A photon Radar / PET shared SiPM imaging method and instrument

Abstract

The present invention provides a photon Radar / PET shared SiPM imaging method and instrument, including: control signal output, laser emitting laser pulses to the target object to be measured, and injecting tracer drugs; laser rotating in all directions to cover all scanning areas, positron annihilation to generate gamma photon pairs; SiPM array converts reflected pulses into electrical signals, gamma photon pairs into scintillation pulses, and transmits them to a storage module; pre-filtering analog electrical pulses, and converting them into digital signals, and extracting their time information, energy information, position information and depth information; reconstructing through their information, and displaying reconstructed images. The present invention can make the micro-movement of the target object to be measured be identified and used for imaging, effectively improve the resolution performance of the system, eliminate the errors caused by the micro-movement of the object, and significantly shorten the imaging time.

Description

Technical Field

[0001] The present invention relates to the fields of visible light photon detection, photoelectric signal processing and digital imaging, and more specifically to a photon Radar / PET shared SiPM imaging method and instrument. Background Art

[0002] Photon Radar (radio detection and ranging) is a new type of radar that uses photons as information carriers. Radar can detect target objects anytime and anywhere and conduct detection of detected targets. It is often used to detect military weapons and is an important part of modern military technology. Excellent radar performance can put our military weapons in a commanding position. Therefore, my country has invested huge resources in the field of radar technology, hoping to continuously improve radar performance.

[0003] We all know that light has "wave-particle duality", that is, light has both wave characteristics and can propagate forward like a wave, and particle characteristics and can show the characteristics of particles. Traditional radar uses electrons as carriers, uses the "wave" characteristics of electromagnetic waves, emits electromagnetic waves, and uses echoes to locate the specific position, height and other information of the target by processing the generated signals. However, there is an upper limit to the accumulation of technology, and this upper limit is the basic principle of the technology. However, traditional radar waves have many limitations, which are caused by their basic principles. The emergence of stealth aircraft is the best proof of the failure of traditional radar. In addition, traditional radars are difficult to use in severe conditions such as fog, rain, and haze. Radars cannot detect targets under the obstruction of obstacles such as clouds. Although the latest synthetic aperture radar can work all day and has penetration capabilities, it still cannot overcome the shortcomings of poor accuracy and slow processing speed. Therefore, finding new technologies to break through the limitations of traditional radars has become a very important task.

[0004] With the development of photonic technology, people have begun to take advantage of the rich spectral resources, using photons as information carriers and the particle nature of light to generate and process radar broadband signals better and faster, thereby achieving rapid and very clear target identification.

[0005] Positron emission tomography (PET) is a new non-invasive medical technology that can non-invasively, quantitatively and dynamically evaluate the metabolic levels, biochemical reactions and functional activities of various organs and tissues in living animals or humans. It plays a unique role in early detection of diseases, research on pathophysiological mechanisms, efficacy monitoring and prognosis evaluation.

[0006] In PET, a scintillation detector is usually used to convert the response of photons into corresponding electrical pulse signals. The energy of gamma photons is obtained by measuring the amplitude (or integral value) of the electrical pulse signals, and the time information of gamma photon pairs is obtained by calculating the difference in arrival time of the electrical pulse signals. In the prior art, since photomultiplier tubes (hereinafter referred to as PMTs) have unique advantages such as high magnification, good photoelectric linearity, high operating frequency, and stable performance, PMTs are usually used as photoelectric conversion devices. PMTs amplify the detected photons one by one through each multiplication stage (usually 8 to 13), and can generate a typical gain of more than 106 at the anode. In addition, PMTs have a fast time response speed, which is very advantageous in calculating the time information of the system. PMTs are made of vacuum glass tubes, which are very fragile and need to be manually manufactured by people, so they are very expensive and difficult to transport. In addition, PMTs have a large sensitive area and are basically difficult to miniaturize.

[0007] With the development of SiPM in the field of high-energy physics, people began to explore the use of SiPM in PET systems. Its operating voltage is much lower than that of PMT, and its gain can reach the same order of magnitude as PMT. It has a simple and compact structure and a fast time response. Its price is lower than that of PMT, and it is compatible with CMOS technology, which can achieve better and faster imaging and significantly improve imaging resolution. Summary of the invention

[0008] The purpose of the present invention is to provide a photon Radar / PET shared SiPM imaging method and instrument, so as to solve the problems of performance limitation, great environmental influence, high cost and slow imaging speed existing in the prior art.

