond to gamma photon interactions in the plurality of crystal groups. The method may also include determining a plurality of candidate locations for gamma photon interaction in the plurality of crystal groups based on the output information. Each of the plurality of candidate locations may correspond to one of the plurality of crystal groups and may include a candidate depth at which gamma photons interact within the corresponding crystal group. The method may further include determining that inter-crystal scattering (ICS) has occurred within the plurality of crystal groups based on the output information. The method may further include designating a candidate location with a smallest candidate depth among the plurality of candidate locations as the location of gamma photon interaction.
In accordance with yet another aspect of the present disclosure, a PET detector may include a plurality of detector rings along an axial direction of the detector. Each of the plurality of detector rings may include a plurality of crystal elements. The plurality of crystal elements may define a plurality of crystal groups arranged along an axial direction of the detector. Each of the plurality of crystal groups may include at least two crystal elements belonging to at least two separate detector rings. Each of the plurality of crystal elements may include a proximal end and a distal end relative to a central axis of the probe, and may extend in an extension direction from its distal end to its proximal end. At least one pair of adjacent crystal groups of the plurality of crystal groups may include a first optical isolator and a second optical isolator. A first optical isolator of a first length along a direction of extension of at least one crystal element in at least one pair of adjacent crystal groups may be located between crystal groups of the at least one pair of adjacent crystal groups. The second optical isolator of the second length may be located between two adjacent crystal elements of the crystal group of the at least one pair of adjacent crystal groups, the second direction being along an extension direction of at least one crystal element of the at least one pair of adjacent crystal groups. The first length of the first optical isolator may be equal to or greater than the second length of the second optical isolator.
In some embodiments, the at least one detector ring may include a plurality of photon sensors configured to receive photons emitted from respective distal ends of the plurality of crystal elements of the at least one detector ring.
In some embodiments, each of the plurality of photon sensors may be optically coupled with one or more crystal elements of at least one detector ring.
In some embodiments, the at least one detector ring may include a third optical isolator positioned between each pair of adjacent crystal elements of the at least one detector ring.
According to another aspect of the disclosure, a computer-implemented method may include one or more of the following operations performed by at least one processor. The method may include acquiring output information of at least two photonic sensors. Each of the at least two photon sensors may be optically coupled with one or more crystal elements of the crystal group belonging to the PET detector. The output information may correspond to gamma photon interactions in the crystal group.
In some embodiments, the method may further include determining a location of the gamma photon interaction within the crystal group based on the output information.
In some embodiments, the method may further include identifying a target crystal element of the crystal elements optically coupled to the at least two photon sensors in which the gamma photon interaction occurred based on the output information.
In some embodiments, the method may further include determining a depth of gamma photon interaction within the target crystal element based on the output information.
In some embodiments, the output information of the at least two photon sensors may include energy detected by each of the at least two photon sensors, and the method may further include determining a total energy detected by the at least two photon sensors based on the energy detected by each of the at least two photon sensors. The method may further include determining a location of a gamma photon interaction within the crystal group based on the energy detected by each of the at least two photon sensors and the total energy.
According to yet another aspect of the present disclosure, a PET detector may include a crystal array and a single-ended read-out structure. The crystal array may include a plurality of crystal elements arranged along a first direction and a second direction to define a plurality of crystal groups along the first direction. Each of the plurality of crystal groups may include at least two crystal elements of the plurality of crystal elements. Each of the plurality of crystal elements may include a first end and a second end, and may extend from the first end to the second end along the third direction. The single-ended readout structure may include a photonic sensor optically coupled to a crystal array. At least one crystal group of the plurality of crystal groups may include an optical transmission window configured to allow optical transmission between at least two crystal elements of the at least one crystal group such that photons excited by gamma photon interaction in a first crystal element of the at least one crystal group may travel through the second end of the first crystal element, the optical transmission window, and the second end of the second crystal element into a second crystal element of the at least one crystal group.
In some embodiments, the optically transparent window of at least one of the crystal groups can include an optical isolator and an optical transmission medium. For each of the at least two crystal elements of the at least one crystal group, an optical isolator may be mounted on each side surface of an adjacent crystal element of the crystal elements facing the crystal element in the first direction. The length of the optical isolator may be equal to the length of at least one of the crystal element or the adjacent crystal element, the length of the optical isolator and the length of at least one of the crystal element or the adjacent crystal element being in the third direction. The light-transmitting medium may cover the second end of at least two crystal elements of at least one crystal group. Each side surface of the light-transmitting medium facing an adjacent crystal group of the at least one crystal group may be coated with a light-reflecting material.
In some embodiments, the optical transmission medium may be glass.
In some embodiments, the photonic sensor array may include a plurality of photonic sensors configured to receive photons emitted from the first ends of the plurality of crystal elements.
In various embodiments, an apparatus for determining a depth of interaction of a PET detector includes: a crystal array including a plurality of crystal elements arranged at least in a first direction and a second direction; and a photosensor array including a plurality of photosensors arranged at least in a first direction and a second direction. In some examples, the plurality of crystal elements extend between the first end and the second end along the third direction. In some examples, the plurality of crystal elements are arranged in a plurality of crystal pairs. In some examples, each crystal pair of the plurality of crystal pairs is optically coupled at the second end to an optical bridge that extends along the first direction and bridges the light. In various examples, each crystal pair of the plurality of crystal pairs includes two crystal elements. In some examples, the two crystal elements in each crystal pair are arranged side-by-side along a first direction and are optically coupled along the first direction only by one optical bridge coupled to each crystal pair. In some examples, each optical bridge is optically shielded from light in the second direction. In various examples, the plurality of crystal pairs are arranged side-by-side along at least the second direction. In some examples, each crystal pair of the plurality of crystal pairs is optically coupled at least with an adjacent crystal pair in the second direction only through the two optical channels. In some examples, each of the two light channels is optically shielded from light in the first direction. In various examples, each of the two optical channels optically couples one crystal element of each crystal pair with one crystal element of an adjacent crystal pair in the second direction. In some examples, the plurality of light sensors are arranged in a plurality of light sensor pairs. In some examples, each of the plurality of photosensor pairs includes two photosensors. In various examples, the two photosensors in each photosensor pair are arranged side-by-side along a first direction. In some examples, one of the plurality of photosensor pairs includes a first photosensor and a second photosensor. In some examples, one crystal pair of the plurality of crystal pairs includes a first crystal element and a second crystal element. In various examples, the first light sensor corresponds to a first crystal element and the second light sensor corresponds to a second crystal element.
In various embodiments, an apparatus for determining a depth of interaction of a PET detector includes: a crystal array including a plurality of crystal elements arranged in crystal rows along a first direction and arranged in crystal columns along a second direction; and a photosensor array comprising a plurality of photosensors arranged in photosensor rows along a first direction and in photosensor columns along a second direction. In some examples, the plurality of crystal elements extend between the first end and the second end along the third direction. In some examples, one of the plurality of crystal rows includes one or more crystal pairs along the first direction. In some examples, one crystal pair of the one or more crystal pairs includes a first crystal element and a second crystal element. In various examples, one of the light sensor rows includes one or more light sensor pairs along a first direction. In some examples, one of the one or more photosensor pairs includes a first photosensor and a second photosensor. In some examples, the first light sensor corresponds to a first crystal element. In various examples, the second light sensor corresponds to a second crystal element. In some examples, one photosensor pair is configured to determine whether a scintillation event occurs within the first crystal element or within the second crystal element and/or to determine a position of the scintillation event along the third direction. In some examples, one of the crystal columns includes a plurality of crystal elements along the second direction. In various examples, one of the plurality of photosensor columns includes a plurality of photosensors along the second direction. In some examples, one column of photosensors corresponds to one column of crystals. In some examples, one photosensor column is configured to determine which crystal element of a plurality of crystal elements a scintillation event occurs within.
In various embodiments, an apparatus for determining the depth of interaction of a PET detector includes a crystal pair and a photosensor pair. In some examples, the crystal pair includes a first crystal element and a second crystal element. In some examples, the first crystal element and the second crystal element are arranged side-by-side along the first direction. In various examples, the first and second crystal elements extend between the first and second ends along a third direction. In some examples, the first and second crystal elements are configured to receive radiation entering from the second end. In some examples, the crystal pair is optically coupled at the second end to an optical bridge that extends along the first direction and bridges the light. In various examples, the first crystal element and the second crystal element are optically coupled only through the optical bridge along the first direction. In some examples, the photo-sensor pair includes a first photo-sensor corresponding to the first crystal element and a second photo-sensor corresponding to the second crystal element. In various examples, the first light sensor and the second light sensor are arranged side-by-side along a first direction.
Additional features will be set forth in part in the description which follows, and in part will become apparent to those having ordinary skill in the art upon examination of the following and the accompanying drawings or may be learned by the manufacture or operation of the examples. The features of the present disclosure may be realized and attained by practice or use of various aspects of the methodologies, instrumentalities and combinations set forth in the detailed examples discussed below.
Drawings
The disclosure is further described in terms of exemplary embodiments. These exemplary embodiments are described in detail with reference to the accompanying drawings. These embodiments are non-limiting exemplary embodiments in which like reference numerals represent like structures throughout the several views of the drawings and wherein:
FIG. 1 is a schematic diagram illustrating an exemplary imaging device, according to some embodiments of the present disclosure;
figure 2a is a schematic diagram illustrating a radial cross-section of an exemplary PET imaging device, according to some embodiments of the present disclosure;
figure 2b is a schematic diagram illustrating an axial cross-section of an exemplary PET imaging device, according to some embodiments of the present disclosure;
FIG. 3a is a schematic diagram illustrating an exemplary probe according to some embodiments of the present disclosure;
FIG. 3b is a schematic diagram illustrating an exemplary probe according to some embodiments of the present disclosure;
FIG. 3c is a schematic diagram illustrating an exemplary probe according to some embodiments of the present disclosure;
FIG. 4 is a schematic diagram illustrating an exemplary probe according to some embodiments of the present disclosure;
FIG. 5 is a schematic diagram illustrating a perspective view of an exemplary crystal group (crystal group) according to some embodiments of the present disclosure;
figure 6a is a schematic diagram illustrating exemplary gamma photon interactions occurring in an exemplary crystal group, according to some embodiments of the present disclosure;
figure 6b is a schematic diagram illustrating exemplary gamma photon interactions occurring in an exemplary crystal group, according to some embodiments of the present disclosure;
FIG. 7 is a schematic diagram illustrating an exemplary crystal group according to some embodiments of the present disclosure;
FIG. 8a is a schematic diagram illustrating an exemplary probe according to some embodiments of the present disclosure;
FIG. 8b is a schematic diagram showing a perspective view of an illustrative crystal set according to some embodiments of the present disclosure;
figure 9a is a schematic diagram illustrating exemplary gamma photon interactions occurring in an exemplary crystal group, according to some embodiments of the present disclosure;
figure 9b is a schematic diagram illustrating exemplary gamma photon interactions occurring in an exemplary crystal group, according to some embodiments of the present disclosure;
FIG. 10a is a schematic diagram illustrating a top view of an exemplary detector, according to some embodiments of the present disclosure;
FIG. 10b is a schematic diagram illustrating a top view of an exemplary detector, according to some embodiments of the present disclosure;
FIG. 11a is a schematic diagram illustrating an exemplary probe according to some embodiments of the present disclosure;
FIG. 11b is a schematic diagram illustrating an exemplary probe according to some embodiments of the present disclosure;
FIG. 12a is a schematic diagram illustrating an exemplary inter-crystal penetration phenomenon (inter-crystal penetration phenomenon) according to some embodiments of the present disclosure;
FIG. 12b is a schematic diagram illustrating an exemplary inter-crystal scattering (ICS) phenomenon, according to some embodiments of the present disclosure;
FIG. 13 is a schematic diagram illustrating an exemplary ICS phenomenon in an exemplary crystal array, according to some embodiments of the present disclosure;
FIG. 14a is a schematic diagram illustrating an exemplary probe according to some embodiments of the present disclosure;
FIG. 14b is a schematic diagram illustrating an exemplary probe according to some embodiments of the present disclosure;
FIG. 15 is a block diagram illustrating an example computing device, according to some embodiments of the present disclosure;
figure 16 is a flow chart illustrating an exemplary process for determining the location of gamma photon interactions in a crystal group according to some embodiments of the present disclosure; and
figure 17 is a flow chart illustrating an exemplary process for determining the location of gamma photon interaction, according to some embodiments of the present disclosure.
Detailed Description
The present disclosure relates to an apparatus, apparatus and method for determining the location of gamma photon interactions in PET detectors. In some embodiments, a PET detector may include a crystal array and a photon sensor array optically coupled to the crystal array. The crystal array may include a plurality of crystal elements arranged along a first direction and a second direction, and the photonic sensor array may include a plurality of photonic sensors. The crystal elements may form a plurality of crystal groups along a first direction. The PET detector may also include a plurality of optical isolators (e.g., a first optical isolator, a second optical isolator, a third optical isolator) of the same or different lengths configured to control light transmission in the PET detector. The location of the gamma photon interaction in the crystal group can be determined based on output information of the photon sensors optically coupled to the crystal group.
Fig. 1 is a schematic diagram illustrating an exemplary imaging device 100, according to some embodiments of the present disclosure. In some embodiments, the imaging device 100 may be a single modality device, such as a Positron Emission Tomography (PET) imaging device. Alternatively, the imaging device 100 may be a multi-modality device, such as a PET-CT imaging device, a PET-MRI imaging device, or the like.
In some embodiments, imaging device 100 may include a PET imaging device 110, a network 120, one or more terminals 130, a computing device 140, and a storage device 150. In some embodiments, the components of imaging device 100 may be connected to each other via network 120. Alternatively or additionally, the components of the imaging device 100 may be directly connected to each other.
The PET imaging device 110 may scan an object and generate scan data corresponding to the object. The object may include, but is not limited to, one or more organs, one or more types of tissue, etc. of a patient. In some embodiments, the PET imaging device 110 may be a medical scanning device, such as a SPET device, a PET-CT device, a PET-MRI device, or the like. The PET imaging device 110 may include a gantry 111, detectors 112, a scanning region 113, and a table 114. The object may be placed on a table 114. The table 114 may convey the object to a target location in the scan area 113. The detector 112 may detect radiation rays (e.g., gamma photons) emitted from a subject in a scanning region 113. In some embodiments, the detector 112 may include a plurality of detector modules. The detector modules may be arranged in a suitable configuration including, but not limited to, a ring (e.g., a detector ring), a rectangle, a triangle, or an array. In some embodiments, the detector 112 may include a plurality of crystal elements, a plurality of photon sensors, and one or more optical isolators as described elsewhere in this disclosure.
For ease of description, a coordinate system including an X-axis, a Y-axis, and a Z-axis is introduced. As shown in fig. 1, the Z-axis direction may refer to a direction along which an object moves into and out of the scanning area 113. The X-axis direction and the Y-axis direction may be perpendicular to each other and form an X-Y plane.
