WO2023179227A1

WO2023179227A1 - Cone beam computed tomography method and system based on scattering recognition

Info

Publication number: WO2023179227A1
Application number: PCT/CN2023/075115
Authority: WO
Inventors: 小野光; 吉振宁; 郭咏梅; 郭咏阳
Original assignee: 康达洲际医疗器械有限公司
Priority date: 2022-03-25
Filing date: 2023-02-09
Publication date: 2023-09-28
Also published as: CN114399564B; CN114399564A

Abstract

The present invention relates to the technical field of image processing. Disclosed is a cone beam computed tomography method based on scattering recognition. The method comprises the following steps: controlling an emitter to emit to target tissue a transmitted ray having a preset spectral width; acquiring, by means of a top detector, a first ray intensity of the transmitted ray at each pixel point after the transmitted ray penetrates the target tissue; acquiring, by means of a base detector, a second ray intensity of the transmitted ray at each pixel point after the transmitted ray is scattered and attenuated by a collimator; estimating a scattered ray intensity after the transmitted ray penetrates the target tissue; in combination with the second ray intensity, estimating a primary ray intensity after a scattered ray is removed; and constructing computed tomography of the target tissue.

Description

A cone beam computed tomography imaging method and system based on scattering recognition

Technical field

The invention relates to the technical field of image processing, and in particular to a cone beam computed tomography imaging method and system based on scattering recognition.

Background technique

Cone beam computed tomography (CBCT) is an imaging method that is widely used in the study of tissue structure. Applications include image-guided targeted controlled release and radiation guidance. The application of this technology on the C-arm provides good clinical imaging capabilities and mobility for the study of target tissue structures, and makes it easier to access the target tissue, effectively supporting operations such as stent or stent placement within the target tissue. implementation.

However, due to the wide coverage of CBCT's cone beam and detector, when the rays (X-rays) penetrate the target tissue, the rays in the target tissue and equipment will be severely scattered and detected by the detector. A high Scattered Photon Ratio (SPR, the ratio of detected scattered rays to primary rays) can seriously degrade imaging quality, such as low contrast-to-noise ratio and/or inaccurate CT numbering, which makes the final image of the target tissue poorly visible. There is a certain deviation between the state and the actual target tissue state, which will cause irreparable adverse effects on subsequent research (the primary ray refers to the pure original ray without any interaction between the ray emitter and the CBCT detector).

To overcome the impact of scattering on the final imaging due to the original ray penetrating the target tissue, there are two main methods in the existing technology. One is a hardware approach, such as adding a collimator to the detector to block scattered rays from the original rays. In principle, this is the best way to obtain an ideal image, but it requires weighing the impact of dose and is technically challenging because too high a density of collimators may also block primary rays, thereby reducing the detection of primary rays. The signal strength detected by the device. The other is through software algorithms that estimate the scattered ray signal from the detected signal. Its main challenge is that the obtained signal contains both scattered rays and primary rays, which is not necessarily suitable for estimating the true scattered rays due to the complexity of the signal composition.

Contents of the invention

In order to obtain higher quality tomography images, the present invention introduces an additional hardware change. By introducing new data information into the software algorithm, the estimation difficulty of the software algorithm is reduced and the final result is improved. The accuracy and acquisition efficiency of the final imaging. Specifically, the present invention proposes a cone beam computed tomography imaging method based on scattering identification, which receives the original rays emitted by the transmitter through a detector, which includes a top detector, a collimator and a collimator arranged in sequence. Base level detector, including steps:

S1: Control the emitter to emit original rays with a preset spectrum width to the target tissue;

S2: Obtain the first ray intensity of the original ray at each pixel point after penetrating the target tissue through the top detector;

S3: Obtain the second ray intensity of the original ray at each pixel point after scattering and attenuation by the collimator through the base layer detector;

S4: Estimate the scattered ray intensity after the original ray penetrates the target tissue through the first ray intensity and the second ray intensity at the corresponding pixel point;

S5: Based on the estimated scattered ray intensity, estimate the primary ray intensity after excluding scattered rays through the second ray intensity;

S6: Construct tomography imaging of the target tissue based on the primary ray intensity at each pixel point.

Furthermore, the top detector has low resistance to radiation, and the base detector has high resistance to radiation.

Furthermore, the top detector has position sensitivity to ray intensity.

