CN106199673B - Dual-mode positron imaging machine based on event counting - Google Patents
Dual-mode positron imaging machine based on event counting Download PDFInfo
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- CN106199673B CN106199673B CN201610807342.3A CN201610807342A CN106199673B CN 106199673 B CN106199673 B CN 106199673B CN 201610807342 A CN201610807342 A CN 201610807342A CN 106199673 B CN106199673 B CN 106199673B
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/16—Measuring radiation intensity
- G01T1/161—Applications in the field of nuclear medicine, e.g. in vivo counting
- G01T1/164—Scintigraphy
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/16—Measuring radiation intensity
- G01T1/161—Applications in the field of nuclear medicine, e.g. in vivo counting
- G01T1/164—Scintigraphy
- G01T1/1641—Static instruments for imaging the distribution of radioactivity in one or two dimensions using one or several scintillating elements; Radio-isotope cameras
- G01T1/1645—Static instruments for imaging the distribution of radioactivity in one or two dimensions using one or several scintillating elements; Radio-isotope cameras using electron optical imaging means, e.g. image intensifier tubes, coordinate photomultiplier tubes, image converter
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/16—Measuring radiation intensity
- G01T1/20—Measuring radiation intensity with scintillation detectors
- G01T1/202—Measuring radiation intensity with scintillation detectors the detector being a crystal
Abstract
A dual mode positron emission tomography based on event counting, comprising: the system comprises an unstable isotope injection module, a gamma detector module, a visible light detector module, a multi-case time window judging and selecting module and a visualization module. The system can simultaneously identify the gamma photon pair generated by annihilation of the cerenkov photon and the positive and negative electron pair emitted by the charged particle motion in the positron emission process, effectively improves the signal-to-noise ratio, the imaging space-time resolution and the sensitivity of the system, and reduces the material cost.
Description
Technical Field
The invention relates to the fields of high-energy physics and particle physics application, nuclear medicine equipment and biomedical photonics, in particular to a dual-mode positron imaging machine based on event counting.
Background
The radioactive events in nuclear medicine are typically accompanied by two or more irradiation types. Particularly when decay events can emit unstable charged particles, the radioactive event can emit multiple radiations simultaneously. Taking a proton-rich unstable isotope as an example, when the emitted positron has a certain momentum, a visible photon is irradiated on a track, and the physical phenomenon is cerenkov radiation. The cerenkov radiation is a very convenient marking method and has very wide application value in biomedical imaging. When the positron annihilates with an electron in the environment, a pair of gamma photons with 511keV energy will be radiated, that is, one isotope label of the proton-rich element will provide two imaging modes: optical imaging and gamma imaging. In addition to proton rich elements, other partially unstable isotopes are also in the context of cascade decay and simultaneous irradiation of multiple particles of different energies, different charges, different penetration depths. The existing imaging system does not perform special detection on the 'body and double functions' probe, but independently adopts a gamma camera (or PET) and an optical camera to perform imaging on organisms or human bodies marked with proton-rich nuclides, the middle signal detection and data acquisition are completely independent, and finally, the rear end alignment (registration) is performed on an image level.
This back-end alignment is extremely critical for the loss of information for both types of irradiation. Among gamma data, a large portion of the data is scatter and random events, which if the optical data can be introduced in the form of events at the physical layer, will provide a very accurate decision. The transportation noise of visible light in a human body is extremely serious, and if the optical data can introduce the collimation information of gamma photons when the cerenkov events are screened, the information accuracy of the single cerenkov events can be greatly improved. For this reason, event-level information fusion, operating at the physical layer, will revolutionarily affect the multi-irradiation system.
Disclosure of Invention
Therefore, the invention aims to provide a dual-mode positron imaging machine based on event counting, which can simultaneously identify the cerenkov photons emitted by the motion of charged particles and gamma photon pairs generated by annihilation of positive and negative electron pairs in the positron emission process, effectively improve the signal-to-noise ratio, imaging space-time resolution and sensitivity of the system and reduce the material cost.