[0009] In order to solve the above technical problems, the present invention provides a photon Radar / PET shared SiPM imaging instrument, comprising: a control module 100, a signal transmission module 200, a pulse receiving module 300, an imaging module 400, and a mechanical support and rotation module 500, wherein:

[0010] The control module 100 is connected to the signal transmitting module 200, the pulse receiving module 300, and the imaging module 400 for providing control signals and determining the timing of signal transmitting and receiving pulses;

[0011] The control module 100 includes a control signal module 110 and a dual-mode clock module 120;

[0012] The control signal module 110 is subordinate to the control module 100 and is used to give a signal to start the system when the external conditions are sufficient;

[0013] The dual-mode clock module 120 is subordinate to the control module 100 and includes a timing sending module 121 and a receiving time module 122.

[0014] The timing sending module 121 is subordinate to the dual-mode clock module 120 and is used to generate a timing pulse when emitting laser to record the laser emission time;

[0015] The receiving time module 122 is subordinate to the dual-mode clock module 120 and is used to record the time when the SiPM and PET detectors receive signals.

[0016] The signal transmitting module 200 is in communication with the pulse receiving module 300 and is used to transmit laser pulses from all directions to detect the target object and generate gamma photon pairs;

[0017] The signal transmitting module 200 includes a laser module 210 and a gamma transmitting module 220;

[0018] The laser emission module 210 is subordinate to the signal emission module 200, wherein the laser emission module 210 outputs to the detection target object, generates an echo and acts on the pulse receiving module 300, including a laser timing module 211, a laser module 212, and a laser deflection module 213;

[0019] The laser timing module 211 is subordinate to the laser emission module 210 and is used to generate a timing pulse of a specific frequency to record the time interval of laser emission;

[0020] The laser module 212 is subordinate to the laser emission module 210 and is used to generate laser pulses of a specific wavelength band and emit them toward the target object to be measured;

[0021] The laser deflection module 213 is subordinate to the laser emission module 210 and is used to adjust the emission angle of the laser so that the laser pulse can be emitted in any direction;

[0022] The gamma pair transmitting module 220 is subordinate to the signal transmitting module 200, wherein after the gamma pair transmitting module 220 transmits the gamma pair, it is detected by the scintillation pulse receiving module 320 to generate the gamma photon pair;

[0023] The gamma-ray emission module 220 includes an isotope generation module 221, a medicine delivery module 222, and an isotope injection module 223;

[0024] The isotope production module 221 is subordinate to the gamma-ray emission module 220 and is used to produce radioactive isotopes that can emit positrons;

[0025] The medicine delivery module 222 is subordinate to the gamma ray emission module 220 and is used to automatically deliver the tracer medicine marked with radioactive isotopes to the target object to be tested to avoid radiation damage;

[0026] The isotope injection module 223 is subordinate to the gamma ray emission module 220 and is used to control the dosage of the tracer drug injected into the target object to be tested.

[0027] The pulse receiving module 300 is connected to the signal transmitting module 200 for communication. After the laser pulse generated by the laser transmitting module 210 detects the target object, an echo is generated and sent to the pulse receiving module 300. The gamma photon pairs generated by the gamma pair transmitting module 220 are detected by the pulse receiving module 300.

[0028] The pulse receiving module 300 includes a reflection pulse receiving module 310 and a scintillation pulse receiving module 320;

[0029] The reflected pulse receiving module 310 is subordinate to the pulse receiving module 300 and includes a SiPM array module 311 and an optical fiber communication transmission module 312;

[0030] The SiPM array module 311 is subordinate to the reflected pulse receiving module 310 and is used to receive the light reflected from the target object to be measured and convert it into an electrical signal;

[0031] The optical fiber communication transmission module 312 is subordinate to the reflected pulse receiving module 310 and is used to transmit the electrical signal generated by the SiPM array module 311 to the imaging module 400 at a high rate and without loss;