Further, in step S4, the estimation of scattered ray intensity can be expressed as the following formula:
S ^est =Iceil/B-Ibase*A/B

In the formula, S ^est is the scattered ray intensity, Iceil is the first ray intensity, Ibase is the second ray intensity, A is the proportion of primary rays absorbed in the top detector, and B is the proportion of scattered rays absorbed in the top detector. Proportion.

Further, in step S5, the estimation of primary ray intensity can be expressed as the following formula:

In the formula, P ^est is the estimated primary ray intensity, A′ is the proportion of primary rays absorbed in the base detector, and B′ is the proportion of scattered rays absorbed in the base detector.

The present invention also proposes a cone beam computed tomography imaging system based on scattering recognition, including:

Emitter, used to emit raw rays with a preset spectrum width to the target tissue;

The top detector is used to obtain the first ray of the original ray at each pixel after penetrating the target tissue. strength;

Collimator, used to attenuate the scattered rays after the original rays penetrate the target tissue and the top detector;

The base layer detector is used to obtain the second ray intensity at each pixel point of the original ray after scattering and attenuation by the collimator;

A data processing unit, configured to estimate the intensity of scattered rays after the original ray penetrates the target tissue based on the intensity of the first ray and the intensity of the second ray at the corresponding pixel point, and based on the estimated intensity of the scattered rays, eliminate them through the second ray intensity estimation Primary ray intensity after scattered rays;

An imaging processing unit, used to construct tomographic imaging of the target tissue based on the primary ray intensity at each pixel point;

The top detector, collimator and base detector are connected in sequence.

Furthermore, the top detector has position sensitivity to ray intensity.

Further, in the data processing unit, the estimation of scattered ray intensity can be expressed as the following formula:
S ^est =Iceil/B-Ibase*A/B

Further, in the data processing unit, the estimation of primary ray intensity can be expressed as the following formula:

Compared with the prior art, the present invention at least contains the following beneficial effects:

(1) A cone beam computed tomography imaging method and system based on scattering identification according to the present invention, through the setting of the top detector, priority is given to detecting scattered rays without external interference, and the top detector is used The primary ray intensity and the scattered ray intensity are established as a function of the ray intensity detected by the base detector. Therefore, by using additional information from the top detector, the primary ray intensity can be better identified. In the existing technology, only a single detector is used, and the detected rays simultaneously include Including primary rays and scattered rays, it is difficult to distinguish primary rays from this mixed ray;

(2) Due to the addition of new hardware, new data are introduced into the software algorithm, so that the final required primary ray intensity data can be derived using a simple functional relationship in one measurement. Compared with the existing technology, A mixed signal of primary rays and scattered rays is used to estimate the scattered rays, so the estimate is not very precise, and some methods even increase the dose because they have to give up some data. Most of the scattered rays can be essentially removed by means of a collimator as a classical method. The present invention can further estimate the scattered X-rays mixed in the signal through the top detector to reduce the estimation error;

(3) The top detector has low resistance to the original rays and will not block the propagation of primary rays, so that the intensity of the rays detected by the final base detector will not be lost and will not affect the actual required irradiation dose. .

Description of the drawings

Figure 1 is a method step diagram of a cone beam computed tomography imaging method based on scattering recognition;

Figure 2 is a system structure diagram of a cone beam computed tomography imaging system based on scattering recognition;

Figure 3 is a schematic diagram of traditional CBCT transmission;

Figure 4 is a schematic structural diagram of the detector of the present invention;

Explanation of reference signs: 1-emitter, 2-target tissue, 3-original ray, 4-scattered ray, 5-FPD, 6-top detector, 7-collimator, 8-base detector.

Detailed ways

The following are specific embodiments of the present invention combined with the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

Embodiment 1

In traditional CBCT, as shown in Figure 3, there is only one flat panel detector (FPD) as the CBCT original ray detector. Among them, FPD is a two-dimensional original ray detector that has position sensitivity after discretization. The original ray 3 generated by emitter 1 is transmitted and projected onto FPD 5, and its ray intensity is recorded as a shadow. By repeating the original radiation exposure around the target tissue 2 and recording at different angles, a cross-sectional image of the target tissue can be reconstructed. However, the original rays produce scattered rays4 in the target tissue, thereby contaminating the data obtained by FPD. Various scattered ray estimation algorithms are then used to estimate scattered rays, but the estimation in this process can basically only use contaminated data obtained on the FPD.