In use, a tracer (e.g., a radioisotope) may be injected (via, for example, a blood vessel of a patient) into a subject. The atoms of the tracer may be added to the biologically active molecule. These molecules may accumulate in the tissues of the patient. When it is estimated that a sufficient amount of molecules have accumulated in the tissue (e.g., after one hour), the patient may be placed on the table 114. The radioisotope can undergo positron emission decay (i.e., beta decay) and emit positrons. Positrons can interact with electrons inside the tissue (the interaction between a positron and an electron is called annihilation). Annihilation of an electron and a positron can each produce a pair of annihilation photons moving in substantially opposite directions. When an annihilation photon is incident on a crystal element of the detector 112, the annihilation photon may be absorbed by the crystal element, producing bursts of optical photons (e.g., visible light photons) that may be detected by one or more photon sensors. The interaction between an annihilation photon and a crystal element that produces a pulse burst of optical photons may be referred to herein as a gamma photon interaction. The depth of gamma photon interaction along the extension direction of the crystal element where the gamma photon interaction occurs may be referred to as DOI.
An image may be generated by the computing device 140 based on information associated with the annihilation photons. For example, the computing device 140 may determine time-of-flight information (time-of-flight information) associated with each of the pairs of annihilation photons. The computing device 140 may also determine DOI information based on output information of the photon sensors in the detector 112. The computing arrangement 140 can also determine the location at which the annihilation occurred based on the time information and the DOI information. After determining the location of the annihilation, the computing arrangement 140 can generate a projection image (also referred to as an acoustic map) based on the location of the annihilation. The computing device 140 may reconstruct the image based on the projection images and a reconstruction technique such as Filtered Back Projection (FBP). The reconstructed image may indicate a tissue containing a large amount of the biologically active molecules of the tracer. In some embodiments, the number of molecules of the tracer in a region can be correlated to a biological function of tissue in the region. For example, if Fluorodeoxyglucose (FDG) is used as a tracer in a PET scan, the number of tracer molecules in a region may be proportional to the metabolic rate of glucose in that region. Since tumors typically consume large amounts of glucose, regions with a large number of molecules can be identified as tumor tissue in the reconstructed image.
Network 120 may include any suitable network that may facilitate the exchange of information and/or data between components of imaging device 100. In some embodiments, one or more components of the imaging device 100 (e.g., the PET imaging device 110, the terminal 130, the computing device 140, the storage device 150, etc.) may communicate information and/or data with one or more other components of the imaging device 100 via the network 120. For example, the computing device 140 may acquire image data (e.g., temporal information, energy information, DOI information) from the PET imaging device 110 via the network 120. As another example, computing device 140 may obtain user instructions from terminal 130 via network 120. Network 120 may include a public network (e.g., the internet), a private network (e.g., a Local Area Network (LAN), a Wide Area Network (WAN), etc.), a wired network (e.g., ethernet), a wireless network (e.g., an 802.11 network, a WiFi network, etc.), a cellular network (e.g., a Long Term Evolution (LTE) network), a frame relay network, a virtual private network ("VPN"), a satellite network, a telephone network, a router, a hub, a switch, a server computer, and/or any combination thereof. By way of example only, network 120 may include a cable network, a wireline network, a fiber optic network, a telecommunications network, an intranet, a Wireless Local Area Network (WLAN), a Metropolitan Area Network (MAN), a Public Switched Telephone Network (PSTN), Bluetooth, or a network such as a Bluetooth networkTMNetwork and ZigBeeTMA network, a Near Field Communication (NFC) network, the like, or any combination thereof.
The terminal 130 may include a mobile device 130-1, a tablet 130-2, a laptop 130-3, etc., or any combination thereof. In some embodiments, the mobile device 130-1 may include smart home devices, wearable devices, mobile devices, virtual reality devices, augmented reality devices, and the like, or any combination thereof. In some embodiments, the terminal 130 may be part of the computing device 140.
The computing device 140 may process data and/or information acquired from the PET imaging device 110, the one or more terminals 130, and/or the storage device 150. For example, the computing device 140 may process the imaging data (including temporal information, energy information, DOI information, etc.) and reconstruct an image based on the image data. In some embodiments, the computing device 140 may be a single server or a group of servers. The server groups may be centralized or distributed. In some embodiments, the computing device 140 may be local or remote. For example, the computing device 140 may access information and/or data stored in the PET imaging device 110, the one or more terminals 130, and/or the storage device 150 via the network 120. As another example, computing device 140 may be directly connected to PET imaging device 110, terminal 130, and/or storage device 150 to access stored information and/or data. In some embodiments, the computing device 140 may be implemented on a cloud platform. By way of example only, the cloud platform may include a private cloud, a public cloud, a hybrid cloud, a community cloud, a distributed cloud, an interconnected cloud (inter-cloud), a multi-cloud (multi-cloud), the like, or any combination thereof. In some embodiments, the computing device 140 or a portion of the computing device 140 may be integrated into the PET imaging device 110.
Computing device 140 may include a processor, a memory module, input/output (I/O), and communication ports. The processor may execute computer instructions (e.g., program code) and perform the functions of the computing device 140 described herein. The computer instructions may include, for example, routines, programs, objects, components, data structures, procedures, modules, and functions that perform the particular functions described herein. The memory module may store data/information obtained from the PET imaging device 110, the terminal 130, the memory device 150, and/or any other component of the imaging device 100. In some embodiments, the memory module may include mass storage, removable storage, volatile read-write memory, read-only memory (ROM), the like, or any combination thereof. I/O may input and/or output signals, data, information, etc. In some embodiments, the I/O may enable a user to interact with the computing device 140. In some embodiments, the I/O may include an input device and an output device. Examples of input devices may include a keyboard, mouse, touch screen, microphone, etc., or any combination thereof. Examples of output devices may include a display device, speakers, a printer, a projector, etc., or any combination thereof. The communication port may be connected to a network (e.g., network 120) to facilitate data communication. The communication port may establish a connection between the computing device 140 and the PET imaging device 110, the terminal 130, and/or the storage device 150. The connection may be a wired connection, a wireless connection, any other communication connection that may enable data transmission and/or reception, and/or any combination of these connections.
Storage device 150 may store data, instructions, and/or any other information. In some embodiments, storage device 150 may store data obtained from one or more terminals 130 and/or computing devices 140. In some embodiments, storage device 150 may store data and/or instructions that computing device 140 may perform or use to perform the exemplary methods described in this disclosure. In some embodiments, the storage device 150 may store image data (e.g., temporal information, energy information, DOI information) acquired from the PET imaging device 110. In some embodiments, storage device 150 may include mass storage, removable storage, volatile read-write memory, read-only memory (ROM), the like, or any combination thereof. In some embodiments, storage device 150 may be connected to network 120 to communicate with one or more other components of imaging device 100 (e.g., computing device 140, one or more terminals 130, etc.). Alternatively or additionally, the storage device 150 may be part of the computing device 140.
It should be noted that the above description of the imaging device 100 is provided for illustrative purposes only and is not intended to limit the scope of the present disclosure. Many variations and modifications may be made in light of the teachings of the present disclosure by those of ordinary skill in the art. For example, the components and/or functionality of the imaging device 100 may vary or change depending on the particular implementation scenario. By way of example only, some other components may be added to the imaging apparatus 100, such as a patient positioning unit, data acquisition electronics, a power supply, and other devices or units. However, those variations and modifications do not depart from the scope of the present disclosure.
Fig. 4 is a schematic diagram illustrating an example detector 400 according to some embodiments of the present disclosure. In some embodiments, the detector 400 may be an example of the detector 112 or a portion of the detector 112. The detector 400 may be configured to detect annihilation photons generated by annihilation events during scanning of the object.
As shown in fig. 4, detector 400 may include a crystal array 410, a photon sensor array 420 coupled to crystal array 410, one or more first optical isolators 412, and one or more second optical isolators 413. The crystal array 410 may include a plurality of crystal elements 411 (e.g., crystal element 411a, crystal element 411b, crystal element 411c, and crystal element 411d), the plurality of crystal elements 411 configured to receive annihilation photons from the object. For simplicity and illustrative purposes, the crystal array 410 is shown to include only one row of crystal elements 411. And are not intended to be limiting. In some embodiments, crystal array 410 may include a two-dimensional array of crystal elements. See, for example, fig. 11a, 11b, and 13 and their description. The photon sensor array 420 may comprise a plurality of photon sensors 421, the plurality of photon sensors 421 being configured to detect optical photons emitted from the first end of the crystal element 411.
The array of crystals 410 may be arranged in a first direction, forming columns of crystals as shown in fig. 4. Each crystal element 411 may include a first end S1 and a second end S2, and extend from the first end S1 to the second end S2 along the third direction. As used herein, the first end S1 of the crystal element 411 may refer to the end through which optical photons exit the crystal element 411 to enter the photonic sensor 421. The second end S2 of the crystal element 411 may refer to the end through which radiation rays (e.g., gamma rays resulting from an annihilation event) enter the crystal element 411. The second end S2 of the crystal element 411 may be closer to the object being scanned than the first end S1 of the same crystal element 411.
The crystal element 411 may be made of any material capable of absorbing radiation rays and emitting a part of the absorbed radiation rays as light. For example, the crystal element 411 may be made of, for example, Bismuth Germanium Oxide (BGO), lutetium oxyorthosilicate (LSO), lutetium yttrium oxyorthosilicate (LYSO), lutetium gadolinium oxyorthosilicate (LGSO), gadolinium oxyorthosilicate (GSO), yttrium oxyorthosilicate (YSO), barium fluoride, sodium iodide, cesium iodide, lead tungstate, yttrium aluminate, lanthanum chloride, lutetium aluminum perovskite (lutetium aluminum perovskite), lutetium disilicate, lutetium aluminate, lutetium iodide, thallium bromide, or the like, or any combination thereof. The different crystal elements 411 may be made of the same material or different materials.
The size and/or shape of the different crystal elements 411 may be the same or different. For example, the crystal elements 411 of the crystal array may have uniform size and shape. As another example, different crystal elements 411 may have different lengths. As used herein, the length of the crystal element 411 may refer to its length along its extension direction (i.e., the third direction). In some embodiments, the size and/or shape of the crystal element 411 may vary depending on one or more conditions, including, for example, the image resolution of the detector 400, the size of the detector 400, or the like, or any combination thereof.
In some embodiments, each of the plurality of photonic sensors 421 may be optically single-ended coupled with one or more crystal elements 411 of crystal array 410. Different photon sensors 421 may be coupled with the same number (or count) or different number (or count) of crystal elements 411. Photonic sensors 421 may be coupled to a corresponding one or more crystal elements 411 in any suitable manner. For example, photonic sensor 421 may directly contact a corresponding one or more crystal elements 411. As another example, photonic sensors 421 may be secured to a corresponding one or more crystal elements 411 by one or more adhesive materials (e.g., a light-transmissive glue). As yet another example, photonic sensor 421 may be single-ended coupled with a corresponding one or more crystal elements 411 via a light transmissive material (e.g., a glass sheet). In some embodiments, one or more photon sensors 421 may be optically coupled with the crystal element 411 (e.g., any of 411 a-411 d) to receive photons from a single end of the crystal element 411 (e.g., the first end S1). As used herein, a detector that detects photons from a single end of each of the crystal elements 411 using one or more photon sensors 421 may be referred to as a detector having a single-ended readout structure.
In some embodiments, the photon sensor 421 may include a photo-transistor, a photomultiplier tube (PMT), a photodiode, an active pixel sensor, a bolometer, a gaseous ionization detector, a photo-resistor, a phototransistor, an Avalanche Photodiode (APD), a single photon avalanche photodiode (SPAD), a silicon photo-multiplier tube (SiPM), a digital silicon photo-multiplier tube (DSiPM), or the like, or any combination thereof. The different photon sensors 421 may be the same type or different types of photon sensors.
In some embodiments, the crystal elements 411 of the crystal array 410 may form a plurality of crystal groups 430 along a first direction. Each crystal group 430 may include at least two crystal elements of the plurality of crystal elements 411. For example, as shown in fig. 4, the crystal element 411a and the crystal element 411b may form a crystal group 430a, and the crystal element 411c and the crystal element 411d may form a crystal group 430 b. It should be noted that the example shown in fig. 4 is provided for illustrative purposes only and is not intended to limit the scope of the present disclosure. The crystal group 430 may include any number or count of crystal elements 411. For example, the crystal element 411a, the crystal element 411b, the crystal element 411c, and the crystal element 411d may together form the crystal group 430.
In some embodiments, light sharing may be allowed between two adjacent (or neighboring) crystal elements 411 belonging to one crystal group 430, while light sharing may be limited or substantially limited between two adjacent crystal groups to facilitate location determination of gamma photon interaction. As used herein, two crystal elements 411 can be considered adjacent or proximate to each other if no other crystal element is located between the two crystal elements 411. In some embodiments, two adjacent or neighboring crystal elements may be separated by a void space (void space), which is an article other than a crystal element, such as a film, a coating, a layer of a material different from the material of any of the neighboring crystal elements, or a combination thereof. By way of example only, there may be a space between two adjacent crystal elements, and a portion of the space may be filled with an optical isolator (e.g., a second optical isolator described elsewhere in this disclosure), and a portion of the space may be empty.
Two crystal groups may be considered adjacent or near each other if there are no other crystal groups between them. In some embodiments, two adjacent or neighboring crystal groups may be separated by a void space, which is an article other than a crystal group, such as a film, a coating, a layer of a material different from the material of any of the crystal elements of the neighboring crystal group, or a combination thereof. By way of example only, there may be a space between two adjacent crystal groups, and a portion of the space may be filled with an optical isolator (e.g., a first optical isolator described elsewhere in this disclosure), and a portion of the space may be empty. As another example, the space between two adjacent crystal groups may be substantially completely filled with an optical isolator (e.g., a first optical isolator described elsewhere in this disclosure).
To control the transmission of light between two adjacent crystal elements 411 or two crystal groups 430, a plurality of optical isolators can be used in the detector 400. The optical isolator may include a reflective film, a reflective foil, a reflective coating (e.g., a white reflective coating), or any other material that may prevent or substantially prevent the transmission of light. For example, as shown in FIG. 4, a first optical isolator 412 of a first length may be configured between two adjacent crystal groups 430a and 430 b. A second optical isolator 413 of a second length may be disposed between two adjacent crystal elements 411a and 411b of the crystal group 430 a. The first length of first optical isolator 412 may be greater than the second length of second optical isolator 413 such that more space is available between crystal group 430a and crystal group 430b for optical photons to travel than between crystal element 411a and crystal element 411 b. As used herein, the length of the optical isolator may refer to its length in the extending direction (i.e., the third direction) of the crystal element 411.
In some embodiments, the first optical isolator 412 may extend in the third direction from the first end S1 of at least one of the two crystal elements 411 (e.g., crystal element 411b and crystal element 411c) between which the first optical isolator 412 is located. The length of the first optical isolator 412 can be equal or substantially equal to the length of at least one of the crystal element 411b and the crystal element 411c to completely or substantially completely block light transmission between the crystal group 430a and the crystal group 430 b.