[0032] The scintillation pulse receiving module 320 is subordinate to the pulse receiving module 300 and includes a crystal array module 321, a light guide module 322, a photoelectric conversion module 323, and a readout electronics module 324;

[0033] The crystal array module 321 is subordinate to the scintillation pulse receiving module 320 and is used to absorb gamma photons and convert them into visible light photons;

[0034] The light guide module 322 is subordinate to the scintillation pulse receiving module 320 and is used to evenly refract the photons generated by the crystal array module to the SiPM array module and effectively prevent the existence of bubbles from scattering the photons;

[0035] The photoelectric conversion module 323 is subordinate to the scintillation pulse receiving module 320 and is used to multiply and amplify the visible light photons output by the crystal array module and convert them into photoelectrons;

[0036] The readout electronics module 324 is subordinate to the scintillation pulse receiving module 320 and multiplexes the photoelectrons generated by the photoelectric conversion module 323 through a resistor network to obtain a scintillation pulse with a steep rising edge.

[0037] The imaging module 400 is connected to the pulse receiving module 300 for storing the scintillation pulse information generated by the pulse receiving module, extracting the scintillation pulse information, and obtaining an image of the detected target object;

[0038] The imaging module 400 includes a storage module 410, a pulse preprocessing module 420, an information extraction module 430, and a reconstruction module 440;

[0039] The storage module 410 is subordinate to the imaging module 400 and is used to receive the analog electrical pulse signal generated by the pulse receiving module and store it according to the pulse arrival time;

[0040] The pulse preprocessing module 420 is subordinate to the imaging module 400 and is used to pre-filter the analog electrical pulses to eliminate some sharp burrs and make the displayed image smoother;

[0041] The information extraction module 430 is subordinate to the imaging module 400 and includes a time information module 431, an energy information module 432, a position information module 433, and a depth information module 434;

[0042] The time information module 431 is subordinate to the information extraction module 430 and uses a time discrimination algorithm to extract the arrival time information of the pulse;

[0043] The energy information module 432 is subordinate to the information extraction module 430, and calculates the energy information of the pulse and extracts the energy value distribution of the pulse;

[0044] The position information module 433 is subordinate to the information extraction module 430 and extracts the position information of the pulse by restoring the pulse attributes;

[0045] The depth information module 434 is subordinate to the information extraction module 430 and calculates the laser pulse and its reflected pulse to extract the depth information of the target object to be measured;

[0046] The reconstruction module 440 is subordinate to the imaging module 400 and reconstructs the functional image and peripheral contour of the target object to be measured through various information, that is, the time-varying image of the target object to be measured with slight motion.

[0047] The mechanical support and rotation module 500 is mechanically connected to the signal transmission module 200 and the pulse receiving module 300, and is used to support the module and realize the rotation of the laser transmission module 210 in all directions according to a certain frequency;

[0048] The mechanical support and rotation module 500 includes a mechanical support module 510 and a rotation module 520;

[0049] The mechanical support module 510 is subordinate to the mechanical support and rotation module 300 and is used to mechanically support the signal transmitting module 200 and the pulse receiving module 300;

[0050] The rotation module 520 is subordinate to the mechanical support and rotation module 500 and is used to realize the rotation of the laser emitting module 210 in all directions according to a certain frequency.

[0051] According to one embodiment of the present invention, the laser refers to an excitation device that can generate photons of a specific continuous wavelength band, including a single-shot laser, a modulated laser, and a fiber laser.

[0052] According to one embodiment of the present invention, the radioactive isotope may be 11C, 13N, 15O, 18F, 64Cu, etc.

[0053] According to one embodiment of the present invention, the crystal array may use crystal clear LYSO crystals.

[0054] According to one embodiment of the present invention, the SiPM array has a fast time response.

[0055] According to an embodiment of the present invention, the photoelectric conversion module uses a photoelectric device with high detection efficiency.

[0056] According to an embodiment of the present invention, the time discrimination method may adopt a leading-edge discriminator (LED) or a constant fraction discriminator (CFD).