Among them, one of the classic algorithms for scattered ray estimation algorithms is filtered convolution. In this algorithm, its convolution kernel is used to estimate scattered rays. The intensity of rays detected by the flat-panel detector is expressed by the following formula, where P and S represent primary rays and scattered rays respectively.
I＝P+S

Among them, the scattered ray intensity at the pixel position (i, j) in the image is estimated as follows:
S＝∑∑P(ik,jl)×kernel(k,l)～∑∑I(ik,jl)×kernel(k,l) (0)

In the formula, the summation is the size of the kernel (that is, the kernel function kernel(k,l)) defined by pixels relative to k and l. However, since this estimation method is an approximate solution of equations designed through empirical theory, it will lead to partial estimation residuals. To solve this part of the residual error, it is necessary to optimize the kernel through additional scans, but this will obviously increase the radiation dose, and the actual operation requirements are also more complex. In the latest technology, there is another method that is to add obstacles between the X-ray tube and the target tissue to block only the primary rays (avoiding the detection of scattered rays). However, this method also increases the radiation dose. Because it blocks the primary rays, part of the signal is lost.

In this patent, in order to accurately estimate the scattered rays without increasing the radiation dose, it is also considered that the existing technology is due to the complex combination of the original rays detected by a single detector at each pixel point. The above problems arise only because of the difficulty in estimating rays. In the present invention, a new device is proposed to improve the existing method, thereby better reducing the interference of scattered rays in the final imaging. As shown in Figure 1, the present invention proposes a cone beam computed tomography imaging method based on scattering identification. The original rays emitted by the transmitter are received through a detector. The detector includes a top detector 6, a collimator, and a top detector 6 arranged in sequence. Detector 7 and base detector 8 (shown in Figure 4), including steps:

S6: Construct tomographic imaging of the target tissue based on the initial ray intensity at each pixel point.

In the present invention, two detectors (top detector and base detector, the detector configuration is not limited to FPD, similar but different configurations can also be achieved by connecting the two detectors in parallel and installing a collimator between them. Realization) can receive the original rays that penetrate or scatter in the target tissue. Part of the original rays reaches the top detector and is transmitted or scattered, and is further attenuated by the collimator between the two detectors before reaching the base detector. In order to reduce the impact of the top detector's blocking of rays on the base detector, the top detector needs to use materials with weak resistance to rays. Among them, the most conservative applications use silicon 200 to 500 microns thick. Within the typical energy range emitted by the emitter (that is, the preset spectrum width, 60 to 80 kev), the top detector composed of silicon material with this thickness can transmit 97% of the original rays, thus minimizing the impact of the top detector on Effects of base detectors. Thus, the data information obtained by the top detector can be utilized without affecting the intensity of rays detected by the base detector.

In a preferred embodiment, the top detector may also consider using a material with stronger blocking properties, such as 150um thick CSL, in which 54% of the rays can react under 60kev conditions. The advantage of CSL is that light absorption dominates low (95% at 60kev) over the typical energy range. Therefore, the probability of further scattering of rays in CSL is much smaller than in other materials such as silicon, and complex reprocessing between scattered rays and primary rays does not occur in CSL. In other words, scattered rays and primary rays will not be further scattered in Csl, but the primary rays can be directly detected by the base detector. Due to the physical characteristics of X-rays, the signals from the top detector and the base detector constitute a low-energy ray part and a high-energy ray part, so that material analysis can be performed and then converted into material information of the target tissue.

At the same time, due to the following reasons:

(1) Compared with the base detector, there is no collimator on the top detector to block scattered rays;

(2) Low-energy rays are more likely to scatter within the target tissue, and the blocking ability of the top detector is generally stronger at low energy;

(3) The scattered rays do not enter the top detector vertically, but at an angle θ. Therefore, the effective detection thickness of the top detector for scattered rays is proportional to 1/cosθ.

Based on the above three reasons, the top detector in the present invention has the characteristic of preferentially detecting scattered rays, which means that the top detector has a higher scattered photon ratio than the base detector. Based on this characteristic, without increasing the ray dose, the difference in ray intensity detected by the top detector and the base detector can be used to estimate scattered rays and primary rays. The specific estimation idea is as follows.

