A radiation detector

Abstract

The application discloses a novel ray detector, characterized in that the novel ray detector comprises a Cerenkov radiation material window, a photocathode surface plated on a light exit surface of the Cerenkov radiation material window, a microchannel plate and a readout circuit board; wherein the Cerenkov radiation material window is a glass optical fiber panel, used for receiving incident gamma rays and inputting Cerenkov light generated by the incident gamma rays into a fiber core to the photocathode surface; the photocathode surface is used for converting the Cerenkov light into photoelectrons and transmitting the photoelectrons to the microchannel plate through a vacuum electric field; and the microchannel plate is used for inputting the received photoelectrons into the readout circuit board after amplification by multiplication. The application can realize better position resolution.

Description

Technical Field

[0001] This invention belongs to the field of nuclear radiation detection and nuclear technology applications, and in particular relates to a novel radiation detector. Background Technology

[0002] Positron emission tomography (PET) is a crucial nuclear medicine imaging technique widely used in the diagnosis of tumors, coronary heart disease, and neurological disorders. Time-of-flight (TOF) PET, with its time-of-flight measurement capability, is currently the mainstream PET technology. Better time resolution in TOF PET detectors results in a higher system signal-to-noise ratio, requiring less radiopharmaceutical injection for the patient and a shorter scan time.

[0003] Currently, the temporal resolution of TOF-PET is improving significantly. Commercially available TOF-PET systems typically achieve a coincidence time resolution below 500 ps, ​​while the latest generation can even reach around 200 ps. Research shows that the signal-to-noise ratio (SNR) of a TOF-PET system increases with improved coincidence time resolution, especially when the system's coincidence time resolution is less than 200 ps. In such cases, the SNR increases rapidly. If the system's coincidence time resolution can reach below 50 ps, ​​PET image reconstruction will undergo a revolutionary change, potentially even enabling dynamic PET imaging.

[0004] Currently, commercially available Time-of-Flight (TOF)-PET detectors all employ scintillation detectors to detect gamma rays generated by positron annihilation. Their scintillation detector structures are primarily based on scintillator-coupled photomultiplier tubes (PMTs) or silicon photomultiplier tubes (SiPMs). However, limited by the emission mechanism of the scintillator and the timing characteristics of the photodetector used, the coincidence time resolution limit of commercially available scintillation detector TOF-PET systems is between 150 ps and 200 ps, ​​still far from the revolutionary coincidence time resolution below 50 ps. To achieve a coincidence time resolution below 50 ps, ​​faster gamma-ray detection methods must be employed, with Cherenkov photodetectors being the most promising approach. The specific principle is that gamma rays interact with the Cherenkov radiator to produce photoelectrons or Compton electrons. If the energy of the electrons is higher than the Cherenkov light generation threshold, Cherenkov light will be generated. The generation of Cherenkov light is almost instantaneous, with a timescale within 10 ps. Therefore, high-precision detection of Cherenkov light can achieve high-precision detection of the interaction time of gamma rays. Thus, the coincidence time resolution of a TOF-PET system based on Cherenkov light detection can potentially reach within 50 ps. To achieve this goal, traditional photodetectors such as PMTs or SiPMs are no longer sufficient and must be replaced with photodetectors with better time characteristics. Microchannel plate photomultiplier tubes (MCP-PMTs) are the preferred choice. Currently, some research institutions have used Cherenkov radiators combined with MCPs to achieve coincidence time resolutions better than 40 ps. Specifically, the photocathode window of the MCP-PMT is replaced with a Cherenkov radiator, such as... Figure 1 As shown. In this way, Cherenkov light is generated directly within the photocathode window and can be directly detected by the photocathode without passing through any optical interface, minimizing the loss of Cherenkov photon numbers and the dispersion of temporal information. However, for 511 keV gamma rays produced by positron annihilation, the number of Cherenkov photons generated in a single event is small, and the number that can be detected is even smaller, usually only one or two, sometimes none at all. While the emission direction of Cherenkov light is generally towards the propagation direction of the gamma rays, it has a certain degree of randomness. Therefore, the position of the Cherenkov photon detected by the MCP will deviate somewhat from the position of the gamma ray's interaction within the Cherenkov radiator, such as... Figure 2 As shown. Therefore, the position resolution capability of the Cherenkov light TOF-PET system based on this model will be affected. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a novel X-ray detector. This invention utilizes a glass fiber optic panel as the photocathode window in an MCP-PMT for use in a Cherenkov-based TOF-PET detector.

[0006] The technical solution of this invention is as follows:

[0007] A novel X-ray detector, characterized by comprising a Cherenkov radiation material window, wherein the light-emitting surface of the Cherenkov radiation material window is coated with a photocathode surface, a microchannel plate, and a readout circuit board; wherein,

[0008] The Cherenkov radiation material window is a glass fiber panel used to receive incident gamma rays and input the Cherenkov light generated by the gamma rays incident into the fiber core into the photocathode surface.

