CN106501838B - A light guide for a radiation detector, its preparation method, and a radiation detector - Google Patents

Abstract

The invention discloses a light guide for a radiation detector, a preparation method thereof, and a radiation detector. The radiation detector of the present invention includes a light guide, a scintillator array and a sensor array, wherein the light guide includes a light-transmitting plate, the upper surface S1 of the light-transmitting plate is the input end of the light guide, and the lower surface of the light-transmitting plate is provided with a trapezoidal array The upper bottom surface S2 of the mesa-shaped unit constituting the mesa-shaped array structure is the output end of the light guide; the scintillator array is coupled to the input end of the light guide, and the sensor array is correspondingly coupled to the output end of the light guide. Compared with the prior art, the design scheme of the present invention avoids the generation of dead zones, improves the light collection efficiency, and can improve the signal-to-noise ratio at the same time.

Description

A light guide for a radiation detector, its preparation method, and a radiation detector

technical field

The invention relates to a nuclear radiation detection device, and more particularly, to a light guide of a scintillation detector in the device.

Background technique

The general method of nuclear imaging technology is to use the change rule or distribution of nuclear-related physical quantities in the measured object to obtain internal information of the object, and process the information through a computer to reconstruct the internal image of the measured object. Nuclear imaging technology based on ray detection is playing an increasingly important role in the fields of social public security, high-energy physics, and biomedicine. For example, as an advanced medical imaging method, Positron Emission Tomography (PET) technology has unique advantages in obtaining functional information of certain biological organs or lesions, so it is useful in the early diagnosis of some diseases, pathological research, It has been widely used in curative effect observation and new drug research; Radiation Camera has been well used in radiation monitoring in some public places and special places because of its intuitive, non-destructive, and high-sensitivity features.

Nuclear detection devices are generally composed of detectors, electronics, and display terminals. Among them, the detector completes the conversion from nuclear radiation to electrical signal, which is the core component of the system.

The scintillation detector is the most widely used detector in nuclear imaging equipment, and its general structure is a scintillator, a light guide, and a photoelectric converter. The scintillator realizes the conversion of rays to scintillation light. Since the effective detection area of the detector is related to the area of the scintillator array, thin crystal strips are generally used to form a large-area crystal array; the photoelectric converter converts the optical signal into an electrical signal that can be processed , which is expensive and generally proportional to the area; in order to save costs, a tapered light guide is often added between the scintillator and the photoelectric converter, and a small-area photoelectric converter is used to detect a large-area scintillator. Since the use of tapered light guides can maintain the detection area and position resolution information and save costs, it has been widely used in the field of nuclear imaging, and various light guides have also been developed.

Existing solution 1: Patent Application No. 200510105211.2, which discloses a scintillation detector for a nuclear imaging device. This is a typical position-sensitive ray detector, which consists of a scintillator, a fiber optic light guide, and a photomultiplier tube. The scintillator strips in the scintillator array are separated by light-reflecting material, and the light cone made of glass fiber is used between the scintillator array and the photodetection device for optical coupling.

Advantages: easy assembly, stable structure, good results can be obtained when the area of the scintillator array is not much different from the effective area of the photodetector device, and has been widely used in small PET systems. Disadvantages: Due to the limitation of the light cone drawing process, the cone ratio cannot be too large. In other words, when the area of the scintillator array is much larger than the effective area of the photodetector device, a light cone with a larger cone ratio is required for decoupling. In this case, the light transmission efficiency at the edge of the light cone, especially at the corner It will be much lower than the light transmission efficiency in the middle, which will cause only a small part of the light of the scintillator strips at the edge of the scintillator array, especially the corners, to be transmitted to the photodetector device, making it difficult to distinguish these scintillator strips . Another disadvantage is the high cost of this light cone.

Existing solution 2: the patent application with application number 201210581442.0 discloses a light guide assembly for a radiation detector. The light guide produced by this method is a combination of single light guide components spliced, which realizes the simple splicing and combination of multi-channel detectors.

Advantages: small light guides can be assembled into large light guides, and the manufacturing method is convenient for mass production. Disadvantages: The premise of applying this method is to make individual light guide components first, and then apply this method. The overall process is still complicated, and the splicing of new light guides does not produce additional benefits compared with single light guide components.

Contents of the invention

Aiming at the problem of low light guide conversion efficiency in the prior art, the object of the present invention is to provide a light guide for a radiation detector and a radiation detector using the light guide.

