Pet detector

Abstract

The application provides a PET detector. The PET detector comprises: a crystal array comprising a plurality of crystal units arranged in a single layer, the crystal units extending in a top-bottom direction and having a top surface, a bottom surface and a side surface between the top surface and the bottom surface; a light reflection film arranged on a surface of at least one crystal unit in the plurality of crystal units; and a semiconductor sensor array comprising a plurality of semiconductor sensors, only part of the crystal units in the crystal array being coupled with the semiconductor sensors, the number of the crystal units in the crystal array being greater than the number of the semiconductor sensors in the semiconductor sensor array. By arranging a light splitting structure on the crystal units, the transmission distance of photons can be effectively shortened relative to arranging a light guide sheet between the crystal array and the semiconductor sensors, and thus the light transmission loss caused by the light guide sheet can be avoided, so that the resolution of the PET detector can be improved.

Description

[0001] This case is a divisional application filed on May 28, 2014, with application number 2014102314836 and invention title PET detector, PET detector setting method and detection method, after a previous divisional application (application number 2018102450330, invention title PET detector, PET detector setting method and detection method). Technical Field

[0002] This invention relates to the field of optical detection technology, specifically to a PET detector. Background Technology

[0003] Positron emission tomography (PET) detectors are typically found in large medical devices that utilize PET technology, such as PET-CT or PET-MRI systems. The PET detector receives gamma rays generated within the patient's body and feeds back the location information of the photons generated by these gamma rays to other components of the large medical device, allowing them to process the data accordingly.

[0004] Currently, such as Figure 1 As shown, a PET detector typically includes: a crystal array 102, an avalanche photodiode (APD) array 104 coupled to the crystal array 102, and a light guide 106 disposed between the crystal array 102 and the APD array 104. The crystal array 102 is composed of multiple crystal units arranged according to a specific design, and the APD array 104 is composed of multiple APDs arranged according to a specific design. Each APD is in contact with at least one crystal unit.

[0005] The gamma rays generated in the patient's body are received by a crystal unit of the crystal array 102 and enter the crystal unit. The gamma rays are excited into photons inside the crystal unit. The photons are transmitted between the crystal units of the crystal array 102 and finally enter the APD array 104 through the light guide 106, where the APD array receives the photons.

[0006] When the gamma rays excite photons inside the crystal units, due to the light guide sheet 106 causing certain light transmission loss, only part of the excited photons can enter the APD array 104, resulting in low resolution of the PET detector. SUMMARY

[0007] The problem solved by the embodiments of the present application is how to improve the resolution of the PET detector.

[0008] To solve the above problem, the embodiments of the present application provide a PET detector, which comprises:

[0009] a crystal array comprising a plurality of crystal units arranged in an array and a light splitting structure arranged on the surface of the crystal units, the light splitting structure defining a light exit surface of the crystal array together;

[0010] a semiconductor sensor array arranged opposite to the light exit surface of the crystal array and adapted to receive photons from the light exit surface, the semiconductor sensor array comprising a plurality of semiconductor sensors arranged in an array.

[0011] Optionally, part of the crystal units in the crystal array are coupled with corresponding semiconductor sensors in the semiconductor sensor array.

[0012] Optionally, at least one semiconductor sensor in the semiconductor sensor array is coupled with a corresponding crystal unit in the crystal array.

[0013] Optionally, the coupling comprises that the semiconductor sensor is in contact with the crystal unit or in contact with the crystal unit through an adhesive material.

[0014] Optionally, the center of gravity of the semiconductor sensor array coincides with the center of gravity of the crystal array.

[0015] Optionally, the semiconductor sensor array covers the light exit surface or partially covers the light exit surface.

[0016] Optionally, the light splitting structure is a light-reflecting film or a white light-reflecting coating arranged on the surface of the crystal unit.

[0017] Optionally, the PET detector further comprises a first amplifier, an input end of the first amplifier being connected with the output end of a preset row of semiconductor sensors in the semiconductor sensor array.

[0018] Optionally, the PET detector further comprises a second amplifier, an input end of the second amplifier being connected with the output end of a preset column of semiconductor sensors in the semiconductor sensor array.

[0019] Optionally, the light splitting structure is arranged on the surface of the crystal unit and matches the light receiving area of the semiconductor sensor, the relative position between semiconductor sensors, and the relative position between the semiconductor sensor and the crystal array.

[0020] Optionally, the number and position of the semiconductor sensor are related to the resolution of the crystal unit on the image.

[0021] The embodiment of the present application also provides a setting method of the PET detector.

[0022] Adjusting the area of the light splitting structure arranged on each crystal unit in the crystal array;

[0023] Arranging the semiconductor sensor array relative to the light emitting surface of the crystal array to obtain the PET detector.

[0024] Optionally, the adjusting the area of the light splitting structure arranged on each crystal unit in the crystal array comprises:

[0025] Adjusting the probability of the occurrence of a photon in the crystal unit;

[0026] When the probability of the occurrence of a photon in the crystal unit meets the resolution condition of the crystal unit on the image, setting the crystal unit with the area of the light splitting structure corresponding to the probability.

[0027] Optionally, the adjusting the probability of the occurrence of a photon in the crystal unit comprises:

[0028] The probability of the occurrence of a photon in the selected crystal unit is adjusted by using the following formula:

[0029]

[0030] Wherein, N represents the total number of photons generated in any crystal unit in the crystal array except the selected crystal unit, m represents the number of photons occurring in the selected crystal unit when the total number of photons generated in the any crystal unit is N, p represents the probability of the occurrence of a photon in the selected crystal unit when the total number of photons generated in the any crystal unit is 1, and P represents the probability of the number of photons occurring in the selected crystal unit being m when the total number of photons generated in the any crystal unit is N.