In some embodiments, the second optical isolator 413 can extend in a third direction from the first end S1 of at least one of the two crystal elements 411 (e.g., crystal element 411a and crystal element 411b) between which the second optical isolator 413 is located. The length of the second optical isolator 413 may be less than or substantially less than the length of at least one of the crystal element 411a and the crystal element 411b to partially block light transmission between the crystal element 411a and the crystal element 411 b. In some embodiments, the length of the second optical isolator 413 may be equal to or greater than the length of at least one of the crystal element 411a and the crystal element 411 b.
For illustrative purposes, only one first optical isolator 412 and one second optical isolator 413 are shown in FIG. 4, but the probe 400 may include any number or count of first and second optical isolators 412, 413. For example, the detector 400 may include a plurality of first optical isolators 412 and/or a plurality of second optical isolators 413. Each first optical isolator 412 can be located between two adjacent or neighboring crystal groups 430 and extend in a third direction from the first end S1 of at least one of the two adjacent crystal elements between which the first optical isolator 412 is located. The length of each first optical isolator 412 may be equal to the length of at least one of two adjacent crystal elements between which the first optical isolator 412 is located. Each second optical isolator 413 can be located between two adjacent or neighboring crystal elements 411 of the crystal group 430 and extend in the third direction from the first end S1 of at least one of the two adjacent or neighboring crystal elements between which the second optical isolator 413 is located. The length of each second optical isolator 413 can be less than the length of at least one of two adjacent or neighboring crystal elements between which the second optical isolator 413 is located. The lengths of the different first optical isolators 412 in the detector 400 may be the same or different. The lengths of the different second optical isolators 413 in the detector 400 may be the same or different. In some embodiments, the detector 400 may include a first optical isolator 412 located between each pair of adjacent or neighboring crystal groups 430. Additionally or alternatively, the detector 400 may include a second optical isolator 413 positioned between each pair of adjacent or neighboring crystal elements 411 of each crystal group 430.
It should be noted that the example shown in fig. 4 is provided for illustrative purposes only and is not intended to limit the scope of the present disclosure. Many variations and modifications will be apparent to those of ordinary skill in the art in light of this disclosure. However, those variations and modifications do not depart from the scope of the present disclosure. In some embodiments, crystal array 410 may include any suitable number or count of crystal elements 411. For example, the crystal array 410 may include an even number or count (e.g., 2, 4, 6, 8, or 12) of crystal elements 411. The crystal elements 411 may be arranged in any suitable manner. For example, the crystal elements 411 of the crystal array 410 may be arranged in a two-dimensional array comprising a plurality of rows and columns. In some embodiments, the first length of the first optical isolator 412 may be equal to the second length of the second optical isolator 413.
Fig. 5 is a schematic diagram illustrating a perspective view of an exemplary crystal group 430a, according to some embodiments of the present disclosure. As described with respect to fig. 4, crystal group 430a may include crystal element 411a and crystal element 411 b. Photon sensor 421a and photon sensor 421b (shown as shaded regions in fig. 5) may be optically coupled with crystal element 411a and crystal element 411b, respectively.
The shaded regions shown in fig. 5 represent one or more optical isolators configured to block or partially block light transmission between the crystal elements 411. For example, first optical isolator 412 may substantially or completely cover the side surfaces of crystal element 411b to prevent optical photons in crystal group 430a from traveling through the side surfaces facing an adjacent crystal group to an adjacent crystal group (not shown in FIG. 5). The first length of the first optical isolator 412 may be equal to the length of the crystal element 411 b. A second optical isolator 413 can be located between the crystal element 411a and the crystal element 411 b. The second optical isolator 413 may extend from the first end S1 of the crystal element 411a or the crystal element 411b in the third direction. The second length of the second optical isolator 413 may be smaller than the length of the crystal element 411a or the crystal element 411b so that it may partially block optical photon transmission between the crystal element 411a and the crystal element 411 b.
In some embodiments, the length of the second optical isolator 413 can be equal to N% of the length of the crystal element 411a or 411 b. N may have any suitable positive value. In some embodiments, N may be in the range of 30 to 90, 50 to 80, and so on. For example, N may be 30, 40, 50, 60, 70, 80, 85, or 90. N may be a parameter used in the determination of the location of gamma photon interaction in the detector 400. In some embodiments, N may be a default parameter stored in a storage device (e.g., storage device 150). Additionally or alternatively, N may be set manually or determined by one or more components of the imaging device 100, depending on the circumstances.
Fig. 6a and 6b are schematic diagrams illustrating exemplary gamma photon interactions occurring in an exemplary crystal group 430a, according to some embodiments of the present disclosure.
Gamma photon interactions occurring in crystal group 430a may excite one or more optical photons, which may be detected by corresponding photon sensors 421a and/or 421b as described elsewhere in this disclosure. The number or count of optical photons detected by photon sensor 421a or photon sensor 421b can be correlated to the location of gamma photon interaction in crystal group 430 a. For example, as shown in FIG. 6a, gamma photon interaction 4 occurs at a position (denoted as T in FIG. 6 a) closer to the first end S1 than the top of the second optical isolator 413 (or lower than the top of the second optical isolator 413). The second optical isolator 413 may block or substantially block one or more optical photons generated by the gamma photon interaction 4 from traveling into the crystal element 411 b. Accordingly, all or substantially all optical photons excited by the gamma photon interaction 4 are detected by the photon sensor 421 a. By way of example only, as shown in fig. 6a, a gamma photon interaction 4 may produce three optical photons 4a, 4b, and 4 c. Optical photons 4a and 4b are detected directly by photon sensor 421a, optical photons 4c are reflected by second optical isolator 413, and then detected by photon sensor 421 a.
As another example, as shown in fig. 6b, gamma photon interaction 5 occurs at a location (denoted as T in fig. 6 b) that is farther from the first end S1 than the top of the second optical isolator 413 (or higher than the top of the second optical isolator 413). The second optical isolator 413 may partially block one or more optical photons excited by the gamma photon interaction 5 from traveling into the crystal element 411 b. Accordingly, optical photons are detected by both photon sensor 421a and photon sensor 421 b. By way of example only, the gamma photon interaction 5 may produce three optical photons 5a, 5b, and 5 c. Optical photons 5a and 5b are detected directly by photon sensor 421a, optical photons 5c travel into crystal element 411, and are detected by photon sensor 421 b.
Fig. 7 is a schematic diagram illustrating an exemplary crystal group 700, according to some embodiments of the present disclosure.
The crystal group 700 may be similar to the crystal group 430a as described with respect to fig. 4-6, except that the second ends S2 of the crystal element 411a and the crystal element 411b may be integrated into a single end. In some embodiments, the crystal group 700 can be fabricated by partially cutting a single crystal block into the crystal element 411a and the crystal element 411 b. The cut may extend from the first end S1 of the crystal block to its second end S2, and the cut may extend to a depth without reaching the second end S2. The second optical isolator 413 can be made by filling the cut grooves of the crystal block with one or more light reflecting materials. In such a case, light transmission between the crystal elements 421a and 421b may be allowed in the uncut portion near the second end S2, while light transmission between the crystal elements 421a and 421b is prevented in the cut portion near the first end S1. One or more first optical isolators 412 may be formed by coating the side surfaces of the crystal element 411a and/or the crystal element 411b with a light reflective material. In such a case, light transmission between crystal group 700 and an adjacent group (not shown in fig. 7) can be prevented.
In some embodiments, the location of gamma photon interaction 7 in crystal group 700 may be determined based on the output information of photon sensor 421a and photon sensor 421 b. The output information may reflect the energy of optical photons excited by gamma photon interaction 6 and detected by photon sensor 421a and/or photon sensor 421 b. In some embodiments, the crystal element in which the gamma photon interaction 6 occurs (also referred to as the target crystal element) and/or the depth of the gamma photon interaction 6 in the target crystal element may be determined based on the output information. More description about determining the location of gamma photon interactions can be found elsewhere in this disclosure. See, for example, fig. 16 and 17 and their associated description.
Fig. 8a is a schematic diagram illustrating an exemplary detector 800a, according to some embodiments of the present disclosure. In some embodiments, probe 800a may be an example of probe 112 or a portion of probe 112. Probe 800a may be similar to probe 400 except for certain components or features.
As shown in fig. 8a, the probe 800a may include a plurality of crystal groups 700 (e.g., crystal group 700a and crystal group 700b) arranged along a first direction. The second ends S2 of the crystal elements 411 in each crystal group 700 may be integrated into a single end. For example, the second ends S2 in the crystal element 411a and the crystal element 411b of the crystal group 700a may form an integrated end.
In some embodiments, detector 800a can be made by cutting a single crystal block in a third direction to create a plurality of cuts. The cuts may extend from the first end S1 of the crystal block and have various lengths in the third direction. For example, to form a plurality of crystal groups 700, one or more first cuts may be made to penetrate (penetrate) the crystal block from its first end S1 to its second end S2. The kerfs of the first cut may be at least partially filled with one or more light reflecting materials, and the one or more light reflecting materials in each kerf may form a first optical isolator 412. As another example, to form the crystal elements in each crystal group 700, one or more second cuts may be made by cutting from the first end S1 toward, but not to, the second end S2. The dicing channels of the second cut may be at least partially filled with one or more light reflecting materials, and the light reflecting material in each dicing channel may form a second optical isolator 413.
In some embodiments, the detector 800a may be fabricated by assembling a plurality of crystal groups 700 along a first direction. Each crystal group 700 may be fabricated in a similar manner as described in fig. 7. The crystal groups 700 may be assembled together in any suitable manner (e.g., by one or more bonding materials).
Fig. 8b is a schematic diagram illustrating a perspective view of an exemplary crystal group 800b, according to some embodiments of the present disclosure. Except for certain components or features, crystal group 800b may be similar to crystal group 430 (e.g., crystal group 430a) as described elsewhere in this disclosure (e.g., fig. 4 and 5 and their associated descriptions).
The crystal group 800b may include a crystal element 411a, a crystal element 411b, a crystal element 411c, and a crystal element 411 d. The photon sensor 421a, the photon sensor 421b, the photon sensor 421c, and the photon sensor 421d may be optically coupled with the crystal element 411a, the crystal element 411b, the crystal element 411c, and the crystal element 411d, respectively. First optical isolator 412 may substantially or completely cover the side surfaces of crystal group 800b to prevent optical photons from traveling through the side surfaces facing an adjacent crystal group to reach an adjacent crystal group (not shown in fig. 8 b). A second optical isolator 413 (e.g., 413a, 413b, and 413c) may be located between each pair of adjacent crystal elements in crystal group 800 b. Optical isolator the length of each second optical isolator 413 in the second optical isolator group 440 may be less than the length of the first optical isolator 412. The lengths of the different second optical isolators 413 may be the same or different. In some embodiments, the second optical isolators 413a, 413b, and 413c may form a second optical isolator group 440.
It should be noted that the examples shown in fig. 7-9 are provided for illustrative purposes only and are not intended to limit the scope of the present disclosure. A crystal group (e.g., crystal group 700 or crystal group 800b) may include any number or count of crystal elements 411. The second ends S2 of the crystal elements 411 in the crystal group may be separate or integrated into a single end.
Fig. 9a and 9b are schematic diagrams illustrating exemplary gamma photon interactions occurring in an exemplary crystal group 900 according to some embodiments of the present disclosure. The crystal group 900 may be similar to the crystal group 430a as described with respect to fig. 4-6, except including certain features of the following description.
As shown in fig. 9a and 9b, the crystal group 900 may include a crystal element 411a, a crystal element 411b, and a light transmissive window (not shown in the figures). The light transmissive window may allow light transmission between the two crystal elements 411a and 411b of the crystal group 900 such that photons excited by gamma photon interaction in a first crystal element of the crystal group 900 may travel through the second end of the first crystal element, the light transmissive window, and the second end of the second crystal element into a second crystal element of the crystal group 900. For example, photons excited by gamma photon interaction in the crystal element 411a may travel into the crystal element 411b through the second end S2 of the crystal element 411a, the light transmissive window, and the second end S2 of the crystal element 411 b.
In some embodiments, the optically transmissive window can include a plurality of optical isolators and an optically transmissive medium 902. For each of the crystal elements of crystal group 900, an optical isolator may be mounted on each side surface of the crystal element facing an adjacent crystal element of the crystal element in the first direction. The optical isolator may be similar to the first optical isolator 412 as described elsewhere in this disclosure. See, for example, fig. 4-8 b and their associated description. The length of the optical isolator may be equal or substantially equal to the length of the crystal element or at least one of the adjacent crystal elements. For example, as shown in fig. 9a and 9b, an optical isolator 901a can be mounted in a first direction on a right side surface of a crystal element 411b facing an adjacent crystal element in an adjacent crystal group (not shown in the figures). The optical isolator 901a may have a length equal to that of the crystal element 411b to prevent photons in the crystal element 411b from traveling through the right side surface of the crystal element 411 to reach an adjacent crystal element (not shown in the drawings). The optical isolator 901b may be installed between the right side surface of the crystal element 411b and the left side surface of the crystal element 411b in the first direction as shown in fig. 9a and 9 b. The length of the optical isolator 901b may be equal to the length of the crystal element 411b and/or the crystal element 411a to prevent light between the crystal element 411a and the crystal element 411b from being transmitted through the surfaces of the crystal element 411a and the crystal element 411b facing each other.
In some embodiments, two adjacent crystal elements of crystal group 900 may share an optical isolator (e.g., a reflective film) located between the two adjacent crystal elements. Alternatively, each of two adjacent crystal elements may be coated with an optical isolator on its side surface facing the other crystal element of the crystal group 900. For example, both the right side surface of the crystal element 411a and the left side surface of the crystal element 411b may be coated with a reflective coating.
The light-transmitting medium 902 may cover the second ends S2 of the crystal elements 411a and 411 b. Each side surface (e.g., side surface 902a and side surface 902b) of the light-transmitting medium 902 facing the light-transmitting medium 902 of an adjacent crystal group 900 of the crystal group 900 may be coated with a light-reflecting material to completely or substantially completely prevent photons in the crystal group 900 from traveling out of the light-transmitting medium 902 from the side surface of the light-transmitting medium 902. The light-transmitting medium 902 may be made of any material substance that allows light to pass through (e.g., glass). Photons excited by gamma photon interactions occurring in one crystal element of crystal group 900 may travel into light-transmitting medium 902, be reflected one or more times by one of the side surfaces of light-transmitting medium 902, and then travel into another crystal element of crystal group 900. For example, as shown in fig. 9B, photons 10B generated by gamma photon interactions 10 in the crystal element 411a may travel through the light-transmitting medium 902 into the crystal element 411B.
The location of the gamma photon interaction occurring in the crystal group 900 can be determined based on the output information of the photon sensors 421a and 421b optically coupled to the crystal group 900. In some embodiments, the location of the gamma photon interaction may be determined based on the energy detected by photon sensor 421a and photon sensor 421 b. For example, as shown in fig. 9a, the gamma photon interaction 9 occurs at a position closer to the first end S1 than to the second end of the crystal element 411 a. All or substantially all of the photons (e.g., photon 9A, photon 9B, and photon 9C) generated by gamma photon interaction 9 may be detected by photon sensor 421B, which is optically coupled to crystal element 411 a. As another example, as shown in fig. 9b, the gamma photon interaction 10 occurs at a position closer to the first end S2 than to the first end S1 of the crystal element 411 a. A portion of the photons generated by the gamma photon interaction 10 (e.g., photon 10A and photon 10B) may be detected by the photon sensor 421 a. A portion of the photons (e.g., photon 10B) may travel into crystal element 411B via light-transmitting medium 902 and be detected by photon sensor 421B. In some embodiments, the gamma photon interaction location may be determined by performing the process 1600 as described with respect to fig. 16 in some embodiments.