A light guide for a radiation detector, characterized in that: the upper surface is an integral plane S1, the lower surface is composed of M*N separated planes S2 and the inverted V-shaped surface S3 between them, the upper surface and the inverted V-shaped The top distance is D1, the inverted V-shaped angle is θ (0<θ≤120°), the height is D2, and the side is composed of a vertical surface S4 and an inclined surface S5.

Its preparation method is:

method one:

a. Process the material used in the light guide into a rectangular cuboid, the upper and lower plane areas are both S1, and the height is D1+D2;

b. Process a V-shaped groove on one S1 surface of the cuboid by cutting or grinding;

c. Process the inclined surface S5 by cutting or grinding;

Method Two:

Cast in one piece using the model.

The upper plane S1 is coupled with a scintillator array, and the lower flat surface is coupled with a discontinuous photoelectric converter array in the sensitive area to form a position-sensitive scintillation detector;

The top of the inverted V-shaped angle can be acute, rounded or flat depending on the production process;

Detectors can be used as core detectors in positron emission tomography or radiography;

The photoelectric converter is a silicon photomultiplier tube.

Technical scheme of the present invention is:

A light guide for a radiation detector, characterized in that it includes a light-transmitting plate, the upper surface S1 of the light-transmitting plate is the input end of the light guide, and the lower surface of the light-transmitting plate is provided with a trapezoidal array structure, forming a trapezoidal unit of the trapezoidal array structure The upper bottom surface S2 is the output end of the light guide.

The angle formed between the side surfaces or side extension surfaces of adjacent mesa-shaped units is θ; where 0<θ≤120°.

The angles formed between the sides of all adjacent mesa-shaped units are θ; or the angles formed between the sides of adjacent mesa-shaped units in different rows or columns in the mesa-shaped array structure are different.

In the mesa-shaped array structure, the angle formed between the sides of the outermost mesa-shaped unit adjacent to the mesa-shaped unit is θ ₁ , and the angle formed between the sides of the other adjacent mesa-shaped units is θ ₂ , where θ ₁ <θ ₂ .

The thickness of the light-transmitting plate is D1, and the height of the mesa-shaped unit is D2, wherein, 0<D1≤a, a is the length of the bottom side of the cross-section of the trapezoidal unit, and b is the length of the bottom side of the cross-section of the trapezoidal unit.

The terrace-shaped unit is a regular quadrangular truss or a rectangular quadrangular truss or a circular truss; the sides of the trapezoidal unit are covered with highly reflective materials.

A method for preparing a light guide for a radiation detector, the steps of which are:

1) Processing the material used for the light guide into a cuboid; the height of the cuboid is D1+D2;

2) Machining two sets of V-shaped grooves perpendicular to each other and having a depth of D2 on a bottom surface of the cuboid;

3) A slope S5 is processed on the side part of the height D2 of the cuboid prepared with a V-shaped groove, so as to obtain a trapezoidal array structure composed of a plurality of trapezoidal units on the bottom surface.

A light guide preparation method for a radiation detector, the steps of which are: firstly prepare a casting mold corresponding to the light guide structure, and then use the casting mold to prepare the light guide.

A radiation detector, characterized in that it includes a light guide, a scintillator array and a sensor array, wherein the light guide includes a light-transmitting plate, the upper surface S1 of the light-transmitting plate is the input end of the light guide, and the lower surface of the light-transmitting plate is provided with There is a mesa-shaped array structure, the upper bottom surface S2 of the mesa-shaped unit constituting the mesa-shaped array structure is the light guide output end; the scintillator array is coupled with the light guide input end, and the sensor array is correspondingly coupled with the light guide output end.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The detector has no detection dead zone.

The general structures of photoelectric converters (such as photomultiplier tubes, photodiodes, and silicon photomultiplier tubes) are shown in Figures 1 and 2 (black is the sensitive area). The sensitive area is C1, surrounded by insensitive areas caused by packaging. When a large-area detector is assembled directly, there will be a dead zone (insensitive zone) at the junction. When the scintillator is placed directly above the dead zone, all the light emitted by the scintillator will be lost; one of the solutions is to combine the crystal array and A glass sheet is added between the photoelectric converters as a light guide to split the light, so that the flickering light emitted by the crystal directly above the dead zone will be received by the photoelectric converters at both ends, but the light shining on the dead zone is still lost.