[0031] The embodiment of the present application also provides a detection method of the PET detector.

[0032] The crystal unit of the PET detector receives a gamma ray;

[0033] The semiconductor sensor of the PET detector receives the photons generated by the gamma rays within the crystal unit;

[0034] The position of the photons generated by the gamma rays inside the crystal unit is determined according to the output of the semiconductor sensor.

[0035] Optionally, the position of the photons generated by the gamma rays inside the crystal unit is determined by using the barycentric reading method.

[0036] Compared with the prior art, the technical scheme of the embodiment of the present application has the following advantages:

[0037] By arranging the light splitting structure on the crystal unit, the transmission distance of the photons can be effectively shortened compared with arranging the light guide sheet between the crystal array and the semiconductor sensor, and thus the light transmission loss caused by the light guide sheet can be avoided, so that the resolution of the PET detector can be improved.

[0038] By coupling part of the crystal units in the crystal array with the corresponding semiconductor sensors in the semiconductor sensor array, or coupling at least one semiconductor sensor with the corresponding crystal unit in the crystal array, without coupling each crystal unit in the crystal array with the corresponding semiconductor sensor, the number of semiconductor sensors can be set more flexibly, so that fewer semiconductor sensors can be used to meet the same resolution requirement of the crystal units on the image under the condition of using the same number of crystal units, and thus the cost of the PET detector can be reduced.

[0039] By arranging the barycenter of the semiconductor sensor array to coincide with the barycenter of the crystal array, the position of the photons can be determined more conveniently by using the barycentric reading method subsequently.

[0040] Since the semiconductor sensor array can completely cover the light emitting surface of the crystal array or partially cover the light emitting surface of the crystal array, the number and position of the sensors can be set more flexibly, so that fewer semiconductor sensors can be used to meet the same resolution requirement of the crystal units on the image under the condition of using the same number of crystal units, and thus the cost of the PET detector can be reduced.

[0041] By arranging the first amplifier and the second amplifier, when the position of the photons is determined by using the barycentric reading method, the position of the photons can be directly determined according to the output of the first amplifier and the second amplifier, without reading the output of each semiconductor sensor respectively, so that the amount of data processing when determining the position of the photons can be reduced, and the difficulty of determining the position of the photons can be reduced.

[0042] By using the formula The probability of the photons appearing in each crystal unit is adjusted, and then the area of the light splitting structure on each crystal unit is adjusted, so that the resolution requirement of the crystal units on the image can be met more quickly. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a schematic diagram of a longitudinal section structure of a PET detector in the prior art.

[0044] Figure 2 is a schematic diagram of a longitudinal section structure of a PET detector in an embodiment of the present application.

[0045] Figure 3 is a schematic diagram of a longitudinal section structure of a PET detector in an embodiment of the present application. Figure 2

[0046] Figure 4 is a schematic diagram of a longitudinal section structure of a PET detector in an embodiment of the present application.

[0047] Figure 5 is a schematic diagram of a longitudinal section structure of a PET detector in an embodiment of the present application.

[0048] Figure 6 is a schematic diagram of a longitudinal section structure of a PET detector in an embodiment of the present application.

[0049] Figure 7 is a schematic diagram of a longitudinal section structure of a PET detector in an embodiment of the present application.

[0050] Figure 8 is a schematic diagram of a longitudinal section structure of a PET detector in an embodiment of the present application.

[0051] Figure 9 is a schematic diagram of a longitudinal section structure of a PET detector in an embodiment of the present application.

[0052] Figure 10 is a schematic diagram of a longitudinal section structure of a PET detector in an embodiment of the present application.

[0053] Figure 11 is a schematic diagram of the distribution of the probability of the photons appearing in each crystal unit in a 1*10 crystal array before adjustment.

[0054] Figure 12 is a schematic diagram of the distribution of the probability of the photons appearing in each crystal unit in a 1*10 crystal array after adjustment.

[0055] Figure 13 is a schematic diagram of a longitudinal section structure of a PET detector in an embodiment of the present application.

[0056] Figure 14 is a schematic diagram of a longitudinal section structure of a PET detector in an embodiment of the present application. Figure 13 ​The probability distribution of the photons appearing inside each crystal unit of the PET detector is shown in the schematic diagram.

[0057] Figure 15 The PET detector is used for Figure 13 The two-dimensional image of the position of each crystal unit obtained by the detection simulation of the PET in the embodiment of the application is shown in the figure.

[0058] Figure 16 The flow chart of the setting method of the PET detector in the embodiment of the application is shown in the figure.

[0059] Figure 17 The flow chart of the detection method of the PET detector in the embodiment of the application is shown in the figure. DETAILED DESCRIPTION

[0060] At present, in the PET detector structure as shown in the figure, Figure 1 After the gamma rays excite the photons in the crystal unit, the photons enter the APD array 104 through the light guide sheet 106. The setting of the light guide sheet 106 increases the distance of the photon transmission and causes certain light transmission loss, which leads to the reduction of the resolution of the PET detector.

[0061] In order to make the above-mentioned objects, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application are described in detail below with reference to the accompanying drawings.

[0062] Referring to Figure 2 The embodiment of the application provides a PET detector, which can include a crystal array and a semiconductor sensor array.

