JP7512094B2 - CT imaging system for radiation therapy and CT imaging method for radiation therapy - Google Patents

Description

Embodiments of the present invention relate to a CT imaging system for radiation therapy and a CT imaging method for radiation therapy.

Radiation therapy is a treatment method in which radiation is applied to the patient's affected area to damage the cells in the lesion, but if the radiation is not applied accurately to the affected area, normal tissue may also be damaged. For this reason, CT (computed tomography) scans are performed in advance to determine the location of the patient's affected area in three dimensions, and a treatment plan is made to most effectively apply radiation to the affected area while avoiding normal tissue. In this type of radiation therapy, the patient's position at the time of treatment planning must be aligned with the patient's position immediately before treatment so that radiation can be applied according to the treatment plan.

Therefore, when planning treatment, the 3D reconstructed image output from the CT imaging device is sliced to obtain a CT image, and this CT image is compared with an X-ray image taken in the treatment room immediately before treatment from an X-ray imaging device, to align the patient's affected area. However, the X-ray imaging device in the treatment room only obtains a 2D image of the patient in the body axis direction, making it difficult to perform a highly accurate comparison with the 3D reconstructed image output from the CT imaging device during treatment planning.

と書き表せる。 X-rays used in CT imaging can be fan beams that spread in a fan shape or cone beams that spread in a cone shape. In a rotating gantry for radiation therapy, CT imaging using cone beam X-rays is used. In CT imaging using cone beam X-rays, the coordinate conversion from the patient's tomographic coordinates V(x, y, z) to the X-ray detector coordinates _Vp ( _xp , _yp , _zp ) is performed as shown in Figure 8.
E x P x T x R x V = V _P
This is done by calculating a series of determinants, where each matrix is

This can be written as:

The rotation matrix R rotates the volume (patient) coordinate system counterclockwise around the y-axis by an angle φ. The translation matrix T translates the volume (patient) coordinate system by a distance d in the negative direction along the x-ray irradiation direction (z-axis). These two matrices R and T map the coordinate system from the volume (patient) coordinate system to the x-ray source coordinate system. The perspective projection matrix P, determined by the x-ray source position D and the x-ray detector sizes w and h, defines the frustum of the cone beam projection. The parameters n and f of this matrix P represent the distances from the x-ray source to the near and far clipping planes of the frustum, respectively. The coordinate transformation matrix E forms the x-ray detector coordinates V _P with the patient slice coordinates V.

Based on the calculations using the above determinant, an X-ray imaging device installed in a rotating gantry acquires image data by capturing X-ray transmission images while rotating around the patient, and generates a 3D reconstructed image. However, the rotation speed of the rotating gantry is about 1 to 2 minutes per revolution, which is too long compared to the patient's respiratory cycle of about 3 to 4 seconds. As a result, the imaging range moves due to the patient's breathing while the rotating gantry makes one rotation to capture images, and the above X-ray imaging device cannot obtain a 3D reconstructed image with high positional accuracy. Therefore, this 3D reconstructed image cannot be matched with CT images or aligned three-dimensionally when planning treatment.

JP 2015-29793 A JP 2010-505562 A

Patent Document 1 describes how the three-dimensional position of a target within a patient captured in an X-ray image taken during CT scan is recognized, and an image that satisfies the therapeutic radiation irradiation conditions of motion tracking therapy is selected to perform image reconstruction and generate a CT image. This makes it possible to irradiate the target with radiation according to the treatment plan, even if the patient is moving, such as breathing. However, the technology described in Patent Document 1 selects only images that satisfy the therapeutic radiation irradiation conditions, so it is not possible to accurately grasp the positional displacement of the affected area. For example, when the positional relationship between the skeleton and organs at the time of treatment planning differs from that at the time of treatment, it is difficult to distinguish whether this is due to a difference in the condition on that day or respiratory movement.

The embodiments of the present invention have been made in consideration of the above circumstances, and aim to provide a CT imaging system and a CT imaging method for radiotherapy that can accurately grasp the positions of affected areas and organs, which change in accordance with the patient's respiratory movements.