In order to achieve the above object, the present invention provides a dual-mode positron imaging apparatus based on event counting, comprising: an unstable isotope injection module 100, a gamma detector module 200, a visible light detector module 300, a multi-instance time window decision module 400, a visualization module 500, wherein,
an unstable isotope injection module 100 for marking substances participating in physiological and biochemical processes in an organism, shielding background light outside the organism, and enabling the organism to carry a marker capable of emitting multiple irradiation events, comprising a radioisotope delivery module 110, a medicament injection module 120, an organism transmission module 130 and a light sealing module 140;
the gamma detector module 200 detects gamma photons in a ring-shaped visual angle manner, acquires time and energy attributes of single gamma photon events, adopts a scintillation detector principle, and comprises a scintillation crystal module 210, a photoelectric conversion module 220, a front-end electronics module 230 and a gamma event attribute encapsulation circuit module 240;
the visible light detector module 300 is configured to detect visible light photons and soft ultraviolet photons in a high detection efficiency manner, and the detector adopts a large-area planar structure, so that large-scale manufacture can be performed by a large-scale optoelectronic chip process, and the detector comprises a cerenkov photon photoelectric conversion module 310, a cerenkov detection front-end electronics module 320, and a cerenkov event attribute packaging circuit module 330;
the Tocase time window judging and selecting module 400 is configured to judge whether the cerenkov event and the gamma photon event belong to a positron event, where the judging criteria are that the gamma photon event and the cerenkov event exist simultaneously in a shorter time window (for example, 30 ns), and the judging criteria include a Tocase timing windowing circuit module 410, a logic AND gate circuit module 420, a total event timing windowing module 430, a coincidence event encapsulation module 440, a power module 450 and a digital circuit clock module 460;
the visualization module 500 is configured to perform subsequent processing or discarding on the irradiation data, and is composed of a processor module 510, an anti-power-off direct current power supply module 520, a display module 530, and a network transmission interface module 540.
A radioisotope delivery module 110, belonging to the unstable isotope injection module 100, for stably and automatically delivering a radiopharmaceutical to an organism, avoiding possible radiation damage to the human body and the organism caused by the radiopharmaceutical, and allowing the radiopharmaceutical to enter the medicine injection module 120 via the radioisotope delivery module 110;
the medicament injection module 120 is attached to the unstable isotope injection module 100 and is used for controlling the dosage of the radioactive medicament injected into the organism or the human body in real time, and consists of a pushing device and a dosage measuring and calculating device;
the organism transmission module 130 belongs to the unstable isotope injection module 100 and is used for controlling the feeding in and out of organisms inside and outside the imaging cavity, and consists of a pushing device and a supporting plate, wherein the supporting plate is used for containing organisms, the pushing device is responsible for feeding the supporting plate and the organisms into the imaging cavity before imaging, and feeding the supporting plate and the organisms out of the imaging cavity after imaging is completed;
the light sealing module 140 is attached to the unstable isotope injection module 100 and is used for sealing the imaging cavity from light, so that no extra external visible light is injected into the imaging cavity during imaging.
The scintillation crystal module 210 is attached to the gamma detector module 200, and is configured to absorb gamma photons, convert energy of one gamma photon into a cluster of visible light or soft ultraviolet photons, and consist of a scintillation crystal bare crystal, a scintillation light reflecting material, a scintillation crystal packaging shell and light-emitting glass;
the photoelectric conversion module 220 is attached to the gamma detector module 200, and is used for energy absorption and electric signal conversion of visible light and soft ultraviolet photons, specifically, the photoelectric current cluster is amplified in a short time through an avalanche process, and then is output to the front-end electronics module 230;
the front-end electronics module 230 is attached to the gamma detector module 200, and is configured to pre-amplify the electrical signal output by the photoelectric conversion module, perform analog-to-digital conversion, and output the digitized scintillation pulse attribute to the gamma event attribute encapsulation circuit module 240 according to the event;
the gamma event attribute packaging circuit module 240, which belongs to the gamma detector module 200, packages the attributes of the gamma event, wherein the packaged contents include event time, gamma photon energy, rising time of the front edge of the scintillation pulse and dispersion sum of the scintillation pulse.
