阅读说明：本技术 一种新型闪烁晶体探测器及其设计方法和应用 (Novel scintillation crystal detector and design method and application thereof ) 是由 许剑锋 于昕 张熙 杜菁 谢思维 彭旗宇 于 2020-12-21 设计创作，主要内容包括：本发明属于闪烁晶体相关技术领域,其公开了一种新型闪烁晶体探测器及其设计方法和应用,该新型闪烁晶体探测器包括：多个阵列排布的闪烁晶体,每一所述闪烁晶体的光输出面上设有有利于降低全反射效应提高光输出的微曲面,所述闪烁晶体之间以及所述闪烁晶体的入射面设有反光层；设于所述闪烁晶体的光输出面的光电传感器；以及密封所述闪烁晶体的侧壁的不透明密封面。本申请通过对传统闪烁晶体进行重新加工设计,将其加工成光子晶体的结构,通过特定的表面结构,增加光输出面的表面积,降低输出光线的入射角度,降低发生全反射效应的输出光线的比例,实现光输出的提高。(The invention belongs to the scintillation crystal correlation technical field, which discloses a novel scintillation crystal detector and a design method and application thereof, wherein the novel scintillation crystal detector comprises: the light output surface of each scintillation crystal is provided with a micro-curved surface which is beneficial to reducing the total reflection effect and improving the light output, and reflecting layers are arranged among the scintillation crystals and the incidence surfaces of the scintillation crystals; the photoelectric sensor is arranged on the light output surface of the scintillation crystal; and an opaque sealing surface sealing the sidewalls of the scintillation crystal. This application is through carrying out the reprocess design to traditional scintillation crystal, with its structure of processing into photonic crystal, through specific surface structure, increases the surface area of light output face, reduces output light's incident angle, reduces the proportion of the output light that takes place total reflection effect, realizes the improvement of light output.)

1. A novel scintillation crystal detector, comprising:

the light output surface of each scintillation crystal is provided with a plurality of micro curved surfaces, so that the incident angle of light in the scintillation crystal when the light is output through the micro curved surfaces is smaller than the critical angle of total reflection, and reflecting layers are arranged among the scintillation crystals and the incident surface of the scintillation crystal;

the photoelectric sensor is arranged on the light output surface of the scintillation crystal;

and an opaque sealing surface sealing the sidewalls of the scintillation crystal.

2. The novel scintillation crystal detector of claim 1, wherein the material of the light reflecting layer is one of barium sulfate, ESR, or teflon.

3. The novel scintillation crystal detector of claim 1, wherein said micro-curved surface is in the shape of a sawtooth, a sphere, a truncated cone, or a frustum.

4. The novel scintillation crystal detector of claim 1, wherein said plurality of micro-curvatures are identical in shape.

5. The novel scintillation crystal detector of claim 1, wherein said plurality of micro-curved arrays are arranged.

6. A design method of a novel scintillation crystal detector according to any one of claims 1 to 5, characterized in that the method comprises:

preparing the scintillation crystal by one or more of femtosecond laser, focused ion beam, laser vapor deposition method, imprinting method or self-assembly method;

and carrying out array arrangement on the scintillation crystals, arranging photoelectric sensors on the light output faces of the scintillation crystals, and arranging sealing faces on the side faces of the scintillation crystals.

7. Use of the novel scintillation crystal detector according to any of claims 1 to 5, characterized in that it is used in PET, SPECT or Gamma Camera.

Technical Field

The invention belongs to the technical field of scintillation crystal correlation, and particularly relates to a novel scintillation crystal detector and a design method and application thereof.

Background

Positron Emission Tomography (PET) is the only new imaging technique that can show biomolecular metabolism, receptor and neuromediator activities in vivo. At present, medical whole-body PET technology has a larger development space, and system sensitivity, system spatial resolution and signal-to-noise ratio are the main indexes for evaluating the PET technology. System sensitivity is one of the most important parameters of a medical whole-body PET system. The sensitivity of PET systems depends on geometric efficiency and intrinsic coincidence event detection efficiency. The geometric efficiency depends on the angle of a solid space surrounded by the detection module, but the geometric design of PET is very mature from birth to the present, and the great improvement is difficult to achieve. The inherent coincidence event detection efficiency depends on the capability of the detection crystal for intercepting gamma photons, the length of the detection crystal, the space filling rate of the detection crystal, the size of a set time window and an energy window and other factors. Methods for improving the inherent coincidence event detection efficiency of the system include developing scintillation crystals with higher density and higher effective atomic number; increasing the length of the crystal; increasing the space filling rate of the detection crystal; time windows and energy windows are optimized, but the method is slow to develop or has the defects of reducing the spatial resolution, the signal-to-noise ratio and the like of the system.

