Radiation-sensitive detector and radiation inspection device

Abstract

A radiation-sensitive detector (30), comprising a plurality of pixels (300), at least one pixel (300) among the plurality of pixels (300) comprising: a radiation-sensitive element (310) for receiving ray photons and converting the ray photons to output same as an analog signal; and an analog-to-digital conversion element (320), which is electrically connected to the radiation-sensitive element (310), wherein the analog-to-digital conversion element (320) is used for converting the analog signal into a digital signal. The analog signal comprises a plurality of sub-analog signals, and the sub-analog signals are generated by means of performing partitioning along at least one of a spatial dimension and a temporal dimension and converting the ray photons. Further provided is a radiation inspection device.

Description

Radiation-sensitive detectors and radiation inspection equipment

[0001] This application claims priority to Chinese Patent Application No. 202411999219.7, filed on December 31, 2024, the contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of radiation inspection technology, specifically to the field of radiation inspection equipment technology, and more specifically to a radiation-sensitive detector and radiation inspection equipment. Background Technology

[0003] X-ray detectors can acquire spatial distribution information of incident X-ray photons and have wide applications in fields such as medicine and security inspection. Currently, most X-ray detectors are linear array or area array detectors, where each pixel can detect X-ray photons, and the spatial distribution information of incident X-ray photons is obtained through the spatial arrangement of multiple pixels.

[0004] A single pixel in an X-ray detector generally consists of two parts: a sensor and a readout section. The main function of the sensor is to convert incident X-ray photons into an initial electrical signal. The readout section processes the initial electrical signal from the sensor and outputs the detection information of the X-ray photons. Currently, the performance of the sensor and / or readout section limits the detector's signal-to-noise ratio (SNR), and there is a problem that the SNR cannot be optimized without modifying the existing sensor and / or readout section.

[0005] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0006] In view of the above problems, this disclosure provides a radiation-sensitive detector and a radiation inspection device, which solves the problem that existing radiation-sensitive detectors cannot optimize the signal-to-noise ratio of the detector without using more precise equipment in the sensor section and signal readout section.

[0007] According to a first aspect of this disclosure, a radiation-sensitive detector is provided, the radiation-sensitive detector comprising a plurality of pixels, at least one of the plurality of pixels comprising: a radiation-sensitive element for receiving X-ray photons and converting and outputting the X-ray photons as an analog signal; and an analog-to-digital converter element electrically connected to the radiation-sensitive element for converting the analog signal into a digital signal; wherein the analog signal comprises a plurality of subdivided analog signals formed by segmenting and converting the X-ray photons using at least one of a spatial dimension and a temporal dimension.

[0008] According to embodiments of this disclosure, the radiation-sensitive element includes an indirect radiation-sensitive element or a direct radiation-sensitive element.

[0009] According to an embodiment of this disclosure, the analog signal includes a plurality of subdivided analog signals formed by segmentation using spatial dimensions, and the analog-to-digital conversion element includes a plurality of analog-to-digital converters, which are electrically connected to the radiation-sensitive element to convert each of the subdivided analog signals into subdivided digital signals, wherein the digital signals include the plurality of subdivided digital signals.

[0010] According to an embodiment of this disclosure, the radiation-sensitive element includes a light receiver and a plurality of photoelectric conversion units; wherein the light receiver is used to receive the X-ray photons; and each of the photoelectric conversion units is used to convert X-ray photons in the region corresponding to the light receiver into the subdivided analog signal.

[0011] According to embodiments of this disclosure, the radiation-sensitive element is an indirect radiation-sensitive element, the light receiving unit is a scintillator element, and the photoelectric conversion unit is a photoelectric conversion device; wherein, the scintillator element is used to receive the ray photons and convert the ray photons into optical signals, and each of the photoelectric conversion devices is used to convert the optical signals in the region corresponding to the scintillator element and output them as the subdivided analog signals.

[0012] According to embodiments of this disclosure, a plurality of the photoelectric conversion units are arranged in an array of M rows × N columns, where M is a positive integer greater than or equal to 1 and N is a positive integer greater than 1.

[0013] According to an embodiment of this disclosure, the radiation-sensitive detector further includes: a first data processing element for merging and processing a plurality of the subdivided digital signals into a pixel signal, the pixel signal being used to characterize at least one of the radiation intensity information and radiation energy information of the pixel corresponding to the radiation-sensitive element.

[0014] According to an embodiment of this disclosure, the analog signal includes a plurality of subdivided analog signals formed by segmenting them using a time dimension, and the analog-to-digital conversion element is used to convert each of the subdivided analog signals located in the same time period into subdivided time digital signals respectively.

[0015] According to an embodiment of this disclosure, the radiation-sensitive detector further includes a second data processing element, which is used to merge and process a plurality of the subdivided time digital signals into a pixel signal, wherein the pixel signal is used to characterize at least one of the radiation intensity information and radiation energy information of the pixel corresponding to the radiation-sensitive element within a fixed time period.

[0016] According to an embodiment of this disclosure, the radiation-sensitive detector further includes: a preamplifier element disposed between the radiation-sensitive element and the analog-to-digital converter element; wherein the analog signal output by the radiation-sensitive element is a current pulse signal, the preamplifier element is used to receive the current pulse signal and convert it into a voltage pulse signal, the preamplifier element can amplify the voltage pulse signal, and output the amplified voltage pulse signal to the analog-to-digital converter element.

[0017] A second aspect of this disclosure provides a radiation-sensitive detector, comprising: a scintillator element for converting X-ray photons into visible light photons, the scintillator element having a light-receiving surface facing a X-ray source and a light-output surface facing away from the X-ray source, the light-receiving surface for receiving the X-ray photons and the light-output surface for outputting the visible light photons; a plurality of photoelectric converters arranged in an M-row × N-column array and attached to the light-output surface, each photoelectric converter converting visible light photons in a region corresponding to the light-output surface into subdivided analog signals, wherein M is a positive integer greater than or equal to 1 and N is a positive integer greater than 1; and a plurality of analog-to-digital converters electrically connected to the plurality of photoelectric converters respectively to convert each subdivided analog signal into a subdivided digital signal.