A radiotherapy CT imaging system according to an embodiment of the present invention includes a treatment table on which a patient is placed, a rotating gantry on which a radiation irradiation unit is installed, the radiation irradiation unit surrounding the treatment table and rotating around the treatment table and irradiating radiation to the patient on the treatment table, an X-ray generation unit attached to the rotating gantry and irradiating X-rays when the rotating gantry rotates, an X-ray imaging unit attached to the rotating gantry and imaging transmitted X-rays that have passed through the patient on the treatment table when the rotating gantry rotates, and outputting image data, a respiratory monitoring device that monitors the respiratory movement of the patient on the treatment table, and a control and computing device that controls the generation of X-rays by the X-ray generation unit and the acquisition of the image data from the X-ray imaging unit, and creates a three-dimensional reconstructed image using the image data from the X-ray imaging unit. and a control calculation device configured to divide an amplitude of a respiratory waveform of the respiratory movement of the patient monitored by the respiratory monitoring device into a plurality of amplitude ranges, classify the image data captured by the X-ray imaging unit for each of these amplitude ranges during the rotation of the rotating gantry together with the rotation angle value of the rotating gantry at the time of capturing the image data, reconstruct the plurality of image data and the rotation angle value of the rotating gantry classified into the same amplitude range to create the three-dimensional reconstructed image, and when there is a bias in the number of pieces of the image data classified for each amplitude range during one rotation of the rotating gantry, determine that the image data is inappropriate for creating the three-dimensional reconstructed image, and discard the image data acquired during one rotation .

A radiotherapy CT imaging method according to an embodiment of the present invention provides a radiotherapy CT imaging system including a treatment couch on which a patient is placed, a rotating gantry surrounding the treatment couch and rotating around the treatment couch and including a radiation irradiation unit for irradiating radiation to the patient on the treatment couch, an X-ray generation unit attached to the rotating gantry and irradiating X-rays as the rotating gantry rotates, an X-ray imaging unit attached to the rotating gantry and imaging transmitted X-rays that have passed through the patient on the treatment couch as the rotating gantry rotates and outputting image data, a respiratory monitoring device for monitoring the respiratory movement of the patient on the treatment couch, and a control and computing device for controlling the generation of X-rays by the X-ray generation unit and the acquisition of the image data from the X-ray imaging unit, and for creating a three-dimensional reconstructed image using the image data from the X-ray imaging unit. The control and computing device sequentially performs the steps of: dividing the amplitude of the respiratory waveform of the respiratory movement of the patient monitored by the respiratory monitoring device into a plurality of amplitude ranges; classifying the image data captured by the X-ray imaging unit for each of these amplitude ranges during the rotation of the rotating gantry, together with the rotation angle value of the rotating gantry at the time of capturing the image data; and reconstructing the plurality of image data and the rotation angle value of the rotating gantry classified into the same amplitude range to create the three-dimensional reconstructed image, and the control and computing device is further characterized in that, when there is a bias in the number of pieces of the image data classified for each amplitude range during one rotation of the rotating gantry, the control and computing device determines that the image data is inappropriate for creating the three-dimensional reconstructed image, and discards the image data acquired during one rotation .

According to an embodiment of the present invention, it is possible to accurately grasp the position of the affected area, organs, etc., which changes with the patient's respiratory movement.

FIG. 2 is a front view showing a rotating gantry, an X-ray generation unit, an X-ray imaging unit, a treatment table, and the like of the radiation therapeutic CT imaging system according to the first embodiment. FIG. 2 is a front view showing the rotating gantry and the like shown in FIG. FIG. 2 is a diagram showing the configuration of an apparatus including a control and calculation device for operating the radiotherapy CT imaging system shown in FIG. 1 . FIG. 4 is a block diagram illustrating the function of the control calculation device of FIG. 3 . 1 is a schematic diagram illustrating how the period of a respiratory waveform of a patient's respiratory movement is divided into a plurality of phase ranges and the acquired image data is classified. FIG. 11 is a block diagram for explaining functions of a control and calculation device of a CT imaging system for radiation therapy according to a second embodiment. 13 is a schematic diagram illustrating how the amplitude of the respiratory waveform of the patient's respiratory movement is divided into a plurality of amplitude ranges and the acquired image data is classified. FIG. 1 is a perspective view showing the concept of coordinate conversion from a patient's slice coordinates to an X-ray detector coordinates.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[A] First embodiment (FIGS. 1 to 5)
Fig. 1 is a front view showing a rotating gantry, an X-ray generating unit, an X-ray imaging unit, a treatment table, etc. of a CT imaging system for radiotherapy according to the first embodiment. Fig. 3 is a configuration diagram of an apparatus including a control and computing device for operating the CT imaging system for radiotherapy shown in Fig. 1. The CT imaging system for radiotherapy 10 shown in Figs. 1 and 3 is for imaging the affected area and organs of the patient 1 with X-rays when irradiating the affected area of the patient 1 with radiation, and for creating a three-dimensional reconstructed image using the image data obtained. The CT imaging system for radiotherapy 10 includes a treatment table 11, a rotating gantry 12, an X-ray generating unit 13, an X-ray imaging unit 14, a respiration monitor 15, and a control and computing device 16.