Additionally or alternatively, the location of the gamma photon interaction in crystal group 900 can be determined based on the time at which photons generated by the gamma photon interaction are received by photon sensor 421a and photon sensor 421 b. Taking gamma photon interaction 10 as an example, the time difference between a first point in time when photon sensor 421a receives a photon (e.g., photon 10A) and a first point in time when photon sensor 421B receives a photon (e.g., photon 10B) can be determined. The DOI of the gamma photon interaction 10 can be estimated based on the time difference and the velocity of the light. A shorter time difference may indicate that the gamma photon interaction 10 occurs at a location closer to the second end of the crystal element 411 a.
It should be noted that the crystal group 900 shown in fig. 9a and 9b is provided for illustrative purposes only and is not intended to limit the scope of the present disclosure. Many variations and modifications may be made in light of the teachings of the present disclosure by those of ordinary skill in the art. However, those variations and modifications do not depart from the scope of the present disclosure. In some embodiments, the light-transmitting medium 902 may have any shape and size. In some embodiments, crystal group 900 may include any number or count of crystal elements.
Fig. 10a and 10b are schematic diagrams illustrating top views of an exemplary detector 1000a and an exemplary detector 1000b, respectively, according to some embodiments of the present disclosure.
The detector 1000a may include a crystal array and a photonic sensor array optically coupled to the crystal array (as shown by the shaded region in fig. 10 a). The crystal array may include a plurality of crystal elements arranged along a first direction and a second direction. Along the first direction, the crystal elements may form a plurality of columns of crystal elements and define one or more crystal groups. Along the second direction, the crystal elements may form a plurality of rows. In some embodiments, the second direction may be orthogonal or approximately orthogonal to the first direction. In some embodiments, the first direction may be along the Z-axis as shown in fig. 1 and the second direction may be along the X-axis of the PET imaging device 110 as shown in fig. 1.
As shown in fig. 10a, the detector 1000a may include two crystal element rows (i.e., a first crystal row g1 and a second crystal row g2) and two crystal columns. The first crystal row g1 may include two crystal elements 1010a and 1010b arranged side-by-side along the second direction, and the second crystal row g2 may include two crystal elements 1010c and 1010d arranged side-by-side along the second direction.
The photon sensor array may include a plurality of photon sensors configured to receive optical photons emitted from the crystal elements of the detector 1000 a. Each photonic sensor may be optically coupled to one or more crystal elements. For example, as shown in fig. 10a, a photonic sensor array may include photonic sensors 1020a and photonic sensors 1020 b. Photon sensor 1020a may directly or indirectly contact an end of crystal element 1010a, be optically coupled to at least one of crystal element 1010a and crystal element 1010b (e.g., optically coupled to crystal element 1010 a), and be configured to receive optical photons emitted from crystal element 1010a and crystal element 1010 b. Photon sensor 1020b may directly or indirectly contact an end of crystal element 1010c, be optically coupled with crystal element 1010c, and be configured to receive optical photons emitted from crystal element 1010c and crystal element 1010 d.
The detector 1000b may be similar to the detector 1000a except for certain components or features. The detector 1000b may include a first crystal row g '1 and a first crystal row g' 2, and each of the first crystal row g '1 and the first crystal row g' 2 may include four crystal elements. The photonic sensor array may include photonic sensors 1020 'a, 1020' b, 1020 'c, and 1020'd. Each photonic sensor may be optically coupled to two crystal elements belonging to one crystal row. For example, photonic sensor 1020 'a may be optically coupled with crystal element 1010' a and crystal element 1010 'b in first crystal row g' 1 and configured to detect optical photons emitted from crystal element 1010 'a and crystal element 1010' b. In some embodiments, the photonic sensors 1020 'a and 1020' b may be aligned with the photonic sensors 1020 'c and 1020'd, respectively, along a first direction.
In some embodiments, the crystal elements in a column of crystals may form one or more crystal groups along a first direction (not shown in fig. 10a and 10 b). Each crystal group may include at least two crystal elements. One or more optical isolators disposed between crystal elements and/or groups of crystals may be used in the detector 1000a and/or the detector 1000a to control light transmission. More descriptions of optical isolators (e.g., a first optical isolator, a second optical isolator, and a third optical isolator) can be found elsewhere in this disclosure (e.g., fig. 11 and its description).
It should be noted that the detectors 1000a and 1000b shown in fig. 10a and 10b are provided for illustrative purposes only and are not intended to limit the scope of the present disclosure. Many variations and modifications may be made in light of the teachings of the present disclosure by those of ordinary skill in the art. However, those variations and modifications do not depart from the scope of the present disclosure. In some embodiments, detector 1000a and/or detector 1000b may include any number or count of rows and columns of crystal elements. The photonic sensor may be optically coupled to any number or count of crystal elements. For example, photonic sensor 1020a may be optically coupled with crystal element 1010a, crystal element 1010b, crystal element 1010c, and crystal element 1010d and configured to detect optical photons emitted from crystal element 1010a, crystal element 1010b, crystal element 1010c, and crystal element 1010 d. Different optical photons may be optically coupled with the same number or count of crystal elements or a different number or count of crystal elements.
Fig. 11a is a schematic diagram illustrating an exemplary detector 1100a according to some embodiments of the present disclosure. In some embodiments, probe 1100a may be an example of probe 112 or a portion of probe 112.
Detector 1000a may include a crystal array 1110 and a photon sensor array 1120 optically coupled to crystal array 1110. Except for certain components or features, crystal array 1110 may be similar to crystal array 410 as described with respect to fig. 4. The crystal elements 411 of the crystal array 1110 may form a plurality of crystal rows arranged along the second direction and a plurality of crystal columns arranged along the first direction. For example, as shown in fig. 11a, crystal array 1110 may have a configuration of 9 x 8 crystal elements. In some embodiments, the second direction may be orthogonal or approximately orthogonal to the first direction. In some embodiments, both the first direction and the second direction may be orthogonal or approximately orthogonal to the direction of extension of the crystal elements of the crystal array 1110 (i.e., the third direction). In some embodiments, the first direction, the second direction, and the third direction may be along a Z-axis, an X-axis, and a Y-axis, respectively, of the PET imaging device 110 as shown in fig. 1.
The photonic sensor 1120 may include a plurality of photonic sensors 421 arranged in a first direction and a second direction. Each photonic sensor 421 may be optically coupled to one or more crystal elements in crystal array 1110. For example, along a first direction, each photonic sensor 421 may be optically coupled with one crystal element 411 of a column of crystals. Along the second direction, each photonic sensor 421 may be optically coupled with one or more crystal elements 411 of the crystal row. In some embodiments, the photon sensor 421 may completely cover the first ends S1 of two adjacent crystal elements 411 and be configured to receive optical photons emitted from the two adjacent crystal elements 411. Alternatively, the photon sensor 421 may completely cover the first end of the crystal element 411 and be configured to detect optical photons emitted from the crystal element 411 and adjacent or neighboring crystal elements of the crystal element 411. Photonic sensors 421 can be optically coupled with corresponding one or more crystal elements 411 in any suitable manner as described elsewhere in this disclosure (e.g., fig. 4 and description thereof).
In some embodiments, in each crystal column, corresponding crystal elements 411 may form a plurality of crystal groups 1130 along the first direction. The crystal group 1130 may be similar to the crystal group 700 in fig. 7. The transmission of light between the crystal groups 1130 and within the crystal groups 1130 can be controlled by the application of one or more first optical isolators 412 and one or more second optical isolators 413. The arrangement of the one or more first optical isolators 412 and the one or more second optical isolators 413 between and among the crystal groups 1130 and 1130 included in the crystal groups 1130 may be similar to that of the crystal group 700, and the description thereof will not be repeated.
Additionally or alternatively, in a crystal row, light transmission in the second direction between two adjacent crystal elements 411 can be controlled by applying a plurality of third optical isolators 1140. For example, as shown in FIG. 11a, each third optical isolator 1140 may be located between two adjacent crystal elements 411 along the second direction. Each third optical isolator 1140 may extend in a third direction from the second end S2 of at least one of the two crystal elements 411 between which the third optical isolator 1140 is located. The length of third optical isolator 1140 may be equal to or less than the length of at least one of the plurality of crystal elements between which third optical isolator 1140 is located. The lengths of the different third optical isolators 1140 may be the same or different. In some embodiments, the length of third optical isolator 1140 may be equal to the length of at least one of the plurality of crystal elements between which third optical isolator 1140 is located.
In some embodiments, third optical isolator 1140 may have the same length when the ratio of the number of crystal elements 411 to the number of photon sensors 421 in detector 1100a is less than a threshold value (such as 2, 3, 5, 10). In some embodiments, third optical isolator 1140 may have a greater length if third optical isolator 1140 is located closer to the edge of crystal array 1110. In some embodiments, the plurality of third optical isolators 1140 in the crystal row may form a third optical isolator group. In some embodiments, a plurality of third optical isolators 1140 may be periodically arranged in a third optical isolator group. A description of the arrangement of the third optical isolator can be found, for example, in CN application No. 201410231483.6 filed on 28/5/2014, which is incorporated herein by reference.
Fig. 11b is a schematic diagram illustrating an example probe 1100b, according to some embodiments of the present disclosure. Probe 1100b may be similar to probe 1100a, except for certain components or features. For example, each crystal group in each crystal column of detector 1100b may include four crystal elements 411.
It should be noted that the detectors 1100a and 1100b are provided for illustrative purposes only and are not intended to limit the scope of the present disclosure. Many variations and modifications may be made in light of the teachings of the present disclosure by those of ordinary skill in the art. However, those variations and modifications do not depart from the scope of the present disclosure. In some embodiments, crystal array 1110 can include any suitable number or count of rows of crystals and any number or count of columns of crystals. The number or count of crystal rows and the number or count of crystal columns may be the same or different. In some embodiments, the second ends S2 of the crystal elements 411 of the crystal group 1130 may be integrated into a single end. In some embodiments, third optical isolator 1140 may be replaced with an external light guide (e.g., a glass sheet) when the ratio of the number or count of crystal elements 411 to the number or count of photon sensors 421 in detector 1100a or detector 1100b is less than a threshold value (such as 2, 3, 5, 10).
Fig. 12a is a schematic diagram illustrating an exemplary inter-crystal penetration phenomenon according to some embodiments of the present disclosure. FIG. 12b is a schematic diagram illustrating an exemplary inter-crystal scattering (ICS) phenomenon, according to some embodiments of the present disclosure.
When annihilation photons travel through the crystal elements of the PET device, they may undergo ICS and/or intercrystalline penetration phenomena, which may result in a reduction in resolution of the PET device. As shown in fig. 12a, an inter-crystal penetration phenomenon occurs when an annihilation photon passes through a crystal element 1210 without interacting with the crystal element 1210, interacts with another crystal element 1220, and a corresponding optical photon is detected by an optical photon corresponding to the crystal element 1220. In some embodiments, intercrystalline penetration is more likely for higher energy annihilation photons, and/or annihilation photons entering the crystal element from an angle (an angle from vertical, which is the length along the extension of the crystal element) when the attenuation coefficient of the detector material is reduced.
As shown in fig. 12b, ICS occurs when an annihilation photon enters crystal element 1230, undergoes one or more Compton scatterers (Compton scatterers), interacts with one or more crystal elements other than crystal element 1230, and a corresponding optical photon is detected by one or more photon sensors corresponding to one or more crystal elements other than crystal element 1230, such as crystal element 1240. In some embodiments, annihilation photons entering the crystal element vertically (e.g., along the length of the crystal element 1230 in its direction of extension) or non-vertically are more likely to undergo ICS.
Both ICS phenomena and inter-crystal penetration phenomena can lead to inaccurate DOI determination and LOR assignment, as annihilation photons can excite optical photons detected by the following photon sensors: the photon sensor is optically coupled to the crystal element other than the crystal element from which the annihilation photon originally entered. As such, ICS phenomena and/or intercrystalline breakthrough phenomena may need to be considered in DOI determination.
Fig. 13 is a schematic diagram illustrating an exemplary ICS phenomenon in an exemplary crystal array 1300 according to some embodiments of the present disclosure. As shown, crystal array 1300 may include a plurality of crystal elements a1, a2, A3, B1, B2, and B3. Crystal element A1 and crystal element B1 can form crystal group A1/B1, crystal element A2 and crystal element B2 can form crystal group A2/B2, and crystal element A3 and crystal element B3 can form crystal group A3/B3. A plurality of photon sensors (not shown in fig. 13) may be optically coupled to one or more crystal elements in crystal array 1300 to detect optical photons emitted from the corresponding one or more crystal elements. For purposes of illustration, a photonic sensor optically coupled to crystal elements in one crystal group may be referred to as a photonic sensor group.
In some embodiments, an annihilation photon may undergo ICS as it travels in the crystal element into which it originally entered. For example, as shown in fig. 13, annihilation photons may be scattered after entering crystal element a1, and one or more optical photons generated by the annihilation photons may be detected in one or more of crystal group a1/B1, crystal group a2/B2, and crystal group A3/B3. In some embodiments, the annihilation photon may interact with crystal element a1 (shown in fig. 13 as gamma photon interaction 7). The location of the gamma photon interaction 7 can be determined based on the respective energies detected in the crystal groups a1/B1, a2/B2, and A3/B3. Without considering ICS, the position of the gamma photon interaction 7 may not be accurately determined. For example, if ICS is ignored, position 1320 can be determined as the position of gamma photon interaction 7.
The methods provided herein for determining the location of gamma photon interactions (e.g., gamma photon interaction 7) may take into account ICS phenomena. For example, in each crystal group, candidate locations may be determined based on the energy detected by the corresponding photon sensor group. Each candidate location in the crystal group may include a candidate depth of gamma photon interaction within the crystal group. The location of the gamma photon interaction may then be determined based on the candidate locations. In some embodiments, the candidate location with the smallest candidate depth may be selected as the location of gamma photon interaction. For example, as shown in fig. 13, candidate location 1310 having candidate depth d1, candidate location 1320 having candidate depth d2, and candidate location 1330 having candidate depth d3 may be determined in crystal group a1/B1, crystal group a2/B2, and crystal group A3/B3, respectively. Candidate location 1310 has a minimum candidate depth, illustrating that the candidate location is the initial location of gamma photon interaction, and is therefore considered the location of gamma photon interaction 7. More description about determining the location of gamma photon interactions can be found elsewhere in this disclosure. See, for example, fig. 16 and 17 and their associated description.
Fig. 14a is a schematic diagram illustrating an exemplary detector 1400, according to some embodiments of the present disclosure. FIG. 14b is a perspective view illustrating a portion of an exemplary detector 1400 according to some embodiments of the present disclosure.