[0018] According to an embodiment of this disclosure, the photoelectric conversion element has a light conversion surface, and the light conversion surfaces of a plurality of photoelectric conversion elements cover and adhere to the light output surface.

[0019] According to embodiments of this disclosure, the light conversion surfaces of the plurality of photoelectric conversion elements have the same area.

[0020] According to an embodiment of this disclosure, the light conversion surface of the photoelectric converter attached to the edge of the light output surface does not extend beyond the light output surface.

[0021] A third aspect of this disclosure provides a radiation inspection apparatus, comprising: a radiation source for emitting radiation; and a radiation-sensitive detector for receiving radiation photons emitted from the radiation source and passing through an object to be inspected, wherein the radiation-sensitive detector is any of the radiation-sensitive detectors described above. Attached Figure Description

[0022] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this application in any way. Furthermore, the shapes and scales of the components in the drawings are merely illustrative to aid in understanding this application and do not specifically limit the shapes and scales of the components. Those skilled in the art, guided by the teachings of this application, can select various possible shapes and scales to implement this application according to specific circumstances. In the drawings:

[0023] Figure 1 is a schematic diagram of the structure of a X-ray scanning detection system according to some exemplary embodiments of this application;

[0024] Figure 2 schematically shows the structure of the linear array pixels of the radiation-sensitive detector;

[0025] Figure 3 schematically shows the structure of the area array pixels of the radiation-sensitive detector;

[0026] Figure 4 schematically illustrates the structure of a single pixel in the pixel detector;

[0027] Figure 5 schematically illustrates the structure of a single pixel in a scintillator detector;

[0028] Figure 6 schematically illustrates the principle of spatial dimension segmentation of a radiation-sensitive detector according to an embodiment of the present disclosure;

[0029] Figure 7 schematically illustrates the spatial segmentation of a single pixel of a radiation-sensitive detector according to an embodiment of the present disclosure;

[0030] Figure 8 schematically illustrates an experimental test diagram of the electronic noise of a single pixel of a radiation-sensitive detector according to an embodiment of the present disclosure.

[0031] Explanation of reference numerals: 10, X-ray source; 20, rack; 30, radiation-sensitive detector; 300, pixel; 310, radiation-sensitive element; 311, light receiver; 312, photoelectric conversion unit; 320, analog-to-digital converter; 321, analog-to-digital converter; 40, support mechanism; 50, controller; 60, data processing device; 70, object to be detected. Detailed Implementation

[0032] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0034] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0035] When using expressions such as "at least one of A, B, and C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C. Similarly, when using expressions such as "at least one of A, B, or C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C.

[0036] Specific embodiments of this application will be described in detail below. It should be noted that the embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. In the following description, numerous specific details are set forth in order to provide a thorough understanding of this application. However, it will be apparent to those skilled in the art that these specific details are not necessary to implement this application. In other instances, well-known structures, materials, or methods have not been specifically described to avoid obscuring this application.

[0037] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of this application. Therefore, the phrases "in an embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0038] The basic structure of a single pixel in an X-ray detector can be divided into two parts: a sensor section and a readout section. The main function of the sensor section is to convert incident X-ray photons into initial electrical signals. The readout section processes the initial electrical signals from the sensor section and outputs the detection information of the X-ray photons.

[0039] The inventors discovered that existing X-ray detectors have a relatively simple and direct signal chain, with a one-to-one correspondence between analog domain measurement signals and digital domain output signals. In short, the sensor measurement signal of a given area corresponds to the pixel output signal of that area, and the sensor measurement signal over a given period corresponds to the pixel output signal over that period. Under this direct correspondence architecture, reducing detector electronic noise and improving the signal-to-noise ratio (SNR) requires replacing the sensor and readout circuit chip with higher-performance ones. Taking a scintillator detector as an example, a single pixel is read out by a CsI scintillator crystal-coupled photodiode (PD) followed by an ADC chip. This pixel directly outputs the analog signal from the large PD after it has been converted into a digital signal by the ADC chip. The area of ​​the PD and the pixel are the same. Therefore, to reduce the electronic noise of this pixel, a higher-performance PD is needed, specifically a PD with lower capacitance and dark current for the same area and an ADC chip with lower noise for the same measurement range. This means that the performance of the PD and ADC chip limits the detector's SNR, creating a problem where the detector's SNR cannot be optimized without modifying the existing PD and ADC chips.

[0040] To this end, embodiments of this disclosure provide a radiation-sensitive detector 30, which includes a plurality of pixels 300. At least one of the pixels 300 includes: a radiation-sensitive element 310 for receiving X-ray photons and converting and outputting the X-ray photons as an analog signal; and an analog-to-digital converter 320 electrically connected to the radiation-sensitive element 310 for converting the analog signal into a digital signal. The analog signal includes a plurality of subdivided analog signals, which are formed by segmenting and converting the X-ray photons using at least one spatial and temporal dimension. In embodiments of this disclosure, further subdivision of the signal acquired by the detector in the analog domain of the signal in the spatial and / or temporal dimensions enables signal subdivision processing without changing the pixel size 300, effectively reducing the electronic noise generated by the radiation-sensitive detector 30 and thus effectively improving the detector's performance.

[0041] The embodiments of this disclosure will now be described in detail using CT scan detection as an example. It should be understood that the embodiments of this disclosure are not limited to CT scan detection scenarios. For example, it can be applied to scan detection scenarios involving various different inspection objects, including but not limited to vehicle scan detection, luggage / parcel scan detection, and human body scan detection. It should be noted that the description of scan detection scenarios herein is not exhaustive and should not be construed as limiting the scope of protection of this disclosure.