The treatment table 11 is for the patient 1 to lie on. The rotating gantry 12 surrounds the treatment table 11 and rotates around it, with a radiation irradiation unit 17 installed on its periphery. The rotation axis O of the rotating gantry 12 is set to the position of the patient 1 lying on the treatment table 11. The radiation irradiation unit 17 irradiates radiation to the patient 1 lying on the treatment table 11.

The X-ray generating unit 13 comprises a first X-ray generating unit 13A and a second X-ray generating unit 13B. As shown in FIG. 2, the first X-ray generating unit 13A and the second X-ray generating unit 13B are installed on the edge of the rotating gantry 12 at positions separated by 90 degrees from the rotation axis O of the rotating gantry 12. The first and second X-ray generating units 13A and 13B are, for example, X-ray tubes, and irradiate X-rays toward the patient 1 on the treatment table 11 when the rotating gantry 12 rotates.

The X-ray imaging unit 14 comprises a first X-ray imaging unit 14A and a second X-ray imaging unit 14B. The first X-ray imaging unit 14A is positioned in a direction of 180 degrees around the rotation axis O of the rotating gantry 12 relative to the first X-ray generation unit 13A, forms a pair with the first X-ray generation unit 13A, and is disposed adjacent to the radiation irradiation unit 17. The second X-ray imaging unit 14B is positioned in a direction of 180 degrees around the rotation axis O of the rotating gantry 12 relative to the second X-ray generation unit 13B, forms a pair with the second X-ray generation unit 13B, and is disposed adjacent to the radiation irradiation unit 17.

The first X-ray imaging unit 14A captures the transmitted X-rays that are irradiated from the first X-ray generating unit 13A and transmitted through the patient 1 on the treatment table 11 while the rotating gantry 12 rotates, and outputs image data (X-ray transmission image) 29. The second X-ray imaging unit 14B captures the transmitted X-rays that are irradiated from the second X-ray generating unit 13B and transmitted through the patient 1 on the treatment table 11 while the rotating gantry 12 rotates, and outputs image data (X-ray transmission image) 29.

As shown in Figs. 1 and 3, the respiratory monitoring device 15 includes a sensor 18 that is installed, for example, on the treatment table 11. This sensor 18 measures the amount of movement of the respiratory movement that appears on the body surface of the patient 1 lying on the treatment table 11. The respiratory monitoring device 15 monitors the respiratory movement of the patient 1 by acquiring measurement data from the sensor 18.

As shown in FIG. 3, the control calculation device 16 controls the generation of X-rays by the X-ray generation unit (first X-ray generation unit 13A and second X-ray generation unit 13B) and the acquisition of image data (X-ray transmission image) 29 from the X-ray imaging unit (first X-ray imaging unit 14A and second X-ray imaging unit 14B), and creates a 3D reconstructed image, etc., using the image data 29 from the X-ray imaging unit 14.

That is, the control calculation device 16 controls the first high voltage generator 19A and the second high voltage generator 19B to generate X-rays from each of the first X-ray generation unit 13A and the second X-ray generation unit 13B by adjusting the timing and intensity. The control calculation device 16 also acquires image data (X-ray transmission image) 29 captured by the first X-ray imaging unit 14A and the second X-ray imaging unit 14B at each X-ray generation timing (i.e., the imaging timing of the image data 29). The control calculation device 16 also sequentially acquires the rotation angle value θ of the rotating gantry 12 from the gantry control device 20 that controls the rotation of the rotating gantry 12. Furthermore, the control calculation device 16 acquires the amount of movement of the respiratory movement of the patient 1 (respiratory waveform) measured by the sensor 18 as a numerical value via the respiratory monitoring device 15.

