KR20210099907A - Cone Beam Computed Tomography Apparatus and Method for Correcting Scatter Using Wheel-Shaped Blocker - Google Patents

Abstract

According to the present invention, disclosed are a cone beam computed tomography apparatus correcting scattering using a wheel blocker and a method thereof, which can accurately identify deformation and movement of an affected area during treatment by improving quality of medical images scattered due to the scattered beam. To this end, the cone beam computed tomography apparatus comprises: a radiation module that is connected to the gantry and irradiates a radiation treatment beam to a subject; an image beam module irradiating an image beam on a path of the radiation treatment beam irradiated from the radiation module; and a beam blocking module positioned in a path between the imaging beam module and the subject to continuously block or non-block at least a portion of the image beam irradiated from the image beam module.

Description

Cone Beam Computed Tomography Apparatus and Method for Correcting Scatter Using Wheel-Shaped Blocker

The present invention relates to a cone-beam-type computed tomography apparatus, and more particularly, to a cone-beam-type computed tomography apparatus and method for correcting scattering using a beam blocker.

Currently, the technological development of radiotherapy is developing into a high-level treatment such as stereotactic body radiation therapy (SBRT). SBRT can dramatically shorten the treatment period by irradiating high-dose radiation by dividing the number of treatments into 1 to 3–4 times, whereas the treatment time for patients lying on the treatment table is increasing due to the large number of beam irradiation times per session. In addition, precise monitoring and evaluation of the patient's posture and changes during radiation therapy is a very important task that determines the success or failure of radiation therapy.

In advanced radiation therapy that requires higher accuracy in positioning the patient, the process of monitoring in real time whether the accurately planned dose is delivered to the patient during treatment is very important, but the current CBCT (Cone Beam CT) It is used to set the same position as when establishing a treatment plan for treatment or as a confirmation imaging device to quantify whether there is a change in patient posture between before and after treatment, but does not provide anatomical information during beam delivery.

With the addition of an option called intrafraction imaging, it is possible to acquire CBCT X-ray images at the same time as volumetric modulated arc therapy (VMAT) through a flat-panel detector. Therefore, it is possible to monitor the deformation and movement of the affected area.

If CBCT X-ray images are acquired at the same time as VMAT, CBCT volume images can be generated during intrafraction, but MV X-rays and kV X-rays interact with particles inside the object to generate a scattering beam. As a result, the overall image quality deteriorates, and its clinical use is very limited. In particular, CBCT with a detector with a large irradiation area has a fundamental problem in acquiring accurate images because the effect of the scattered beam increases exponentially compared to general CT.

The present invention is a cone-beam-type computed tomography apparatus and method for correcting scattering using a wheel breaker. A radiation module connected to a gantry and irradiating a radiation therapy beam to a subject, on the path of the radiation therapy beam irradiated from the radiation module A scattered beam comprising: an imaging beam module irradiating an image beam; and a beam blocking module positioned in a path between the imaging beam module and the object to continuously block or non-block at least a portion of the image beam irradiated from the imaging beam module; The purpose of this study is to improve the quality of the medical image caused by this and to accurately identify the deformation and movement status of the affected area during treatment.

In addition, adaptive radiotherapy using CBCT images during segmentation treatment is possible by creating a model for the movement of the target during radiotherapy and recalculating the dose distribution for the target and adjacent risk organs using CBCT during segmentation treatment. There is another purpose of making it clinically applicable.

Other objects not specified in the present invention may be additionally considered within the scope that can be easily inferred from the following detailed description and effects thereof.

In order to solve the above problems, a cone beam type computed tomography apparatus for correcting scattering using a wheel breaker according to an embodiment of the present invention is a gantry that is formed to be rotatable in one direction, is connected to the gantry, and gives radiation to a subject A radiation module for irradiating a treatment beam, an imaging beam module for irradiating an image beam on a path of the radiation treatment beam irradiated from the radiation module, and a path between the image beam module and the object to be irradiated from the image beam module and a beam blocking module that continuously blocks or does not block at least a portion of the image beam.