[0042] Figure 1 is a schematic diagram of the structure of a radiation inspection apparatus according to some exemplary embodiments of the present application. In Figure 1, a CT scanning apparatus is schematically shown as an example of a radiation inspection apparatus. As shown in Figure 1, the radiation inspection apparatus according to this embodiment includes: a gantry 20, a support mechanism 40, a controller 50, a data processing device 60 (e.g., a computer), etc. The gantry 20 includes a radiation source 10, such as an X-ray machine, that emits X-rays for inspection, and a radiation-sensitive detector 30. The support mechanism 40 carries the object to be inspected (e.g., luggage to be inspected) 70 through the scanning area between the radiation source 10 and the radiation-sensitive detector 30 of the gantry 20, while the gantry 20 rotates about the direction of travel of the object to be inspected 70, so that the radiation emitted by the radiation source 10 can pass through the object to be inspected 70 to perform a CT scan on the object to be inspected 70. The radiation-sensitive detector 30 includes, for example, a modular detector with a radiation-sensitive element 310 and an analog-to-digital converter 320, for receiving X-ray photons transmitted through the object 70 (e.g., luggage being inspected), obtaining an analog signal, and converting the analog signal into a digital signal to output projection data of the object 70 against X-rays. The controller 50 controls the synchronous operation of all parts of the system. The data processing unit 60 processes the data acquired by the data acquisition unit, reconstructs the data, and outputs the results.

[0043] As shown in Figure 1, the X-ray source 10 is placed on one side where the object to be inspected can be placed, and the radiation-sensitive detector 30 is placed on the other side of the object to be inspected 70. The detector includes a radiation-sensitive element 310 and an analog-to-digital converter 320, used to acquire transmission data and / or multi-angle projection data of the object to be inspected 70. The data output cable of the radiation-sensitive detector 30 is connected to the controller 50 and the data processing device 60, and the acquired data is stored in the data processing device 60 according to a trigger command.

[0044] In embodiments of this disclosure, the radiation source 10 may be, for example, an X-ray machine, and a suitable X-ray machine focal size may be selected based on the imaging resolution. In other embodiments, an X-ray machine may not be used; instead, a linear accelerator or the like may be used to generate the X-ray beam.

[0045] The radiation-sensitive detector 30 includes a radiation-sensitive element 310 and an analog-to-digital converter 320, etc. The radiation-sensitive element 310 can be a solid-state detector, a gas detector, or other detectors, and the embodiments disclosed herein are not limited thereto. The analog-to-digital converter 320 includes a readout circuit, a data acquisition trigger circuit, and a data transmission circuit, etc.

[0046] The combination of controller 50 and data processing device 60 includes, for example, a computer device equipped with control and data processing programs, responsible for controlling the operation of the CT scanning device, including mechanical rotation, electrical control, and safety interlock control.

[0047] Figure 2 schematically illustrates the structure of a linear array of pixels in a radiation-sensitive detector. Figure 3 schematically illustrates the structure of an area array of pixels in a radiation-sensitive detector. Figure 4 schematically illustrates the structure of a single pixel in a pixel detector. Figure 5 schematically illustrates the structure of a single pixel in a scintillator detector. Figure 6 schematically illustrates the principle of spatial dimensional segmentation of the radiation-sensitive detector 30 according to an embodiment of the present disclosure.

[0048] As shown in Figures 2 to 6, as one aspect of an embodiment of this disclosure, a radiation-sensitive detector 30 is provided. The radiation-sensitive detector 30 includes a plurality of pixels 300. At least one of the plurality of pixels 300 includes: a radiation-sensitive element 310 for receiving X-ray photons and converting and outputting the X-ray photons as an analog signal; and an analog-to-digital converter 320 electrically connected to the radiation-sensitive element 310 for converting the analog signal into a digital signal. The analog signal includes a plurality of subdivided analog signals, which are formed by segmenting and converting X-ray photons using at least one of spatial and temporal dimensions.

[0049] The radiation-sensitive detector 30 provided in this embodiment includes multiple subdivided analog signals formed by segmenting ray photons using a spatial dimension. That is, within a single pixel 300, the area of ​​the single pixel 300 is divided into multiple subdivided regions, and the ray photons in each subdivided region are converted into subdivided analog signals and output, which can effectively reduce the electronic noise of the radiation-sensitive detector 30 and thus improve the signal-to-noise ratio. Furthermore, the analog signal also includes multiple subdivided analog signals formed by segmenting ray photons using a time dimension. That is, for the sampling time of a single pixel 300, the unit sampling time is divided into multiple subdivided times, and the ray photons received in each subdivided time are converted into subdivided analog signals and output, which can also effectively reduce the electronic noise of the radiation-sensitive detector 30 and thus improve the signal-to-noise ratio. In other words, both dimensions of segmentation can effectively reduce the noise generated by the radiation-sensitive detector 30 through subdivision processing without changing the size of the pixel 300.

[0050] Specifically, in this embodiment, referring to Figures 4 to 6, taking the spatial division of multiple subdivided simulated signals formed by X-ray photons as an example, the area of ​​a single pixel 300 is divided into four subdivided regions for illustration. When a single pixel is not divided into four subdivided regions, the signal output by the radiation-sensitive detector 30 is N0, and the electronic noise generated by the radiation-sensitive detector 30 is σ0. When a single pixel 300 is divided into four equal subdivided regions, since the total area of ​​the pixel 300 remains unchanged, assuming that the detection efficiency loss of the radiation-sensitive element 310 of the radiation-sensitive detector 30 caused solely by the spatial division is negligible, the sum of the output signals of the four subdivided regions is approximately equal to N0, that is... Here, N1, N2, N3, and N4 represent the signals of the four subdivided regions. The electronic noise generated by the four subdivided regions is approximately equal, that is... Where σ1, σ2, σ3, and σ4 represent the electronic noise generated by the radiation-sensitive element 310 corresponding to the four subdivided regions, respectively. According to the calculation method for the total electronic noise generated when the four equally divided subdivided regions are arranged side-by-side, the total electronic noise generated by the four subdivided regions is σ, where... Furthermore, it can be seen that σ = 2σ1. Therefore, in this embodiment, when a single pixel 300 is divided into four equally subdivided regions, the expected total analog signal output by the four radiation-sensitive elements 310 corresponding to the single pixel 300 remains unchanged, but the total electronic noise generated by the four radiation-sensitive elements 310 corresponding to the single pixel 300 is effectively reduced, that is, the capacitance noise is effectively reduced. In this embodiment, the noise sources of electronic noise include capacitance noise and dark current noise, wherein capacitance noise is proportional to the area of ​​the radiation-sensitive element 310, and dark current noise is proportional to the integration time.