In this embodiment, at a certain pixel point, Iceil is used to represent the first ray intensity obtained by the top detector, and Ibase is used to represent the second ray intensity obtained by the base detector, since both are determined by the primary ray intensity. (assumed to be defined as P) and scattered ray intensity (assumed to be defined as S), so it can be expressed by the following linear combination formula:
Iceil＝A*P+B*S
Ibase＝A′*P+B′*S (1)

Among them, A is the proportion of primary rays absorbed in the top detector, B is the proportion of scattered rays absorbed in the top detector, A′ is the proportion of primary rays absorbed in the base detector, and B′ is the scattered rays. The proportion of absorption in the base detector.

Then based on the above formula group (1), the expressions of primary ray intensity and scattered ray intensity can be obtained as follows:
P＝C*Iceil+D*Ibase
S＝C′*Iceil+D′*Ibase (2)

In the formula, C, C′, D, and D′ are simplified coefficients, which are obtained from A, A′, B, and B′ through a series of transformations. In order to achieve the simplification of formula (2), the present invention uses the following facts. Considering the conservation of energy and the original ray attenuation caused by the collimator, in actual situations, the following equation should be satisfied:
A+A′+Δa=1
B+B′+Δb＝1 (3)

In the present invention, since the top detector uses weak resistance material, the values of A and B are much less than 1 (for example, silicon <0.03). Where Δa is the blocking ratio of the collimator to primary rays, and Δb is the blocking ratio of the collimator to scattered rays. When the collimator blocks a small part of the primary rays, most of the scattered rays are also blocked, that is, Δa＜＜1,1-Δb＜＜1. At the same time, since primary rays have higher energy than scattered rays, the blocking ability of the top detector against high-energy rays is weak, and A and B are consistent or even smaller.

Specifically, the derivation of C, C′, D, and D′ can be expressed by the following formula set:

And since A<<1, B<<1, Δa<<1, A+A′+Δa=1, 1-Δb<<1, B+B′+Δb=1, so A′≈1,B′ <<1. Based on this, each simplified coefficient is actually expressed as:

Then, by eliminating A′ and B′ and taking advantage of the fact of formula (3), P and S can be further expressed as the following formula:
P＝Ibase+Iceil*(B+Δb-1)/B
S＝Iceil/B-Ibase*A/B (4)

Intuitively, formula (4) is reasonable. Since the ray intensity detected by the base detector contains most of the signal at the pixel of interest, the primary ray is basically determined by the ray intensity detected by the base detector. It should be noted that Iceil is related to scattering S. After normalization by its test efficiency, the second term of each sub-formula in formula group (4) is a correction factor.

It is not difficult to see from the formula group (4) that the most direct way to obtain the primary ray intensity is to use its first sub-formula P. In this case, the primary rays are estimated directly from the linear combination of the signals from the top and bottom detectors. In fact, since equation (4) is only an approximation, we can best estimate the primary ray by experimentally obtaining C and D in equation (2). To perform calibration, X-ray blocker technology can be used to obtain pure primary rays when scanning various objects.

The second method used in the present invention is to estimate the intensity of scattered rays. First, the air is scanned to calibrate the base detector. Since there is no scattering when calibrating with air, the estimated primary ray P ^est is expressed by equation (5) as follows, where Represents the intensity obtained when scanning air with a base detector:

At this time, when scanning an object of limited size and calibrating the base detector, the influence of scattered rays is slightly considered, and the estimated primary ray P ^{est,tentative} is as follows:

In the formula, P ^obj is the primary ray intensity detected in the base layer detector during scanning, and S ^obj is the scattered ray intensity detected in the base layer detector during scanning.

Therefore, in order to further eliminate this effect, the present invention uses the second equation S of formula (4) multiplied by B′/A′ to estimate the scattered rays, and subtracts them to obtain the following final solution formula:

In the formula, S ^est refers to the scattered ray intensity estimated using equation (4). This method requires calibration of the three coefficients 1/A′, B′/A′B, and AB′/A′B in formula (7).

Among them, the coefficients of the second sub-formula S of formula (4), namely 1/B and A/B, can be determined or calibrated before the experiment starts. The classic method for determining scattered rays is the beam resistor array.

Since the calibration of equation (5) is basically the same as that of CT. However, for the C-arm, due to its simple mechanical structure, the top detector and collimator can be designed separately to perform calibration in a simpler manner. After scanning the air with and without the top detector and collimator, the true primary ray signal can be obtained and the attenuated signal in the top detector plus collimator

Based on equation (1), the first coefficient A′ in equation (7) can be calibrated by the following formula.

