CN101455574A - Imaging system and method - Google Patents

Abstract

The invention discloses an imaging system, which includes: a sample stage for placing samples to be imaged; a ray source part for emitting rays; a ray detection and acquisition part for receiving ray images; a rotation control part with two ends respectively fixedly connected to the ray source The part and the ray detection part drive the ray source part and the ray detection part to rotate; the computer sends control instructions to the ray source part, the rotation control part and the ray detection acquisition part, and receives the images received by the ray detection acquisition part and performs imaging processing. The present invention also provides an imaging method correspondingly, inputting desired imaging requirements, calculating relevant parameters, and sending control instructions; the ray source part and the ray detection part are fixed at both ends of the rotation control part, and the ray source part emits rays according to the control instructions , the ray detection part collects the projection image after the ray is transmitted through the sample, and performs imaging processing on the projection image. The invention solves the problems of deformation and motion artifacts caused by sample rotation.

Description

Imaging system and method

technical field

The invention relates to biomedical imaging technology, in particular to an imaging system and method for digital X-ray transmission imaging, tomography imaging and three-dimensional imaging of small animals.

Background technique

Digital X-ray transmission imaging technology is a relatively mature medical imaging technology and has been successfully applied in clinical practice. This technique plays an important role in the study of bone tissue and can provide detailed structural information of small animals. Micro-CT, also known as micro-CT, differs from hospital-used CT mainly in spatial resolution. The spatial resolution of CT used in hospitals is generally on the order of millimeters, while the spatial resolution of micro-CT can reach the order of microns.

The Chinese invention patent application with the application number 200510135935.1 discloses an X-CT scanning system, including a main control and data processing computer, a base, an object turntable and its mechanical control device, an X-ray generating device, and a data acquisition system. The detector array is arranged perpendicular to the line connecting the X-ray source of the X-ray generating device and the center of the object turntable, and one side of the detector array is flush with the extension line of the line connecting the X-ray source of the X-ray generating device and the center of the object turntable Or exceed a part, and the length of this protruding part is less than the radius of object turntable. The characteristic of this CT system is that the sample rotates, but the light source and the detector do not move. In the process of shooting small animals in this imaging method, once the animal sample moves, the shape will be deformed due to motion distortion, so that the continuous rotating projection During the process, the animal sample is always in a state of motion and deformation. Compared with the static projection state of the animal, obvious artifacts will be produced. This kind of artifact is called motion artifact. big impact.

Contents of the invention

In view of this, the purpose of the present invention is to provide an imaging system and method for solving the problems of deformation and motion artifacts in the CT imaging process of small animals existing in the prior art.

The invention provides an imaging system, which includes:

The sample stage is used to place the sample to be imaged;

The ray source part is used to emit rays;

The ray detection acquisition part is used to receive the ray image;

A rotation control part, the two ends of the rotation control part are fixedly connected to the radiation source part and the radiation detection part, and are used to drive the radiation source part and the radiation detection part to rotate;

The computer is used to send control instructions to the ray source part, the rotation control part and the ray detection and acquisition part, and to receive the images received by the ray detection and acquisition part and perform imaging processing.

The present invention also provides an imaging method, the method comprising:

A. Input the desired imaging requirements, calculate relevant parameters, and send control instructions;

B. The ray source part and the ray detection part are fixed at both ends of the rotating control part. According to the control instructions, the ray source part emits rays, and the ray detection part collects projection images after the rays pass through the sample;

C. Perform imaging processing on the projected image.

As can be seen from the above, in the imaging system and method provided by the present invention, the X-ray detector, stage and X-ray source are arranged sequentially from bottom to top, their centers are located on the same straight line, and the X-ray source and detector are fixed on a rotating Both ends of the bracket move in a circle around the sample. In this way, when the method of the present invention is used to photograph the sample, the sample maintains a horizontally stationary natural form during the data collection process, and the sample always maintains the initial form during the data collection process when the X-ray source and the detector rotate around the sample, eliminating the Motion Artifacts of Small Animal Deformation Due to Movement in a Sample Rotation Acquisition System.

Description of drawings

FIG. 1 is a structural diagram of an imaging system in an embodiment of the present invention;

Fig. 2 is a structural diagram of a radiation source controller in an embodiment of the present invention;

Fig. 3 is the structural diagram of the rotating frame in the embodiment of the present invention;

Fig. 4 is the top view of the flat panel detector fixed mount and the micro-focus ray source fixed mount on the rotating frame in the embodiment of the present invention;

FIG. 5 is a flow chart of an imaging method in an embodiment of the present invention;

Fig. 6 is the perspective projection diagram of experimental rat in the embodiment of the present invention;

Fig. 7 is a tomographic image reconstructed on the plane position in Fig. 5 in the embodiment of the present invention;

Fig. 8 is an effect diagram of three-dimensional rendering of the experimental rat's head after three-dimensional reconstruction in the embodiment of the present invention.