[0051] In one specific embodiment, as shown in Figure 2, the radiation-sensitive detector is a linear array detector, consisting of multiple pixels arranged in a linear array. In yet another specific embodiment, as shown in Figure 3, the radiation-sensitive detector is a planar array detector, consisting of multiple pixels arranged in a planar array.

[0052] In one embodiment of this disclosure, a structure of radiation-sensitive element 310 and analog-to-digital converter 320 is used for some pixels 300 in the radiation-sensitive detector 30, wherein the analog signal output by the radiation-sensitive element 310 includes multiple subdivided analog signals; in another embodiment of this disclosure, a structure of radiation-sensitive element 310 and analog-to-digital converter 320 is used for all pixels 300 in the radiation-sensitive detector 30.

[0053] In this embodiment, the radiation-sensitive element 310 receives X-ray photons in a quantized form of electromagnetic radiation. The radiation used in this embodiment is specifically X-ray photons, and the energy of these photons generated in the X-ray tube is related to the tube voltage. A higher tube voltage results in greater kinetic energy for the electrons, leading to higher energy and a wider energy distribution range for the X-ray photons generated when they strike the target. For example, in medical X-ray imaging, adjusting the tube voltage of the X-ray tube can change the energy of the generated X-ray photons to suit different imaging needs. For instance, higher-energy X-rays may be needed for bone imaging, while lower-energy X-rays can be used for soft tissue imaging. Therefore, the radiation-sensitive detector 30 receives X-ray photons and generates at least one set of radiation intensity and radiation energy information for a single pixel 300.

[0054] In this embodiment, the radiation-sensitive element 310 converts incident X-ray photons into an initial electrical signal based on the photoelectric effect. That is, when X-ray photons are incident on the radiation-sensitive element 310, the photon energy is absorbed by the material, causing the atoms or molecules in the material to ionize or be excited to generate an electrical signal. In a specific embodiment, the radiation-sensitive element 310 includes an indirect radiation-sensitive element or a direct radiation-sensitive element.

[0055] In one embodiment, the indirect radiation sensing element includes a scintillator crystal and a photodiode coupled to the scintillator crystal, or a scintillator crystal and a photomultiplier tube coupled to the scintillator crystal, or a SiPM (Silicon Photomultiplier). The indirect radiation sensing element generates visible light photons after receiving X-ray photons. In a specific embodiment, the scintillator crystal of the indirect radiation sensing element is a cesium iodide (CsI) crystal. When the scintillator crystal receives X-ray photons, the electrons in the atoms of the scintillator crystal absorb the photon energy and jump to a higher energy level. The electrons in the excited state then return to the ground state through radiative or non-radiative transitions, emitting visible light photons in the process. Furthermore, the photodiode or photomultiplier tube converts the visible light photons into electrical signals.

[0056] In another embodiment, the direct radiation-sensitive element includes a semiconductor detector. After receiving X-ray photons, the semiconductor detector directly generates electron-hole pairs. In a specific embodiment, the semiconductor detector uses silicon semiconductors or germanium semiconductors, etc. When X-ray photons are incident on the semiconductor material, electron-hole pairs are generated through the photoelectric effect. An X-ray photon has a certain energy. After its energy is absorbed by the semiconductor material, it can generate a number of electron-hole pairs related to the photon energy. These electron-hole pairs move directionally under the action of the electric field inside the semiconductor, forming a current pulse signal.

[0057] In this embodiment, the analog-to-digital converter (ADC) 320 is used to convert analog signals into digital signals. In one specific embodiment, the ADC 320 samples the analog signal at a certain sampling frequency. The sampling frequency must satisfy the Nyquist sampling theorem to ensure accurate reconstruction of the analog signal. For example, if the highest frequency of the analog signal is 100kHz, the sampling frequency should be at least 200kHz. In one specific embodiment, the ADC 320 compares the sampled analog voltage value with a preset quantization level to determine its quantization level. The number of quantization levels depends on the bit depth of the ADC 320. For example, an 8-bit ADC 320 has 2^8 = 256 quantization levels, and a 12-bit ADC 320 has 2^12 = 4096 quantization levels. If the analog signal voltage range of the 8-bit ADC 320 is 0–5V, then the voltage interval corresponding to each quantization level is 5V / 256 ≈ 0.0195V. The sampled analog voltage value is compared with these quantization levels to determine its quantization level, and then the quantization level is converted into the corresponding digital code output. For example, if the sampled analog voltage value is 2.3V, it is at the 118th quantization level (2.3V / 0.0195V≈118), and the corresponding 8-bit binary code is 01110110, which is the converted digital signal. In this embodiment, multiple subdivided analog signals are converted into subdivided digital signals using an analog-to-digital converter 320.

[0058] Figure 7 schematically illustrates the spatial division of a single pixel 300 of a radiation-sensitive detector 30 according to an embodiment of the present disclosure.

[0059] As shown in Figure 7, in one specific embodiment, the analog signal includes multiple subdivided analog signals formed by spatial dimension segmentation. The analog-to-digital conversion element 320 includes multiple analog-to-digital converters 321, which are electrically connected to the radiation-sensitive element 310 to convert each subdivided analog signal into a subdivided digital signal. The digital signal includes multiple subdivided digital signals.