Here, an image acquisition unit for acquiring a plurality of projection data by detecting the radiation treatment beam that has passed through the target object using a detector and a scattered beam scattered by the image beam, and scattering of the plurality of projection data It further includes an image processing unit to generate a reconstructed image by estimating the beam map.

Here, the beam blocking module is rotatable, and is formed in a partially shielded and partially open structure, wherein the partially shielded portion includes a plurality of structures formed in the shape of a circular arc around the axis of rotation, The image processing unit may estimate the scattered beam map by the structures formed in the shape.

Here, the beam blocking module includes a driving wheel rotatable in one direction and having an open inner side, a step motor for rotating the driving wheel, and a shielding portion provided to cover at least a portion of the inner side of the driving wheel.

Here, the shielding part has a structure in which a plurality of arc-shaped strips are disposed to coincide with the rotational direction of the driving wheel.

Here, the image acquisition unit continuously acquires first projection data when the image beam is blocked and second projection data when the image beam is not blocked by rotation of the shielding unit.

Here, the image processing unit estimates a scattered beam map by applying an interpolation method in a direction orthogonal to the arc strip shape in projection data when the image beam is blocked by the shielding unit.

Here, the image processing unit estimates a scattering map for the entire first projection data, reconstructs a 3D scattering volume using backprojection, and re-projects the 3D scattering volume ( Reprojection) to estimate and generate a scattering map for the entire second projection data.

Here, the image processing unit may be configured to use a weighted sum based on distances from two first projection data from scattering maps for two pieces of first projection data adjacent to the successively acquired second projection data to obtain the second projection data. Estimate and generate scatter maps for

Here, the image processing unit generates scatter corrected data by subtracting a scatter map for the second projection data estimated from the second projection data, and uses a reconstruction algorithm to generate scatter corrected data from the scattering correction data. Create a reconstructed image.

The cone-beam-type computed tomography method by the cone-beam-type computed tomography apparatus according to an embodiment of the present invention comprises the steps of: irradiating a radiation treatment beam to a subject using a radiation module; irradiating an image beam on a path of the beam, and continuously blocking or non-blocking at least a portion of the image beam irradiated from the image beam module with a beam blocking module located in a path between the imaging beam module and the subject , obtaining a plurality of projection data by detecting the radiation treatment beam that has passed through the subject and a scattered beam scattered by the image beam, and a reconstructed image by estimating a scattered beam map for the plurality of projection data It includes the step of creating

Here, the beam blocking module includes a driving wheel rotatable in one direction and having an open inner side, a step motor for rotating the driving wheel, and a shield provided to cover at least a portion of the inner side of the driving wheel, The shielding portion has a structure in which a plurality of arc-shaped strips are disposed to coincide with the rotational direction of the driving wheel.

Here, the acquiring of the plurality of projection data may include, by rotation of the shielding part, first projection data when the image beam is blocked and second projection data when the image beam is not blocked. obtained successively.

Here, the step of generating a reconstructed image by estimating a scattered beam map for the plurality of projection data is orthogonal to the arc-shaped strip shape in the projection data when the image beam is blocked by the shielding unit. The scattered beam map is estimated by applying interpolation to the direction.

Here, the step of generating a reconstructed image by estimating a scattering beam map for the plurality of projection data includes estimating a scattering map for the entire first projection data and using a backprojection to generate a 3D scattering volume ( 3D Scatter Volume) and reprojecting the 3D scattering volume to estimate and generate a scattering map for the entire second projection data.

Here, the generating a reconstructed image by estimating a scattering beam map for the plurality of projection data includes subtracting a scattering map for the second projection data estimated from the second projection data to obtain scatter corrected data (Scatter Corrected Data). ) and generating the reconstructed image from the scattering correction data using a reconstruction algorithm.