The cerenkov photon photoelectric conversion module 310 is attached to the visible light detector module 300, and is configured to absorb cerenkov photons and convert the cerenkov photons into an electrical signal, specifically, amplify a photoelectron current cluster in a short time through a photoelectric effect and an avalanche process, and output the photoelectron current cluster to the cerenkov detection front-end electronics module 320;
the cerenkov detection front-end electronics module 320 is attached to the visible light detector module 310, and is configured to pre-amplify cerenkov induction electric pulses, perform analog-to-digital conversion, and output digitized cerenkov induction electric pulse attributes to the cerenkov event attribute encapsulation circuit module 330 according to events;
the cerenkov event attribute packaging circuit module 330 is subordinate to the visible light detector module 300 and packages the attributes of cerenkov events, wherein the packaged contents comprise event time, gamma photon energy, rising time of the front edge of cerenkov induction electric pulse and dispersion sum of cerenkov induction electric pulse.
A multi-case timing windowing circuit module 410, belonging to the multi-case time window judging and selecting module 400, for performing timing windowing on each gamma event and cerenkov event, i.e. starting timing 1 output from the event arrival time;
the logic AND gate circuit module 420 is subordinate to the multi-case time window judging and selecting module 400, and performs AND logic judgment on a plurality of cases through the AND gate circuit after receiving the 1 setting signal output by the multi-case timing window judging and selecting module 410, when two gamma photons and more than one channel of Cerenkov events exist, the 1 setting output is performed, otherwise, the zero clearing output is kept;
the total event timing windowing module 430 belongs to the multiple event time window judging and selecting module 400, receives an AND gate judging and selecting signal of the logic AND gate circuit module 420, and outputs the AND gate judging and selecting signal with fixed time window 1 from the receiving of the 1 setting signal;
the coincidence event encapsulation module 440, which belongs to the multiple event time window judging and selecting module 400, encapsulates each event attribute received from the multiple event timing windowing circuit module into a binary bit stream from the reception of the 1 signal of the total event timing windowing module;
the power supply module 450 belongs to the multi-case time window selection module 400 and is used for stably supplying power to each circuit module, and the power supply is externally connected with 220V alternating current commercial power;
the digital circuit clock module 460 belongs to the multiple case time window judging and selecting module 400, and is used for sending clock signals to each digital circuit module, wherein the clock signals are sine wave voltage signals and are provided by the active crystal oscillator.
The processor module 510 is subordinate to the visualization module 500, performs correlation analysis, histogram counting and statistical calculation on the packaged cases, and transmits the analysis and calculation result to the display module 530;
the anti-power-off direct current power supply module 520 belongs to the visualization module 500 and is used for ensuring the stable operation of the display module and the processor module, and can still keep the working power supply for more than 8 hours after the system is powered off so as to perform the repairing and archiving actions before the shutdown;
the display module 530 is subordinate to the visualization module 500, and displays various spectral properties of the positron event after receiving the gamma property and the cerenkov property of the positron event;
the network transmission interface module 540 is attached to the visualization module 500 and is used for transmitting gamma attribute, cerenkov attribute and its spectroscopy chart of positron event.
Preferably, in the dual-mode positron imaging machine based on event counting, the event arrival time is the time of the detector responding to the gamma event or the cerenkov event, or the time of the detector responding to the gamma event or the cerenkov event is added with a constant, and the constant is applicable to the whole system at any moment.
Preferably, in the dual-mode positron imaging apparatus based on event counting, the gamma attribute of the positron event refers to a response characteristic that a pair of gamma photons generated after annihilation of the positron and the electron hit the gamma detector.
Preferably, in the dual-mode positron imaging apparatus based on event counting, the cerenkov attribute of the positron event refers to a response characteristic that a cerenkov photon generated before positron annihilates with an electron hits a visible light detector.
Preferably, in the above dual-mode positron imaging apparatus based on event counting, the positron event refers to emission of positrons by decay of a proton-rich nuclide. The positrons produce a cerenkov effect when in motion, and after annihilation with nearby electrons, a pair of gamma photons are produced, the properties of which are captured by a gamma detector, and the properties of which are captured by a visible light detector.
Preferably, in the above dual-mode positron imaging machine based on event counting, the multi-case time window judgment refers to that when the visible light photon detector and the gamma photon detector of the system capture two signals at the same time, the probability that the visible light photon and the gamma photon in this case are background photons or dark excitation photons is considered to be smaller by the system, and the gamma photon pair and the cerenkov photon of the positron event are judged.