[0063] The crystal array can include a plurality of crystal units 202 arranged in an array, and a light splitting structure 204 arranged on the surface of the crystal unit 202. The light splitting structures 204 arranged on the plurality of crystal units 202 jointly define a light exit surface 206 of the crystal array. The semiconductor sensor array is arranged relative to the light exit surface 206 of the crystal array, and includes a plurality of semiconductor sensors 208 arranged in an array. The semiconductor sensor array is integrated on a driving board 210, the driving board 210 is connected with the semiconductor sensor 208, and is suitable for driving the corresponding semiconductor sensor 208 to work.

[0064] It should be noted that in the embodiment of the application, the light exit surface 206 is composed of the light exit surfaces of the crystal units 202, that is, the surface of the crystal unit through which the photons finally pass when entering the corresponding semiconductor sensor 208.

[0065] The crystal array includes at least three crystal units 202, and the number and arrangement of the crystal units 202 are not limited, and can be set according to the actual size of the PET detector by those skilled in the art. The more the number of crystal units 202, the larger the size of the PET detector. As shown in the figure, the crystal array can be arranged in 8*8, 8*9, or 8*19 crystal units 202, and different numbers of crystal units correspond to different sizes of PET detectors. Figures 3 to 5 As shown in the figure, the crystal array can be arranged in 8*8, 8*9, or 8*19 crystal units 202, and different numbers of crystal units correspond to different sizes of PET detectors.

[0066] In specific embodiments, the crystal unit 202 can be made of various materials. For example, the material of the crystal unit can be at least one of the following: bismuth germanate, lutetium silicate, yttrium lutetium silicate, gadolinium lutetium silicate, gadolinium silicate, yttrium silicate, barium fluoride, sodium iodide, cesium iodide, lead tungstate, yttrium aluminate, lanthanum bromide, lanthanum chloride, calcium titanium lutetium aluminum, lutetium pyrosilicate, lutetium aluminate, and lutetium iodide.

[0067] The gamma rays excite photons inside the crystal unit. During the transmission process, the photons will be reflected when encountering the light splitting structure, thereby changing the transmission path of the photons. Therefore, the photons excited inside the crystal unit can enter the semiconductor sensor corresponding to the crystal unit from the side of the crystal unit defining the light surface, or enter the semiconductor sensor corresponding to other crystal units from the side of the other crystal units defining the light surface. The semiconductor sensor corresponding to the crystal unit and the semiconductor sensor corresponding to the other crystal unit can be the same semiconductor sensor or different semiconductor sensors. That is, one of the semiconductor sensors can receive photons from the side of one of the crystal units defining the light surface, or can receive photons from the side of each of the plurality of crystal units defining the light surface.

[0068] Therefore, when the semiconductor sensor array receives photons from the light-emitting surface of the crystal unit array, there can be various coupling modes between the semiconductor sensor and the crystal unit. For example, the semiconductor sensor can be in contact with the crystal unit or can be in contact through an adhesive material, so that the connection between the semiconductor sensor and the corresponding crystal unit is more stable. In specific embodiments, silicone grease can be used as the adhesive material.

[0069] In an embodiment of the present application, part of the crystal units in the crystal array are coupled with the corresponding semiconductor sensors in the semiconductor sensor array, so that the semiconductor sensor can receive photons from the light-emitting surface of the crystal array. The part of the crystal units in the crystal array can correspond to one semiconductor sensor or a plurality of semiconductor sensors.

[0070] like Figure 3 The diagram shows a cross-sectional structure of a PET detector. The PET detector has an 8x8 crystal array and a 2x2 semiconductor sensor array. Some crystal units 202 in the crystal array correspond to four semiconductor sensors 208 in the semiconductor sensor array. In the crystal units not covered by the semiconductor sensors 208, when photons are excited by gamma rays, the photons are transmitted to the crystal units covered by the semiconductor sensors 208 through a beam-splitting structure on the surface of these uncovered crystal units. The photons are then received by the corresponding semiconductor sensors in the uncovered crystal units.

[0071] In another embodiment of the present invention, at least one semiconductor sensor in the semiconductor sensor array is coupled to a corresponding crystal unit in the crystal array, so that the semiconductor sensor can receive photons from the light-emitting surface of the crystal array. The semiconductor sensor array may have only one semiconductor sensor with a corresponding crystal unit in the crystal array, or it may have multiple semiconductor sensors with corresponding crystal units in the crystal array, as long as at least one semiconductor sensor in the semiconductor sensor array can receive photons from the light-emitting surface of the crystal array.

[0072] like Figure 6 The schematic diagram of the cross-sectional structure of the PET detector shown shows that the crystal array of the PET detector is an 8*8 array and its semiconductor sensor array is a 2*2 array. Semiconductor sensor 2081 and semiconductor sensor 2082 are coupled to the corresponding crystal unit 202 in the crystal array, while semiconductor sensor 2083 and semiconductor sensor 2084 do not have corresponding crystal units 202 in the crystal array.

[0073] In another embodiment of the present invention, the semiconductor sensor array is used to cover or partially cover the light-emitting surface of the crystal array, so that the semiconductor sensor can receive photons from the light-emitting surface.