As described above, according to the embodiments of the present invention, a radiation module connected to a gantry and irradiating a radiation treatment beam to an object, an imaging beam irradiating an image beam on a path of the radiation treatment beam irradiated from the radiation module and a beam blocking module positioned in a path between the module and the imaging beam module and the subject to continuously block or non-block at least a portion of the imaging beam irradiated from the imaging beam module, thereby improving the quality of a medical image due to the scattered beam. By improving it, it is possible to accurately identify the deformation and movement status of the affected area during treatment.

In addition, adaptive radiotherapy using CBCT images during segmentation treatment is possible by creating a model for the movement of the target during radiotherapy and recalculating the dose distribution for the target and adjacent risk organs using CBCT during segmentation treatment. It can be made clinically applicable.

Even if it is an effect not explicitly mentioned herein, the effects described in the following specification expected by the technical features of the present invention and their potential effects are treated as if they were described in the specification of the present invention.

FIG. 1 is a diagram for explaining the effect of scattered beams of MV X-rays and kV X-rays.
2 and 3 are views showing a cone beam type computed tomography apparatus according to an embodiment of the present invention.
4 and 5 are diagrams illustrating a beam blocking module of a cone beam type computed tomography apparatus according to various embodiments of the present disclosure.
6 is a diagram illustrating image acquisition using a cone-beam-type computed tomography apparatus according to an embodiment of the present invention.
7 is a view for explaining a method of calculating a scattered beam distribution map of the cone beam type computed tomography apparatus according to an embodiment of the present invention.
8 is a view for explaining a method of estimating a scattered beam distribution map from a blocked X-ray image of the cone beam type computed tomography apparatus according to an embodiment of the present invention.
9 is a view for explaining a method of estimating a scattered beam distribution map from a non-blocking X-ray image of the cone beam type computed tomography apparatus according to an embodiment of the present invention.
10 is a flowchart illustrating a cone-beam-type computed tomography method according to an embodiment of the present invention.

Hereinafter, a cone-beam-type computed tomography apparatus and method for correcting scattering using a wheel breaker according to the present invention will be described in more detail with reference to the drawings. However, the present invention may be embodied in various different forms, and is not limited to the described embodiments. In addition, in order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals in the drawings indicate the same members.

The suffixes "module" and "part" for the components used in the following description are given or mixed in consideration of only the ease of writing the specification, and do not have a meaning or role distinct from each other by themselves.

The present invention relates to a cone-beam-type computed tomography apparatus and method for correcting scattering using a wheel breaker.

FIG. 1 is a diagram for explaining the effect of scattered beams of MV X-rays and kV X-rays.

As shown in Fig. 1, when CBCT X-ray images are acquired simultaneously with VMAT, CBCT volume images can be generated during intrafraction, but MV X-rays and kV X-rays interact with particles inside the object. It causes overall image quality deterioration due to the influence of the generated scattered beam, so its clinical use is very limited. In particular, CBCT with a detector with a large irradiation area has a fundamental problem in acquiring accurate images because the effect of the scattered beam increases exponentially compared to general CT.

The cone-beam-type computed tomography apparatus according to an embodiment of the present invention is a wheel-based blocker-based high-definition on- treatment Cone-Beam CT (CBCT) imaging system. Quality of on-treatment CBCT image due to megavolt (MV)-kilovolt (kV) scattered beam generated when radiation treatment beam and CBCT image beam are transmitted simultaneously This is to maximize the patient's treatment effect by improving the deterioration so that the deformation and movement of the affected part can be accurately identified during treatment.

2 and 3 are views illustrating a cone beam type computed tomography apparatus according to an embodiment of the present invention.

2 is a block diagram illustrating a cone-beam-type computed tomography apparatus according to an embodiment of the present invention, and FIG. 3 illustrates a cone-beam-type computed tomography apparatus according to an embodiment of the present invention.

2 and 3 , the cone beam type computed tomography apparatus 10 according to an embodiment of the present invention includes a gantry 100 , a radiation module 200 , an image beam module 300 , and a beam blocking module 400 . ), an image acquisition unit 500 , and an image processing unit 600 .