Therefore, in order to improve the sensitivity of the PET system, a design optimization needs to be performed from a brand new perspective, the scintillation crystal is a crystal which can convert the kinetic energy of the high-energy particles into light energy to emit flash light under the impact of the high-energy particles, and is a key component of imaging in the PET system, and the applicant finds that the capture capability of the scintillation crystal on photons directly affects the sensitivity of the PET system, so that a brand new scintillation crystal detector needs to be designed.

Disclosure of Invention

In view of the above drawbacks and needs of the prior art, the present invention provides a novel scintillation crystal detector to solve the total reflection problem during imaging of a detector with a scintillation crystal. This application is through carrying out the reprocess design to traditional scintillation crystal, with its structure of processing into photonic crystal, through specific surface structure, increases the surface area of light output face, reduces output light's incident angle, reduces the proportion of the output light that takes place total reflection effect, realizes the improvement of light output.

To achieve the above object, according to one aspect of the present invention, there is provided a novel scintillation crystal detector comprising: the light output surface of each scintillation crystal is provided with a plurality of micro curved surfaces, so that the incident angle of light in the scintillation crystal when the light is output through the micro curved surfaces is smaller than the critical angle of total reflection, and reflecting layers are arranged among the scintillation crystals and the incident surface of the scintillation crystal; the photoelectric sensor is arranged on the light output surface of the scintillation crystal; and an opaque sealing surface sealing the sidewalls of the scintillation crystal.

Preferably, the material of the light reflecting layer is one of barium sulfate, ESR or teflon.

Preferably, the shape of the micro-curved surface is a sawtooth-shaped, spherical-shaped, truncated cone-shaped or truncated cone-shaped groove.

Preferably, the plurality of micro-curved surfaces are identical in shape.

Preferably, the plurality of micro-curved surface arrays are arranged.

According to another aspect of the present invention, there is provided a method for designing the above-mentioned novel scintillation crystal detector, the method comprising: preparing the scintillation crystal by one or more of femtosecond laser, focused ion beam, laser vapor deposition method, imprinting method or self-assembly method; and carrying out array arrangement on the scintillation crystals, arranging photoelectric sensors on the light output faces of the scintillation crystals, and arranging sealing faces on the side faces of the scintillation crystals.

According to a further aspect of the invention, there is provided the use of the novel scintillation crystal detector described above, characterized in that it is used in PET, SPECT or Gamma Camera.

In general, compared with the prior art, the above technical solutions contemplated by the present invention have the following beneficial effects:

1. the light output surface area of the scintillation crystal is improved on one hand, and the incident angle of output light is reduced on the other hand, so that total reflection is not easy to occur in the transmission process, the light output is effectively improved, and the sensitivity of the system is improved;

2. the reflecting layers are arranged between the scintillation crystals and on the incident surface of the scintillation crystals, so that light rays in the scintillation crystals cannot interfere with each other, and simultaneously, generated visible light cannot be emitted from the incident surface but is totally emitted from the light emitting surface, so that the light collection efficiency is further ensured, and the sensitivity of the system is improved;

3. the micro-curved surface in the application can be in various forms, a plurality of related micro-curved surfaces can be the same or different, the requirement is low, all curved surface structures with large openings can meet the requirement, and the preparation requirement is low;

4. the related micro-curved surfaces can be prepared in various ways, the preparation methods are various, and different forms can be prepared according to different requirements.

Drawings

FIG. 1 schematically illustrates a total reflection of light;

FIG. 2 schematically illustrates a structural schematic of a conventional scintillation crystal;

FIG. 3 schematically shows a structural representation of a groove-like array of scintillation crystals of one configuration;

FIG. 4 schematically shows a circular hole array structure schematic of a scintillation crystal of another configuration;

FIG. 5 is a schematic diagram showing a package structure of the novel flash crystal detector of the present embodiment;

fig. 6 schematically shows a structural diagram of the packaging structure of the novel flash crystal detector of the embodiment after shading processing.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Before describing the new scintillation crystal detector in this application in more detail, the principle on which this application is designed is first described.