[0060] The radiation-sensitive detector 30 provided in this embodiment of the present disclosure, by setting multiple analog-to-digital converters 321, enables each of the multiple analog-to-digital converters 321 to correspond to multiple subdivided analog signals generated by the radiation-sensitive element 310, thereby converting each subdivided analog signal into a corresponding subdivided digital signal. Simultaneously, because the radiation area in a single pixel 300 corresponding to each analog-to-digital converter 321 is smaller than the radiation area corresponding to the analog-to-digital converter 320 when it is not subdivided, the signal strength of the subdivided analog signal corresponding to each analog-to-digital converter 321 is stronger than the signal strength of the analog signal generated by the radiation-sensitive element 310 when it is not subdivided. The smaller resolution allows for the use of analog-to-digital converters (ADCs) with smaller ranges and poorer noise suppression, expanding the selection range of ADCs and improving the ease of use and maintainability of the radiation-sensitive detector 30. Furthermore, compared to unsegmented pixels, the spatially segmented pixels 300 generate analog signals that are multiplied into multiple subdivided analog signals. These subdivided analog signals are converted and output as multiple subdivided digital signals by multiple ADCs 321, providing higher energy resolution in the radiation-sensitive detector 30.

[0061] Specifically, in this embodiment, the multiple analog-to-digital converters 321 corresponding to the analog-to-digital converter 320 occupy multiple channels of the chip corresponding to the analog-to-digital converter 320. The multiple subdivided analog signals output by the radiation-sensitive element 310 are respectively input to the channels where each analog-to-digital converter 321 is located. Each analog-to-digital converter 321 converts each subdivided analog signal into a subdivided digital signal. Compared with using the entire analog-to-digital converter 320 for single-channel batch processing, the processing speed is faster.

[0062] In one specific embodiment, the radiation-sensitive element 310 includes a light receiver 311 and a plurality of photoelectric conversion units 312; wherein, the light receiver 311 is used to receive X-ray photons; and each photoelectric conversion unit 312 is used to convert X-ray photons in the region corresponding to the light receiver 311 into subdivided analog signals.

[0063] In the radiation-sensitive detector 30 provided in this embodiment, multiple photoelectric conversion units 312 are provided to achieve spatial segmentation of the X-ray photons received by the light receiving unit 311. The light receiving unit 311 is located on the side of the radiation-sensitive element 310 closest to the X-ray source 10 to receive X-ray photons. The multiple photoelectric conversion units 312 are located on the side of the light receiving unit 311 furthest from the X-ray source 10. The multiple photoelectric conversion units 312 are electrically connected to the light receiving unit 311 respectively, realizing the conversion of X-ray photons into corresponding fine particles through a multi-channel approach. The generation speed of subdivided analog signals is improved. At the same time, because the area of ​​the light receiving part 311 in a single pixel 300 corresponding to each photoelectric conversion unit 312 is reduced, the signal strength of each subdivided analog signal required by each photoelectric conversion unit 312 is reduced compared with the strength of the analog signal required by the photoelectric conversion element when it is not divided. This allows each photoelectric conversion unit 312 to adopt a smaller working range and a photoelectric conversion unit 312 with worse noise suppression, expanding the selection range of photoelectric conversion units 312 and improving the ease of use and maintainability of the radiation sensitive detector 30.

[0064] For example, the radiation-sensitive element 310 is an indirect radiation-sensitive element, the light receiving unit 311 is a scintillator element, and the photoelectric conversion unit 312 is a photoelectric conversion device; wherein, the scintillator element is used to receive ray photons and convert the ray photons into light signals, and each photoelectric conversion device is used to convert the light signals in the region of the corresponding scintillator element and output them as subdivided analog signals. In this embodiment, the scintillator element includes a scintillator crystal. The scintillator element has a light-receiving surface facing the radiation source 10 and a light-output surface facing away from the radiation source 10. The light-receiving surface is used to receive radiation photons and transport the radiation photons into the scintillator crystal. After the scintillator crystal receives the radiation photons, the electrons in the atoms of the scintillator crystal absorb the photon energy and jump to a higher energy level, emitting visible light photons and outputting the visible light photons from the light output surface. In this embodiment, multiple photoelectric converters are attached to the light output surface. Each photoelectric converter converts the visible light photons in the corresponding area of ​​the light output surface into a subdivided analog signal. Multiple analog-to-digital converters 321 are electrically connected to the multiple photoelectric converters respectively to convert the subdivided analog signals output by each photoelectric converter into subdivided digital signals.

[0065] For example, the radiation-sensitive element 310 is a direct radiation-sensitive element, that is, the radiation-sensitive element 310 is a semiconductor. The light-receiving part 311 is the surface of the semiconductor facing the radiation source 10 for receiving radiation photons. A plurality of photoelectric conversion parts 312 are disposed at the end of the semiconductor away from the radiation source 10. The plurality of photoelectric conversion parts 312 are electrically isolated from each other. Each photoelectric conversion part 312 is used to directionally move the electron-hole pairs in the region corresponding to the light-receiving part 311 under the action of the electric field inside the semiconductor to form a current pulse signal and output it as a subdivided analog signal. In this embodiment, the semiconductor has a light-receiving surface facing the radiation source 10 and a plurality of signal receiving parts away from the radiation source 10. The output surface and the light receiving surface are used to receive X-ray photons and transport them into the semiconductor. Multiple signal output surfaces are formed on the surfaces of multiple photoelectric conversion units 312 away from the X-ray source 10. After the semiconductor receives the X-ray photons, electron-hole pairs are generated through the photoelectric effect. The semiconductor is divided into multiple photoelectric conversion regions according to the spatial dimension of the areas where the multiple photoelectric conversion units 312 are located. The electron-hole pairs in each photoelectric conversion region move directionally under the action of the electric field inside the semiconductor to form a current pulse signal, which is converted into a subdivided analog signal by the corresponding photoelectric conversion unit 312. The subdivided analog signal generated by each photoelectric conversion unit 312 is output from the signal output surface. Multiple analog-to-digital converters 321 are electrically connected to the multiple photoelectric conversion units 312 respectively to convert the subdivided analog signal output by each photoelectric conversion unit 312 into a subdivided digital signal.