[0057] The photon Radar / PET shared SiPM imaging method provided by the present invention comprises the following steps:

[0058] Step S1: a control signal is given, and the dual-mode clock module outputs a timing pulse. At this moment, the laser emits a laser pulse to the target object to be measured, and injects a tracer drug into the target object to be measured;

[0059] Step S2: The laser rotates around the target object to be measured to cover all areas; the radioactive isotope emits positrons in the target object to be measured, and the positrons combine and annihilate with negative electrons in the surrounding environment to produce gamma photon pairs;

[0060] Step S3: After the laser reaches the target object to be measured, it is transmitted back, and the SiPM array converts it into an electrical signal, and the electrical pulse carrying time information and depth information is transmitted and stored; the gamma photon pair is absorbed by the scintillation crystal and converted into visible light photons, which are converted into photoelectrons and multiplied, and then multiplexed through the resistor network to obtain scintillation pulses rich in original information and stored; at the same time, the dual-mode clock records the time of each pulse;

[0061] Step S4: pre-filtering the analog electric pulse, converting the analog signal into a digital signal, and extracting its time information, energy information, position information and depth information through coincidence processing;

[0062] Step S5: Reconstruct the acquired time information, energy information, position information and depth information using a reconstruction algorithm to display an image.

[0063] According to one embodiment of the present invention, the gamma photon pair is two gamma photons with an energy of 511 keV and a direction of 180°.

[0064] According to an embodiment of the present invention, the timing pulse can be set to be triggered by either a rising edge or a falling edge.

[0065] According to an embodiment of the present invention, the reconstruction algorithm may use an analytical reconstruction algorithm or an iterative reconstruction algorithm.

[0066] The photon Radar / PET shared SiPM imaging instrument provided by the present invention comprises: a control module, the control module is connected to a signal transmitting module and a pulse receiving module for communication, and receives a timing pulse signal sent by the control module; a signal transmitting module, the signal transmitting module is connected to the pulse receiving module for communication, and sends reflected light and gamma photon pairs to the pulse receiving module; a pulse receiving module, the pulse receiving module is connected to the signal transmitting module for communication, and receives reflected light and gamma photon pairs sent by the signal transmitting module; and an imaging module, the imaging module is connected to the pulse receiving module for communication, and receives reflected pulses and scintillation pulse signals sent by the pulse receiving module.

[0067] According to an embodiment of the present invention, the device communicates and transmits by means of data frame packet capture.

[0068] According to an embodiment of the present invention, the information extraction refers to extracting the original pulse using a dedicated software algorithm.

[0069] The photon Radar / PET shared SiPM imaging method and instrument provided by the present invention adopts a photon radar to obtain the depth information of the target object to be measured, and simultaneously adopts a PET detector to obtain the functional image of the target object to be measured, so that the tiny movement of the target object to be measured can be identified and used for imaging, effectively improving the resolution performance of the system, eliminating the error caused by the tiny movement of the object, and significantly shortening the imaging time. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 This is the structural block diagram of the photon Radar / PET shared SiPM imaging instrument.

[0071] Figure 2 This is a flow chart of the photon Radar / PET shared SiPM imaging method.

[0072] Figure 3 It is a schematic structural diagram of a photon Radar / PET shared SiPM imaging instrument according to an embodiment of the present invention.

[0073] Figure 4 This is a comparison chart of various aspects of performance between the photon Radar / PET shared SiPM imaging instrument according to the present invention and traditional radar. DETAILED DESCRIPTION

[0074] The present invention is further described below in conjunction with specific examples. It should be understood that the following examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0075] Figure 3 FIG. 1 is a schematic diagram of the structure of a photon Radar / PET shared SiPM imaging instrument according to an embodiment of the present invention. Figure 3 It can be seen that the photon Radar / PET shared SiPM imaging instrument in the present invention includes a control system 110, a dual-mode clock source 120, a laser 212, a deflection adjustment device 213, a SiPM array 311, a PET detector 320 and a display 400, wherein the control system is connected to the dual-mode clock source and receives a control signal sent by the control system; the laser emits a laser pulse, which is reflected by the target object to be measured and then received by the SiPM array; the PET detector receives a gamma photon pair and converts it into a scintillation pulse; the display processes the electrical pulse to obtain a reconstructed image and displays it.