The cone-beam-type computed tomography apparatus 10 according to an embodiment of the present invention is an apparatus for reconstructing a plurality of tomographic images at once from a two-dimensional perspective image obtained by irradiating cone-shaped X-rays.

A plurality of horizontal tomographic images can be calculated only by measuring the projection image in one rotation, so that the three-dimensional structure of the subject can be restored at high speed.

The gantry 100 is formed to be rotatable in one direction.

The radiation module 200 is connected to the gantry and irradiates a radiation treatment beam to the subject.

The imaging beam module 300 irradiates the imaging beam on the path of the radiation treatment beam irradiated from the radiation module.

The beam blocking module 400 is positioned in a path between the imaging beam module and the object to continuously block or non-block at least a portion of the imaging beam irradiated from the imaging beam module.

The beam blocking module 400 uses lead or solid tungsten, which is easy to process for shielding primary and scattered X-rays for kV and scattered X-rays for MV, in an arc-shaped strip shape to match the wheel rotation direction. It is preferably a circuit breaker of a constructed wheel model.

Specifically, the beam blocking module is rotatable, partially shielded and formed in a partially open structure, wherein the partially shielded portion includes a plurality of structures in the shape of an arc around the rotation axis, including a plurality of structures of the arc. The image processing unit may estimate the scattered beam map by the structures formed in the shape.

The image acquisition unit 500 acquires a plurality of projection data by detecting a radiation treatment beam that has passed through the target object and a scattered beam scattered by the image beam using a detector.

Specifically, by rotation of the shielding unit of the beam blocking module 400 , first projection data when the image beam is blocked and second projection data when the image beam is not blocked are successively acquired.

The image processing unit 600 generates a reconstructed image by estimating a scattered beam map for the plurality of projection data.

Specifically, the image processing unit 600 estimates a scattered beam map by applying an interpolation method in a direction orthogonal to the arc strip shape in projection data when the image beam is blocked by the shielding unit.

As shown in FIG. 3 , the cone beam-type computed tomography apparatus 10 according to an embodiment of the present invention includes a gantry 100 , a main body 110 , a rotating shaft 120 , a radiation irradiation module 210 , and a table. (300) is further included.

Various gantry 100 may be used as the gantry 100 according to required conditions and design specifications, and the present invention is not limited or limited by the type and characteristics of the gantry 100 . As an example, the gantry 100 may be connected to the main body 110 by a rotation shaft 120 and configured to rotate. In some cases, a conventional ring gantry, a partial ring gantry, a C-shaped gantry, etc. may be used as the gantry, or alternatively, instead of the gantry, any other frame capable of positioning the radiation module in various rotational and/or axial positions relative to the patient. Work may also be used.

A radiation module 210 may be provided inside the gantry 100 , and the radiation module 210 may include a radiation source operable to generate a radiation beam and a linear accelerator.

A table 130 may be provided at a lower portion of the gantry 100, and the table 130 may be provided to enable horizontal and vertical position adjustment as a place for the patient to be treated to lie down.

As shown in FIG. 3 , in the cone beam type computed tomography apparatus 10 according to an embodiment of the present invention, when the radiation treatment beam L1 is irradiated to the subject from the radiation irradiation module 210 of the radiation module, the path The image beam module 300 irradiates the image beam L2.

The beam blocking module 400 is positioned in a path between the imaging beam module and the object to block at least a portion of the image beam irradiated from the imaging beam module, and an arc-shaped strip to match the wheel rotation direction. As a circuit breaker in the shape of a wheel, the shield rotates during rotation, and a part rotates and a part opens continuously.

Accordingly, the detector 510 of the image acquisition unit 500 is positioned in parallel with the image beam irradiation direction to detect the radiation treatment beam passing through the subject and the scattered beam scattered by the image beam to perform a plurality of projections. data will be acquired.