In order to determine the second and third coefficients in equation (7), an object needs to be scanned. First, the object is scanned and signals are obtained at the top and bottom detectors, i.e. Now our goal is to do this by using and the following expressions to estimate the second and third terms in equation (7).

In other words, α and β need to be determined. In order to do this, we need to obtain the true value of the left-hand side of equation (8). True values can be obtained by using a beam stop array placed between the X-ray tube and the target tissue. Beam stop array creates shadows on certain pixels, only stopping the primary ray instead of Scattered rays. Therefore, the signal of a basic detector with a beam stop array changes from equation (1) to Will Substitute into equation (6) Then we can get the true value on the left side of equation (8).

Comparing equation (8) with the two unknown coefficients α and β, and comparing the value obtained by equation (9) with the beam stop array, the coefficients α and β can be determined. Since we have two unknown coefficients, we need to scan several different objects with different sizes and/or structures, or just scan a fixed structure object from different angles.

Additionally, it is important to note that Iceil's statistics may be relatively poor if a top detector with weak resistance is used. In this case, the noise of each signal is controlled by Iceil. However, the scattered ray distribution depends weakly on the detector position. By smoothing S at the pixel coordinate (i, j) to the 100 pixel level, the noise generated by the statistical difference of the top detector can be eliminated and can be easily Easily reduce noise levels to those of base level detectors. That is, the signal-to-noise ratio level of the final image for each pixel is determined by the signals from the top detector and the bottom detector. Therefore, a poor signal from the top detector will significantly deteriorate the quality of the final image. However, the signal from the top detector can be smoothed over approximately 100 pixels to improve statistics, since the scattering distribution is generally smooth.

The third method is to use the conventional method described at the beginning of this example, since the top detector is basically the same as the detector used in this conventional method. First, the air is scanned to calibrate the detector, we use equation (5). Also, as in Equation (6), when scanning an object of finite size and calibrating it to the detector, the effects of scattered rays are slightly included. We then use equation (7) again, but this time we estimate the scattering S ^est in a different way. Unlike the second method, we take I _ceil into I in equation (0) and estimate the scattering. Finally, the beam stop array is used to obtain pure scattering data, and the kernel in formula (0) is calibrated.

Embodiment 2

In order to better understand the technical content of the present invention, this embodiment explains the present invention through the system structure. As shown in Figure 2, a cone beam computed tomography imaging system based on scattering recognition includes:

The top detector is used to obtain the first ray intensity of the original ray at each pixel point after penetrating the target tissue;

An imaging processing unit, used to construct tomographic imaging of the target tissue based on the initial ray intensity at each pixel point;

The top detector, collimator and base detector are connected in sequence.

Furthermore, the top detector has low resistance to rays, and the base detector has high resistance to rays.

Furthermore, the top detector has position sensitivity to ray intensity.

To sum up, the cone beam computed tomography imaging method and system based on scattering recognition according to the present invention, through the setting of the top detector, preferentially detects scattered rays without external interference, and uses the top detector to The functional relationship between the ray intensity detected by the detector and the base detector and the primary ray and scattered ray is used to estimate the primary ray intensity using the scattered ray intensity which is relatively more stable in calculation. level of ray intensity, resulting in better final imaging quality.

Due to the addition of new hardware, new data are introduced into the software algorithm, so that the final required primary ray intensity data can be derived using a simple functional relationship in one measurement. Compared with the existing technology, which only sets There is a single detector, and the detected rays include both primary rays and scattered rays. If only a single detection is used, it will take a lot of computing power to estimate the actual scattered ray intensity, and if a secondary detection is used, the number of targets will be increased. The radiation dose of the tissue affects the target tissue structure. Therefore, the present invention can obtain imaging results more quickly while ensuring the safety of the radiation dose.

The top detector has low resistance to the original rays and will not block the propagation of primary rays, so that the intensity of the rays detected by the final base detector will not be lost and will not affect the actual required irradiation dose. Since the function coefficient of scattered ray intensity in the actual calculation process is only related to the new hardware, it can be confirmed and calibrated before actual operation. Therefore, it will not be affected by the structure and shape of the target tissue, and has a wider application range.

It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiment of the present invention are only used to explain the relationship between components in a specific posture (as shown in the drawings). Relative positional relationship, movement conditions, etc., if the specific posture changes, the directional indication will also change accordingly.