The design scheme of the present invention avoids the generation of dead zones, improves the light collection efficiency, and improves the signal-to-noise ratio;

(2) Combining the weight algorithm to achieve high position resolution, the resolution can be smaller than the size of the light guide and the size of the photoelectric converter;

Crystal array pixels can be made very small, and the light distribution shown in Figure 5 enables the light emitted by even a small crystal to be detected, and the position is calculated, so that the final position resolution is no longer limited by photoelectric conversion device size;

(3) The thickness of the light guide is thinner, which reduces the propagation time of light in the light guide and ensures the time performance of the detector;

(4) The actual sensitive area of the photoelectric converter is smaller than that of the scintillator array, saving the cost of the photoelectric converter;

(5) The material is made of quartz glass, K9 glass, plexiglass or other transparent materials, which greatly reduces the cost of optical fiber light guides;

(6) It is convenient for mechanized production, and the processing cost is low.

Description of drawings

Figure 1 is a schematic diagram of the photoelectric converter structure;

Figure 2 is a schematic diagram of the traditional detector structure;

Fig. 3 is a schematic diagram of the light guide structure of the present invention;

(a) cross-sectional view, (b) three-dimensional structure view, (c) top view;

Fig. 4 is a schematic diagram of the sensor array;

Fig. 5 is a structural principle diagram of the detector of the present invention.

Detailed ways

In order to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

A light guide for a radiation detector, as shown in Figure 3, is characterized in that the upper surface is an integral plane S1, the lower surface is composed of M*N separated planes S2 and the inverted V-shaped surface S3 between them, and the upper surface The distance from the top of the inverted V is D1, the included angle of the inverted V is θ, the height is D2, and the side is composed of a vertical surface S4 and an inclined surface S5.

S1 matches the area of the light output surface of the scintillator array; discretely arranged photoelectric converter units form an array, the photoelectric converters are arranged in M*N, and the sensitive area of each photoelectric converter unit matches S2. When S1 and S2 are determined, the values of a and b are determined, and a, b, θ, D1, and D2 need to satisfy the constraint relationship:

0<D1≤a;

1<θ≤120° 0<θ≤120°

a is the length of the bottom side of the cross section of the mesa-shaped unit, b is the length of the bottom side of the cross-section of the mesa-shaped unit, the distance between the sensitive areas of the photoelectric converter is a-b, the area of the circuit board of the fixed photoelectric converter and the area of S1 unanimous. Figure 4.

A scintillator array, a light guide and a photoelectric converter array form a detector.

As shown in Figure 5, the upper surface S1 of the light guide is coupled with a scintillator, and the lower surface S2 is coupled with a photoelectric converter, and the sensitive area of the photoelectric converter is discontinuous.

The distance D1 between the upper surface and the inverted V-shaped top is used to provide light distribution, so that the light emitted by each pixel scintillator is distributed to multiple photoelectric converters through the light splitting layer, and the photons received by each photoelectric converter in an instance are calculated The weight of the number to calculate the scintillator pixel position, the calculation formula is

Among them, X and Y are the X coordinate value and Y coordinate value of the energy deposition position of the ray incident event in the detector, k _n and km _m are the weight factors when calculating the position of the nth column and the mth row, and Cmn is the M*N photoelectric The number of scintillation photons obtained by the unit located in the mth row and the nth column in the converter array or the equivalent value, A and B are constants.

Considering the requirements for position resolution in practical applications, the value of the included angle θ of the V-shaped grooves in each row and column may be different. For example, the photoelectric converter array is M*N, and the included angles of the V-groove of the light guide are θ _ij (0<i<M-1, 0<j<N-1), in order to enhance the edge position resolution ability of the detector, One implementation is that the θ value of the V-shaped grooves on the outermost ring is equal to θ ₁ , and the θ values of the remaining V-shaped grooves are θ ₂ , θ ₁ <θ ₂ .

The scintillator array coupled on the upper surface of the light guide is a P*Q array composed of scintillators with a pixel size of a. The array can be made into any size as required, and the crystals are separated by highly reflective materials. The area ratio of the upper plane S1 of the light guide to the lower plane is greater than 1. In the interval (1, ∞), the larger the value, the larger the scintillator area that the photoelectric converter can detect per unit area, and the lower the cost. It can be determined according to actual application requirements. This value and the angle θ.

The side is covered with highly reflective material to increase the light collection rate. According to the size of the scintillator array, S1 matches the size and shape of the array, and S2 is coupled to the discrete photoelectric converter. The sensitive area of the photoelectric converter matches the area of the small end face S2, which is smaller than the area of the large end face. . The material of the light guide can be quartz or K9 glass or other materials transparent to specific wavelength light.

