JP7563951B2 - Positioning device, radiation therapy system, and positioning method - Google Patents

Description

This disclosure relates to technology for matching images.

One method of treating cancer is radiation therapy, in which radiation is irradiated onto the patient. The radiation used in radiation therapy is broadly divided into uncharged particle beams, such as X-rays and gamma rays, and charged particle beams, such as proton beams and carbon beams. Treatment using the latter type of charged particle beams (hereafter also referred to as charged particle beams) is generally called particle beam therapy.

The dose delivered by uncharged particle beams decreases at a constant rate from shallow to deep positions inside the body. On the other hand, charged particle beams can form a dose distribution (Brugh curve) with an energy peak at a specific depth. Therefore, by aligning the peak with the position of the tumor, it is possible to significantly reduce the dose delivered to normal tissue deeper than the tumor.

In radiation therapy, irradiating the targeted tumor with the desired dose of a charged particle beam as accurately as possible leads to improved therapeutic effects. In order to accurately irradiate the tumor with a charged particle beam, it is necessary to create a treatment plan in advance using a treatment planning system, and then align the patient at the same position during actual irradiation as in the treatment plan. This alignment of the patient is called patient positioning.

Patient positioning in radiation therapy is generally performed using fluoroscopic X-ray images of the patient taken from two directions using two sets of X-ray tubes and flat panel detectors arranged perpendicular to each other. The fluoroscopic X-ray images of the patient are compared with a projection processing image (hereinafter referred to as a pseudo-fluoroscopic X-ray image) created by placing a CT image at the time of treatment planning in a virtual space and calculating the amount of attenuation of X-rays entering the virtual flat panel detector from the virtual X-ray tube, and the amount of displacement required to match the patient's position in both images is determined. Here, the amount of displacement is determined so that the bone, which is the structure that serves as a marker for positioning on the fluoroscopic X-ray image (hereinafter referred to as the structure to be positioned), matches the bone of the same part on the pseudo-fluoroscopic X-ray image. The amount of displacement is determined by manual alignment by visual inspection by a medical professional, or automatic alignment by automatic calculation.

In addition, in order to perform automatic alignment only on structures to be positioned on fluoroscopic X-ray images, a medical professional may draw and set a Region of Interest (ROI) on a fluoroscopic X-ray image or pseudo-fluoroscopic X-ray image in advance, and during automatic alignment, only the area within the ROI is subject to calculations and alignment is performed using structures within the ROI. Patent Document 1 discloses a technology that uses an image with enhanced bone edges for patient positioning. It describes extracting the ROI area from an image with enhanced bone edges and using it to compare with an image of the patient.

JP 2005-305048 A

The technology disclosed in Patent Document 1 is effective in areas such as the head and lumbar region, where the bone contours can be relatively clearly distinguished from the surrounding tissues on an image.

However, when viewed from the direction of fluoroscopy, other structures such as intestinal cavities, soft tissues, and fixation devices may be present in front of or behind the bone that is the structure to be positioned (hereinafter also referred to as the target bone). In such cases, the target bone and other structures may overlap in the fluoroscopy X-ray image, reducing the visibility of the target bone. In the case of patients with a large body thickness, the visibility of the target bone is already low due to the thick layer of soft tissue, and this further reduces the visibility of the target bone. Adding an imaging device increases the possibility of obtaining an image with good visibility of the structure to be positioned, but increases costs.

In contrast, if an ROI is set along the contour of the target bone (hereinafter also referred to as the bone contour), the importance of the target bone can be increased in terms of calculations relative to other structures. However, if a medical professional were to draw the ROI along the bone contour in advance, it would take a long time to draw the ROI. Furthermore, no method has been proposed to draw an ROI along the contour of a structure to be positioned by computational processing without requiring long hours of manual work.

One objective of the present disclosure is to provide technology that facilitates accurate patient positioning.

A positioning device according to one aspect of the present disclosure includes a pseudo-perspective X-ray image creation unit that acquires a three-dimensional image of a target structure, which is a structure contained in the human body and used for positioning, from a three-dimensional image used to create a treatment plan for irradiating a patient with radiation in radiation therapy, by extracting the target structure based on the density of the target structure, and creates a pseudo-perspective X-ray image by projecting the three-dimensional image of the target structure onto a predetermined surface; an edge enhancement processing unit that performs processing to enhance edges on the pseudo-perspective X-ray image to create an edge-enhanced pseudo-perspective X-ray image; and a first region of interest that includes the region of the target structure in the edge-enhanced pseudo-perspective X-ray image. an edge-enhanced region of interest creation unit that creates a second region of interest including the contour of the target structure that appears as the edge in the edge-enhanced pseudo-fluoroscopic X-ray image based on the edge-enhanced pseudo-fluoroscopic X-ray image and the first region of interest; and an image matching unit that calculates the amount of movement for moving the bed based on a fluoroscopic X-ray image of the patient placed on a bed taken by X-ray fluoroscopy, the pseudo-fluoroscopic X-ray image or the edge-enhanced pseudo-fluoroscopic X-ray image, and the second region of interest so that the position of the target structure in the fluoroscopic X-ray image coincides with the position of the target structure in the pseudo-fluoroscopic X-ray image.