Furthermore, as shown in FIG. 4, the control calculation device 16 has an image pre-processing unit 21, a respiratory waveform division unit 22, an image data classification unit 23, a 3D reconstruction unit 24, and a 3D image creation unit 25 to realize the function of creating 3D reconstructed images and animated 3D images.

The image pre-processing unit 21 performs image pre-processing on the image data (X-ray transmission image) 29 acquired from the X-ray imaging unit 14 (first X-ray imaging unit 14A and second X-ray imaging unit 14B). This image pre-processing is, for example, noise removal by image filtering. In addition, the respiratory waveform division unit 22 performs a first step of dividing the period S of the respiratory waveform 26 (Figure 5), which is the amount of movement of the respiratory movement of the patient 1 monitored by the respiratory monitoring device 15, into multiple (for example, 10) phase ranges α.

The rotating gantry 12 in the radiation therapy CT imaging system 10 differs from a typical CT imaging device in that it takes 1 to 2 minutes to make one rotation. On the other hand, the period S of the respiratory waveform 26 in the respiratory motion of the patient 1 (the time from maximum inspiration through maximum expiration to maximum inspiration) is about 3 to 4 seconds. Therefore, the patient 1 breathes multiple times during one rotation of the rotating gantry 12. The affected area and organs that change with the respiratory motion of the patient 1 are in the same position in the same phase range α in the respiratory waveform 26 of this respiratory motion, for example, in the first phase range α, the second phase range α, etc.

As shown in Figures 4 and 5, the image data classification unit 23 performs a second step of classifying image data (X-ray transmission image) 29 captured by the X-ray imaging unit 14 (first X-ray imaging unit 14A, second X-ray imaging unit 14B) for each phase range α set by the respiratory waveform division unit 22 together with the rotation angle value θ of the rotating gantry 12 when this image data 29 was captured. Therefore, for each phase range α of the respiratory waveform 26, multiple sets of data sets combining the image data 29 captured by the X-ray imaging unit 14 and the rotation angle value θ of the rotating gantry 12 when this image data 29 was captured are classified.

The three-dimensional reconstruction unit 24 performs a third step of reconstructing the multiple data sets (image data 29 from the X-ray imaging unit 14 and the rotation angle value θ of the rotating gantry 12) classified by the image data classification unit 23 for each identical phase range α of the respiratory waveform 26, and creating a three-dimensional reconstructed image for each phase range α.

The three-dimensional image creation unit 25 performs a fourth step of creating a three-dimensional image having a time axis (i.e., animated) by sequentially arranging and integrating multiple three-dimensional reconstruction images created by the three-dimensional reconstruction unit 24 for each phase range α of the respiratory waveform 26 along the time series of the phases of the respiratory waveform 26.

The control computing device 16 sequentially performs the first to fourth steps in the respiratory waveform division unit 22, image data classification unit 23, three-dimensional reconstruction unit 24, and three-dimensional image creation unit 25 to create a three-dimensional reconstruction image and an animated three-dimensional image. Both of these images are configured to be output to an external output unit 27 (Figure 4) so that they can be displayed. The control computing device 16 may also be connected to a user interface 28. This user interface 28 may be in the form of a program that runs simultaneously inside the same computer as the control computing device 16, for example, or may be in the form of running inside a computer separate from the control computing device 16 and sending and receiving information to and from the control computing device 16 via a network line.

As configured as above, the first embodiment provides the following advantages (1) to (3).
(1) When the respiratory waveform 26 of the patient 1's respiratory motion is regular as shown in Fig. 5, the affected area and organs of the patient 1 are at the same position at the same phase position in the respiratory waveform 26. Therefore, the control calculation device 16 reconstructs the image data 29 captured by the X-ray imaging unit 14 (the first X-ray imaging unit 14A and the second X-ray imaging unit 14B) for each of the same phase ranges α in the respiratory waveform 26 of the patient 1's respiratory motion to create a three-dimensional reconstruction image, so that the positions of the affected area and organs that change with the respiratory motion of the patient 1 can be accurately grasped from the three-dimensional reconstruction image. As a result, when performing radiation therapy, it becomes clear at which phase position of the respiratory waveform 26 of the patient 1 radiation is irradiated, so that radiation therapy can be performed with high accuracy.