[0074] like Figure 7 The schematic diagram of the cross-sectional structure of the PET detector shown illustrates that when the semiconductor sensor array completely covers the light-emitting surface of the crystal array, each crystal unit in the crystal array is covered by a semiconductor sensor. Each crystal unit 202 in the crystal array has a corresponding semiconductor sensor in the semiconductor sensor array. The corresponding semiconductor sensor can be some of the semiconductor sensors in the semiconductor sensor array, or it can be all of the semiconductor sensors.

[0075] When the semiconductor sensor array partially covers the light exit surface of the crystal array, some crystal cells in the crystal array are coupled with corresponding semiconductor sensors 208. In an embodiment of the present application, as shown in FIG. 2, each semiconductor sensor 208 in the semiconductor sensor array is coupled with a crystal cell in the crystal array, and the semiconductor sensor array covers the light exit surface of each crystal cell in the crystal array. In another embodiment of the present application, as shown in FIG. 3, some semiconductor sensors in the semiconductor sensor array are coupled with crystal cells in the crystal array, and the semiconductor sensor array only covers the light exit surface of some crystal cells in the crystal array. Figure 3 Figure 6

[0076] In order to more conveniently determine the position of the photon generated in the crystal cell according to the output of the semiconductor sensor, the center of gravity of the semiconductor sensor array can be arranged to coincide with the center of gravity of the crystal array. When the center of gravity of the semiconductor sensor array is arranged to coincide with the center of gravity of the crystal array, the center of gravity reading method can be used to determine the position of the photon generation. As shown in FIG. 4, the semiconductor sensor array includes semiconductor sensors 208 arranged in an array, and the crystal array includes a plurality of crystal cells 202 arranged in an array. The center of gravity of the semiconductor sensor array coincides with the center of gravity of the crystal array. Therefore, the position of the photon generation can be determined according to the center of gravity of the crystal array. Figures 3 to 5

[0077] In a specific implementation, the semiconductor sensor array includes at least three semiconductor sensors. The semiconductor sensor can be a photoresistor, a photodiode, a phototriode or the like. The number and position of the semiconductor sensors are related to the resolution of the crystal cells on the image. In a specific implementation, a person skilled in the art can adjust the number and position of the semiconductor sensors in the above embodiments according to the resolution requirement of the crystal cells on the image. For example, the semiconductor sensor array can include four, five or eight semiconductor sensors, and the corresponding arrangement mode can be set, as shown in FIG. 5. Figures 3 to 5

[0078] It should be noted that the resolution of the crystal cells on the image, that is, the resolution of the positions corresponding to the crystal cells on the image obtained by using the PET detector. The higher the resolution of the crystal cells on the image, the clearer the positions corresponding to the crystal cells on the image, and the clearer the boundaries between the positions of different crystal cells.

[0079] ​​​​It can be seen from the above that, in the embodiments of the present application, the number and position of the semiconductor sensors are less limited, and each semiconductor sensor does not need to correspond to a crystal unit in the crystal array, so that the number of semiconductor sensors can be effectively reduced relative to the existing PET detector while ensuring the resolution of the image crystal unit, thereby reducing the cost of the PET detector.

[0080] In the embodiments of the present application, the semiconductor sensor is used to convert the optical signal into an electrical signal based on the internal photoelectric effect, which has the advantages of small size, light weight, and no working influence of a magnetic field relative to a device for converting an optical signal into an electrical signal based on the external photoelectric effect.

[0081] For example, the diameter size of a photomultiplier tube for converting an optical signal into an electrical signal based on the external photoelectric effect usually includes 3 / 4 inch, 1 inch, and 1.5 inch, while the diameter size of a semiconductor sensor is usually 3*3 mm or 6*6 mm. When in contact with a crystal unit, the area of the crystal unit that can be contacted by a 1-inch photomultiplier tube is about 8*8 cm, while the area of the crystal unit that can be contacted by a 6*6 mm semiconductor sensor is about 2*2 cm. The greater the area of the crystal unit that can be contacted, the greater the number of events received per unit time, the longer the dead time of the PET detector, the more likely the signal to be stacked, and the poorer the detection sensitivity of the PET. Through calculation, it can be known that the number of events received per unit time by a 1-inch photomultiplier tube is about 16 times that of a 6*6 mm semiconductor sensor. Under the same other conditions, the dead time of the PET detector with a semiconductor sensor is about 2-3 times that of the PET detector with a semiconductor sensor, so the detection sensitivity of the PET detector with a semiconductor sensor is higher. Moreover, the PET detector with a semiconductor sensor is not affected by a magnetic field, which can be more convenient for users to use.

[0082] When the light splitting structure is arranged on the surface of the crystal unit, the light splitting structure can be arranged on the surface of part of the crystal units in the crystal array, or the light splitting structure can be arranged on the surface of each crystal unit. The positions and areas of the light splitting structures arranged on each crystal unit can be the same or different.

[0083] For example, the PET detector can include a plurality of semiconductor sensors, and each semiconductor sensor can be arranged on the surface of a corresponding crystal unit in the crystal array. Figure 8As shown, when the light splitting structure is arranged on one surface of the crystal unit 802, the light splitting structure can be arranged on part of the surface of the crystal unit 802, or arranged on each surface of the crystal unit 802. When the light splitting structure is arranged on the surface of the crystal unit 802 for defining the light emitting surface, the area of the light splitting structure should be smaller than the area of the surface. The area of the light splitting structure arranged on each surface of the crystal unit can be the same or different. For example, taking the surface 03 of the crystal unit 802 as the surface for defining the light emitting surface, the light splitting structure 01a can be arranged on the surface 01 of the crystal unit 802, and the light splitting structure 02a can be arranged on the surface 02. The area of the light splitting structure 01a can be the same as or different from the area of the light splitting structure 02a. When the light splitting structure is arranged on the surface 03, the area of the light splitting structure should be smaller than the area of the surface 03.