Detailed ways

The embodiment of the present invention provides a system and method for imaging small animals, which uses the rotation of the light source and the detector to replace the sample rotation, keeps the sample still, and the light source and the detector rotate around it, which solves the problem of deformation caused by the rotation of the sample. Motion artifact problem.

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the imaging system provided by the embodiment of the present invention specifically includes:

Computer 1 , motor driver 2 , electric rotating mechanism 3 , radiation source controller 4 , microfocus X-ray source 5 , data acquisition device 6 , flat panel detector 7 , rotating frame 8 , and sample stage 10 .

The micro-focus X-ray source 5 is connected to an interface of the radiation source controller 4, and the other interface of the radiation source controller 4 is connected to the communication port of the computer 1; the flat panel detector 7 is connected to the data acquisition device 6, and the data acquisition device 6 passes The data transmission line is connected with the computer 1 .

The micro-focus X-ray source 5 and the flat panel detector 7 are fixed at both ends of the rotating frame 8, the rotating frame 8 is installed on the electric rotating mechanism 3, the electric rotating mechanism 3 is directly fixed on the base, and then placed on the ground through the base superior. One interface of the motor driver 2 is connected with the electric rotating mechanism 3 , and the other interface is connected with the communication port of the computer 1 .

The sample stage 10 is fixed directly on the base.

in,

The computer 1 is used for setting and sending control instructions to the radiation source controller 4 and the motor driver 2, and receiving the digital X-ray image sent by the data acquisition device 6, and performing imaging processing on the image.

The motor driver 2 is connected to the computer 1 through the communication serial port, and is used to receive the control instruction sent by the computer 1, and according to the instruction sent by the computer 1, the rotation of the electric rotating mechanism 3 is driven through the driving cable, thereby driving the micro focus at both ends of the rotating frame 8 Rotation of X-ray source 5 and flat panel detector 7 . The control instruction can be an instruction to set the rotation speed and the number of rotation steps. After the motor driver 2 analyzes the serial port instruction, it drives the rotation of the electric rotating mechanism 3 according to the information such as the rotation speed and the number of steps carried in the control instruction.

The electric rotating mechanism 3 is used to drive the micro-focus X-ray source 5 and the flat panel detector 7 at both ends to rotate under the drive of the motor driver. The electric rotating mechanism can be a stepping motor or a servo motor.

The ray source controller 4 is connected to the computer 1 through a communication parallel port, which may be a printing port. The radiation source controller 4 is used to receive the control instructions sent by the computer 1, and control the on and off of the power supply of the micro-focus X-ray source 5. When the ray source controller 4 received the instruction that the micro-focus X-ray source 5 sent by the computer 1 was opened, the micro-focus X-ray source 5 sent rays, at this moment at first the focus size of the required micro-focus X-ray source 5 can be selected. After the focus size of the micro-focus X-ray source 5 is selected, the voltage value of the ray tube is selected, and finally the tube current value is determined within a certain range.

The structure of the radiation source controller 4 and the connection mode with the micro-focus X-ray source 5 are shown in Figure 2, and its realization principle is: through the TTL level of the parallel port, the winding coil of the drive relay is turned on or off the 220V power supply circuit . The structure consists of the following parts:

The computer communication parallel port 11 is used to receive the high and low levels of the representative control command sent by the computer 1;

The digital inverter 12 is used to convert the high level sent by the computer 1 into a low level, and the low level into a high level. Why invert?

The DC power supply 13 is used to provide the voltage required by the digital inverter 12 and the triode 14 .

The triode 14 , the base of the triode 14 is connected to the inverter 12 , and receives the high and low levels after the reverse driving of the inverter 12 , and the collector of the triode 14 is connected to the 5V DC power supply 13 . When the triode is turned on, the current of the DC power supply 13 is amplified to trigger the relay 17 and the signal indicator light.

Light-emitting diode 15, the electromagnetic winding of light-emitting diode 15 and relay 17 is connected in parallel, as signal indicator light, is used for indicating the on-off status of relay contact switch, if contact switch conduction, then light-emitting diode 15 is luminous.

The AC power supply 16 energizes the micro-focus ray source when the relay 17 is turned on.

The relay 17 is used to connect the circuit of the micro-focus X-ray source through the triggering of the relay. The relay 17 forms a circuit together with the micro-focus X-ray source 5 and the 220V AC power supply 16. As long as the relay is connected, the radiation source starts to work; the relay is disconnected , the ray source stops working.