(2) The control calculation device 16 reconstructs the image data 29 captured by the X-ray imaging unit 14 (first X-ray imaging unit 14A, second X-ray imaging unit 14B) for each identical phase range α in the respiratory waveform 26 of the patient 1's respiratory movement to create a three-dimensional reconstruction image, and outputs a three-dimensional image having an animated time axis by sequentially arranging and integrating multiple three-dimensional reconstruction images for each phase range α along the time series of the phase of the respiratory waveform 26. Therefore, the state of the changes in the affected area and organs, etc., which change due to the respiratory movement of the patient 1 can be confirmed three-dimensionally, so that the positions of the affected area and organs, etc., which change due to the respiratory movement of the patient 1 can be grasped more accurately. As a result, when performing radiation therapy, it becomes even clearer at which phase position of the respiratory waveform 26 of the patient 1 radiation should be irradiated, and radiation therapy can be performed with higher accuracy.

(3) In the control computing device 16, the respiratory waveform division unit 22 divides the period S in the respiratory waveform 26 of the respiratory movement of the patient 1 into multiple parts to set multiple phase ranges α, the image data classification unit 23 and the three-dimensional reconstruction unit 24 create a three-dimensional reconstruction image for each phase range α, and the three-dimensional image creation unit 25 creates a three-dimensional image having an animated time axis from these multiple three-dimensional reconstruction images, so the algorithm of the control computing device 16 is simplified. This makes it possible to facilitate the configuration of a radiotherapy CT imaging system 10 that implements this control computing device 16.

[B] Second embodiment (FIGS. 6 and 7)
6 is a block diagram for explaining the functions of a control and calculation device of a CT imaging system for radiation therapy according to the second embodiment. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the explanations thereof will be simplified or omitted.

The radiation therapy CT imaging system 30 of the second embodiment differs from the first embodiment in that the function of creating a three-dimensional reconstructed image and an animated stereoscopic image in the control calculation device 16 of the first embodiment is realized by the image pre-processing unit 21, the respiratory waveform division unit 32, the image data classification unit 33, the three-dimensional reconstruction unit 34, and the stereoscopic image creation unit 35 of the control calculation device 31.

In the same manner as the control calculation device 16, the control calculation device 31 also controls the generation of X-rays by the X-ray generation unit 13 (first X-ray generation unit 13A, second X-ray generation unit 13B), controls the acquisition of image data 29 from the X-ray imaging unit 14 (first X-ray imaging unit 14A, second X-ray imaging unit 14B), controls the acquisition of the rotation angle value θ of the rotating gantry 12 from the gantry control device 20, and controls the acquisition of the respiratory motion movement amount (respiratory waveform) of the patient 1 from the respiratory monitoring device 15.

As shown in FIG. 7, the respiratory waveform 36 of the respiratory movement of the patient 1 may be irregular, with the maximum inspiration or maximum expiration varying for each breath. Even in such cases, the affected area and organs that change with the respiratory movement of the patient 1 are at the same position in the amplitude direction in the respiratory waveform 36 of this respiratory movement, for example, at the same position within the same amplitude range β described below.

Based on the above facts, as shown in Figures 6 and 7, the respiratory waveform division unit 32 performs an eleventh step of dividing the amplitude L in the respiratory waveform 36, which is the amount of movement of the respiratory movement of the patient 1 monitored by the respiratory monitoring device 15, into multiple (e.g., 10) amplitude ranges β. In the same amplitude range β in the respiratory waveform 36, for example, between the first amplitude range β, between the second amplitude range β, etc., the affected area and organs of the patient 1 are in the same position.