4 and 5 are diagrams illustrating a beam blocking module of a cone-beam-type computed tomography apparatus according to various embodiments of the present invention.

4 and 5 , the beam blocking module 400 of the cone beam type computed tomography apparatus 10 according to an embodiment of the present invention includes a driving wheel 410 , a shielding unit 420 , and a stepper motor 440 . ) is included.

The beam blocking module 400 is positioned in a path between the imaging beam module and the object to block at least a portion of the imaging beam irradiated from the imaging beam module.

The beam blocking module 400 uses lead or solid tungsten, which is easy to process for shielding primary and scattered X-rays for kV and scattered X-rays for MV, in an arc-shaped strip shape to match the wheel rotation direction. It is preferably a circuit breaker of a constructed wheel model.

The driving wheel 410 is rotatable in one direction and has an open inner side. The step motor 440 rotates the driving wheel. The shielding part 420 is provided to cover at least a part of the inner side of the driving wheel.

As shown in FIG. 4 , the shielding part 420 has a structure in which a plurality of arc-shaped strips 421 are disposed to coincide with the rotational direction of the driving wheel. The arrangement structure of the strip portion and the open portion 423 is not limited thereto, and combinations of various widths and arrangements are possible. For example, a shape of a strip that draws an arc around a rotation axis is also possible, a shape in which a part of the strip is cut is possible, and a shape in which a part of the strip is cut off is deviated and arranged in the form of a checkerboard.

As the shape of the strip is designed to draw an arc around the axis of rotation, it is possible to estimate the scattered beam map from the projection data obtained by blocking or non-blocking of the image beam. Images can be acquired without performing.

That is, by rotating the shielding unit 420 , the first projection data when the image beam is blocked and the second projection data when the image beam is not blocked may be continuously acquired.

In addition, it may further include an immobilization device so that the wheel breaker can be fixed well in front of the X-ray tube.

As shown in FIG. 5 , a shielding wall 450 may be further included to distinguish the boundary of the shielding part, and the shielding wall is preferably located in the boundary region with lead. In addition, it is preferable that the thickness T1 of the driving wheel is 1 to 4 mm, and when it is less than 1 mm, the blocking effect is reduced, and when it is more than 4 mm, it is difficult to rotate.

The shielding portion is preferably formed at an angle of 90 to 180 degrees, and can be changed by those skilled in the art according to the purpose of correcting the image of the scattered beam.

In addition, according to various embodiments of the present invention, another shield including copper for average energy modulation is placed on one side of the strip-shaped shield, so that the driving wheel is filled with the strip-shaped shield, copper. It may be provided in a structure capable of obtaining dual energy CBCT, including a shielding part and a space part.

The cone-beam-type computed tomography apparatus according to various embodiments of the present invention rotates a wheel breaker at a constant speed in one direction using a stepping motor at the same time as the gantry is rotated to produce a blocked X-ray image and a non-blocking X-ray image. - Acquire line images continuously. In the conventional method, it is important to synchronize the time for maintaining the blocked state when the radiation beam is on, and synchronize the time and delay time for changing the state when the radiation beam is off, whereas according to an embodiment of the present invention Since the wheel rotates in one direction without changing the direction, there is no backlash problem when changing the direction of rotation, so the burden on gantry rotation and synchronization is less. It is a structure that is easy to automatically classify non-blocking images and blocking images after acquiring a projection image because it passes through .

6 is a diagram illustrating image acquisition using a cone-beam-type computed tomography apparatus according to an embodiment of the present invention.

The image beam (X-ray) light source irradiates X-rays while rotating, and the beam blocking module blocks a portion of the X-rays in the path between the light source and the subject. The first projection data acquired by the image acquisition unit includes a shaded region and an unshaded region. The shaded area has a strip pattern in the form of an arc. The second projection data obtained by the panel detector includes an unshaded area.