[0084] When the gamma ray is received by the crystal unit 802, the gamma ray generates a plurality of photons inside the crystal unit 802. Part of the photons enter the corresponding semiconductor sensor through the surface 03, and another part of the photons enter other crystal units through the surface 01, the surface 02 or other surfaces. The other part of the photons finally enter the semiconductor sensors corresponding to the other crystal units after being transmitted between the other crystal units. The position of the photons generated inside the crystal unit can be analyzed according to the output of the semiconductor sensor.

[0085] In specific implementations, the light splitting structure can be a reflective film or a white reflective coating arranged on the surface of the crystal unit. The area and position of the light splitting structure on the surface are different, which results in different number of photons transmitted to the surface of the light splitting structure entering other crystal units through the surface, and further results in different number of photons received by each semiconductor sensor, and finally affects the result of analyzing the position of the photons according to the output of the semiconductor sensor. Taking two crystal units as an example, the different number of photons generated by different arrangement of the light splitting structure entering other crystal units is described as follows:

[0086] As shown in FIG. 8, the light splitting structure 01a is arranged on the surface 01 of the crystal unit 802, and the light splitting structure 02a is arranged on the surface 02 of the crystal unit 802. The area of the light splitting structure 01a is smaller than the area of the surface 01, and the area of the light splitting structure 02a is smaller than the area of the surface 02. Figure 9 and Figure 10As shown in FIG. 6, the crystal unit 902 and the crystal unit 904 are adjacent crystal units, and the contact surface of the crystal unit 904 and the crystal unit 902 is provided with a white light-reflecting coating (see the shaded part in the figure). Three photons are excited in the crystal unit 902. When the photons generated in the crystal unit 902 are transmitted to the white light-reflecting coating, the photons transmitted to the white light-reflecting coating are reflected by the white light-reflecting coating and cannot enter the crystal unit 904 through the white light-reflecting coating. When the photons are transmitted to the part of the contact surface which is not provided with the white light-reflecting coating, the photons can enter the crystal unit 904 through the part of the contact surface which is not provided with the white light-reflecting coating.

[0087] As shown in FIG. 7, since the area of the white light-reflecting coating is equal to the area of the contact surface, at this time, two photons transmitted to the contact surface do not enter the crystal unit 904. Figure 9 As shown in FIG. 8, since the area of the white light-reflecting coating is about half of the area of the contact surface, at this time, one of the two photons transmitted to the contact surface enters the crystal unit 904. Figure 10

[0088] As can be seen from the above, the different setting of the light splitting structure on each surface of the crystal unit leads to different number of photons generated in other crystal units. Therefore, in order to meet the resolution requirement of the crystal units on the image, when the PET detector in the embodiment of the present application is set, the area of the light splitting structure set on each crystal unit can be adjusted by adjusting the probability of the photons generated in each crystal unit.

[0089] It is proved by a large number of practices that the probability of the photons generated in each crystal unit of the crystal array meets the following formula:

[0090]

[0091] Wherein, N represents the total number of photons generated in any crystal unit of the crystal array except the selected crystal unit, m represents the number of photons appearing in the selected crystal unit when the total number of photons generated in the any crystal unit is N, p represents the probability of the photon appearing in the selected crystal unit when one photon is generated in the any crystal unit, and P represents the probability of the number of photons appearing in the selected crystal unit being m when the total number of photons generated in the any crystal unit is N.

[0092] ​When the area of the light splitting structure arranged on each crystal unit is adjusted by using formula (1), the values of N, m and p can be obtained by corresponding detection equipment or a limited number of experiments. When the position of the photon generation is analyzed according to the output of the semiconductor sensor, the resolution of the crystal unit on the image needs to meet certain requirements, so that the position of the photon generation can be accurately determined according to the image display result. Generally, the more the number of photons appearing in each crystal unit of the crystal array, the higher the resolution of each crystal unit on the image. When the probability P of the photon appearing in the selected crystal unit meets the condition of the resolution of the crystal unit on the image, the area of the light splitting structure corresponding to the probability P is arranged on the crystal unit.

[0093] When the probability of the photon appearing in the selected crystal unit is high, the area of the light splitting structure on the crystal unit can be reduced, the position of the light splitting structure on the crystal unit can be adjusted, or the area of the light splitting structure on the crystal unit can be reduced while the position of the light splitting structure on the crystal unit is adjusted. Conversely, the area of the light splitting structure on the crystal unit can be increased, the position of the light splitting structure on the crystal unit can be adjusted, or the area of the light splitting structure on the crystal unit can be increased while the position of the light splitting structure on the crystal unit is adjusted.

[0094] In an embodiment of the present application, a 1*10 crystal array is selected, wherein the crystal array includes 10 crystal units, and a light splitting structure is arranged on each crystal unit. The adjustment of the light splitting structure arranged on the surface of each crystal unit is described in detail by using formula (1) with the PET detector composed of the 1*10 crystal array as an example.