This respiratory waveform division unit 32 holds in advance information regarding the division regions (regions from maximum inspiration to maximum expiration) and division numbers into which the amplitude L should be divided in order to divide the amplitude L in the respiratory waveform 36 of the patient 1's respiratory movement into a plurality of amplitude ranges β. In other words, in order to divide the amplitude L of the respiratory waveform 36 of the patient 1, the respiratory waveform division unit 32 does not first determine the division regions and division numbers into which the amplitude L should be divided from the distribution of the respiratory waveform 36 of the patient 1's respiratory movement after the rotating gantry 12 has completed one rotation, but rather determines and holds in advance the division regions (regions from maximum inspiration to maximum expiration) and division parts from the distribution of the respiratory waveform 36 of the patient 1.

The image data classification unit 33 performs a twelfth step of classifying the image data (X-ray transmission image) 29 captured by the X-ray imaging unit 14 (first X-ray imaging unit 14A, second X-ray imaging unit 14B) together with the rotation angle value θ of the rotating gantry 12 when the image data 29 was captured, for each of the multiple amplitude ranges β divided by the respiratory waveform division unit 32. Therefore, for each amplitude range β of the respiratory waveform 36, multiple sets of data sets combining the image data 29 captured by the X-ray imaging unit 14 and the rotation angle value θ of the rotating gantry 12 when the image data 29 was captured are classified.

The three-dimensional reconstruction unit 34 performs a thirteenth step of reconstructing the multiple data sets (image data 29 from the X-ray imaging unit 14 and the rotation angle value θ of the rotating gantry 12) classified by the image data classification unit 33 for each identical amplitude range β of the respiratory waveform 36 to create a three-dimensional reconstructed image.

When creating this three-dimensional reconstruction image, if the three-dimensional reconstruction unit 34 determines that the image data 29 classified for each amplitude range β is inappropriate, such as there being an insufficient number of images to create a three-dimensional reconstruction image, the three-dimensional reconstruction unit 34 discards the image data 29. This discarding ensures the accuracy of the three-dimensional reconstruction image created for each amplitude range β.

In other words, when classifying image data 29 for each amplitude range β obtained by dividing the amplitude L of the respiratory waveform 36, it may not be possible to acquire image data 29 in the amplitude range β close to maximum inspiration or maximum expiration. Therefore, in such an amplitude range β, the number of image data for creating a three-dimensional reconstructed image during one rotation of the rotating gantry 12 is insufficient. Also, the center position of the respiratory waveform 36 of the respiratory movement of the patient 1 may shift during one rotation of the rotating gantry 12. In such a case, image data 29 was acquired (classified) in the amplitude range β close to the maximum amplitude of the respiratory waveform 36 at the start of imaging, but it may not be possible to acquire it thereafter, and the number of image data may be insufficient for creating a three-dimensional reconstructed image.

Therefore, when the number of image data (X-ray transmission images) 29 classified into the amplitude range β of the respiratory waveform 36 of the patient 1 during one rotation of the rotating gantry 12 is insufficient and does not reach the minimum number of images required to create a three-dimensional reconstructed image in this amplitude range β, the three-dimensional reconstruction unit 34 does not perform three-dimensional reconstruction in that amplitude range β. The three-dimensional reconstruction unit 34 discards the image data 29 classified into the amplitude range β for which three-dimensional reconstruction is not performed. Here, the minimum number of images is preset in the three-dimensional reconstruction unit 34.

In addition, even if the number of image data classified into the amplitude range β satisfies the minimum number of images, if there is a bias in the number of image data 29 classified into each amplitude range β during one rotation of the rotating gantry 12, the 3D reconstruction unit 34 does not perform 3D reconstruction from the image data 29 acquired during that one rotation of the rotating gantry 12, and discards all of the image data 29. For example, if the angle range (360 degrees) of one rotation of the rotating gantry 12 is divided into a number of equal angle ranges, and the number of image data classified into each amplitude range β is not approximately equal within each divided angle range (for example, the variation in the number of images is within 20%), 3D reconstruction images are not created in any of the amplitude ranges β from the image data 29 acquired during one rotation of the rotating gantry 12, and all of the image data 29 is discarded.

The stereoscopic image creation unit 35 performs a fourteenth step of sequentially arranging and integrating multiple three-dimensional reconstructed images created by reconstructing for each amplitude range β in the respiratory waveform 36 of the respiratory movement of the patient 1 from maximum inspiration to maximum expiration in the respiratory waveform 36, and outputting an animated stereoscopic image that sequentially changes between maximum inspiration and maximum expiration in the respiratory waveform 36. Here, the multiple three-dimensional reconstructed images may be sequentially arranged and integrated from maximum expiration to maximum inspiration in the respiratory waveform 36.