As shown, the detector 1400 may include a plurality of detector rings 1401 (e.g., detector ring 1401-1 through detector ring 1401-n) arranged along an axial direction (also referred to as a Z-axis direction) of the detector 1400. The detector ring may form a scanning channel configured to accommodate an object to be examined. The detector ring 1401 may have any suitable configuration. For example, each detector ring 1401 may form a complete ring as shown in fig. 14 a. Alternatively, the detector ring 1401 may form an incomplete ring. In some embodiments, the detector ring 1401 may include two or more curved detector arrays. For example, each detector ring 1401 may be formed by one or more pairs of curved detector arrays spaced apart from each other by a distance. Each pair of curved detector arrays may be arranged in an opposing configuration. In some embodiments, the configuration of different detector rings 1401 in detector 1400 may be the same or different.
As shown in fig. 14b, a detector ring 1401 (e.g., detector ring 1401-1) may include a plurality of crystal elements 411 and a plurality of photon sensors 421. The crystal elements 411 may be arranged circumferentially along the circumferential direction of the probe ring 1401. Each crystal element 411 may include a proximal end and a distal end with respect to the central axis Z of the probe 1400 and extend in a direction extending from its distal end to its proximal end. The proximal end of the crystal element 411 may be proximate to the central axis and configured to receive radiation rays (e.g., gamma rays resulting from an annihilation event) from the scan region. The distal end of the crystal element 411 may be remote from the central axis and optically coupled with a photonic sensor 421 (shown as a shaded area in fig. 14 b).
In some embodiments, photon sensor 421 may be optically coupled with one or more crystal elements 411 of detector ring 1401. Different photon sensors 421 may be coupled with the same number/count or different number/count of crystal elements 411. For example, each photon sensor 421 may be coupled to two adjacent crystal elements 411 in the detector ring 1401 in the circumferential direction of the detector ring 1401. In some embodiments, the plurality of photonic sensors 421 may form a plurality of photonic sensor rows along the Z-axis direction as shown in fig. 14 b. In some embodiments, coincidence events detected by photon sensors 421 of the same detector ring 1401 may be referred to as direct coincidence, and the coincidence events may define a direct plane. Coincidence events detected by the photon sensors 421 of different detector rings 1401 may be referred to as cross-coincidence, and the coincidence events may define a cross-plane. The direct plane may be parallel or substantially parallel to the X-Y plane as shown in fig. 14a, and the intersecting plane may be at an angle to the X-Y plane.
In some embodiments, the crystal elements 411 may form a plurality of crystal groups 1402 arranged along the Z-axis. Crystal group 1402 may be similar to crystal group 430, except for certain components or features. Each crystal group 1402 may include at least two crystal elements 411 belonging to at least two separate detector rings 1401. For example, as shown in FIG. 14b, crystal element 411e of detector ring 1401-1 and crystal element 411f of detector ring 1401-2 may form a crystal group. As another example, crystal element 411g of detector ring 1401-3 and another crystal element 411 (not shown in FIG. 14 b) in an adjacent detector ring 1401 may form a crystal group.
Similar to the crystal group 430 shown in fig. 4-6 b and the description thereof, one or more first optical isolators 412 and second optical isolators 413 (not shown in fig. 14a and 14 b) may be used in the crystal group 1402 and/or between the crystal groups 1402 to control light transmission between the crystal groups 1402 and within the crystal groups 1402. For example, a first optical isolator 412 of a first length can be disposed or located between two adjacent crystal groups 1402. A second optical isolator 413 of a second length may be disposed or located between two adjacent crystal elements 411 of the crystal group 1402. The first length of the first optical isolator may be greater than the second length of the second optical isolator. As used herein, the length of the optical isolator of two adjacent crystal groups 1402 may refer to its length along the extending direction (or the third direction) of the at least one crystal element 411 of the two adjacent crystal groups 1402. Further description of the first optical isolator 412 and the second optical isolator 413 can be found elsewhere in this disclosure (e.g., fig. 4 and its description).
In some embodiments, to control the transmission of light between two adjacent crystal elements 411 of the detector ring 1401, one or more third optical isolators 1140 (not shown in fig. 14a and 14 b) may be applied. For example, a third optical isolator 1140 (not shown) may be located between each pair of adjacent crystal elements of each detector ring 1401. Further description of third optical isolator 1140 (e.g., fig. 11a and 11b and their description) may be found elsewhere in this disclosure.
It should be noted that the detector 1400 shown in fig. 14a and 14b is provided for illustrative purposes only and is not intended to limit the scope of the present disclosure. Many variations and modifications may be made in light of the teachings of the present disclosure by those of ordinary skill in the art. However, those variations and modifications do not depart from the scope of the present disclosure. In some embodiments, the detector 1400 may include any number/count of detector rings 1401. For example, the detector ring 1400 may include 16, 32, 64, or 96 detector rings. In some embodiments, the crystal group 1402 can include any number/count of crystal elements 411 arranged along the Z-axis direction. For example, the crystal element 411e, the crystal element 411f, and the crystal element 411g may form a crystal group.
Fig. 15 is a block diagram illustrating an example computing device 140, according to some embodiments of the present disclosure. As shown in fig. 15, computing device 140 may include an acquisition module 1501 and a determination module 1502.
The acquisition module 1501 may be configured to acquire information used to determine the location of gamma photon interactions in a crystal group. For example, acquisition module 1501 may acquire output information of a plurality of photonic sensors optically coupled to a crystal group. As another example, acquisition module 1501 may acquire a lookup table that records the relationship between the depth of gamma photon interaction and the output information of photon sensors. In some embodiments, acquisition module 1501 may acquire information from one or more components of imaging device 100 (such as PET imaging device 110, storage device 150). Additionally or alternatively, acquisition module 1501 may acquire information from external sources via network 120.
The determination module 1502 may be configured to determine a location of a gamma photon interaction in a crystal group. For example, the determination module 1502 may determine the target crystal elements of a crystal group for which gamma photon interactions occur. As another example, the determination module 1502 may determine a depth of gamma photon interaction in the target crystal element. In some embodiments, the determination module 1502 may take into account ICS phenomena in determining gamma photon interaction locations. More description about determining the location of gamma photon interactions can be found elsewhere in this disclosure. See, for example, fig. 16 and 17 and their associated description.
It should be noted that the above description of computing device 140 is provided for illustrative purposes only and is not intended to limit the scope of the present disclosure. Many variations and modifications may be made in light of the teachings of the present disclosure by those of ordinary skill in the art. However, those variations and modifications do not depart from the scope of the present disclosure. For example, the computing device 140 may include a storage module configured to store data generated by the aforementioned modules of the computing device 140. As an example, one or more modules may be integrated into a single module to perform its functions. By way of example only, acquisition module 1501 and determination module 1502 may be integrated as modules to acquire and analyze information.
Figure 16 is a flow chart illustrating an exemplary process for determining the location of gamma photon interactions in a crystal group according to some embodiments of the present disclosure. In some embodiments, one or more operations of process 1600 shown in fig. 16 may be implemented in imaging device 100 shown in fig. 1. For example, the process 1600 illustrated in fig. 16 may be stored in the storage device 150 in the form of instructions and invoked and/or executed by the computing device 140.
In 1601, the acquisition module 1501 may acquire output information of the first and second photon sensors. The first and second photonic sensors may be optically coupled with a crystal group (e.g., crystal group 430, crystal group 1402, or crystal group 900) as described elsewhere in this disclosure. The crystal group may include a plurality of crystal elements. Each of the first and second photonic sensors may be optically coupled with one or more crystal elements of the plurality of crystal elements. For example, the crystal group may include two crystal elements, each of which may be optically coupled with the first and second photonic sensors, respectively.
When a gamma photon interaction occurs in a crystal group coupled to the first photon sensor and the second photon sensor, the gamma photon interaction may excite one or more optical photons, which in turn may be detected by the first photon sensor and/or the second photon sensor. In response to the detected optical photons, the first photon sensor and the second photon sensor output electrical signals, which are referred to herein as output information. The output information may include first output information of the first photonic sensor and second output information of the second photonic sensor. In some embodiments, the first output information or the second output information may include a value of energy detected by the corresponding first photon sensor or second photon sensor. Alternatively, the output information of the first photon sensor or the second photon sensor may be a parameter other than the energy value, such as signal intensity, pulse width. The determination module 1502 may determine a corresponding energy value based on the output information.
In 1602, the determination module 1502 may identify a target crystal element in the crystal group in which the gamma photon interaction occurred based on the output information. In some embodiments, the target crystal element in the crystal group may be determined by comparing the energies detected by the first photon sensor and the second photon sensor. The target crystal element may be the crystal element whose corresponding photon sensor detects the greatest energy. For example, if the output information indicates that a greater energy is detected by the first photon sensor than the second photon sensor, the one or more crystal elements corresponding to the first photon sensor may be considered the target crystal element. In some embodiments, the first photonic sensor or the second photonic sensor may correspond to a plurality of crystal elements, and it is possible that the target crystal element may accordingly comprise a plurality of crystal elements.
In 1603, the determination module 1502 may determine a depth of gamma photon interaction within the target crystal element based on the output information. The depth of gamma photon interaction (or DOI) within the target crystal element may refer to the distance between the gamma photon interaction and the first end S1 of the target crystal element along the extension direction of the target crystal element. In some embodiments, the depth may be determined based on a ratio of the energy detected by the first photon sensor to the energy detected by the second photon sensor. For example, the depth d of gamma photon interaction within the target crystal element can be determined according to equation (1):
d＝LUT[E1/(E1+E2)] (1)
wherein E1 represents the energy detected by the first photon sensor; e2 represents the energy detected by the second photon sensor; the LUT represents the operation of looking up a look-up table. The look-up table may refer to a table that records the depth of gamma photon interaction in the target crystal element versus the value of E1/(E1+ E2). In some embodiments, the lookup table may be determined based on the depths of interaction of the plurality of gamma photons and their corresponding E1/(E1+ E2) values. The lookup table may be stored in a storage device (e.g., storage device 150) of the imaging device 100. In determining the depth, the computing device 140 may retrieve a look-up table from the storage device and determine the depth d of gamma photon interaction by querying the look-up table.
It should be noted that the above description of process 1600 is provided for illustrative purposes only and is not intended to limit the scope of the present disclosure. Many variations and modifications of process 600 may occur to those of ordinary skill in the art in light of the present disclosure. However, those variations and modifications do not depart from the scope of the present disclosure. In some embodiments, output information for two or more photonic sensors may be acquired in 1601. The two or more photonic sensors may be optically coupled with a crystal group (e.g., crystal group 430, crystal group 1402) as described elsewhere in this disclosure. The location of the gamma photon interaction may be determined based on the output information by performing operations 1602 and 1603. In some embodiments, as described with respect to fig. 9a and 9b, the DOI within a crystal group (e.g., crystal group 900) at which gamma photon interaction occurs may be determined based on the time at which the corresponding photons are detected by the first and second photon sensors.
Figure 17 is a flow chart illustrating an exemplary process for determining the location of gamma photon interaction, according to some embodiments of the present disclosure. In some embodiments, one or more operations of the process 1700 illustrated in fig. 17 may be implemented in the imaging device 100 illustrated in fig. 1. For example, the process 1700 illustrated in fig. 17 may be stored in the storage device 150 in the form of instructions and invoked and/or executed by the computing device 140. In some embodiments, process 1700 may be an example of process 1600 when considering ICS phenomena.
At 1701, an acquisition module 1501 may acquire output information for a plurality of photonic sensor groups. Each photonic sensor group of the plurality of photonic sensor groups may include two or more photonic sensors and is optically coupled with a crystal group of the detector (e.g., crystal group 430, crystal group 1402). The output information may include output information of the photon sensor groups and is related to gamma photon interactions occurring in the crystal groups.
In 1702, the determination module 1502 may determine a plurality of candidate locations for gamma photon interactions in a crystal group based on the output information. The candidate location may correspond to one of a plurality of crystal groups. The candidate locations corresponding to the crystal groups may include candidate target elements in which gamma photon interactions may have occurred and/or candidate depths of gamma photon interactions in the crystal groups. In some embodiments, for each crystal group, determination module 1502 may determine the location of gamma photon interaction in the crystal group based on the output information of the corresponding photon sensor group by implementing at least a portion of process 1600. The determination module 1502 may then designate the locations in each crystal group as a candidate location.
In 1703, the determination module 1502 may determine that ICS occurred within the crystal group based on the output information. In some embodiments, the determination module 1502 may determine whether ICS has occurred within a crystal group based on the output information of each photon sensor group and the energy of annihilation photons involved in the gamma photon interaction. For example, if the sum of the energies detected by one or more photon sensors in a photon sensor group is equal to the energy of an annihilation photon, determination module 1502 may determine that ICS occurred within multiple crystal groups.
In 1704, the determination module 1502 may designate a candidate location of the plurality of candidate locations having a smallest candidate depth as the location of gamma photon interaction. Since backscatter is rare, the candidate location with the smallest candidate depth may be closest to the object being scanned and correspond to the crystal element from which the annihilation photon originally entered, and thus may be considered the location of the gamma photon interaction.
It should be noted that the above description of process 1700 is provided for illustrative purposes only and is not intended to limit the scope of the present disclosure. Many variations and modifications of the process 1700 may be made by one of ordinary skill in the art in light of the present disclosure. However, those variations and modifications do not depart from the scope of the present disclosure. For example, operation 1702 and operation 1703 may be performed concurrently, or operation 1703 may be performed before operation 1702.
Certain embodiments of the present invention relate to an imaging device. More specifically, some embodiments of the present invention provide an apparatus for medical imaging. By way of example only, some embodiments of the present invention have application to positron emission tomography detectors. It will be appreciated that the invention has a broader range of applicability.
As discussed above and further emphasized here, fig. 9b is merely an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize many variations, substitutions, and modifications. According to some embodiments of the present invention, as shown in fig. 9b, a crystal pair (e.g., a crystal group comprising two crystal elements) is coupled to an optical bridge (e.g., an optical transmission medium 902 of an optical transmission window). While the above has been shown using a selected set of components, there are many alternatives, modifications, and variations. For example, some of the components may be expanded and/or combined. Other components may be inserted into those mentioned above. Depending on the embodiment, the arrangement of components may be interchanged with the arrangement of other components being replaced.
In certain embodiments, the optical bridge of the crystal pair is an internal optical bridge and there is no optical interface between the internal optical bridge and the first crystal of the crystal pair and between the internal optical bridge and the second crystal of the crystal pair. For example, a crystal pair having an internal optical bridge can be formed by cutting a crystal block from a first end up to the internal optical bridge, the internal optical bridge having a height from a second end of the crystal block, thereby defining the first and second crystals each on one side of a cut, and the internal optical bridge at the second end connecting the first and second crystals. As an example, the first and second crystals are physically separated by an optical isolator (e.g., an optical shield) and connected by an internal optical bridge (e.g., located at the second end).