According to the technical scheme, the dual-mode positron imaging machine based on event counting can acquire the distribution information of the positron sources under low activity. The system can work at room temperature without cooling the detector in advance, and has better space-time resolution and signal-to-noise ratio, thus having better universality and practicability.
Compared with the prior art, the invention has the beneficial effects that:
(1) Better space-time resolution;
(2) Better image signal-to-noise ratio;
(3) Can work at room temperature;
(4) The cost is low;
(5) And various information of the positron source is fully utilized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings related to the present invention in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a system block diagram of a dual mode positron imaging machine based on event counting in accordance with the present invention;
FIG. 2 is a schematic diagram of the paths of two lights according to the present invention.
Detailed Description
The invention discloses a double-mode positron imaging machine based on event counting, which can simultaneously identify a Cherenkov photon emitted by charged particle motion and a gamma photon pair generated by annihilation of a positive electron pair in a positron emission process, effectively improve the signal-to-noise ratio, the imaging space-time resolution and the sensitivity of the system and reduce the material cost.
The following detailed description of the technical solutions according to embodiments of the present invention will be given with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 1, the dual-mode positron imaging machine based on event counting disclosed by the invention captures gamma properties and cerenkov properties of positron events through a gamma detector and a visible light photon detector, and realizes imaging of a positron-labeled organism or human body, and specifically comprises the following steps:
an unstable isotope injection module 100, a gamma detector module 200, a visible light detector module 300, a multi-instance time window decision module 400, a visualization module 500, wherein,
an unstable isotope injection module 100 for marking substances participating in physiological and biochemical processes in an organism, shielding background light outside the organism, and enabling the organism to carry a marker capable of emitting multiple irradiation events, comprising a radioisotope delivery module 110, a medicament injection module 120, an organism transmission module 130 and a light sealing module 140;
the gamma detector module 200 detects gamma photons in a ring-shaped visual angle manner, acquires time and energy attributes of single gamma photon events, adopts a scintillation detector principle, and comprises a scintillation crystal module 210, a photoelectric conversion module 220, a front-end electronics module 230 and a gamma event attribute encapsulation circuit module 240;
the visible light detector module 300 is configured to detect visible light photons and soft ultraviolet photons in a high detection efficiency manner, and the detector adopts a large-area planar structure, so that large-scale manufacture can be performed by a large-scale optoelectronic chip process, and the detector comprises a cerenkov photon photoelectric conversion module 310, a cerenkov detection front-end electronics module 320, and a cerenkov event attribute packaging circuit module 330;
the Tocase time window judging and selecting module 400 is configured to judge whether the cerenkov event and the gamma photon event belong to a positron event, where the judging criteria are that the gamma photon event and the cerenkov event exist simultaneously in a shorter time window (for example, 30 ns), and the judging criteria include a Tocase timing windowing circuit module 410, a logic AND gate circuit module 420, a total event timing windowing module 430, a coincidence event encapsulation module 440, a power module 450 and a digital circuit clock module 460;
the visualization module 500 is configured to perform subsequent processing or discarding on the irradiation data, and is composed of a processor module 510, an anti-power-off direct current power supply module 520, a display module 530, and a network transmission interface module 540.
A radioisotope delivery module 110, belonging to the unstable isotope injection module 100, for stably and automatically delivering a radiopharmaceutical to an organism, avoiding possible radiation damage to the human body and the organism caused by the radiopharmaceutical, and allowing the radiopharmaceutical to enter the medicine injection module 120 via the radioisotope delivery module 110;
the medicament injection module 120 is attached to the unstable isotope injection module 100 and is used for controlling the dosage of the radioactive medicament injected into the organism or the human body in real time, and consists of a pushing device and a dosage measuring and calculating device;
the organism transmission module 130 belongs to the unstable isotope injection module 100 and is used for controlling the feeding in and out of organisms inside and outside the imaging cavity, and consists of a pushing device and a supporting plate, wherein the supporting plate is used for containing organisms, the pushing device is responsible for feeding the supporting plate and the organisms into the imaging cavity before imaging, and feeding the supporting plate and the organisms out of the imaging cavity after imaging is completed;
the light sealing module 140 is attached to the unstable isotope injection module 100 and is used for sealing the imaging cavity from light, so that no extra external visible light is injected into the imaging cavity during imaging.