Variations:

(1) In order to enhance the spatial resolution of edge positions, the upper surface of the outermost light guide pixel unit can be smaller than the upper surface area of the middle light guide pixel unit. In this case, the heights of D2 and S5 will be different.

(2) In order to enhance the resolution capability of a specific area, the inverted V-shaped included angles between different rows or columns can be the same or different.

(3) M=N; M≠N.

(4) The surface technology of S1, S2, S3, S4, and S5 is rough or polished.

(5) The surfaces of S3, S4, and S5 are covered with reflective layers.

(6) The light guide material is quartz, K9 glass, plexiglass and other materials that are transparent to light waves of specific wavelengths.

(7) S1 and S2 are rectangles; S1 and S2 are other shapes.

(8) The photoelectric converter can be PMT, PD, APD, SiPM, etc.

To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (8)

1. a kind of light guide of radiation detector, which is characterized in that the light-transmitting plate including the effect of light splitting together, on the light-transmitting plate Surface S1 is light guide input terminal, which is equipped with a shape array structure, constitutes the platform of this shape array structure Shape unit bottom surface is connect with light-transmitting plate, and upper bottom surface S2 is light guide output end, and upper bottom surface S2 area is less than bottom surface；Its In, the angle formed between the side or side extended surface of adjacent described shape unit is θ；Wherein 0 < θ≤120 °, described shape The angle formed between the side of the adjacent described shape unit of outmost turns in array structure is θ₁, remaining adjacent described shape unit Side between the angle that is formed be θ₂, and θ₁<θ₂。

2. light guide as described in claim 1, which is characterized in that the folder formed between the side of all adjacent described shape units Angle is θ；Or do not go together in described shape array structure or the side of the adjacent described shape unit of different lines between formed Angle it is different.

3. light guide as described in claim 1, which is characterized in that the light-transmitting plate with a thickness of D1, described shape unit Height is D2, wherein 0 < D1≤a,A is the cross section bottom side length of described shape unit, and b is described The cross section upper bottom edge of platform shape unit is long.

4. the light guide as described in claims 1 to 3 is any, which is characterized in that described shape unit is positive truncated rectangular pyramids or rectangle Truncated rectangular pyramids or rotary table；High reflecting material is applied in the side of described shape unit.

5. a kind of light guide preparation method of radiation detector, the steps include:

1) light guide material therefor is processed into cuboid；The cuboid height is D1+D2；

2) two groups are processed on a bottom surface of the cuboid is mutually perpendicular to distribution and depth for the V-groove of D2, below the V-groove For the light-transmitting plate with a thickness of D1；

3) the height D2 lateral parts for being prepared with V-groove to the cuboid process inclined-plane S5, thus the bottom surface obtain one by The platform shape array structure that multiple shape units are constituted；Wherein, the adjacent described shape unit of outmost turns in described shape array structure Side between the angle that is formed be θ₁, the angle formed between the side of remaining adjacent described shape unit is θ₂, and θ₁<θ₂。

6. a kind of light guide preparation method of radiation detector the steps include: that preparing one first corresponds to light as described in claim 1 Then the casting die of guide structure prepares light guide using the casting die.

7. such as method described in claim 5 or 6, which is characterized in that the side of adjacent described shape unit or side extended surface Between the angle that is formed be θ；The light-transmitting plate with a thickness of D1, the height of described shape unit is D2, wherein 0 < θ≤ 120 °, 0 < D1≤a,A is the cross section bottom side length of described shape unit, and b is described shape unit Cross section upper bottom edge is long.

8. a kind of radiation detector, which is characterized in that including a light guide, scintillator arrays and sensor array, wherein the light The light-transmitting plate including the effect of light splitting together is led, which is light guide input terminal, the light-transmitting plate lower surface Equipped with a shape array structure, the platform shape unit bottom surface for constituting this shape array structure is connect with light-transmitting plate, upper bottom surface S2 For light guide output end, and upper bottom surface S2 area is less than bottom surface；The scintillator arrays are coupled with the light guide input terminal, the biography The coupling corresponding with the light guide output end of sensor array；Wherein, between the side or side extended surface of adjacent described shape unit The angle of formation is θ；Wherein 0 < θ≤120 °, in described shape array structure the side of the adjacent described shape unit of outmost turns it Between the angle that is formed be θ₁, the angle formed between the side of remaining adjacent described shape unit is θ₂, and θ₁<θ₂。