In some embodiments, the optical bridge of the crystal pair is an external optical bridge with optical interfaces between the external optical bridge and a first crystal of the crystal pair and between the external optical bridge and a second crystal of the crystal pair. For example, a crystal pair having an external optical bridge may be formed by coupling a first crystal and a second crystal together with the external optical bridge at a second end (e.g., such as by bonding with an optical glue) such that the three separate sheets are coupled together. As an example, the first and second crystals are physically separated by an optical isolator (e.g., an optical shield) and connected by an external optical bridge (e.g., at the second end). In some examples, the external optical bridge is configured to create a substantially seamless interface between the external optical bridge and the crystal pair. The seamless interface may increase the sensitivity and/or accuracy of the prediction of the coordinates of scintillation events occurring in the crystal pair. In some examples, the external optical bridge is configured to create a reflective surface at an interface between the external optical bridge and the crystal pair. In some examples, the reflective surface is configured to assist optical radiation to travel from one crystal to the other crystal of the crystal pair.
In various embodiments, the detector 112 for detecting the three-dimensional position of a scintillation event that converts gamma radiation to visible radiation or light photons includes: a crystal array 410 including a plurality of crystal elements 411 arranged at least in a first direction and a second direction; and a photon sensor array 420 comprising a plurality of photon sensors 421 arranged at least along a first direction and a second direction. In some examples, the plurality of crystal elements 411 extend between the first end S1 and the second end S2 along the third direction. In certain examples, the plurality of crystal elements 411 are configured to receive gamma radiation entering from the second end S2. In various examples, the plurality of photon sensors 421 are configured to receive visible radiation or light photons at the first end S1. In some embodiments, the plurality of crystal elements 411 are arranged into a plurality of crystal groups 430. In certain examples, each crystal group of the plurality of crystal groups 430 is optically coupled to one light transmissive medium 902 of the light transmissive window at the second end S2, the light transmissive medium 902 extending in the first direction and bridging the visible radiation or the visible photons. In various examples, each crystal group of plurality of crystal groups 430 includes two crystal elements. For example, one crystal group includes a crystal 411a and a crystal 411 b. In some examples, the two crystal elements in each crystal group are arranged side-by-side along the first direction and are only optically coupled through the light-transmitting medium 902 coupled to the light-transmissive window of each crystal group for visible radiation or visible photons along the first direction. In some examples, the light-transmitting medium 902 of each light-transmissive window is optically shielded from light in the second direction. In various examples, the plurality of crystal groups 430 are arranged side-by-side along at least the second direction. In some examples, each crystal group of the plurality of crystal groups 430 is optically coupled at least with an adjacent crystal group through only two optical channels for visible radiation or visible photons in the second direction. For example, the columns of crystals are optically coupled only through the first optical channel 1172a and the second optical channel 1172b (see, e.g., fig. 11a) for visible radiation or visible photons in the second direction. In some examples, each of the two optical channels is optically shielded from visible radiation or visible photons along the first direction. For example, the first optical channel 1172a and the second optical channel 1172b are each optically shielded from visible radiation or visible photons along the first direction. In some examples, a group of light channels corresponds to each crystal group. In various examples, each optical channel optically couples one crystal element of each crystal group with one crystal element of an adjacent crystal group for visible radiation or optical photons in the second direction. In some examples, the plurality of photonic sensors 421 are arranged into a plurality of photonic sensor groups. In some examples, each of the plurality of photon sensor groups includes two photon sensors, such as only two photon sensors. In various examples, the two photonic sensors in each photonic sensor group are arranged side-by-side along the first direction. In some examples, one of the plurality of photon sensor groups includes a first photon sensor 421a and a second photon sensor 421 b. In certain examples, one crystal group of the plurality of crystal groups 430 includes a first crystal 411a and a second crystal 411 b. In various examples, the first photonic sensor 421a corresponds to the first crystal 411a and the second photonic sensor 421b corresponds to the second crystal 411 b.
In some embodiments, each crystal element of the plurality of crystal elements 411 (see, e.g., fig. 11a) is defined by one or more optical isolators that extend along the third direction. In some examples, the one or more spacers are configured to shield at least visible radiation or visible photons.
In some embodiments, the one or more spacers include a first optical isolator 412 (see, e.g., fig. 11a), the first optical isolator 412 being disposed at an interface between two adjacent crystal groups of the plurality of crystal groups 430 along the first direction. In some examples, first optical isolator 412 extends from first end S1 to second end S2 to optically shield two adjacent crystal groups in a first direction.
In some embodiments, the one or more isolators include a second optical isolator 413, the second optical isolator 413 being disposed at an interface between the first crystal 411a and the second crystal 411b included in one of the plurality of crystal groups 430. In some examples, the second optical isolator 413 (see, e.g., fig. 11a) extends from the first end S1 toward the second end S2 until reaching the light-transmitting medium 902 of the light-transmissive window optically coupling the first crystal 411a and the second crystal 411 b.
In some embodiments, the one or more spacers include a third optical isolator 414, the third optical isolator 414 being disposed along the second direction at an interface between two adjacent crystal groups of the plurality of crystal groups 430. In some examples, the third optical isolator 414 extends from the second end S2 toward the first end S1 until reaching an optical channel that optically couples two adjacent crystal groups in the second direction.
In some embodiments, the light-transmissive window light-transmitting medium 902 that optically couples the two crystal elements (e.g., crystal 421a and crystal 421b) in each crystal group is an inner light-transmissive window configured to be optically transparent to visible radiation or visible photons when the visible radiation or photons travel between the two crystal elements.
In some embodiments, the light-transmissive window light-transmitting medium 902 that optically couples the two crystal elements (e.g., crystal 421a and crystal 421b) in each crystal group is an external light-transmissive window configured such that the external optical bridge creates an optical interface to visible radiation or visible photons as the visible radiation or photons travel between the two crystal elements.
In some embodiments, the light transmissive medium 902 of the light transmissive window optically coupling the two crystal elements (e.g., crystal 421a and crystal 421b) in each crystal group comprises a scintillation material or a transmissive material.
In some embodiments, the first direction is orthogonal to the second direction, the first direction is orthogonal to the third direction, and the second direction is orthogonal to the third direction.
In some embodiments, the first direction is non-linear and is along at least a portion of a circle. For example, when crystal array 410 includes detector ring 1401 forming a complete or incomplete ring, crystal array 410 is arranged in a first direction that is non-linear.
In some embodiments, the plurality of crystal elements 411 are polished at the second end S2.
In various embodiments, the detector 112 for detecting one or more three-dimensional locations of one or more scintillation events that convert gamma radiation into visible radiation or light photons includes: a crystal array 410 including a plurality of crystal elements 411 arranged in crystal rows along a first direction and arranged in crystal columns along a second direction; and a photon sensor array 420 comprising a plurality of photon sensors 421 arranged in photon sensor rows along a first direction and in photon sensor columns along a second direction. In some examples, the plurality of crystal elements 411 extend between the first end S1 and the second end S2 along the third direction. In certain examples, the plurality of crystal elements 411 are configured to receive gamma radiation from the second end S2. In various examples, the plurality of photon sensors 421 are configured to receive visible radiation or light photons at the first end S1. In some examples, one of the crystal rows includes one or more crystal groups 430 along the first direction. In some examples, one of the one or more crystal groups includes a first crystal element (e.g., crystal 411a) and a second crystal element (e.g., crystal 411 b). In various examples, one of the photon sensor rows includes one or more photon sensor groups along a first direction. In some examples, one of the one or more photonic sensor groups includes a first photonic sensor (e.g., photonic sensor 421a) and a second photonic sensor (e.g., photonic sensor 421 b). In some examples, the first photonic sensor (e.g., photonic sensor 421a) corresponds to a first crystal element (e.g., crystal 411 a). In various examples, the second photonic sensor (e.g., photonic sensor 421b) corresponds to a second crystal element (e.g., crystal 411 b). In some examples, one photonic sensor group is configured to determine whether a scintillation event occurs within a first crystal element (e.g., crystal 411a) or a second crystal element (e.g., crystal 411b) and/or to determine a position of the scintillation event along a third direction. In some examples, one of the crystal columns includes a plurality of crystal elements along the second direction. In various examples, one of the photon sensor columns includes a plurality of photon sensors along the second direction. In some examples, one photonic sensor column corresponds to one crystal column. In some examples, one photonic sensor column is configured to determine which crystal element of a plurality of crystal elements within which a scintillation event occurred.
In some embodiments, the first photon sensor 421a is configured to acquire a first energy, the second photon sensor 421b is configured to acquire a second energy, and one photon sensor group is configured to determine whether the location of the scintillation event is within the first crystal 411a or the second crystal 411b based at least in part on the first energy and the second energy.
In some embodiments, one photon sensor group is further configured to determine a location of the scintillation event along the third direction based at least in part on the first energy and the second energy based at least in part on: if the first energy is greater than the second energy, the location of the scintillation event is determined to be in the first crystal 411a, and if the first energy is less than the second energy, the location of the scintillation event is determined to be in the second crystal 411 b.
In some embodiments, the first photon sensor 421a is configured to acquire a first energy, the second photon sensor 421b is configured to acquire a second energy, and one photon sensor group is configured to determine a location of the scintillation event in a third direction based at least in part on the first energy and the second energy.
In some embodiments, the one photon sensor group is further configured to determine the location of the scintillation event in the third direction based at least in part on the calculated energy ratio (the calculated energy ratio based at least in part on the first energy and the second energy) and determining the location of the scintillation event in the third direction based at least in part on the energy ratio and the lookup table.
In some embodiments, the one photon sensor group is further configured to determine the location of the scintillation event in the third direction based at least in part on a calculated energy ratio (the calculated energy ratio based at least in part on the first energy and the second energy) and based at least in part on a distance ratio between the first path and the second path. The first path is from the location of the scintillation event to the first photon sensor 421a and the second path is from the location of the scintillation event to the second photon sensor 421 b.
In some embodiments, the crystal array 410 includes a first crystal group a1/B1 and a second crystal group A3/B3, and the photonic sensor array 420 includes a first photonic sensor group and a second photonic sensor group. In some examples, the first photon sensor group is configured to determine a first three-dimensional position of the first scintillation event within the first crystal group a 1/B1. In some examples, the first three-dimensional location includes a first depth along the third direction. In some examples, the second photon sensor group is configured to determine a second three-dimensional position of the second scintillation event within the second crystal group a 3/B3. In some examples, the second three-dimensional location includes a second depth along the third direction. In various examples, the first photon sensor group and the second photon sensor group are configured to determine that the first scintillation event occurred before the second scintillation event in response to the first depth being less than the second depth, and/or determine that the first scintillation event occurred after the second scintillation event in response to the first depth being greater than the second depth.
In some embodiments, the photon sensor array 420 is configured to generate event coordinates corresponding to a location of a scintillation event based at least in part on the determined crystal element within which the scintillation event occurred and the determined location of the scintillation event along the third direction.
In various embodiments, the detector 112 for detecting the three-dimensional position of a scintillation event that converts gamma radiation into visible radiation or light photons includes a crystal group and a photon sensor group. In some examples, the crystal group includes a first crystal 411a and a second crystal 411 b. In some examples, the first crystal 411a and the second crystal 411b are arranged side by side along the first direction. In various examples, the first and second crystals 411a, 411b extend between the first and second ends S1, S2 along the third direction. In some examples, the first and second crystals 411a, 411b are configured to receive gamma radiation entering from the second end S2. In certain examples, the crystal set is optically coupled to one light transmitting medium 902 of the light transmissive window at the second end S2, the light transmitting medium 902 extending in the first direction and bridging the visible radiation or the visible photons. In various examples, the first crystal 411a and the second crystal 411b are only optically coupled through the light transmissive medium 902 of the light transmissive window for visible radiation or visible photons along the first direction. In some examples, the photonic sensor group includes a first photonic sensor 421a corresponding to the first crystal 411a and a second photonic sensor 421b corresponding to the second crystal 411 b. In certain examples, the first and second photon sensors 421a and 421b are configured to receive visible radiation or visible photons at the first end S1. In various examples, the first and second photonic sensors 421a and 421b are arranged side-by-side along a first direction.
In various embodiments, an apparatus (e.g., detector 112) for detecting a three-dimensional location of a scintillation event that converts radiation (e.g., gamma radiation) to light (e.g., visible radiation or visible photons) includes: a crystal array (e.g., crystal array 410) comprising a plurality of crystal elements (e.g., a plurality of crystal elements 411) arranged at least along a first direction and a second direction; and a photosensor array (e.g., photon sensor array 420) comprising a plurality of photosensors (e.g., a plurality of photon sensors 421) arranged at least along the first direction and the second direction. In some examples, a plurality of crystal elements (e.g., the plurality of crystal elements 411) extends between a first end (e.g., the first end S1) and a second end (e.g., the second end S2) along the third direction. In certain examples, the plurality of crystal elements (e.g., the plurality of crystal elements 411) is configured to receive radiation (e.g., gamma radiation) entering from the second end (e.g., the second end S2). In various examples, a plurality of light sensors (e.g., a plurality of photon sensors 421) are configured to receive light (e.g., visible radiation or visible photons) at a first end (e.g., first end S1). In some embodiments, a plurality of crystal elements (e.g., a plurality of crystal elements 411) are arranged into a plurality of crystal pairs (e.g., a plurality of crystal groups 430). In certain examples, each crystal pair of the plurality of crystal pairs (e.g., the plurality of crystal groups 430) is optically coupled at a second end (e.g., the second end S2) to an optical bridge (e.g., the light transmissive window' S light transmissive medium 902) that extends along the first direction and bridges light (e.g., visible radiation or visible photons). In various examples, each crystal pair of the plurality of crystal pairs (e.g., the plurality of crystal groups 430) includes two crystal elements (e.g., crystal 411a and crystal 411 b). In some examples, the two crystal elements in each crystal pair (e.g., crystal group) are arranged side-by-side along a first direction and are optically coupled along the first direction only through one optical bridge (e.g., light transmissive window light transmissive medium 902) coupled to each crystal pair (e.g., crystal group). In some examples, each optical bridge (e.g., the light transmissive medium 902 of the light transmissive window) is optically shielded from light in the second direction. In various examples, a plurality of crystal pairs (e.g., a plurality of crystal groups 430) are arranged side-by-side along at least the second direction. In some examples, each crystal pair of the plurality of crystal pairs (e.g., the plurality of crystal groups 430) is optically coupled in the second direction with at least an adjacent crystal pair (e.g., a crystal group) through only two optical channels (e.g., the first optical channel 1172a and the second optical channel 1172 b). In certain examples, each of the two optical channels (e.g., the first optical channel 1172a and the second optical channel 1172b) is optically shielded from light (e.g., visible radiation or visible photons) in a first direction. In various examples, each of the two optical channels (e.g., optical channel 1172a and optical channel 1172b) optically couples one crystal element of each crystal pair (e.g., crystal group) with one crystal element of an adjacent crystal pair (e.g., crystal group) in the second direction. In some examples, the plurality of photosensors (e.g., plurality of photon sensors 421) are arranged in a plurality of photosensor pairs (e.g., a plurality of photon sensor groups). In some examples, each of the plurality of photosensor pairs (e.g., the plurality of photonic sensor groups) includes two photosensors (e.g., photonic sensors). In various examples, two photosensors (e.g., photon sensors) in each photosensor pair (e.g., photon sensor group) are arranged side-by-side along a first direction. In some examples, one of the plurality of photosensor pairs (e.g., the plurality of photonic sensor groups) includes a first photosensor (e.g., photonic sensor 421a) and a second photosensor (e.g., photonic sensor 421 b). In some examples, one crystal pair (e.g., crystal group) of a plurality of crystal pairs (e.g., a plurality of crystal groups 430) includes a first crystal element (e.g., crystal 411a) and a second crystal element (e.g., crystal 411 b). In various examples, a first photosensor (e.g., photon sensor 421a) corresponds to a first crystal element (e.g., crystal 411a) and a second photosensor (e.g., photon sensor 421b) corresponds to a second crystal element (e.g., crystal 411 b).