[0066] As shown in Figure 7, in one specific embodiment, a plurality of photoelectric conversion units 312 are arranged in an array of M rows × N columns, where M is a positive integer greater than or equal to 1 and N is a positive integer greater than 1.

[0067] In the radiation-sensitive detector 30 provided in this embodiment, by arranging it in an array, it is possible to achieve standard segmentation of the light receiving unit 311 in the spatial dimension, that is, to standard segment the region of the single light receiving unit 311 corresponding to a single pixel 300, which facilitates subsequent calculation of the subdivided analog signal and electronic noise output by each photoelectric conversion unit 312.

[0068] In this embodiment, rows and columns do not refer to specific locations, but are only used to indicate the relative positional relationship of multiple photoelectric conversion units 312. That is, the names of rows and columns can be interchanged. In one specific embodiment, M and N can be the same number, that is, multiple photoelectric conversion units 312 are arranged in a square array. In another specific embodiment of this embodiment, M can be 1, and N is any positive integer greater than 1, that is, multiple photoelectric conversion units 312 are arranged in a column or row. In yet another specific embodiment, multiple photoelectric conversion units 312 are arranged in a square array of M rows × N columns, where M and N are both positive integers greater than 1, and N and M are not equal positive integers, that is, multiple photoelectric conversion units 312 are arranged in a rectangular array.

[0069] The specific array arrangement of the multiple photoelectric conversion units 312 is set according to the shape of the light receiving unit 311.

[0070] As shown in Figure 7, in one specific embodiment, the photoelectric conversion element has a light conversion surface, and the light conversion surfaces of multiple photoelectric conversion elements cover and adhere to the light output surface.

[0071] The radiation-sensitive detector 30 provided in this embodiment of the present disclosure uses multiple photoelectric conversion elements to overlap and cover the light output surface, avoiding gaps between multiple photoelectric conversion elements that would prevent visible light photons output from some light output surfaces from finding their corresponding photoelectric conversion elements. In other words, it avoids the problem that the sum of multiple subdivided analog signals deviates too much from the analog signal output by the radiation-sensitive detector 30 when it is not subdivided.

[0072] In one embodiment, the light conversion surfaces of multiple photoelectric converters have the same area. In the radiation-sensitive detector 30 provided in this embodiment, by setting the light conversion surfaces of multiple photoelectric converters to have the same area, the subdivided analog signals and electronic noise output by each photoelectric conversion unit 312 can be made to be basically the same, which is more conducive to reducing the electronic noise generated by the radiation-sensitive detector 30. In a specific embodiment, referring to FIG7, the scintillator element has a light output surface with a size of 5×5mm. 2 Using 4 pieces with a size of 2.5×2.5mm 2 The photoelectric conversion components are arranged in a 2x2 square array and covered and attached to the light output surface, thus achieving complete coverage.

[0073] In another embodiment, the light conversion surface of the photoelectric converter attached to the edge of the light output surface does not extend beyond the light output surface. That is, by avoiding the light conversion surface from extending beyond the light output surface, the utilization efficiency of the photoelectric converter is improved. In a specific embodiment, the light conversion surfaces of multiple photoelectric converters cover the light output surface and do not extend beyond the light output surface, so as to achieve precise setting of multiple photoelectric converters and improve setting efficiency.

[0074] Figure 8 schematically illustrates an experimental test diagram of the electronic noise of a single pixel 300 of a radiation-sensitive detector 30 according to an embodiment of the present disclosure. In Figure 8, the horizontal axis represents the range of the analog-to-digital conversion element 320 in pC; the vertical axis represents the electronic noise in f℃. In the illustration, “Meas” represents the average measured value, and “Esti” represents the predicted value.

[0075] Referring to Figures 5, 7, and 8, actual test experiments were conducted for the above embodiments. As shown in Figure 5, the structure of a single pixel in a conventional scintillator detector uses a 5×5mm... 2The photoelectric conversion section is electrically connected to the readout section of the DDC232 chip. The capacitance of the photoelectric conversion section is 180pF. As shown in Figure 7, the single pixel 300 of the radiation-sensitive detector 30 is spatially segmented, using four 2.5×2.5mm pixels. 2 The photoelectric conversion element is connected to the analog-to-digital conversion element 320 corresponding to the DDC264 chip. The analog-to-digital conversion element 320 corresponding to the DDC264 chip has four analog-to-digital conversion elements 321 connected to the photoelectric conversion element. The capacitance of the photoelectric conversion element is 45pF.

[0076] The experimental results are shown in Figure 8. From the results, the top solid line represents the electronic noise σ0 of a single pixel using a 180pF photoelectric conversion section and a DDC232 chip. The second solid line from the top represents twice the measured electronic noise 2σ1 of a single pixel 300 of the radiation-sensitive detector 30 using a 45pF photoelectric conversion section and a DDC264 chip. The first dashed line from the top represents twice the theoretically calculated electronic noise 2σ1 of a single pixel 300 of the radiation-sensitive detector 30 using a 45pF photoelectric conversion section and a DDC264 chip. The experimental data in Figure 8 shows that twice the measured electronic noise 2σ1 of a single pixel 300 of the radiation-sensitive detector 30 is lower than the electronic noise σ0 of a single pixel of an existing scintillator detector at different measurement ranges, indicating that the electronic noise of the radiation-sensitive detector 30 is significantly lower than that of existing scintillator detectors.