[0095] As shown in Figure 11 and Figure 12 , a distribution diagram of the probability of the photon appearing in each crystal unit in the crystal array before adjustment is shown in Figure 11 , and a distribution diagram of the probability of the photon appearing in each crystal unit in the crystal array after adjustment is shown in Figure 12 . Wherein, Figure 11 and Figure 12 the horizontal axis represents the position of each crystal unit, and the waveform between the adjacent two troughs represents the probability distribution of the photon appearing at different positions in one crystal unit. The vertical axis represents the probability value of the photon appearing in each crystal unit. The greater the ratio of the peak to the trough of each waveform representing the probability of the photon appearing in the crystal unit, the higher the resolution of the crystal unit on the obtained image.

[0096] It can be seen from the comparison between Figure 11 and Figure 12 that, in Figure 12In the middle, the ratio of the peak to the trough of the waveform representing the probability of the occurrence of the photon inside the crystal unit is greater than 1 Figure 11 In the middle, the ratio of the peak to the trough of the waveform representing the probability of the occurrence of the photon inside the crystal unit is greater than 1

[0097] In the specific implementation, in order to better meet the requirement of the resolution of the crystal unit on the image, when the light splitting structure is arranged on the surface of the crystal unit, the light splitting structure on the crystal unit can also be arranged according to the light receiving area of the semiconductor sensor, the relative position between the semiconductor sensors, and the relative position between the semiconductor sensor and the crystal array. That is, the arrangement of the light splitting structure on the surface of the crystal unit also needs to be matched with the light receiving area of the semiconductor sensor, the relative position between the semiconductor sensors, and the relative position between the semiconductor sensor and the crystal array.

[0098] In the specific implementation, in order to further reduce the size of the PET detector, the semiconductor sensor with a light receiving area of 3*3 mm can be selected.

[0099] In general, among the factors such as the light receiving area of the semiconductor sensor, the relative position between the semiconductor sensors, the relative position between the semiconductor sensor and the crystal array, and the probability of the occurrence of the photon inside each crystal unit, when the parameters of one or more factors are determined, the parameters of other factors can be adjusted to make the PET detector meet the requirement of the resolution of the crystal unit on the image.

[0100] For example, in the case that the light receiving areas of the semiconductor sensors are determined, the resolution of the crystal cells on the image can be satisfied by adjusting the relative positions between the semiconductor sensors, the relative positions between the semiconductor sensors and the crystal array, and the probabilities of the occurrence of the photons in the crystal cells. In the case that the light receiving areas of the semiconductor sensors and the relative positions between the semiconductor sensors are determined, the resolution of the crystal cells on the image can be satisfied by adjusting the relative positions between the semiconductor sensors and the crystal array, and the probabilities of the occurrence of the photons in the crystal cells. In the case that the light receiving areas of the semiconductor sensors and the probabilities of the occurrence of the photons in the crystal cells are determined, the resolution of the crystal cells on the image can be satisfied by adjusting the relative positions between the semiconductor sensors, and the relative positions between the semiconductor sensors and the crystal array. In the case that the light receiving areas of the semiconductor sensors, the relative positions between the semiconductor sensors, and the relative positions between the semiconductor sensors and the crystal array are determined, the resolution of the crystal cells on the image can be satisfied by adjusting the probabilities of the occurrence of the photons in the crystal cells.

[0101] Therefore, when the PET detector in the embodiment of the present application is set, the area of the light splitting structure arranged on each crystal cell in the crystal array can be adjusted first, and then the semiconductor sensor array is arranged relative to the light emitting surface of the crystal array, or the semiconductor sensor array can be arranged relative to the light emitting surface of the crystal array first, and then the area of the light splitting structure arranged on each crystal cell in the crystal array is adjusted. No matter which order is adopted, as long as the resolution of the crystal cells on the image can be satisfied.

[0102] When the PET detector in the embodiment of the present application is used to detect the position of the generated photons, as described above, a certain crystal cell of the crystal array receives the gamma ray, and the gamma ray excites to generate photons inside the crystal cell. After the semiconductor sensor receives the photons from the light emitting surface of the crystal array, the position of the photons generated inside the crystal cell by the gamma ray can be determined according to the output of the semiconductor sensor.

[0103] When determining the photon generation location using the centroid reading method based on the output of semiconductor sensors, it is necessary to calculate the total energy E of the generated photons, the energy X1 of the photons received by one row of semiconductor sensors, and the energy Y1 of the photons received by one column of semiconductor sensors. Thus, the position of the photon generation location in the row is x = X1 / E, and the position in the column is y = Y1 / E. The photon generation location can be determined based on the values ​​of x and y. The total energy E of the generated photons is equal to the sum of the energies of the photons received by each semiconductor sensor of the PET detector. Similarly, the energy X1 of the photons received by one row of semiconductor sensors is equal to the sum of the energies of the photons received by each semiconductor sensor in that row, and the energy Y1 of the photons received by one column of semiconductor sensors is equal to the sum of the energies of the photons received by each semiconductor sensor in that column.

[0104] Currently, the common practice for determining the photon generation location is to read the output data of each semiconductor sensor and then determine the photon's location based on the read data. In other words, when using this method, the number of data read is the same as the number of semiconductor sensors. This increases the amount of data processing required for determining the photon generation location when the PET detector includes multiple semiconductor sensors, thus increasing the difficulty of determining the photon generation location. For example, in applications... Figure 5 When the PET detector shown determines the photon generation location, since the PET detector includes eight semiconductor sensors, a total of eight data points are read when reading the data from these semiconductor sensors. Subsequent processing to determine the photon generation location requires processing these eight data points, increasing the difficulty of determining the photon location.