In some embodiments, each crystal element of the plurality of crystal elements (e.g., the plurality of crystal elements 411) is defined by a plurality of optical shields (e.g., one or more spacers) extending along the third direction. In some examples, the plurality of optical shields (e.g., one or more spacers) are configured to at least shield light (e.g., visible radiation or visible photons).
In some embodiments, the plurality of optical shields (e.g., one or more dividers) includes a first optical shield (e.g., first optical isolator 412) disposed at an interface between two adjacent crystal pairs (e.g., crystal groups) of the plurality of crystal pairs (e.g., plurality of crystal groups 430) along the first direction. In some examples, a first optical shield (e.g., first optical isolator 412) extends from a first end (e.g., first end S1) to a second end (e.g., second end S2) to optically shield two adjacent crystal pairs (e.g., crystal groups) in a first direction.
In some embodiments, the plurality of optical shields (e.g., one or more dividers) includes a second optical shield (e.g., second optical isolator 413) disposed at an interface between a first crystal element (e.g., crystal 411a) and a second crystal element (e.g., crystal 411b) included in a crystal pair (e.g., crystal group) of the plurality of crystal pairs (e.g., plurality of crystal groups 430). In some examples, the second optical shield (e.g., second optical isolator 413) extends from the first end (e.g., first end S1) toward the second end (e.g., second end S2) until reaching an optical bridge (e.g., light transmissive window' S light transmissive medium 902) that optically couples the first crystal element (e.g., crystal 411a) and the second crystal element (e.g., crystal 411 b).
In some embodiments, the plurality of optical shields (e.g., one or more dividers) includes a third optical shield (e.g., third optical isolator 414) disposed at an interface between two adjacent crystal pairs (e.g., crystal groups) of the plurality of crystal pairs (e.g., plurality of crystal groups 430) along the second direction. In some examples, a third optical shield (e.g., third optical isolator 414) extends from the second end (e.g., second end S2) toward the first end (e.g., first end S1) until reaching an optical channel (e.g., optical channel 1172a) that optically couples two adjacent crystal pairs (e.g., crystal groups) in the second direction.
In some embodiments, the optical bridge (e.g., the light transmissive medium 902 of the light transmissive window) that optically couples the two crystal elements (e.g., crystal 421a and crystal 421b) in each crystal pair (e.g., crystal group) is an internal optical bridge (e.g., an internal light transmissive window) that is configured to be optically transparent to light (e.g., visible radiation or visible photons) as the light travels between the two crystal elements.
In some embodiments, the optical bridge (e.g., the light transmissive medium 902 of the light transmissive window) that optically couples the two crystal elements (e.g., crystal 421a and crystal 421b) in each crystal pair (e.g., crystal group) is an external optical bridge (e.g., an external light transmissive window) configured to create an optical interface for light (e.g., visible radiation or visible photons) as the light travels between the two crystal elements.
In some embodiments, the optical bridge (e.g., the light-transmitting medium 902 of the light-transmissive window) that optically couples the two crystal elements (e.g., crystal 421a and crystal 421b) in each crystal pair (e.g., crystal group) comprises a scintillation material or a transmissive material.
In some embodiments, the first direction is orthogonal to the second direction, the first direction is orthogonal to the third direction, and the second direction is orthogonal to the third direction.
In some embodiments, the first direction is non-linear and is along at least a portion of a circle (e.g., when crystal array 410 includes detector ring 1401, where detector ring 1401 forms a complete ring or an incomplete ring).
In some embodiments, a plurality of crystal elements (e.g., a plurality of crystal elements 411) are polished at a second end (e.g., second end S2).
In various embodiments, an apparatus (e.g., detector 112) for detecting one or more three-dimensional locations of one or more scintillation events that convert radiation (e.g., gamma radiation) to light (e.g., visible radiation or visible photons) includes: a crystal array (e.g., crystal array 410) comprising a plurality of crystal elements (e.g., a plurality of crystal elements 411) arranged in crystal rows along a first direction and arranged in crystal columns along a second direction; and a photosensor array (e.g., photon sensor array 420) comprising a plurality of photosensors (e.g., a plurality of photon sensors 421) arranged in a photosensor row (e.g., a photon sensor row) along a first direction and a photosensor column (e.g., a photon sensor column) along a second direction. In some examples, a plurality of crystal elements (e.g., the plurality of crystal elements 411) extends between a first end (e.g., the first end S1) and a second end (e.g., the second end S2) along the third direction. In certain examples, the plurality of crystal elements (e.g., the plurality of crystal elements 411) is configured to receive radiation (e.g., gamma radiation) from the second end (e.g., the second end S2). In various examples, a plurality of light sensors (e.g., a plurality of photon sensors 421) are configured to receive light (e.g., visible radiation or visible photons) at a first end (e.g., first end S1). In some examples, one of the crystal rows includes one or more crystal pairs (e.g., one or more crystal groups) along the first direction. In some examples, one crystal pair (e.g., crystal group) of the one or more crystal pairs (e.g., one or more crystal groups) includes a first crystal element (e.g., crystal 411a) and a second crystal element (e.g., crystal 411 b). In various examples, one of the photosensor rows (e.g., photon sensor rows) includes one or more photosensor pairs (e.g., one or more photon sensor groups) along a first direction. In some examples, one photosensor pair (e.g., photon sensor group) of the one or more photosensor pairs (e.g., one or more photon sensor groups) includes a first photosensor (e.g., photon sensor 421a) and a second photosensor (e.g., photon sensor 421 b). In some examples, the first light sensor (e.g., photon sensor 421a) corresponds to a first crystal element (e.g., crystal 411 a). In various examples, the second light sensor (e.g., photon sensor 421b) corresponds to a second crystal element (e.g., crystal 411 b). In some examples, one photosensor pair (e.g., a photonic sensor group) is configured to determine whether a scintillation event occurs within a first crystal element (e.g., crystal 411a) or within a second crystal element (e.g., crystal 411b) and/or to determine a position of the scintillation event along a third direction. In some examples, one of the crystal columns includes a plurality of crystal elements along the second direction. In various examples, one of the plurality of photosensor columns (e.g., a photon sensor column) includes a plurality of photosensors (e.g., photon sensors) along the second direction. In some examples, one column of photosensors (e.g., a column of photon sensors) corresponds to one column of crystals. In some examples, one column of photosensors (e.g., a column of photon sensors) is configured to determine which crystal element of a plurality of crystal elements within which scintillation event occurred.
In some embodiments, a first photosensor (e.g., photon sensor 421a) is configured to acquire a first energy, a second photosensor (e.g., photon sensor 421b) is configured to acquire a second energy, and one photosensor pair (e.g., a group of photon sensors) is configured to determine whether a scintillation event occurs within a first crystal element (e.g., crystal 411a) or a second crystal element (e.g., crystal 411b) based at least in part on the first energy and the second energy.
In some embodiments, one photosensor pair (e.g., a photon sensor group) is further configured to determine a location of a scintillation event in a third direction based at least in part on the first energy and the second energy based at least in part on: if the first energy is greater than the second energy, then the location of the scintillation event is determined to be in a first crystal element (e.g., crystal 411a), and if the first energy is less than the second energy, then the location of the scintillation event is determined to be in a second crystal element (e.g., crystal 411 b).
In some embodiments, a first photosensor (e.g., first photon sensor 421a) is configured to acquire a first energy, a second photosensor (e.g., second photon sensor 421b) is configured to acquire a second energy, and one photosensor pair (e.g., a group of photon sensors) is configured to determine a location of a scintillation event along a third direction based at least in part on the first energy and the second energy.
In some embodiments, one photosensor pair (e.g., a photon sensor group) is further configured to determine a location of the scintillation event along the third direction based at least in part on a calculated energy ratio (the calculated energy ratio based at least in part on the first energy and the second energy) and determining the location of the scintillation event along the third direction based at least in part on the energy ratio and a lookup table.
In some embodiments, one photosensor pair (e.g., a photon sensor group) is further configured to determine a location of the scintillation event along the third direction based at least in part on a calculated energy ratio based at least in part on the first energy and the second energy and based at least in part on a distance ratio between the first path and the second path. The first path is from the location of the scintillation event to the first photosensor (e.g., photon sensor 421a) and the second path is from the location of the scintillation event to the second photosensor (e.g., photon sensor 421 b).
In some embodiments, the crystal array (e.g., crystal array 410) includes a first crystal pair (e.g., crystal group a1/B1) and a second crystal pair (e.g., crystal group A3/B3), and the photosensor array (e.g., photon sensor array 420) includes a first photosensor pair (e.g., a first photon sensor group) and a second photosensor pair (e.g., a second photon sensor group). In some examples, a first photosensor pair (e.g., a first photonic sensor group) is configured to determine a first three-dimensional position of a first scintillation event within a first crystal pair (e.g., crystal group a 1/B1). In some examples, the first three-dimensional location includes a first depth along the third direction. In some examples, the second photosensor pair (e.g., the second photonic sensor group) is configured to determine a second three-dimensional position of the second scintillation event within the second crystal pair (e.g., crystal group a 3/B3). In some examples, the second three-dimensional location includes a second depth along the third direction. In various examples, the first and second photosensor pairs (e.g., the first and second photon sensor groups) are configured to determine that the first scintillation event occurred before the second scintillation event in response to the first depth being less than the second depth, and/or determine that the first scintillation event occurred after the second scintillation event in response to the first depth being greater than the second depth.
In some embodiments, the photosensor array (e.g., photon sensor array 420) is configured to generate event coordinates corresponding to a location of the scintillation event based at least in part on the determined crystal element within which the scintillation event occurred and the determined location of the scintillation event along the third direction.
In various embodiments, an apparatus (e.g., detector 112) for detecting a three-dimensional location of a scintillation event that converts radiation (e.g., gamma radiation) to light (e.g., visible radiation or visible photons) includes a crystal pair (e.g., a crystal group) and a photosensor pair (e.g., a photon sensor group). In some examples, a crystal pair (e.g., a crystal group) includes a first crystal element (e.g., crystal 411a) and a second crystal element (e.g., crystal 411 b). In some examples, the first crystal element (e.g., crystal 411a) and the second crystal element (e.g., crystal 411b) are arranged side-by-side along the first direction. In various examples, the first crystal element (e.g., crystal 411a) and the second crystal element (e.g., crystal 411b) extend between the first end (e.g., first end S1) and the second end (e.g., second end S2) along the third direction. In some examples, the first crystal element (e.g., crystal 411a) and the second crystal element (e.g., crystal 411b) are configured to receive radiation (e.g., gamma radiation) entering from the second end (e.g., second end S2). In certain examples, a crystal pair (e.g., a crystal group) is optically coupled at a second end (e.g., second end S2) to an optical bridge (e.g., one light-transmitting medium 902 of an optically transmissive window) that extends along a first direction and bridges light (e.g., visible radiation or visible photons). In various examples, the first crystal element (e.g., crystal 411a) and the second crystal element (e.g., crystal 411b) are optically coupled only through the optical bridge (e.g., the light transmissive medium 902 of the light transmissive window) along the first direction. In some examples, a photosensor pair (e.g., a photonic sensor group) includes a first photosensor (e.g., photonic sensor 421a) corresponding to a first crystal element (e.g., crystal 411a) and a second photosensor (e.g., photonic sensor 421b) corresponding to a second crystal element (e.g., crystal 411 b). In certain examples, the first light sensor (e.g., photon sensor 421a) and the second light sensor (e.g., photon sensor 421b) are configured to receive light (e.g., visible radiation or visible photons) at a first end (e.g., first end S1). In various examples, a first photosensor (e.g., photon sensor 421a) and a second photosensor (e.g., photon sensor 421b) are arranged side-by-side along a first direction.
In various embodiments, an apparatus for determining a depth of interaction of a PET detector includes: a crystal array including a plurality of crystal elements arranged at least in a first direction and a second direction; and a photosensor array including a plurality of photosensors arranged at least in a first direction and a second direction. In some examples, the plurality of crystal elements extend between the first end and the second end along the third direction. In some embodiments, the plurality of crystal elements are arranged in a plurality of crystal pairs. In some examples, each crystal pair of the plurality of crystal pairs is optically coupled at the second end to an optical bridge that extends along the first direction and bridges the light. In various examples, each crystal pair of the plurality of crystal pairs includes two crystal elements. In some examples, the two crystal elements in each crystal pair are arranged side-by-side along a first direction and are optically coupled along the first direction only by one optical bridge coupled to each crystal pair. In some examples, each optical bridge is optically shielded from light in the second direction. In various examples, the plurality of crystal pairs are arranged side-by-side along at least the second direction. In some examples, each crystal pair of the plurality of crystal pairs is optically coupled at least with an adjacent crystal pair in the second direction only through the two optical channels. In some examples, each of the two light channels is optically shielded from light in the first direction. In various examples, each of the two optical channels optically couples one crystal element of each crystal pair with one crystal element of an adjacent crystal pair in the second direction. In some examples, the plurality of light sensors are arranged in a plurality of light sensor pairs. In some examples, each of the plurality of photosensor pairs includes two photosensors. In various examples, the two photosensors in each photosensor pair are arranged side-by-side along a first direction. In some examples, one of the plurality of photosensor pairs includes a first photosensor and a second photosensor. In some examples, one crystal pair of the plurality of crystal pairs includes a first crystal element and a second crystal element. In various examples, the first light sensor corresponds to a first crystal element and the second light sensor corresponds to a second crystal element.
In some embodiments, each crystal element of the plurality of crystal elements is defined by a plurality of optical shields extending along the third direction. In some examples, the plurality of optical shields are configured to at least shield light.
In some embodiments, the plurality of optical shields includes a first optical shield disposed along the first direction at an interface between two adjacent crystal pairs of the plurality of crystal pairs. In some examples, the first optical shield extends from the first end to the second end to optically shield two adjacent crystal pairs along the first direction.
In some embodiments, the plurality of optical shields includes a second optical shield disposed at an interface between the first crystal element and the second crystal element included in one of the plurality of crystal pairs. In some examples, the second optical shield extends from the first end toward the second end until reaching an optical bridge optically coupling the first crystal element and the second crystal element.
In some embodiments, the plurality of optical shields includes a third optical shield disposed at an interface between two adjacent crystal pairs of the plurality of crystal pairs along the second direction. In some examples, the third optical shield extends from the second end toward the first end until reaching an optical channel that optically couples two adjacent crystal pairs in the second direction.