The scintillation crystal module 210 is attached to the gamma detector module 200, and is configured to absorb gamma photons, convert energy of one gamma photon into a cluster of visible light or soft ultraviolet photons, and consist of a scintillation crystal bare crystal, a scintillation light reflecting material, a scintillation crystal packaging shell and light-emitting glass;
the photoelectric conversion module 220 is attached to the gamma detector module 200, and is used for energy absorption and electric signal conversion of visible light and soft ultraviolet photons, specifically, the photoelectric current cluster is amplified in a short time through an avalanche process, and then is output to the front-end electronics module 230;
the front-end electronics module 230 is attached to the gamma detector module 200, and is configured to pre-amplify the electrical signal output by the photoelectric conversion module, perform analog-to-digital conversion, and output the digitized scintillation pulse attribute to the gamma event attribute encapsulation circuit module 240 according to the event;
the gamma event attribute packaging circuit module 240, which belongs to the gamma detector module 200, packages the attributes of the gamma event, wherein the packaged contents include event time, gamma photon energy, rising time of the front edge of the scintillation pulse and dispersion sum of the scintillation pulse.
The cerenkov photon photoelectric conversion module 310 is attached to the visible light detector module 300, and is configured to absorb cerenkov photons and convert the cerenkov photons into an electrical signal, specifically, amplify a photoelectron current cluster in a short time through a photoelectric effect and an avalanche process, and output the photoelectron current cluster to the cerenkov detection front-end electronics module 320;
the cerenkov detection front-end electronics module 320 is attached to the visible light detector module 310, and is configured to pre-amplify cerenkov induction electric pulses, perform analog-to-digital conversion, and output digitized cerenkov induction electric pulse attributes to the cerenkov event attribute encapsulation circuit module 330 according to events;
the cerenkov event attribute packaging circuit module 330 is subordinate to the visible light detector module 300 and packages the attributes of cerenkov events, wherein the packaged contents comprise event time, gamma photon energy, rising time of the front edge of cerenkov induction electric pulse and dispersion sum of cerenkov induction electric pulse.
A multi-case timing windowing circuit module 410, belonging to the multi-case time window judging and selecting module 400, for performing timing windowing on each gamma event and cerenkov event, i.e. starting timing 1 output from the event arrival time;
the logic AND gate circuit module 420 is subordinate to the multi-case time window judging and selecting module 400, and performs AND logic judgment on a plurality of cases through the AND gate circuit after receiving the 1 setting signal output by the multi-case timing window judging and selecting module 410, when two gamma photons and more than one channel of Cerenkov events exist, the 1 setting output is performed, otherwise, the zero clearing output is kept;
the total event timing windowing module 430 belongs to the multiple event time window judging and selecting module 400, receives an AND gate judging and selecting signal of the logic AND gate circuit module 420, and outputs the AND gate judging and selecting signal with fixed time window 1 from the receiving of the 1 setting signal;
the coincidence event encapsulation module 440, which belongs to the multiple event time window judging and selecting module 400, encapsulates each event attribute received from the multiple event timing windowing circuit module into a binary bit stream from the reception of the 1 signal of the total event timing windowing module;
the power supply module 450 belongs to the multi-case time window selection module 400 and is used for stably supplying power to each circuit module, and the power supply is externally connected with 220V alternating current commercial power;
the digital circuit clock module 460 belongs to the multiple case time window judging and selecting module 400, and is used for sending clock signals to each digital circuit module, wherein the clock signals are sine wave voltage signals and are provided by the active crystal oscillator.
The processor module 510 is subordinate to the visualization module 500, performs correlation analysis, histogram counting and statistical calculation on the packaged cases, and transmits the analysis and calculation result to the display module 530;
the anti-power-off direct current power supply module 520 belongs to the visualization module 500 and is used for ensuring the stable operation of the display module and the processor module, and can still keep the working power supply for more than 8 hours after the system is powered off so as to perform the repairing and archiving actions before the shutdown;
the display module 530 is subordinate to the visualization module 500, and displays various spectral properties of the positron event after receiving the gamma property and the cerenkov property of the positron event;
the network transmission interface module 540 is attached to the visualization module 500 and is used for transmitting gamma attribute, cerenkov attribute and its spectroscopy chart of positron event.