[0077] It should be noted that the two solid lines from bottom to top, which correspond to the two solid lines marked 0pF PD in the figure, represent the basic electronic noise of the DDC232 chip and the DDC264 chip under different ranges. As can be seen from the figure, the noise performance of the DDC232 chip and the DDC264 chip is similar, only the range and number of channels are different, which can be considered as no change.

[0078] In one specific embodiment, the radiation-sensitive detector 30 further includes: a first data processing element for merging and processing multiple subdivided digital signals into pixel signals, wherein the pixel signals are used to characterize at least one of the radiation intensity information and radiation energy information of the pixel 300 corresponding to the radiation-sensitive element 310.

[0079] In the radiation-sensitive detector 30 provided in this embodiment, by merging and processing multiple subdivided digital signals into pixel signals, at least one of the radiation intensity information and radiation energy information of pixel 300 can be substantially fed back. This enables the monitoring and feedback of the radiation intensity information and radiation energy information received by pixel 300. In this embodiment, the radiation intensity information represents the strength of the radiation beam, and the unit is typically watts per square meter (W / m²). 2In X-ray imaging, the intensity of X-rays determines the contrast and brightness of the image; a stronger intensity of X-rays can make the image clearer.

[0080] In this embodiment, the X-ray energy information refers to the energy possessed by a single X-ray photon, typically measured in electron volts (eV) or kiloelectron volts (keV). It reflects the intrinsic properties of X-ray photons; photons of different energies exhibit different behaviors when interacting with matter, such as penetrating power and ionizing ability. For example, high-energy X-ray photons have stronger penetrating power and can penetrate thicker materials; while low-energy X-ray photons are more easily absorbed or scattered by matter.

[0081] Specifically, in this embodiment, the ray intensity information of the incident rays of the corresponding pixel 300 within a certain period can be calculated based on the pre-calibrated relationship. The calibration process usually involves establishing the correspondence between the pixel signal and the ray intensity by using the pixel signal output by the radiation-sensitive detector 30 under the illumination of a standard source with known ray intensity. For example, the voltage value contained in the subdivided digital signal under different ray intensities can be obtained through experiments, thereby determining the functional relationship.

[0082] In actual measurements, the ray intensity information corresponding to the subdivided digital signal is calculated based on the voltage value in the measured subdivided digital signal using this functional relationship. By merging and processing multiple subdivided digital signals, the ray intensity information of the incident ray corresponding to pixel 300 can be calculated. In a specific example of this embodiment, the integral result related to the ray intensity information is obtained by integrating the electrical signal converted from a photodiode or photomultiplier tube per unit time; that is, the ray intensity information of the corresponding region is included in the subdivided analog signal. In another specific example of this embodiment, the number of electron-hole pairs converted from the semiconductor detector is counted, and the number of photons detected within a certain time period is recorded. This number directly reflects the intensity information of the incident ray.

[0083] In a specific example, since the number of electron-hole pairs is related to the energy of the X-ray photon, and the amplitude of the current pulse signal formed by electron-hole pairs under the influence of an electric field is proportional to the number of electron-hole pairs, the energy of each X-ray photon can be determined by measuring the amplitude of the voltage pulse signal and based on a pre-calibrated amplitude-energy relationship. The calibration process involves establishing the correspondence between amplitude and energy by measuring the amplitude of the simulated signal output by the radiation-sensitive detector 30 under irradiation from a monoenergetic X-ray source 10 with known energy. For example, the voltage pulse amplitudes corresponding to X-ray photons of different energies can be obtained experimentally, thereby determining the functional relationship. In actual measurements, the energy of the X-ray photon can be calculated using this functional relationship based on the measured voltage amplitude.

[0084] In one specific embodiment, the analog signal includes multiple subdivided analog signals formed by dividing them using a time dimension, and the analog-to-digital conversion element 320 is used to convert each subdivided analog signal located in the same time period into a subdivided time digital signal.

[0085] In the radiation-sensitive detector 30 provided in this embodiment, multiple subdivided analog signals are formed by time-division, enabling the analog-to-digital converter 320 to sequentially convert each subdivided analog signal within the same time period into a subdivided time digital signal. Simultaneously, because the sampling time corresponding to each subdivided analog signal is reduced, electronic noise is effectively suppressed, i.e., dark current noise is effectively reduced. The signal strength of the subdivided analog signal corresponding to the analog-to-digital converter 320 is lower than the signal strength of the analog signal generated by the analog-to-digital converter 320 without subdivision. This allows the analog-to-digital converter 320 to be used with a smaller range and poorer noise suppression, expanding the selection range of the analog-to-digital converter 320 and improving the usability and maintainability of the radiation-sensitive detector 30. Furthermore, compared to pixels without subdivision, the analog signal in this embodiment, which is divided by time-division, includes multiple subdivided analog signals, and these multiple subdivided analog signals are converted and output into subdivided time digital signals by the analog-to-digital converter 320. The merging of these multiple subdivided analog signals can provide higher energy resolution in the resolution performance of the radiation-sensitive detector 30.

[0086] In one specific embodiment, the radiation-sensitive detector 30 further includes a second data processing element, which is used to merge and process multiple subdivided time digital signals into a pixel signal, and the pixel signal is used to characterize at least one of the radiation intensity information and radiation energy information of the pixel 300 corresponding to the radiation-sensitive element 310 within a fixed time period.

[0087] In the radiation-sensitive detector 30 provided in the embodiments of this disclosure, by merging and processing multiple subdivided time digital signals into pixel signals, at least one of the radiation intensity information and radiation energy information of pixel 300 can be substantially fed back, thereby realizing the monitoring and feedback of the radiation intensity information and radiation energy information of the radiation received by pixel 300.