In the blocked state, a 'blocked X-ray image' is acquired, including the scattered beam (shaded area) due to the influence of the blocker and the image beam without the influence of the blocker (the primary beam and the scattered beam are accumulated). In the non-blocking state, there is no effect of the breaker, so a 'non-blocking X-ray image' containing only the image beam is acquired.

The image acquisition unit 500 acquires a plurality of projection data by detecting a radiation treatment beam that has passed through the target object and a scattered beam scattered by the image beam using a detector.

Specifically, by rotation of the shielding unit of the beam blocking module 400 , first projection data when the image beam is blocked and second projection data when the image beam is not blocked are successively acquired.

7 is a view for explaining a method of calculating a scattered beam distribution map of the cone beam type computed tomography apparatus according to an embodiment of the present invention.

The scattered beam map is estimated by applying 1-D cubic B-Spline interpolation in the direction orthogonal to the arc-shaped strip shape using the information detected in the blocked area in the arc-shaped strip-shaped blocked X-ray images.

The image processing unit 600 generates a reconstructed image by estimating a scattered beam map for the plurality of projection data.

Specifically, the image processing unit 600 estimates a scattered beam map by applying an interpolation method in a direction orthogonal to the arc strip shape in projection data when the image beam is blocked by the shielding unit.

8 is a view for explaining a method of estimating a scattered beam distribution map from a blocked X-ray image of the cone beam type computed tomography apparatus according to an embodiment of the present invention.

A scattered beam volume is generated by applying a backprojection technique to the scattered beam map calculated from the blocked X-ray image. A corresponding scattered beam distribution map is estimated using geometric information obtained by applying a projection technique to a non-blocking X-ray image.

The image processing unit 600 estimates a scattering map for the entire first projection data, reconstructs a 3D scattering volume using backprojection, and reprojects the 3D scattering volume. ) to estimate and generate a scattering map for the entire second projection data.

Back projection is a method of continuously summing the values of the projected images obtained in each direction by returning them backwards. After the summation is complete, the basic value with the lowest value among all pixel values is subtracted from each pixel value, and then divided again by the least common multiple of the pixels to reconstruct the original pixel value.

Thereafter, scattering corrected data is generated by subtracting a scattering map for the second projection data estimated from the second projection data, and the reconstructed image is generated from the scattering correction data using a reconstruction algorithm. .

9 is a view for explaining a method of estimating a scattered beam distribution map from a non-blocking X-ray image of the cone beam type computed tomography apparatus according to an embodiment of the present invention.

By subtracting the scattered beam map estimated from the non-blocking X-ray images from the image component, a scattered beam-removed non-blocking X-ray image is finally obtained.

The image processing unit 600 uses a weighted sum based on a distance from two first projection data from scattering maps for two first projection data adjacent to the second projection data that is continuously acquired to the second projection data. Estimate and generate scatter maps for

A CBCT image is generated during scatter-corrected segmentation therapy by applying a compression sensing-based iterative reconstruction algorithm with non-blocking X-ray images.

By continuously acquiring the second projection data, the first projection data and the second projection data may be acquired at a ratio of 1 to N (where N is a natural number), and the image processing unit may obtain two adjacent N pieces of second projection data. From the scattering maps for the first projection data, the scattering maps for the N pieces of second projection data may be estimated by using a weighted sum based on distances from the two pieces of first projection data.

10 is a flowchart illustrating a cone-beam-type computed tomography method according to an embodiment of the present invention.

Referring to FIG. 10 , the cone-beam-type computed tomography method by the cone-beam-type computed tomography apparatus starts in the step ( S100 ) of irradiating a radiation treatment beam to the subject with a radiation module.

In step S200, the imaging beam module irradiates the imaging beam on the path of the radiation therapy beam irradiated from the radiation module.

In step S300, at least a portion of the image beam irradiated from the image beam module is blocked by a beam blocking module located in a path between the image beam module and the subject.

Here, the beam blocking module, a driving wheel rotatable in one direction, the inner side of which is open; a step motor for rotating the driving wheel and a shielding part provided to cover at least a part of the inside of the driving wheel, wherein the shielding part has a structure in which a plurality of arc-shaped strips are disposed to coincide with the rotational direction of the driving wheel am.