In the above dual-mode positron imaging machine based on event counting, the event arrival time is the time of the detector responding to the gamma event or the cerenkov event, or the time of the detector responding to the gamma event or the cerenkov event plus a constant, and the constant is applicable to the whole system at any moment.
In the above dual-mode positron imaging machine based on event counting, the gamma attribute of the positron event refers to the response characteristic that a pair of gamma photons generated after annihilation of the positron and an electron hit a gamma detector.
In the above dual-mode positron imaging machine based on event counting, the cerenkov attribute of the positron event refers to the response characteristic that cerenkov photons generated before positron annihilation with electron hit the visible light detector.
In the above dual-mode positron imaging machine based on event counting, the multi-case time window judgment refers to that when the visible light photon detector and the gamma photon detector of the system capture two signals at the same time, the system considers that the probability that the visible light photon and the gamma photon are background photons or dark excitation photons is smaller, and the judgment refers to gamma photon pairs and cerenkov photons of positron events.
FIG. 1 is a system block diagram of a dual mode positron imaging machine based on event counting in accordance with the present invention; FIG. 2 is a schematic diagram of the paths of two lights according to the present invention. The dual mode positron imaging system based on event counting of the present invention is further described with reference to fig. 1 and 2 in several embodiments. The invention provides a dual-mode positron imaging system based on event counting, which relates to set division, function derivation modes, priority orders thereof, a coding system and threshold parameters, and the parameters need to be adjusted according to the characteristics of acquired data so as to achieve sufficient statistical performance. The parameters of the application embodiments referred to in processing data are listed herein.
Example 1: dual-mode positron imaging machine based on event counting
Parameters of the process data of this example 1 are listed here:
the activity of the radioactive source used in the module 100 was 100 uCi, the size of the light-tight module was a cup-shaped geometry with a diameter of 10 cm and a ring thickness of 5 cm;
the size of the scintillation crystal strips adopted in the module 200 is 2 mm x 2 mm x 13 mm, the detection surface is 2 mm x 2 mm, and the scintillation crystal adopts sodium iodide crystal;
the photon detection unit size adopted in the module 300 is 2 mm x 2 mm, and the detector adopts a silicon photomultiplier;
the time window employed in module 400 is 5 ns;
the processor in the module 500 is an FPGA (field programmable gate array) processor, the display is a liquid crystal display, and the network transmission interface is an industrial ethernet protocol.
Example 2: dual-mode positron imaging machine based on event counting
The parameters of the process data of this example 2 are listed here:
the radioactivity source used in the module 100 was 200 uCi, the light-tight module size was a barrel geometry with a diameter of 20 cm and a loop thickness of 15 cm;
the size of the scintillation crystal strip adopted in the module 200 is 3 mm x 3 mm x 13 mm, the detection surface is 3 mm x 3 mm, and the scintillation crystal adopts lanthanum bromide crystal;
the photon detection unit size adopted in the module 300 is 3 mm x 3 mm, and the detector adopts a silicon photomultiplier;
the time window employed in module 400 is 15 ns;
the processor in the module 500 adopts a singlechip processor, the display adopts a liquid crystal display, and the network transmission interface adopts an Ethernet protocol.
Example 3: dual-mode positron imaging machine based on event counting
Parameters of the process data of this example 3 are listed here:
the radioactivity employed in the module 100 was 1.00 mCi, the light-tight module size was a barrel geometry with a diameter of 50 cm and a loop thickness of 50 cm;
the size of the scintillation crystal strip adopted in the module 200 is 5 mm x 5 mm x 13 mm, the detection surface is 5 mm x 5 mm, and the scintillation crystal adopts lanthanum bromide crystal;
the photon detection unit size adopted in the module 300 is 4 mm x 3 mm, and the detector adopts a silicon photomultiplier;
the time window employed in module 400 is 25 ns;
the processor in module 500 is a digital signal processor, the display is a valve display, and the network transmission interface is PCIe protocol.