[0105] Therefore, in view of the above situation, in the embodiment of the present invention, when setting the PET detector, the PET detector may further include a first amplifier, the input terminal of the first amplifier being connected to the output terminal of a preset row of semiconductor sensors in the semiconductor sensor array. The number of the first amplifiers can be set according to the number of rows in the semiconductor sensor array, and the number of the first amplifiers is less than or equal to the number of rows in the semiconductor sensor array. When the input terminal of the first amplifier is connected to the output terminal of a preset row of semiconductor sensors in the semiconductor sensor array, the input terminal of the first amplifier is connected to the output terminal of each preset row of semiconductor sensors, and the output data of each preset row of semiconductor sensors is an input data of the first amplifier. In this way, when using the centroid reading method to determine the photon generation position, the output of one row of semiconductor sensors can be directly determined based on the output of the first amplifier, without needing to read the output of each semiconductor sensor separately. This reduces the amount of data processing required to determine the photon generation position and lowers the difficulty of determining the photon position.

[0106] Similarly, when configuring the PET detector in this embodiment of the invention, a second amplifier may also be included, the input terminal of which is connected to the output terminal of a predetermined column of semiconductor sensors in the semiconductor sensor array. The specific configuration of the second amplifier can be referred to the above description of the first amplifier, and will not be repeated here.

[0107] In specific implementations, the PET detector may include only the first amplifier, only the second amplifier, or both the first and second amplifiers. When the PET detector includes both the first and second amplifiers, the amount of data processing required to determine the location of photons can be further reduced, thus lowering the difficulty of determining the photon location.

[0108] The following is based on Figure 13 Taking the PET detector shown as an example, the setup and detection of the PET detector in this embodiment of the invention will be explained:

[0109] like Figure 13 As shown, the PET detector includes: a crystal array of crystal units 202 arranged in an 8*8 array, and a semiconductor sensor array of semiconductor sensors 2081 to 2084 arranged in a 2*2 array.

[0110] In setting the PET detector, after selecting the specific semiconductor sensor, the relative positions between the semiconductor sensors 2081-2084 and the relative positions between the semiconductor sensors and the crystals can be determined first, and then the area of the light splitting structure arranged on the surface of each crystal unit is adjusted so that the resolution of the crystal unit on the image obtained by applying the PET detector meets certain requirements.

[0111] In adjusting the area of the light splitting structure arranged on the surface of each crystal unit, the probability of the occurrence of a photon inside each crystal unit 202 can be adjusted, and when the value of the probability meets the condition of the resolution of the crystal unit on the image, the area of the light splitting structure corresponding to the value of the probability is arranged. For example, the probability distribution of the occurrence of a photon inside each crystal unit 202 can be adjusted to the probability distribution shown in FIG. 13B. After adjusting the area of the light splitting structure arranged on each crystal unit, the semiconductor sensor array is arranged relative to the light emitting surface of the crystal array, and the PET detector is obtained. Figure 14

[0112] In order to facilitate subsequent determination of the position of the photon generation according to the output of the semiconductor sensor, a first amplifier and a second amplifier can also be arranged in the obtained PET detector. In arranging the first amplifier, it can be arranged on the row where the semiconductor sensors 2081 and 2083 are located, or on the row where the semiconductor sensors 2082 and 2084 are located, or it can be arranged on both the row where the semiconductor sensors 2081 and 2083 are located and the row where the semiconductor sensors 2082 and 2084 are located. In the embodiment of the present application, the first amplifier 1301 arranged on the row where the semiconductor sensors 2081 and 2083 are located is taken as an example for illustration. Similarly, in arranging the second amplifier, it can be arranged on the column where the semiconductor sensors 2081 and 2082 are located, or on the column where the semiconductor sensors 2083 and 2084 are located, or it can be arranged on both the column where the semiconductor sensors 2081 and 2082 are located and the column where the semiconductor sensors 2083 and 2084 are located. In the embodiment of the present application, the second amplifier 1302 arranged on the column where the semiconductor sensors 2081 and 2082 are located and the second amplifier 1303 arranged on the column where the semiconductor sensors 2083 and 2084 are located are taken as an example for illustration.

[0113] ​The output of the first amplifier 1301 is out1, the output of the second amplifier 1302 is out2, and the output of the second amplifier 1303 is out3. Thus, the total photon energy E = out2 + out3. The photon energy received by the semiconductor sensor in one row is X1 = out1, and the photon energy received by the semiconductor sensor in one column is Y1 = out2 or Y1 = out3. It should be noted that after determining the row and column, i.e., using the row as the x-axis and the column as the y-axis, the position of the photon generation is determined in the coordinate system established by the x-axis and y-axis. Taking the photon energy Y1 = out2 received by the semiconductor sensor in one column as an example, according to the centroid reading method, the position of the row where the photon is generated is x = X1 / E = out1 / (out2 + out3), and y = Y1 / E = out2 / (out2 + out3). In this way, the location where the photon is generated can be determined based on the outputs of the first amplifier 1301, the second amplifier 1302, and the second amplifier 1303. Compared to determining the location of the photon generation based on the outputs of the semiconductor sensors 2081, 2082, 2083, and 2084, this effectively reduces the amount of data processing required to determine the location of the photon generation.

[0114] The simulation using the aforementioned PET detector yielded the following two-dimensional image analysis results regarding the positions of each crystal unit: Figure 15 As shown. Among them Figure 15 The horizontal axis represents the column position of each crystal unit, and the vertical axis represents the row position of each crystal unit. Figure 15 As can be seen, the positions of the crystal units are relatively uniform, and each crystal unit is clearly visible, resulting in a high resolution of the crystal units in the corresponding image. When using the PET detector described above to actually detect the photon generation location, the photon position can be obtained relatively accurately.