The control calculation device 31 sequentially performs steps 11 to 14 in the respiratory waveform division unit 32, image data classification unit 33, 3D reconstruction unit 34, and 3D image creation unit 35 to create a 3D reconstructed image and an animated 3D image. Both of these images are configured to be output to the external output unit 27 so that they can be displayed.

As configured as above, the second embodiment provides the following advantages (4) to (7).
(4) Even if the respiratory waveform 36 of the patient 1 is irregular as shown in FIG. 7, the affected area and organs of the patient 1 are at the same position at the same position in the amplitude L of the respiratory waveform 36. Therefore, when the respiratory waveform 36 is particularly irregular, the control calculation device 31 reconstructs the image data 29 captured by the X-ray imaging unit 14 (the first X-ray imaging unit 14A and the second X-ray imaging unit 14B) for each of the same amplitude ranges β of the respiratory waveform 36 of the patient 1 to create a three-dimensional reconstruction image, thereby reducing the occurrence of artifacts such as shadows on the three-dimensional reconstruction image. As a result, the positions of the affected area and organs that change with the respiratory motion of the patient 1 can be accurately grasped by the three-dimensional reconstruction image. As a result, when performing radiation therapy, it is clear at which phase position of the respiratory waveform 36 of the patient 1 radiation is irradiated, so that radiation therapy can be performed with high accuracy.

(5) The control calculation device 31 reconstructs the image data 29 captured by the X-ray imaging unit 14 (first X-ray imaging unit 14A, second X-ray imaging unit 14B) for each of the same amplitude ranges β in the respiratory waveform 36 of the patient 1's respiratory motion to create a three-dimensional reconstruction image, and outputs an animated three-dimensional image that changes sequentially between maximum inspiration and maximum expiration by sequentially arranging and integrating multiple three-dimensional reconstruction images for each amplitude range β of the respiratory waveform 36 from one side to the other of maximum inspiration and maximum expiration. Therefore, the state of the changes in the affected area and organs, etc., that change due to the respiratory motion of the patient 1 can be confirmed three-dimensionally, and the positions of the affected area and organs, etc., that change due to the respiratory motion of the patient 1 can be grasped more accurately. As a result, when performing radiation therapy, it becomes even clearer at which phase position of the respiratory waveform 36 of the patient 1 radiation should be irradiated, so that more accurate radiation therapy can be performed.

(6) When the three-dimensional reconstruction unit 34 of the control calculation device 31 determines that the image data 29 classified for each amplitude range β in the respiratory waveform 36 of the respiratory movement of the patient 1 is inappropriate for creating a three-dimensional reconstructed image (e.g., there is an insufficient number of images), the three-dimensional reconstructed image is not created from the image data 29, and the image data 29 is discarded. As a result, the time spent by the three-dimensional reconstruction unit 34 in performing unnecessary data processing can be reduced, and three-dimensional reconstructed images can be quickly created using the image data 29 in other amplitude ranges β.

(7) The respiratory waveform division unit 32 of the control calculation device 31 holds in advance information regarding the division regions (regions from maximum inspiration to maximum expiration) into which the amplitude L should be divided and the number of divisions in order to divide the amplitude L in the respiratory waveform 36 of the respiratory movement of the patient 1 into a plurality of amplitude ranges β. Therefore, while acquiring image data 29 from the X-ray imaging unit 14 while the rotating gantry 12 is rotating, the control calculation device 31 can classify the image data 29 into amplitude ranges β together with the rotation angle value θ of the rotating gantry 12 at the time of acquiring the image data 29 by the respiratory waveform division unit 32. As a result, classification into each amplitude range β of the image data 29 etc. is performed while the rotating gantry 12 is rotating, so that a three-dimensional reconstructed image can be created promptly after acquiring the image data 29 from the X-ray imaging unit 14.

Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. Furthermore, such substitutions and modifications are included in the scope and gist of the invention, as well as in the scope of the invention and its equivalents as described in the claims.