As shown in fig. 1, when light is incident from the optically dense medium to the optically thinner medium, a total reflection phenomenon occurs when an incident angle is larger than a critical angle, and only the reflected light is reflected without refracting the light. In the PET detector, after the scintillation crystal captures the gamma ray, the propagation direction of the generated visible light is random, wherein a great amount of light rays exist, the angle of the light rays reaching the light output surface is larger than the critical angle, and the total reflection phenomenon causes that the scintillation crystal intercepts the gamma photon, but only the reflected light rays continue to propagate in the crystal due to the total reflection phenomenon, and no matter how many times the incident angle is reflected, the visible light cannot be emitted to irradiate on the photoelectric sensor, so that the number of originally lower coincidence events is reduced, and the sensitivity of the system is influenced.

Referring to fig. 1 and fig. 2, the present invention provides a novel scintillation crystal detector, which includes a scintillation crystal, a photosensor, and a sealing surface, wherein:

the light output surface of each scintillation crystal is provided with a plurality of micro curved surfaces, so that the incident angle of light in the scintillation crystal when the light is output through the micro curved surfaces is smaller than the critical angle of total reflection, and reflecting layers are arranged among the scintillation crystals and the incident surface of the scintillation crystal;

the light output surface of the conventional flash crystal is planar, as shown in fig. 2, and the shape of the micro-curved surface in this embodiment is zigzag (as shown in fig. 3), spherical (as shown in fig. 4), truncated cone, or frustum. The shapes of the multiple micro-curved surfaces can be the same or different, and the shapes and the sizes of the multiple micro-curved surfaces are preferably the same for the convenience of preparation, and the multiple micro-curved surfaces are arranged in an array. The gamma photons strike the scintillation crystal to obtain visible light, the visible light is output from the output surface of the scintillation crystal, and the included angle between the visible light and the output surface is smaller than the total reflection critical angle due to the micro-curved surface on the output surface, so that the visible light is output.

Be equipped with the reflector layer between the adjacent scintillation crystal strip to avoid mutual light interference, the light input face is equipped with the reflector layer, because gamma photon can pierce through the reflector layer, so the reflector layer does not influence gamma photon's capture, makes the visible light of generating can not follow incident surface output moreover.

The photoelectric sensor is arranged on the light output surface of the scintillation crystal; a photosensor is coupled to the scintillation crystal.

And an opaque sealing surface sealing the sidewalls of the scintillation crystal to shield ambient light.

Because the light output surface is processed, the total reflection phenomenon of light is avoided, visible light generated by gamma photons is totally irradiated on the photoelectric sensor, the sensitivity of the detector is obviously improved, and better imaging effect and imaging efficiency are realized.

On the other hand, the application provides a design method of the novel scintillation crystal detector, the method is that firstly, one or more of femtosecond laser, focused ion beam, laser vapor deposition method, imprinting method or self-assembly method is adopted to prepare the scintillation crystal, so that the scintillation crystal can reach the structural characteristics of the photonic crystal; and then, the scintillation crystals are arranged in an array, a photoelectric sensor is arranged on the light output surface of the scintillation crystals, and a sealing surface is arranged on the side surface of the scintillation crystals.

The light output surface of the scintillation crystal is punched, grooved or has other micro-curved surfaces through the femtosecond laser, the surface area of the light output surface is improved, the original surface quality is not sacrificed, the surface area of the light output surface of the scintillation crystal is increased, and because the surface structure of the light output surface is changed, the surface structure of the photonic crystal enables the angle of incidence of output light to be reduced, so that the total reflection is not easy to occur in the transmission process, and the light output can be effectively improved. The device is used for reducing the light incidence angle during light output and reducing the proportion of output light for sending total reflection so as to improve the light output, and on the premise of not influencing other performances of the device, the system sensitivity of the device is improved and the imaging effect is improved. Further, the optimized scintillation crystal is subjected to array packaging, as shown in fig. 5 and 6, a reflective layer is coated between each crystal strip and on a gamma ray incidence surface, then a photoelectric sensor is coupled on a light output surface, and then sealing treatment is performed to shield ambient light, so that the design of a complete detector is realized. When the gamma ray is intercepted by the scintillation crystal to generate visible light, the photoelectric sensor coupled with the specific crystal generating the photoelectric effect can receive the optical signal, and the optical signal is read by the back-end processor and used for calculating the position for emitting the gamma ray for imaging.

The novel scintillation crystal detector of the application is particularly suitable for various instruments needing crystal output light, such as PET, SPECT, Gamma Camera and other devices for reducing the total reflection phenomenon of the output process.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.