When the computer sends out the high level of the micro-focus ray source, the digital inverter is connected through the signal line to output a low level, and the triode is turned on at this time to amplify the DC power supply current, triggering the indicator light of the relay and the micro-focus ray source switch, After the relay is triggered, it will connect to the AC circuit where the micro-focus ray source is located. At this time, the micro-focus ray source emits rays; otherwise, when the computer sends out the low level of the micro-focus ray source, the digital inverter is connected through the signal line to output a high level. At this time, the triode is not turned on, the relay does not work under the low-current DC power supply, the AC circuit where the micro-focus ray source is located is in an open circuit state, and the micro-focus ray source does not emit X-rays.

The micro-focus X-ray source 5 is used to emit X-rays to small animal samples under the control of the radiation source controller 4 . The focal point of the micro-focus X-ray source 5 is in the range of 1 micron to 100 microns, and the tube voltage is in the range of 10 kV to 100 kV.

The data acquisition device 6 is connected to the computer 1 through the PCI slot, and is connected to the flat panel detector 7 through a digital interface. On the one hand, it receives the connection of the flat panel detector 7 sent by the computer, the preprocessing of the flat panel detector, and the data of the flat panel detector. Acquisition and other control commands, on the other hand, receive the projection image of the X-ray detected by the flat panel detector 7 after it passes through the object, and send it to the computer 1 . In this way, the computer 1 can control the work of the flat panel detector through the data acquisition device 6 and receive the data collected by the detector.

The flat panel detector 7, the flat panel detector 7 and the micro-focus X-ray source 5 are fixed together at both ends of the rotating frame 8 for detecting the X-rays emitted by the micro-focus X-ray source 5, and the ray is transmitted through the sample stage The sample 9 above 10 is received by the flat panel detector 7, and then transmitted to the data acquisition device 6 through the data transmission line. The flat panel detector 7 can be an amorphous silicon flat panel detector or an amorphous selenium flat panel detector.

The rotating frame 8 is fixedly connected to the micro-focus X-ray source 5 and the flat panel detector 7 at both ends, and the middle part is connected with the electric rotating mechanism 3 and can rotate under the drive of the electric rotating mechanism 3 . During the imaging process of small animal samples, the micro-focus X-ray source 5 and the flat panel detector 7 move in a circle around the rotating frame 8, so as to image the sample from multiple angles, and the static sample can eliminate the motion artifacts caused by the sample movement .

The structure of the rotating frame 8 is shown in Fig. 3 and Fig. 4. The rotating frame 8 is mainly built with a 40mm*40mm type FSA-181A profile, and the specific dimensions are marked in Fig. 3, unit: meter. It mainly includes a vertical rotating support frame, a micro-focus ray source fixing frame and a flat panel detector fixing frame. In Figure 3, the left figure (a) is a front view of the rotating frame, and the right figure (b) is a side view of the rotating frame , A and B in Fig. 4 are the top views of the flat panel detector fixing frame and the micro-focus ray source fixing frame respectively. The vertical rotating support frame, the micro-focus ray source fixing frame and the flat panel detector fixing frame are fixed by M8 T-shaped nuts. Please redraw the dotted line in Figure 4, otherwise the printout is not clear

The sample stage 10 is used for placing small animal samples. When shooting and imaging, the small animal sample 9 to be tested lies flat on the sample stage 10, and the sample stage 10 is composed of a three-dimensional translation platform, so the position of the sample stage can be adjusted, and the purpose is to ensure that the sample 9 is in the The center of rotation of the microfocus X-ray source 5 and the flat panel detector 7 .

Through the above imaging system, the rotation of the sample is replaced by the rotation of the light source and the detector, the sample is kept still, and the light source and the detector rotate around it, which solves the problem of deformation and motion artifacts caused by the rotation of the sample. The invention creates favorable conditions for obtaining more ideal small animal images, and provides an effective research tool for studying the structure information of small animals.

Fig. 5 is a flowchart of an imaging method provided by an embodiment of the present invention, including the following steps:

Step 501, the user inputs desired imaging requirements. The user mainly inputs necessary parameters to the computer, including sample length and required resolution, etc. The sample length is the total length of the object to be imaged, and the required resolution is the spatial resolution of the final reconstructed slice image.

Step 502, the computer calculates relevant parameters according to imaging requirements. Such as magnification, number of rotation steps, number of translation steps, etc. The magnification refers to the ratio of the distance between the micro-focus ray source and the detector to the distance between the micro-focus ray source and the imaging object, and the number of rotation steps refers to the rotation The rotation angle of each step of the bracket, the number of translation steps refers to the distance that the rotation bracket needs to translate, assuming that the length of the object to be imaged is 20cm, and the system can only image a length of 5cm each time, then the rotation bracket can only be translated 4 times Each translation is 5 cm to achieve an imaging length of 20 cm.

Step 503, turn on the ray source. The computer controls the X-ray source to emit X-rays, and the source remains on throughout the data acquisition process.

Step 504, rotating the frame by one step according to the number of rotation steps preset by the computer.

Step 505, collecting a frame of X-ray projection image.