1...Patient, 10...CT imaging system for radiation therapy, 11...Treatment table, 12...Rotating gantry, 13...X-ray generating unit, 14...X-ray imaging unit, 15...Respiratory monitoring device, 16...Control calculation device, 17...Radiation irradiation unit, 22...Respiratory waveform division unit, 23...Image data classification unit, 24...3D reconstruction unit, 25...3D image creation unit, 26...Respiratory waveform, 30...CT imaging system for radiation therapy, 31...Control calculation device, 32...Respiratory waveform division unit, 33...Image data classification unit, 34...3D reconstruction unit, 35...3D image creation unit, 36...Respiratory waveform, S...Period, L...Amplitude, α...Phase range, β...Amplitude range, θ...Rotation angle value

Claims (4)

A treatment table on which a patient is placed;
a rotating gantry that surrounds the treatment table and rotates around the treatment table and includes a radiation irradiation unit that irradiates radiation to the patient on the treatment table;
an X-ray generating unit attached to the rotating gantry and configured to irradiate X-rays when the rotating gantry rotates;
an X-ray imaging unit attached to the rotating gantry, capturing an image of the transmitted X-rays that have passed through the patient on the treatment table during rotation of the rotating gantry, and outputting image data;
a respiratory monitor for monitoring the respiratory movements of the patient on the treatment couch;
a control and calculation device that controls the generation of X-rays by the X-ray generation unit and the acquisition of the image data from the X-ray imaging unit, and creates a three-dimensional reconstructed image using the image data from the X-ray imaging unit,
The control and computing device divides an amplitude of a respiratory waveform of the patient's respiratory movement monitored by the respiratory monitoring device into a plurality of amplitude ranges;
classifying the image data captured by the X-ray imaging unit for each of these amplitude ranges, together with the rotation angle value of the rotating gantry at the time of capturing the image data, during the rotation of the rotating gantry;
a plurality of image data and a rotation angle value of the rotating gantry that are classified into the same amplitude range are reconstructed to generate the three-dimensional reconstruction image ;
a CT imaging system for radiation therapy, characterized in that, when there is a bias in the number of image data classified by the amplitude range during one rotation of the rotating gantry, the image data is determined to be inappropriate for creating the three-dimensional reconstructed image, and the image data acquired during the one rotation is discarded . The control and calculation device is configured to output a stereoscopic image that changes sequentially between maximum inspiration and maximum expiration by sequentially arranging and integrating a plurality of three-dimensional reconstructed images created by reconstructing for each amplitude range of the respiratory waveform of the patient's respiratory movement from one of maximum inspiration and maximum expiration of the respiratory waveform to the other. 3. The radiotherapeutic CT imaging system according to claim 1, wherein the control and calculation device is configured to hold in advance information regarding a division region and a division number for dividing an amplitude in a respiratory waveform of a patient's respiratory motion into a plurality of amplitude ranges. A treatment table on which a patient is placed;
a rotating gantry that surrounds the treatment table and rotates around the treatment table and includes a radiation irradiation unit that irradiates radiation to the patient on the treatment table;
an X-ray generating unit attached to the rotating gantry and configured to irradiate X-rays when the rotating gantry rotates;
an X-ray imaging unit attached to the rotating gantry, capturing an image of the transmitted X-rays that have passed through the patient on the treatment table during rotation of the rotating gantry, and outputting image data;
a respiratory monitor for monitoring the respiratory movements of the patient on the treatment couch;
a control and calculation device that controls the generation of the X-rays by the X-ray generation unit and the acquisition of the image data from the X-ray imaging unit, and creates a three-dimensional reconstructed image using the image data from the X-ray imaging unit;
dividing an amplitude of a respiratory waveform of the patient's respiratory motion monitored by the respiratory monitoring device into a plurality of amplitude ranges;
classifying the image data captured by the X-ray imaging unit for each of these amplitude ranges while the rotating gantry is rotating, together with a rotation angle value of the rotating gantry at the time of capturing the image data;
a step of reconstructing a plurality of the image data and a rotation angle value of the rotating gantry classified into the same amplitude range to generate the three-dimensional reconstruction image ,
the control and computing device further determines that the image data classified for each amplitude range is inappropriate for creating the three-dimensional reconstructed image when there is a bias in the number of images during one rotation of the rotating gantry, and discards the image data acquired during the one rotation .

Images