In some embodiments, the optical bridge optically coupling the two crystal elements in each crystal pair is an internal optical bridge configured to be optically transparent to light as the light travels between the two crystal elements.
In some embodiments, the optical bridge optically coupling the two crystal elements in each crystal pair is an external optical bridge configured to create an optical interface for light as it travels between the two crystal elements.
In some embodiments, the optical bridge optically coupling the two crystal elements in each crystal pair comprises a scintillation material or a transmissive material.
In some embodiments, the first direction is orthogonal to the second direction, the first direction is orthogonal to the third direction, and the second direction is orthogonal to the third direction.
In some embodiments, the first direction is non-linear and is along at least a portion of a circle.
In some embodiments, the plurality of crystal elements are polished at the second end.
In various embodiments, an apparatus for determining a depth of interaction of a PET detector includes: a crystal array including a plurality of crystal elements arranged in crystal rows along a first direction and arranged in crystal columns along a second direction; and a photosensor array comprising a plurality of photosensors arranged in photosensor rows along a first direction and in photosensor columns along a second direction. In some examples, the plurality of crystal elements extend between the first end and the second end along the third direction. In some examples, one of the crystal rows includes one or more crystal pairs along the first direction. In some examples, one crystal pair of the one or more crystal pairs includes a first crystal element and a second crystal element. In various examples, one of the light sensor rows includes one or more light sensor pairs along a first direction. In some examples, one of the one or more photosensor pairs includes a first photosensor and a second photosensor. In some examples, the first light sensor corresponds to a first crystal element. In various examples, the second light sensor corresponds to a second crystal element. In some examples, one photosensor pair is configured to determine whether a scintillation event occurs within the first crystal element or within the second crystal element and/or to determine a position of the scintillation event along the third direction. In some examples, one of the plurality of crystal columns includes a plurality of crystal elements along the second direction. In various examples, one of the plurality of photosensor columns includes a plurality of photosensors along the second direction. In some examples, one column of photosensors corresponds to one column of crystals. In some examples, one photosensor column is configured to determine within which crystal element of a plurality of crystal elements a scintillation event occurred.
In some embodiments, the first photosensor is configured to acquire a first energy, the second photosensor is configured to acquire a second energy, and the one photosensor pair is configured to determine whether the scintillation event occurred within the first crystal element or the second crystal element based at least in part on the first energy and the second energy.
In some embodiments, the one light sensor pair is further configured to determine a location of the scintillation event in the third direction based at least in part on the first energy and the second energy based at least in part on: if the first energy is greater than the second energy, the location of the scintillation event is determined to be in the first crystal element, and if the first energy is less than the second energy, the location of the scintillation event is determined to be in the second crystal element.
In some embodiments, the first photosensor is configured to acquire a first energy, the second photosensor is configured to acquire a second energy, and the one photosensor pair is configured to determine a location of the scintillation event in the third direction based at least in part on the first energy and the second energy.
In some embodiments, the one photosensor pair is further configured to determine the location of the scintillation event in the third direction based at least in part on the calculated energy ratio (which is based at least in part on the first energy and the second energy) and determining the location of the scintillation event in the third direction based at least in part on the energy ratio and the lookup table.
In some embodiments, the one light sensor pair is further configured to determine the location of the scintillation event in the third direction based at least in part on a calculated energy ratio (the calculated energy ratio being based at least in part on the first energy and the second energy) and based at least in part on a distance ratio between the first path and the second path. The first path is from the location of the scintillation event to the first photosensor and the second path is from the location of the scintillation event to the second photosensor.
In some embodiments, the crystal array includes a first crystal pair and a second crystal pair, and the photosensor array includes a first photosensor pair and a second photosensor pair. In some examples, the first photosensor pair is configured to determine a first three-dimensional location of the first scintillation event within the first crystal pair. In some examples, the first three-dimensional location includes a first depth along the third direction. In some examples, the second photosensor pair is configured to determine a second three-dimensional location of the second scintillation event within the second crystal pair. In some examples, the second three-dimensional location includes a second depth along the third direction. In various examples, the first photosensor pair and the second photosensor pair are configured to determine that the first scintillation event occurred before the second scintillation event in response to the first depth being less than the second depth, and/or determine that the first scintillation event occurred after the second scintillation event in response to the first depth being greater than the second depth.
In some embodiments, the photosensor array is configured to generate event coordinates corresponding to a location of a scintillation event based at least in part on the determined crystal element within which the scintillation event occurred and the determined location of the scintillation event along the third direction.
In various embodiments, an apparatus for determining the depth of interaction of a PET detector includes a crystal pair and a photosensor pair. In some examples, the crystal pair includes a first crystal element and a second crystal element. In some examples, the first crystal element and the second crystal element are arranged side-by-side along the first direction. In various examples, the first and second crystal elements extend between the first and second ends along a third direction. In some examples, the first and second crystal elements are configured to receive radiation entering from the second end. In some examples, the crystal pair is optically coupled at the second end to an optical bridge that extends along the first direction and bridges the light. In various examples, the first crystal element and the second crystal element are optically coupled only through the optical bridge along the first direction. In some examples, the photo-sensor pair includes a first photo-sensor corresponding to the first crystal element and a second photo-sensor corresponding to the second crystal element. In various examples, the first light sensor and the second light sensor are arranged side-by-side along a first direction.
In various embodiments, the scintillation event has corresponding event coordinates (e.g., x, y, z), which may be determined based at least in part on determining the crystal element within which the scintillation event occurred (e.g., providing x, y) and determining the position of the scintillation event along the third direction (e.g., providing z). In some examples, if the plurality of scintillation events are determined using a plurality of corresponding event coordinates, determining the direction of the traveling radiation (e.g., gamma radiation) within the crystal is based at least in part on the depth of the event coordinates along the third direction.
In certain embodiments, an optical shield (e.g., an optical isolator) is configured to allow transmission of a first radiation (e.g., gamma radiation) but block transmission of a second radiation (e.g., visible light). In some examples, an optical shield (e.g., an optical isolator) disposed between the two crystal elements is configured to block transmission of the second radiation (e.g., visible light) at least in a direction perpendicular to an interface of the two crystal elements. In various examples, an optical shield (e.g., an optical isolator) is optically transparent to radiation (e.g., gamma radiation) as the radiation travels between two crystal elements, indicating that the optical shield allows radiation to pass through the optical shield from one crystal element to the other. In certain examples, an optical shield (e.g., an optical isolator) configured to shield radiation (e.g., visible light) indicates that the optical shield is configured to block transmission of radiation through the optical shield, such as at an interface between two crystal elements.

Claims (20)

1. An apparatus for determining the depth of interaction of a PET detector, the apparatus comprising:
a crystal array comprising a plurality of crystal elements arranged at least along a first direction and a second direction, the plurality of crystal elements extending between a first end and a second end along a third direction; and
a photosensor array comprising a plurality of photosensors arranged at least along the first direction and the second direction;
wherein:
the plurality of crystal elements are arranged in a plurality of crystal pairs;
each crystal pair of the plurality of crystal pairs is optically coupled at the second end to an optical bridge extending along the first direction to bridge light;
each crystal pair of the plurality of crystal pairs comprises two crystal elements;
the two crystal elements in each crystal pair are arranged side-by-side along the first direction and are optically coupled along the first direction only by one optical bridge coupled to each crystal pair; and is
Each optical bridge is optically shielded from light in the second direction;
wherein:
the plurality of crystal pairs are arranged side by side at least along the second direction;
each crystal pair of the plurality of crystal pairs is optically coupled in the second direction with at least an adjacent crystal pair only through two optical channels;
each of the two light channels is optically shielded from the light in the first direction; and
each of the two optical channels optically couples one crystal element of each crystal pair with one crystal element of an adjacent crystal pair in the second direction;
wherein:
the plurality of light sensors are arranged in a plurality of light sensor pairs;
each of the plurality of photosensor pairs comprises two photosensors; and
the two photosensors in each photosensor pair are arranged side-by-side along the first direction;
wherein:
one of the plurality of photosensor pairs comprises a first photosensor and a second photosensor;
one crystal pair of the plurality of crystal pairs comprises a first crystal element and a second crystal element;
the first photosensor corresponds to the first crystal element; and
the second photosensor corresponds to the second crystal element.
2. The apparatus of claim 1, wherein each crystal element of the plurality of crystal elements is defined by a plurality of optical shields extending along the third direction, the plurality of optical shields configured to at least shield light.
3. The apparatus of claim 2, wherein the plurality of optical shields comprises a first optical shield disposed at an interface between two adjacent crystal pairs of the plurality of crystal pairs along the first direction, wherein the first optical shield extends from the first end to the second end to optically shield the two adjacent crystal pairs along the first direction.
4. The apparatus of claim 2, wherein the plurality of optical shields comprises a second optical shield disposed at an interface between the first crystal element and the second crystal element included in the one of the plurality of crystal pairs, wherein the second optical shield extends from the first end toward the second end until reaching an optical bridge optically coupling the first crystal element and the second crystal element.
5. The apparatus of claim 2, wherein the plurality of optical shields comprises a third optical shield disposed at an interface between two adjacent crystal pairs of the plurality of crystal pairs along the second direction, wherein the third optical shield extends from the second end toward the first end until reaching an optical channel that optically couples the two adjacent crystal pairs along the second direction.
6. The apparatus of claim 1, wherein the optical bridge optically coupling the two crystal elements in each crystal pair is an internal optical bridge configured to be optically transparent to the light as the light travels between the two crystal elements.
7. The apparatus of claim 1, wherein the optical bridge optically coupling the two crystal elements in each crystal pair is an external optical bridge configured to create an optical interface to the light as the light travels between the two crystal elements.
8. The apparatus of claim 1, wherein the optical bridge optically coupling the two crystal elements in each crystal pair comprises a scintillation material or a transmissive material.
9. The apparatus of claim 1, wherein the first direction is orthogonal to the second direction, the first direction is orthogonal to the third direction, and the second direction is orthogonal to the third direction.
10. The apparatus of claim 9, wherein the first direction is non-linear and is along at least a portion of a circle.
11. The apparatus of claim 1, wherein the plurality of crystal elements are polished at the second end.
12. An apparatus for determining the depth of interaction of a PET detector, the apparatus comprising:
a crystal array comprising a plurality of crystal elements arranged in crystal rows along a first direction and in crystal columns along a second direction, the plurality of crystal elements extending between a first end and a second end along a third direction; and
a photosensor array comprising a plurality of photosensors arranged in photosensor rows along the first direction and in photosensor columns along the second direction;
wherein the content of the first and second substances,
one of the plurality of crystal rows includes one or more crystal pairs along the first direction;
one crystal pair of the one or more crystal pairs comprises a first crystal element and a second crystal element;
one of the plurality of rows of photosensors comprises one or more pairs of photosensors along the first direction;
one of the one or more photosensor pairs comprises a first photosensor and a second photosensor;
the first photosensor corresponds to the first crystal element; and
the second photosensor corresponds to the second crystal element;
wherein the one light sensor pair is configured to:
determining whether a scintillation event occurs within the first crystal element or within the second crystal element; and
determining a position of the scintillation event along the third direction;
wherein:
one of the plurality of crystal columns includes a plurality of crystal elements along the second direction;
one of the plurality of photo sensor columns comprises a plurality of photo sensors along the second direction; and
the one photosensor column corresponds to the one crystal column;
wherein the one photosensor column is configured to determine within which crystal element of the plurality of crystal elements the scintillation event occurred.
13. The apparatus of claim 12, wherein:
the first light sensor is configured to acquire a first energy;
the second light sensor is configured to acquire a second energy; and
the one photosensor pair is configured to determine whether the scintillation event occurred within the first crystal element or within the second crystal element based at least in part on the first energy and the second energy.
14. The apparatus of claim 13, wherein the one photosensor pair is further configured to determine the location of the scintillation event in the third direction based at least in part on the first energy and the second energy by:
determining that the location of the scintillation event is in the first crystal element if the first energy is greater than the second energy; and
determining that the location of the scintillation event is in the second crystal element if the first energy is less than the second energy.
15. The apparatus of claim 12, wherein:
the first light sensor is configured to acquire a first energy;
the second light sensor is configured to acquire a second energy; and
the one photosensor pair is configured to determine a position of the scintillation event along the third direction based at least in part on the first energy and the second energy.
16. The apparatus of claim 15, wherein the one photosensor pair is further configured to determine the location of the scintillation event along the third direction by:
calculating an energy ratio based at least in part on the first energy and the second energy; and
determining a location of the scintillation event along the third direction based at least in part on a lookup table.
17. The apparatus of claim 15, wherein the one photosensor pair is further configured to determine the location of the scintillation event along the third direction by:
calculating an energy ratio based at least in part on the first energy and the second energy; and
determining a location of the scintillation event along the third direction based at least in part on a distance ratio between a first path from the location of the scintillation event to the first photosensor and a second path from the location of the scintillation event to the second photosensor.
18. The apparatus of claim 12, wherein the array of crystals comprises a first crystal pair and a second crystal pair;
the photosensor array includes a first photosensor pair and a second photosensor pair;
the first photosensor pair is configured to determine a first three-dimensional location of a first scintillation event within the first crystal pair, the first three-dimensional location comprising a first depth from the second end along the third direction;
the second photosensor pair is configured to determine a second three-dimensional location of a second scintillation event within the second crystal pair, the second three-dimensional location including a second depth from the second end along the third direction; and
the first and second light sensor pairs are configured to:
in response to the first depth being less than the second depth, determining that the first scintillation event occurred before the second scintillation event; and
in response to the first depth being greater than the second depth, determining that the first scintillation event occurred after the second scintillation event.
19. The apparatus of claim 12, wherein the photosensor array is configured to generate event coordinates corresponding to a location of the scintillation event based at least in part on the determined crystal element within which the scintillation event occurred and the determined location of the scintillation event along the third direction.
20. An apparatus for determining the depth of interaction of a PET detector, the apparatus comprising:
a crystal pair comprising a first crystal element and a second crystal element; and
a pair of light sensors;
wherein:
the first and second crystal elements are arranged side by side along a first direction;
the first and second crystal elements extend between first and second ends along a third direction;
the first and second crystal elements are configured to receive radiation entering from the second end;
the crystal pair is optically coupled at the second end to an optical bridge extending along the first direction and bridging light; and
the first and second crystal elements optically couple light in the first direction only through the optical bridge; and
wherein the pair of light sensors includes:
a first photosensor corresponding to the first crystal element; and
a second photosensor corresponding to the second crystal element;
wherein the first and second light sensors are arranged side by side along the first direction.
CN202021116983.2U 2019-07-30 2020-06-16 Device for determining the depth of interaction of a PET detector Active CN213240527U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116626738A (en) * 2023-07-24 2023-08-22 武汉联影生命科学仪器有限公司 Photon action position parameter determination method, PET detector and PET system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116626738A (en) * 2023-07-24 2023-08-22 武汉联影生命科学仪器有限公司 Photon action position parameter determination method, PET detector and PET system

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