Step 506, is the shooting completed? If it has not been completed, go to step 504; otherwise go to the next step.

Step 507, turn off the ray source, and after the shooting is finished, the collected data is stored, and the computer performs imaging processing on the image data.

A specific shooting experiment is taken as an example below to illustrate the effects of the above embodiments. The biological material for this experiment was SD rats, the length of which was about 100 mm excluding the tail. Animal breeding and experiments were carried out in strict accordance with the "Regulations on the Administration of Experimental Animals" of the People's Republic of China. Rats were anesthetized and placed flat on the stage. Adjust the position of the stage so that the imaging area is just aligned with the head of the rat.

The X-ray source voltage is 70 kV, the current is 0.3 mA; the imaging speed is 1 frame/second. Figure 6 is a perspective projection diagram of an experimental rat. The bones and contours of the rat's head are very clear, and the brightness and contrast are ideal. Fig. 6 is a tomographic image reconstructed on the plane position in Fig. 5. The bone and soft tissue of the rat can be clearly distinguished from the tomographic image, and the image of the stage is also very clear. Figure 8 is a three-dimensional rendering of the rat's head after three-dimensional reconstruction after collecting multiple frames of images. The skull, spine, scapula, and front paws are very clear.

As can be seen from the above, in the imaging system and method provided by the present invention, the X-ray detector, stage and X-ray source are arranged sequentially from bottom to top, their centers are located on the same straight line, and the X-ray source and detector are fixed on the rotating bracket Both ends, make a circular motion around the sample. Like this, when adopting the method of the present invention to carry out sample photographing, the sample maintains the natural form of horizontal stillness in the data collection process, in the process that the X-ray source and the detector rotate around the sample to collect data, the sample keeps the initial form all the time, compared with For a CT system in which the sample rotates, the X-ray source and the detector are stationary, the motion artifact of small animal deformation caused by movement in the sample rotation acquisition system is eliminated.

Claims (10)

[Claim 1] An imaging system, characterized in that the system comprises: The sample stage is used to place the sample to be imaged; The ray source part is used to emit rays; The ray detection acquisition part is used to receive the ray image; A rotation control part, the two ends of the rotation control part are fixedly connected to the radiation source part and the radiation detection part, and are used to drive the radiation source part and the radiation detection part to rotate; The computer is used to send control instructions to the ray source part, the rotation control part and the ray detection and acquisition part, and to receive the images received by the ray detection and acquisition part and perform imaging processing. [Claim 2] The system according to claim 1, wherein the sample stage is composed of a three-dimensional translation stage whose position can be adjusted to ensure that the sample is located between the radiation source part and the radiation detection part center of rotation. [Claim 3] The system according to claim 2, wherein the system further comprises: The ray source controller is used to receive the control instruction sent by the computer, control the ray source part to emit ray and interrupt the ray emission. [Claim 4] The system according to claim 3, wherein the radiation source controller specifically comprises: The computer communication parallel port is used to receive the high and low level of the representative control command sent by the computer; A digital inverter is used to convert the high level sent by the computer 1 into a low level, and the low level into a high level; DC power supply, used to provide the voltage required by the digital inverter and triode; A triode, the base is connected to the inverter, and the collector is connected to the DC power supply, for amplifying the current of the DC power supply and triggering a relay; an alternating current power supply, used to partially charge the radiation source when the relay is turned on; The relay is used to trigger the working state of the circuit of the radiation source part by switching on and off. [Claim 5] The system according to claim 4, wherein the system further comprises: The light-emitting diode is connected in parallel with the electromagnetic winding of the relay, and is used to indicate the on-off status of the relay under the trigger of the triode, and emits light when it is on. [Claim 6] The system according to any one of claims 1 to 5, wherein the system further comprises: The motor driver is used to receive the control instruction sent by the computer, and control the rotation control part to drive the radiation source part and the radiation detection part to rotate. [Claim 7] The system according to claim 6, wherein the system further comprises: The data acquisition device is used to receive the radiation images collected by the radiation detection and acquisition part and send them to the computer, and receive control instructions from the computer to control the working state of the radiation detection and acquisition part. [Claim 8] The system according to claim 7, characterized in that the focal point of the ray source part is in the range of 1 micron to 100 microns, and the tube voltage is in the range of 10 kV to 100 kV. [Claim 9] An imaging method, characterized in that the method comprises: A. Input the desired imaging requirements, calculate relevant parameters, and send control instructions; B. The ray source part and the ray detection part are fixed at both ends of the rotating control part. According to the control instructions, the ray source part emits rays, and the ray detection part collects projection images after the rays pass through the sample; C. Perform imaging processing on the projected image. [Claim 10] The method according to claim 9, wherein the radiation source part and the radiation detection part make a circular motion around the rotation control part to image the sample from multiple angles.

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