The invention relates to the fields of high-energy physics and particle physics application, nuclear medicine equipment and biomedical diagnosis and treatment, in particular to a dual-mode positron imaging machine system based on event counting.
By contrast, the dual-mode positron imaging machine based on event counting can be used for identifying gamma photon pairs generated by annihilation of cerenkov photons and positive and negative electron pairs emitted by charged particle motion in the positron emission process, so that the signal-to-noise ratio, the imaging space-time resolution and the sensitivity of the system are effectively improved, and the material cost is reduced.
Compared with the prior art, the invention has the beneficial effects that:
(1) Better space-time resolution;
(2) Better image signal-to-noise ratio;
(3) Can work at room temperature;
(4) The cost is low;
(5) And various information of the positron source is fully utilized.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present disclosure describes embodiments, not every embodiment is provided with a separate embodiment, and that this description is provided for clarity only, and that the disclosure is not limited to the embodiments described in detail below, and that the embodiments described in the examples may be combined as appropriate to form other embodiments that will be apparent to those skilled in the art.
Claims (10)
1. A dual-mode positron imaging machine based on event counting, characterized by comprising the following modules:
the unstable isotope injection module is used for marking substances participating in physiological and biochemical processes in the organism, shielding background light outside the organism and enabling the organism to be provided with a marker capable of emitting multiple irradiation events;
the gamma detector module detects gamma photons in a ring-shaped visual angle mode, acquires time and energy attributes of single gamma photon events, and detects gamma photons by adopting a scintillation detector principle;
the visible light detector module is used for detecting visible light photons and soft ultraviolet photons in a high detection efficiency mode, and the detector adopts a large-area planar structure and can be used for large-scale manufacture of a large-scale photoelectronic chip process;
the Toxoplasma time window judging and selecting module is used for judging whether the Cherenkov event and the gamma photon event belong to a positron event or not, and judging whether the gamma photon event and the Cherenkov event exist in the time window or not at the same time;
the visualization module is used for carrying out subsequent processing or discarding on irradiation data and comprises a processor module, an anti-power-off direct current power supply module, a display module and a network transmission interface module.
2. The dual mode positron imaging apparatus of claim 1, wherein the unstable isotope injection module comprises:
the radioisotope delivery module is used for stably and automatically delivering the radioactive drug to the organism, so that radiation damage of the radioactive drug to the human body and the organism is avoided, and the drug enters the drug injection module through the radioisotope delivery module;
the medicament injection module is used for controlling the dosage of the radioactive medicament injected into the organism or the human body in real time and consists of a pushing device and a dosage measuring and calculating device;
the biological transmission module is used for controlling the feeding and discharging of organisms inside and outside the imaging cavity, and consists of a pushing device and a supporting plate, wherein the supporting plate is used for accommodating the organisms, the pushing device is responsible for feeding the supporting plate and the organisms into the imaging cavity before imaging, and feeding the supporting plate and the organisms out of the imaging cavity after imaging is completed;
and the light sealing module is used for carrying out light-shielding packaging on the imaging cavity and ensuring that no extra external visible light is injected into the imaging cavity during imaging.
3. The dual mode positron imaging camera based on event counting of claim 1, wherein the gamma detector module comprises:
the scintillation crystal module is used for absorbing gamma photons, converting the energy of one gamma photon into a cluster of visible light or soft ultraviolet photons and consists of a scintillation crystal bare crystal, a scintillation light reflecting material, a scintillation crystal packaging shell and light-emitting glass;
the photoelectric conversion module is used for energy absorption and electric signal conversion of visible light and soft ultraviolet photons, specifically, the photoelectric current cluster is amplified in a short time through an avalanche process and then output to the front-end electronics module;
the front-end electronics module is used for pre-amplifying the electric signal output by the photoelectric conversion module, performing analog-to-digital conversion, and outputting the digitized scintillation pulse attribute to the gamma event attribute packaging circuit module according to the event;
and the gamma event attribute packaging circuit module is used for packaging the attribute of the gamma event, wherein the packaged content comprises event time, gamma photon energy, rising time of the front edge of the scintillation pulse and dispersion sum of the scintillation pulse.