[0076] Example 1: Utilization Figure 2 When the device shown is performing imaging, the PET detector is an annular detector, and its diameter is placed perpendicular to the ground. The target object to be measured is located in the annular detector. The photon radar is kept perpendicular to the annular detector, that is, parallel to the ground. The photon radar takes the center of the annular detector as the center of the circle and performs a circular motion in a direction parallel to the ground.

[0077] Example 2: Utilization Figure 2 When the device shown is performing imaging, the PET detector is a flat-panel detector, the two detectors are placed parallel to the ground, the two detectors remain parallel, the target object to be measured is located between the two flat-panel detectors, the photon radar remains parallel to the flat-panel detector, that is, parallel to the ground, and the photon radar performs a circular motion in a direction parallel to the ground with the center of the flat-panel detector as the center of the circle.

[0078] Example 3: Utilization Figure 2When the device shown is performing imaging, the PET detector is a flat-panel detector, the two detectors are placed parallel to the ground, the two detectors remain parallel, the target object to be measured is located between the two flat-panel detectors, the photon radar remains parallel to the flat-panel detectors, that is, parallel to the ground, and the photon radar performs uniform spiral motion around the target object to be measured with the central axis of the two flat-panel detectors as the axis.

[0079] The photon Radar / PET shared SiPM imaging method and instrument provided by the present invention adopts a photon radar to obtain the depth information of the target object to be measured, and simultaneously adopts a PET detector to obtain the functional image of the target object to be measured, so that the tiny movement of the target object to be measured can be identified and used for imaging, effectively improving the resolution performance of the system and significantly shortening the imaging time.

[0080] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A photon Radar / PET shared SiPM imaging method, characterized in that: The method comprises: step S1: giving a control signal, the dual-mode clock outputs a timing pulse, at which moment the laser emits a laser pulse to the target object to be measured, and injects a tracer drug into the target object to be measured; Step S2: The laser rotates around the target object to be measured to cover all areas; the radioactive isotope emits positrons in the target object to be measured, and the positrons combine and annihilate with negative electrons in the surrounding environment to produce gamma photon pairs; Step S3: After the laser reaches the target object to be measured, it is reflected and the SiPM array converts it into an electrical signal. The electrical pulse carrying time information and depth information is transmitted and stored; the gamma photon pair is absorbed by the scintillation crystal and converted into visible light photons. The visible light photons are converted into photoelectrons and multiplied. The scintillation pulses rich in original information are obtained through resistor network multiplexing and stored; at the same time, the dual-mode clock records the time of each pulse; Step S4: pre-filtering the analog electric pulse, converting the analog signal into a digital signal, and extracting its time information, energy information, position information and depth information through coincidence processing; Step S5: Reconstruct the acquired time information, energy information, position information and depth information using a reconstruction algorithm to display an image.

2. The photon Radar / PET shared SiPM imaging method according to claim 1, characterized in that: The control signal of the method is rising edge triggered or falling edge triggered.

3. The photon Radar / PET shared SiPM imaging method according to claim 1, characterized in that: The laser of the method can rotate 360 ​​degrees in the horizontal direction and the vertical direction.

4. The photon Radar / PET shared SiPM imaging method according to claim 1, characterized in that: The SiPM array of the method has a fast time response of less than 10ns.

5. The photon Radar / PET shared SiPM imaging method according to claim 1, characterized in that: The pre-filtering process of the method includes a first-order filtering method, a limiting filtering method or an image median filtering method.

6. The photon Radar / PET shared SiPM imaging method according to claim 1, characterized in that: The method converts analog electrical pulses into digital signals at a sampling rate of 65Msps.

7. The photon Radar / PET shared SiPM imaging method according to claim 1, characterized in that: The resistor network of the method adopts a multiplexing method of a symmetrical charge distribution circuit.

8. The photon Radar / PET shared SiPM imaging method according to claim 1, characterized in that: The position information of the method is multiplexed into X+, X-, Y+, and Y-.

9. The photon Radar / PET shared SiPM imaging method according to claim 1, characterized in that: The reconstruction algorithm of the method includes using an analytical reconstruction algorithm or an iterative reconstruction algorithm.

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