In step S400, a plurality of projection data is obtained by detecting the radiation treatment beam that has passed through the target object and the scattered beam scattered by the image beam.

In the step of acquiring a plurality of projection data (S400), the first projection data when the image beam is blocked and the second projection data when the image beam is not blocked by the rotation of the shielding part obtained successively.

In step S500, a reconstructed image is generated by estimating a scattered beam map for the plurality of projection data.

The step (S500) of generating a reconstructed image by estimating a scattered beam map for a plurality of projection data is orthogonal to the arc strip shape in the projection data when the image beam is blocked by the shielding unit. Estimate a scattering beam map by applying interpolation in the direction, estimating a scattering map for the entire first projection data, reconstructing a 3D scattering volume using backprojection, and the 3D The scattering volume is reprojected to estimate and generate a scattering map for the whole of the second projection data.

Thereafter, scattering corrected data is generated by subtracting a scattering map for the second projection data estimated from the second projection data, and the reconstructed image is generated from the scattering correction data using a reconstruction algorithm. .

The cone-beam computed tomography apparatus and method for correcting scattering using a wheel breaker according to an embodiment of the present invention can reduce the target adjacent margin during treatment planning by utilizing a CBCT image during high-definition segmentation treatment during VMAT treatment, Targeting accuracy is improved and the dose to at-risk organs adjacent to the tumor is reduced.

In addition, it is possible to create a model for the movement of the target during radiation therapy, and after each radiation therapy, CBCT during split therapy can be used to recalculate the dose distribution for the target and adjacent at-risk organs. Therefore, adaptive radiotherapy using CBCT images can be applied clinically during segmentation therapy and can be a new clinical guideline. As a result, the incidence of complications related to radiation therapy is lowered and the survival rate can be improved.

In the past, after only taking CBCT before and after treatment, the cone-beam-type computed tomography apparatus and method for correcting scattering using a wheel blocker according to an embodiment of the present invention, if the radiation was irradiated by estimating the location based on this during treatment. It is possible to perform CBCT for confirmation in real time while irradiating the radiation therapy beam during each treatment. It does not take more treatment time, but the accuracy of treatment can be further improved.

Since the manufactured wheel breaker does not need to stop in the middle of rotation, change direction, or change rotation speed while rotating, no backlash problem occurs, so it is easy to control. Compared to the linear type circuit breaker, it is possible to secure higher stability by reducing the problems caused by CBCT X-ray image acquisition synchronization during breaker movement and gantry rotation.

The above description is only one embodiment of the present invention, and those of ordinary skill in the art to which the present invention pertains will be able to implement it in a modified form without departing from the essential characteristics of the present invention. Therefore, the scope of the present invention is not limited to the above-described embodiments, and should be construed to include various embodiments within the scope equivalent to the content described in the claims.

10: cone beam type computed tomography apparatus
100: gantry
200: radiation module
300: image beam module
400: beam blocking module
500: image acquisition unit
600: image processing unit

Claims (15)