4. The dual mode positron emission tomography apparatus as claimed in claim 1, wherein the visible light detector module includes:
the cerenkov photon photoelectric conversion module is used for absorbing cerenkov photons and converting the cerenkov photons into electric signals, specifically amplifying photoelectron current clusters in a short time through a photoelectric effect and an avalanche process, and outputting the photoelectron current clusters to the cerenkov detection front-end electronics module;
the front-end electronic module for detecting the cerenkov is used for pre-amplifying cerenkov induction electric pulses, performing analog-to-digital conversion, and outputting the digitized cerenkov induction electric pulse attributes to the cerenkov event attribute packaging circuit module according to the events;
and the cerenkov event attribute packaging circuit module is used for packaging attributes of cerenkov events, wherein the packaged contents comprise event time, gamma photon energy, rising time of the front edge of cerenkov induction electric pulse and dispersion sum of cerenkov induction electric pulse.
5. The dual-mode positron emission tomography apparatus as claimed in claim 1, wherein the multi-instance time window decision module comprises:
the multi-instance timing windowing circuit module is used for timing windowing each gamma event and each cerenkov event, namely starting timing 1 output from the event arrival time;
the logic AND gate circuit module receives the 1 setting signal output by the multi-instance timing windowing circuit module, then carries out AND logic judgment on a plurality of instances through the AND gate circuit, when two gamma photons and more than one channel of Cerenkov events exist, sets 1 for output, otherwise, keeps zero clearing output;
the total event timing windowing module receives an AND gate judging signal of the logic AND gate circuit module and outputs the AND gate judging signal at a fixed time window 1 from the receiving of the 1 setting signal;
the coincidence event encapsulation module is used for encapsulating each event attribute received from the multi-event timing windowing circuit module into a binary bit stream from the beginning of receiving a 1 signal of the total event timing windowing module;
the power supply module is used for stably supplying power to each circuit module, and the power supply is externally connected with Alternating Current (AC) mains supply;
the digital circuit clock module is used for sending clock signals to each digital circuit module, wherein the clock signals are sine wave voltage signals and are provided by the active crystal oscillator.
6. The dual mode positron imaging machine based on event counting of claim 1, wherein the visualization module comprises:
the processor module is used for carrying out correlation analysis, histogram counting and statistical calculation on the packaged cases and transmitting the analysis and calculation result to the display module;
the anti-power-off direct current power supply module is used for ensuring the stable work of the display module and the processor module, and can still keep the working power supply for more than 8 hours after the system is powered off so as to carry out repairing and archiving actions before the shutdown;
the display module is used for displaying various spectroscopy attributes of the positron event after receiving the gamma attribute and the cerenkov attribute of the positron event;
and the network transmission interface module is used for transmitting gamma attributes and cerenkov attributes of the positron events and a spectroscopy chart of the cerenkov attributes.
7. The dual mode positron imaging apparatus of claim 1, wherein the event arrival time is the time of the detector responding to a gamma event or a cerenkov event or the time of the detector responding to a gamma event or cerenkov event plus a constant which is applicable to the overall system at any time.
8. The dual-mode positron imaging apparatus of claim 1, wherein the gamma attribute of a positron event is a response characteristic of a pair of gamma photons generated after annihilation of a positive electron with an electron hitting a gamma detector, and the cerenkov attribute of a positron event is a response characteristic of a cerenkov photon generated before annihilation of a positive electron with an electron hitting a visible light detector.
9. The dual-mode positron imaging apparatus of claim 1, wherein the positron event is a positron emitted by a proton-rich nuclide through decay, the positron producing a cerenkov effect when in motion, and a pair of gamma photons generated after annihilation with a nearby electron, the gamma photons having properties captured by a gamma detector, the cerenkov photons having properties captured by a visible light detector.
10. The dual-mode positron imaging apparatus as claimed in claim 1, wherein the multi-case time window judgment is that when the visible photon detector and the gamma photon detector of the system capture two signals at the same time, the probability that the visible photon and the gamma photon in the case are background photons or dark excitation photons is considered to be smaller by the system, and the gamma photon pair and the cerenkov photon of the positron event are judged.
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