[0009] The photocathode surface is used to convert the Cherenkov light into photoelectrons and transmit them to the microchannel plate via a vacuum electric field.

[0010] The microchannel plate is used to amplify the received photoelectrons before inputting them into the readout circuit board.

[0011] Furthermore, the glass fiber panel transmits the Cherenkov light generated by the incident gamma rays in the fiber core to the photocathode surface through total internal reflection of the fiber wall.

[0012] Furthermore, the core of the glass fiber panel is made of a material with high refractive index and high effective atomic number, and is used as a Cherenkov radiator.

[0013] Furthermore, the core of the glass fiber panel is made of lead glass.

[0014] Furthermore, the photocathode surface is a photoelectric conversion film.

[0015] The advantages of this invention are as follows:

[0016] This invention replaces the Cherenkov radiation window of the Cherenkov optical MCP-PMT with a glass fiber panel to achieve better position resolution. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a Cherenkov window MCP-PMT.

[0018] Figure 2 This is a schematic diagram showing the deviation of the detected Cherenkov photon position p1 or p2 from the actual gamma-ray interaction position p0.

[0019] Figure 3 This is a schematic diagram of the Cherenkov window (MCP-PMT) result of the glass fiber panel of the present invention.

[0020] Figure 4 This is due to the total internal reflection of Cherenkov light on the fiber wall. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0022] This invention designs a Cherenkov-based MCP-PMT detector with precise gamma-ray positioning capability, achieving extreme time resolution while retaining excellent position resolution, and is expected to be used in next-generation TOF-PET detectors. A schematic diagram of the structural design of this invention is shown below. Figure 3 As shown, the specific structure includes:

[0023] 1) Glass fiber optic panel window

[0024] Traditional MCP-PMTs use ordinary optical glass as the window material, allowing scintillating light from an external scintillator to enter smoothly. Cherenkov-window MCP-PMTs replace this traditional window material with a Cherenkov radiator with a high effective atomic number. When gamma rays are incident on the window material of the Cherenkov radiator, the photoelectric effect or Compton effect occurs, generating photoelectrons or Compton electrons. These electrons move within the window material, producing Cherenkov light. To ensure that the Cherenkov light reaches the photocathode surface without deviating from the position where the gamma rays interact within the window, this invention replaces the Cherenkov radiating material window with a glass fiber panel. The fiber core is made of a material with a high refractive index and a high effective atomic number, such as lead glass, and serves as the Cherenkov radiator. When incident gamma rays enter the core (i.e., Cherenkov radiator) of a glass optical fiber panel, they first undergo the photoelectric effect or Compton effect, generating photoelectrons or Compton electrons. These electrons then propagate forward within the core, producing Cherenkov light. The secondary electrons from the gamma rays also generate Cherenkov light within the core. This Cherenkov light is transmitted to the photocathode surface via total internal reflection through the fiber wall. Thus, the position of the Cherenkov photon detected at the photocathode surface will coincide with the position of the gamma ray's interaction. Figure 4 As shown, this invention achieves extreme time resolution while maintaining excellent position resolution, and is more likely to be used in the next generation of TOF-PET.

[0025] 2) Photocathode surface

[0026] The photocathode surface is a photoelectric conversion film coated on the inside of the glass fiber optic panel window, used to convert Cherenkov light into photoelectrons.

[0027] 3) Microchannel plates

[0028] It is used to multiply photoelectrons to form an electrical signal that is easy to measure.

[0029] 4) Read the circuit board

[0030] Used to read out the multiplied electrical signal for subsequent processing.

[0031] Although specific embodiments of the invention have been disclosed for illustrative purposes to aid in understanding and implementing the invention, those skilled in the art will understand that various substitutions, variations, and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the invention should not be limited to the content disclosed in the preferred embodiments, and the scope of protection claimed by the invention is defined by the claims.

Claims

1. A radiation detector, characterized by, The Cerenkov radiation material window comprises a light-emitting surface coated with a photocathode surface, a micro-channel plate and a readout circuit board. The Cerenkov radiation material window is a glass fiber panel for receiving incident gamma rays and causing photoelectric effect or Compton effect in the fiber core of the glass fiber panel to generate secondary electrons of the gamma rays; then the generated Cerenkov light is input to the photocathode surface through total reflection of the fiber wall during the forward transmission of the secondary electrons in the fiber core; the fiber core of the glass fiber panel is made of a material with high refractive index and high effective atomic number, which is used as a Cerenkov radiator; The photocathode surface is used for converting the Cerenkov light into photoelectrons and transmitting the photoelectrons to the micro-channel plate through a vacuum electric field. The micro-channel plate is used for amplifying the received photoelectrons and inputting the amplified photoelectrons to the readout circuit board.

2. The radiation detector of claim 1, wherein, The fiber core of the glass fiber panel is made of lead glass.

3. The radiation detector of claim 1, wherein, The photocathode surface is a photoelectric conversion film.

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