A gantry formed to be rotatable in one direction;
a radiation module connected to the gantry and irradiating a radiation treatment beam to the subject;
an imaging beam module irradiating an image beam onto a path of the radiation treatment beam irradiated from the radiation module; and
and a beam blocking module positioned in a path between the imaging beam module and the subject to continuously block or non-block at least a portion of the image beam irradiated from the imaging beam module; . According to claim 1,
an image acquisition unit for acquiring a plurality of projection data by detecting a radiation treatment beam that has passed through the target object using a detector and a scattered beam scattered by the image beam; and
and an image processor configured to generate a reconstructed image by estimating a scattered beam map of the plurality of projection data. 3. The method of claim 2,
The beam blocking module is rotatable, and is formed in a partially shielded and partially open structure. The cone beam type computed tomography apparatus, characterized in that the image processing unit can estimate the scattered beam map by the structures formed. 3. The method of claim 2,
The beam blocking module,
a driving wheel rotatable in one direction and having an open inner side;
a step motor for rotating the driving wheel; and
and a shield provided to cover at least a portion of the inner side of the driving wheel;
The shielding unit, cone beam type computed tomography apparatus, characterized in that the structure in which a plurality of arc-shaped strips are arranged to coincide with the rotational direction of the driving wheel. 5. The method of claim 4,
The image acquisition unit,
The cone beam type computed tomography apparatus according to claim 1, wherein the first projection data when the image beam is blocked and the second projection data when the image beam is not blocked are successively acquired by rotation of the shielding part. 5. The method of claim 4,
The image processing unit,
A cone beam type computed tomography apparatus, characterized in that the scattered beam map is estimated by applying an interpolation method in a direction orthogonal to the arc strip shape in projection data when the image beam is blocked by the shielding unit. 6. The method of claim 5,
The image processing unit,
Estimating a scattering map for the entire first projection data, reconstructing a 3D scattering volume using backprojection, and reprojecting the 3D scattering volume to perform second projection data A cone-beam-type computed tomography apparatus, characterized in that it is generated by estimating a scattering map for the whole. 6. The method of claim 5,
The image processing unit,
By estimating the scattering maps for the second projection data using a weighted sum based on the distances from the two first projection data from the scattering maps for the two first projection data adjacent to the second projection data obtained continuously A cone-beam-type computed tomography apparatus, characterized in that it generates. 8. The method of claim 7,
The image processing unit,
generating scatter corrected data by subtracting a scattering map for the second projection data estimated from the second projection data, and generating the reconstructed image from the scattering correction data using a restoration algorithm A cone-beam computed tomography apparatus. A cone-beam computed tomography method using a cone-beam computed tomography apparatus, the method comprising:
irradiating a radiation therapy beam to the subject with a radiation module;
irradiating an image beam onto a path of a radiation treatment beam irradiated from the radiation module to an image beam module;
continuously blocking or non-blocking at least a portion of the image beam irradiated from the imaging beam module with a beam blocking module located in a path between the imaging beam module and the subject;
acquiring a plurality of projection data by detecting a radiation treatment beam that has passed through the subject and a scattered beam scattered by the image beam; and
and generating a reconstructed image by estimating a scattered beam map for the plurality of projection data. 11. The method of claim 10,
The beam blocking module,
a driving wheel rotatable in one direction and having an open inner side; a step motor for rotating the driving wheel; and a shield provided to cover at least a part of the inner side of the driving wheel.
The shielding portion, cone beam type computed tomography method, characterized in that the structure in which a plurality of arc-shaped strips are arranged to coincide with the rotational direction of the driving wheel. 12. The method of claim 11,
The step of acquiring the plurality of projection data,
The cone-beam computed tomography method according to claim 1, wherein the first projection data when the image beam is blocked and the second projection data when the image beam is not blocked are successively obtained by rotation of the shielding unit. 12. The method of claim 11,
The step of generating a reconstructed image by estimating a scattered beam map for the plurality of projection data,
A cone beam type computed tomography method, characterized in that the scattering beam map is estimated by applying an interpolation method in a direction orthogonal to the arc strip shape from projection data when the image beam is blocked by the shielding unit. 13. The method of claim 12,
The step of generating a reconstructed image by estimating a scattered beam map for the plurality of projection data,
estimating a scattering map for the entire first projection data, and reconstructing a 3D scattering volume using backprojection; and
and generating and estimating a scattering map for the entire second projection data by reprojecting the 3D scattering volume. 15. The method of claim 14,
The step of generating a reconstructed image by estimating a scattered beam map for the plurality of projection data,
generating scatter corrected data by subtracting a scattering map for the second projection data estimated from the second projection data, and generating the reconstructed image from the scattering correction data using a reconstruction algorithm; Cone beam computed tomography method further comprising a.

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