In addition, descriptions such as "first", "second", "a", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the indicated technical features. quantity. Therefore, features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

In the present invention, unless otherwise clearly stated and limited, the terms "connection", "fixing", etc. should be understood in a broad sense. For example, "fixing" can be a fixed connection, a detachable connection, or an integral body; It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be an internal connection between two elements or an interactive relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

In addition, the technical solutions of the various embodiments of the present invention can be combined with each other, but they must be based on the present invention. It is based on what a person of ordinary skill in the field can realize. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that such combination of technical solutions does not exist and is not within the protection scope required by the present invention.

Claims

A cone beam computed tomography imaging method based on scattering identification, characterized in that the original rays emitted by the emitter are received through a detector, and the detector includes a top detector, a collimator and a base detector arranged in sequence, including step:

S1: Control the emitter to emit original rays with a preset spectrum width to the target tissue;

S2: Obtain the first ray intensity of the original ray at each pixel point after penetrating the target tissue through the top detector;

S3: Obtain the second ray intensity of the original ray at each pixel point after scattering and attenuation by the collimator through the base layer detector;

S4: Estimate the scattered ray intensity after the original ray penetrates the target tissue through the first ray intensity and the second ray intensity at the corresponding pixel point;

S5: Based on the estimated scattered ray intensity, estimate the primary ray intensity after excluding scattered rays through the second ray intensity;

S6: Construct tomography imaging of the target tissue based on the primary ray intensity at each pixel point.
A cone beam computed tomography imaging method based on scattering identification as claimed in claim 1, characterized in that the top detector has low resistance to rays and the base detector has high resistance to rays.
A cone beam computed tomography imaging method based on scattering identification as claimed in claim 1, wherein the top detector has position sensitivity to ray intensity.
A cone beam computed tomography imaging method based on scattering identification as claimed in claim 1, characterized in that in step S4, the estimation of scattered ray intensity can be expressed as the following formula:
S est =Iceil/B-Ibase*A/B

In the formula, S est is the estimated scattered ray intensity, Iceil is the first ray intensity, Ibase is the second ray intensity, A is the proportion of primary rays absorbed in the top detector, and B is the proportion of scattered rays absorbed in the top detector. absorption ratio.
A cone beam computed tomography imaging method based on scattering identification as claimed in claim 4, characterized in that in step S5, the estimation of primary ray intensity can be expressed as The following formula:

In the formula, P est is the estimated primary ray intensity, A′ is the proportion of primary rays absorbed in the base detector, and B′ is the proportion of scattered rays absorbed in the base detector.
A cone beam computed tomography imaging system based on scattering recognition, characterized by including:

Emitter, used to emit raw rays with a preset spectrum width to the target tissue;

The top detector is used to obtain the first ray intensity of the original ray at each pixel point after penetrating the target tissue;

Collimator, used to attenuate the scattered rays after the original rays penetrate the target tissue and the top detector;

The base layer detector is used to obtain the second ray intensity at each pixel point of the original ray after scattering and attenuation by the collimator;

A data processing unit, configured to estimate the intensity of scattered rays after the original ray penetrates the target tissue based on the intensity of the first ray and the intensity of the second ray at the corresponding pixel point, and based on the estimated intensity of the scattered rays, eliminate them through the second ray intensity estimation Primary ray intensity after scattered rays;

An imaging processing unit, used to construct tomographic imaging of the target tissue based on the primary ray intensity at each pixel point;

The top detector, collimator and base detector are connected in sequence.
A cone beam computed tomography imaging system based on scattering identification as claimed in claim 6, characterized in that the top detector has low resistance to rays and the base detector has high resistance to rays.
A cone beam computed tomography imaging system based on scattering identification as claimed in claim 6, wherein the top detector has position sensitivity to ray intensity.
A cone beam computed tomography imaging system based on scattering identification according to claim 6, characterized in that in the data processing unit, the estimation of scattered ray intensity can be expressed as the following formula:
S est =Iceil/B-Ibase*A/B

In the formula, S est is the scattered ray intensity, Iceil is the first ray intensity, Ibase is the second ray intensity, A is the proportion of primary rays absorbed in the top detector, and B is the proportion of scattered rays absorbed in the top detector. Proportion.
A cone beam computed tomography imaging system based on scattering identification according to claim 9, characterized in that in the data processing unit, the estimation of primary ray intensity can be expressed as the following formula:

In the formula, P est is the estimated primary ray intensity, A′ is the proportion of primary rays absorbed in the base detector, and B′ is the proportion of scattered rays absorbed in the base detector.