[0088] In one specific embodiment, the radiation-sensitive detector 30 further includes a preamplifier element disposed between the radiation-sensitive element 310 and the analog-to-digital converter element 320; wherein the analog signal output by the radiation-sensitive element 310 is a current pulse signal, the preamplifier element is used to receive the current pulse signal and convert it into a voltage pulse signal, the preamplifier element can amplify the voltage pulse signal, and output the amplified voltage pulse signal to the analog-to-digital converter element 320.

[0089] In the radiation-sensitive detector 30 provided in this embodiment, the current pulse signal converted by the photoelectric conversion unit 312 is relatively weak. Its amplitude is easily identified as noise and filtered out or easily unrecognizable in subsequent circuit processing. Therefore, a preamplifier is used to convert the current pulse signal into a voltage pulse signal and amplify it so that the amplitude of the converted voltage pulse signal is sufficient for subsequent circuit processing. Specifically, in this embodiment, a low-noise field-effect transistor (FET) can be used as the input stage of the preamplifier to reduce the influence of thermal noise and amplifier noise on the signal.

[0090] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A radiation-sensitive detector, characterized in that, The radiation-sensitive detector includes a plurality of pixels, and at least one of the plurality of pixels includes: A radiation-sensitive element for receiving X-ray photons and converting the X-ray photons into an analog signal; An analog-to-digital converter is electrically connected to the radiation-sensitive element, and the analog-to-digital converter is used to convert the analog signal into a digital signal; The analog signal includes a plurality of subdivided analog signals, which are formed by segmenting and converting the X-ray photon using at least one of the spatial and temporal dimensions.

2. The radiation-sensitive detector according to claim 1, characterized in that, The radiation-sensitive element includes an indirect radiation-sensitive element or a direct radiation-sensitive element.

3. The radiation-sensitive detector according to claim 2, characterized in that, The analog signal includes multiple subdivided analog signals formed by segmentation using spatial dimensions, and the analog-to-digital conversion element includes: Multiple analog-to-digital converters are provided, each of which is electrically connected to the radiation-sensitive element, to convert each of the subdivided analog signals into subdivided digital signals, wherein the digital signals include the multiple subdivided digital signals.

4. The radiation-sensitive detector according to claim 3, characterized in that, The radiation-sensitive element includes a light receiver and multiple photoelectric conversion units; The light receiving unit is used to receive the ray photons; Each of the photoelectric conversion sections is used to convert the X-ray photons in the region corresponding to the light receiving section into the subdivided analog signal.

5. The radiation-sensitive detector according to claim 4, characterized in that, The radiation-sensitive element is the indirect radiation-sensitive element, the light receiver is a scintillator element, and the photoelectric conversion unit is a photoelectric conversion device. The scintillator element is used to receive the ray photons and convert them into optical signals, and each of the photoelectric converters is used to convert the optical signals in the region corresponding to the scintillator element and output them as the subdivided analog signals.

6. The radiation-sensitive detector according to claim 4, characterized in that, The plurality of photoelectric conversion units are arranged in an array of M rows × N columns, where M is a positive integer greater than or equal to 1 and N is a positive integer greater than 1.

7. The radiation-sensitive detector according to claim 3, characterized in that, The radiation-sensitive detector also includes: A first data processing element is used to merge and process multiple subdivided digital signals into a pixel signal, the pixel signal being used to characterize at least one of the radiation intensity information and radiation energy information of the pixel corresponding to the radiation-sensitive element.

8. The radiation-sensitive detector according to claim 1 or 2, characterized in that, The analog signal includes multiple subdivided analog signals formed by dividing them using a time dimension, and the analog-to-digital conversion element is used to convert each of the subdivided analog signals located in the same time period into subdivided time digital signals respectively.

9. The radiation-sensitive detector according to claim 8, characterized in that, The radiation-sensitive detector also includes: The second data processing element is used to merge and process multiple subdivided time digital signals into a pixel signal, wherein the pixel signal is used to characterize at least one of the radiation intensity information and radiation energy information of the pixel corresponding to the radiation sensitive element within a fixed time period.

10. The radiation-sensitive detector according to claim 1, characterized in that, The radiation-sensitive detector also includes: A preamplifier element is disposed between the radiation-sensitive element and the analog-to-digital converter element; The analog signal output by the radiation-sensitive element is a current pulse signal. The preamplifier is used to receive the current pulse signal and convert it into a voltage pulse signal. The preamplifier can amplify the voltage pulse signal and output the amplified voltage pulse signal to the analog-to-digital converter.

11. A radiation-sensitive detector, characterized in that, include: A scintillator element for converting X-ray photons into visible light photons, the scintillator element having a light-receiving surface facing the X-ray source and a light-output surface facing away from the X-ray source, the light-receiving surface for receiving the X-ray photons and the light-output surface for outputting the visible light photons; Multiple photoelectric conversion elements are arranged in an array of M rows × N columns and attached to the light output surface. Each photoelectric conversion element is used to convert visible light photons in the region corresponding to the light output surface into subdivided analog signals, where M is a positive integer greater than or equal to 1 and N is a positive integer greater than 1. Multiple analog-to-digital converters are provided, each of which is electrically connected to a corresponding optoelectronic converter to convert each of the subdivided analog signals into subdivided digital signals.

12. The radiation-sensitive detector according to claim 11, characterized in that, The photoelectric conversion element has a light conversion surface, and the light conversion surfaces of multiple photoelectric conversion elements cover and adhere to the light output surface.

13. The radiation-sensitive detector according to claim 12, characterized in that, The light conversion surfaces of the plurality of photoelectric conversion elements have the same area.

14. The radiation-sensitive detector according to claim 12 or 13, characterized in that, The light conversion surface of the photoelectric conversion element, which is attached to the edge of the light output surface, does not extend beyond the light output surface.

15. A radiation inspection device, characterized in that, include: A radiation source, used to emit radiation; A radiation-sensitive detector for receiving radiation photons emitted from the radiation source and passing through the object being detected, wherein the radiation-sensitive detector is a radiation-sensitive detector as described in any one of claims 1 to 14.

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