[0115] To enable those skilled in the art to better understand and implement the embodiments of the present invention, the method corresponding to the above-described PET detector is described in detail below.

[0116] like Figure 16 As shown, embodiments of the present invention also provide a method for setting up a PET detector, the method including:

[0117] Step 1602: Adjust the area of ​​the beam-splitting structure set on each crystal unit in the crystal array.

[0118] When adjusting the area of ​​the beam-splitting structure on each crystal unit in the crystal array, the probability of photons appearing in each crystal unit can be adjusted first. When the probability of photons appearing in the crystal unit satisfies the resolution condition of the crystal unit in the image, the crystal unit is set with the area of ​​the beam-splitting structure corresponding to the probability.

[0119] When adjusting the probability of photons appearing in each crystal unit, the above formula (1) can be used to adjust the probability of photons appearing in the selected crystal unit.

[0120] Step 1604: The semiconductor sensor array is arranged relative to the light-emitting surface of the crystal array to obtain the PET detector.

[0121] It should be noted that, in specific implementations, the order of steps 1602 and 1604 is not limited. That is, one can either first adjust the area of ​​the beam-splitting structure on each crystal unit in the crystal array and then set the semiconductor sensor array relative to the light-emitting surface of the crystal array, or one can first set the semiconductor sensor array relative to the light-emitting surface of the crystal array and then adjust the area of ​​the beam-splitting structure on each crystal unit in the crystal array; no limitation is imposed here.

[0122] When setting the PET detector using the setting method in the embodiments of the present invention, the setting method can be implemented with reference to the description of the PET detector in the above embodiments, and will not be repeated here.

[0123] like Figure 17 As shown, embodiments of the present invention also provide a detection method for a PET detector, the method comprising:

[0124] Step 1702: The crystal unit of the PET detector receives γ-rays.

[0125] Step 1704: The semiconductor sensor of the PET detector receives photons generated by the excitation of the γ-rays within the crystal unit.

[0126] Steps 1702 and 1703 can be implemented with reference to the description in the above embodiments of the PET detector.

[0127] Step 1706: Determine the location where the γ-rays generate photons inside the crystal unit based on the output of the semiconductor sensor.

[0128] In a specific implementation, the position where the γ-rays generate photons inside the crystal unit can be determined by the centroid reading method, as described in the above embodiment of the PET detector.

[0129] Although the present application has been disclosed with reference to the above embodiments, the application is not limited to the above embodiments. It will be apparent to those skilled in the art that various modifications and changes can be made thereto without departing from the spirit and scope of the application. The scope of the application should be limited only by the appended claims.

Claims

1. A PET detector, characterized by, The application comprises: a crystal array comprising a plurality of crystal units arranged in a single layer, the crystal units extending in a vertical direction and having a top surface, a bottom surface, and a side surface between the top surface and the bottom surface; a light-reflecting film disposed on a surface of at least one of the plurality of crystal units; a semiconductor sensor array comprising a plurality of semiconductor sensors, only a part of the crystal units in the crystal array being coupled with the semiconductor sensors, the number of the crystal units in the crystal array being greater than the number of the semiconductor sensors in the semiconductor sensor array; adjusting the relative positions among the semiconductor sensors, the relative positions between the semiconductor sensors and the crystal array, and the probabilities of occurrence of photons in the crystal units to meet the requirements for the resolution of the crystal units on an image; or, adjusting the relative positions between the semiconductor sensors and the crystal array and the probabilities of occurrence of photons in the crystal units to meet the requirements for the resolution of the crystal units on an image; or, adjusting the relative positions among the semiconductor sensors and the relative positions between the semiconductor sensors and the crystal array to meet the requirements for the resolution of the crystal units on an image.

2. The PET detector of claim 1, wherein, The areas of the light-reflecting films disposed on the surfaces of at least two of the crystal units in the crystal array are different.

3. The PET detector of claim 1, wherein, The application further comprises: The areas of the light-reflecting films disposed on the surfaces of the crystal units are adjusted by adjusting the probabilities of occurrence of photons in the crystal units to meet the requirements for the resolution of the crystal units on an image.

4. The PET detector of claim 1, wherein, The crystal array comprises at least three of the crystal units.

5. The PET detector of claim 1, wherein, When the light-reflecting film is disposed on the surface of the crystal unit for defining the light-emitting surface, the area of the light-reflecting film is smaller than the area of the surface for defining the light-emitting surface.

6. The PET detector of claim 1, wherein, At least one of the semiconductor sensors in the semiconductor sensor array is coupled with one of the crystal units in the crystal array.

7. The PET detector of claim 1, wherein, The coupling comprises the direct contact or contact through an adhesive material between the semiconductor sensor and the crystal unit.

8. The PET detector of claim 1, wherein, The application further comprises: a first amplifier, the input end of the first amplifier being connected with the output ends of the semiconductor sensors in a preset row of the semiconductor sensor array.

9. The PET detector of claim 8, wherein, The number of the first amplifiers is smaller than or equal to the number of rows of the semiconductor sensor array.

10. The PET detector of claim 1 or 8, wherein, The application further comprises: a second amplifier, the input end of the second amplifier being connected with the output ends of the semiconductor sensors in a preset column of the semiconductor sensor array.

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