One aspect of the present disclosure makes it possible to easily and accurately position a patient.

1 is a diagram showing an overall configuration of a particle beam therapy system. 13 is a flowchart of an edge enhancement ROI creating process. 1A and 1B are diagrams showing images and ROIs used sequentially in the process of edge-enhanced ROI creation processing; 13 is a flowchart of an ROI setting process. 11 is a diagram showing how the ROI 300 is searched for in the ROI setting process. FIG. 13 is a flowchart illustrating a process for patient positioning.

The following description of the embodiment of the present invention will be described with reference to the drawings. Note that the following description and drawings are illustrative for explaining the present invention, and appropriate omissions and simplifications have been made to clarify the explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural. In addition, in the drawings explaining the embodiment, the same reference numerals are given to parts having the same functions, and repeated explanations are omitted. In addition, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. For this reason, the present invention is not limited to the position, size, shape, range, etc. disclosed in the drawings. In addition, when there are multiple identical or similar components, they may be described with different subscripts added to the same reference numeral. However, when it is not necessary to distinguish between these multiple components, the subscripts may be omitted.

The particle beam therapy system of this embodiment is a group of devices for irradiating a particle beam to a patient, which is a target. The particle beam therapy system irradiates the patient with a particle beam after positioning the patient. In positioning the patient, the particle beam therapy system creates an edge-enhanced ROI using an image in which edge enhancement processing is applied to a pseudo-fluoroscopic X-ray image (digitally reconstructed radiography: DRR) created only from bone information and a pre-drawn ROI. Furthermore, when irradiating the patient with a particle beam, the particle beam therapy system aligns the captured fluoroscopic X-ray image with the pseudo-fluoroscopic X-ray image using the edge-enhanced ROI.

This embodiment is described in detail below.

Figure 1 shows the overall configuration of a particle beam therapy system. Particle beam therapy system A includes an accelerator 1, a beam transport device 2, a gantry 3, an irradiation nozzle 4, flat panel detectors 5A and 5B, X-ray tubes 6A and 6B, a bed 7, a robot arm 8, a treatment planning device 10, a communication device 11, a data server 12, a fluoroscopic X-ray image capture device 14, a bed control device 15, and a patient positioning device 20. The patient positioning device 20 includes a pseudo-fluoroscopic X-ray image creation unit 21, an ROI drawing unit 22, an edge enhancement processing unit 23, an edge-enhanced ROI creation unit 24, and an image matching unit 25.

During particle beam therapy, the patient 9 is placed on the bed 7 and moved to a pre-planned position by a robot arm 8 connected to the bed 7. The planned position here refers to a position of the patient 9 in the radiation treatment room that reproduces the same position as the patient's position in a treatment plan created in advance using a treatment planning device 10. The robot arm 8 can be driven in three translational directions and three rotational directions, and the bed 7 with the patient 9 on it can be positioned at an appropriate position and angle.

The particle beam generated by the accelerator 1 and accelerated to an energy level suitable for treatment is transported to the gantry 3 by the beam transport device 2. The gantry 3 has a rotation mechanism and can irradiate the affected area of the patient with the particle beam from various angles. In the gantry 3, the particle beam is deflected in an appropriate direction and passes through the irradiation nozzle 4 to be irradiated to the affected area of the patient 9.

The irradiation nozzle 4 incorporates a mechanism that changes the shape of the particle beam to match the shape of the affected area on the patient.

The treatment planning device 10 is a device that creates a treatment plan based on three-dimensional image information of the patient 9 before actually irradiating the patient with a particle beam. In the treatment plan, the treatment planning device 10 acquires three-dimensional image information of the patient 9 from the data server 12 via the communication device 11, calculates the appropriate irradiation angle, irradiation shape, and irradiation amount of the particle beam for the three-dimensional image, and determines it as irradiation information. The determined irradiation information is stored in the data server 12 via the communication device 11.

The fluoroscopic X-ray imaging device 14 controls the flat panel detector 5A and the X-ray tube 6A, and the flat panel detector 5B and the X-ray tube 6B, which are arranged in mutually orthogonal directions, to obtain a fluoroscopic X-ray image. The obtained fluoroscopic X-ray image is sent to the patient positioning device 20.

The patient positioning device 20 is a device that determines the amount of movement of the bed 7 so that the position of the patient 9 when the treatment plan is created coincides with the position of the patient 9 placed on the bed 7 for irradiation with the particle beam.

The patient positioning device 20 acquires irradiation information created during treatment planning and three-dimensional image information of the patient 9 from the data server 12 via the communication device 11.

In the patient positioning device 20, the pseudo-fluoroscopic X-ray image creation unit 21 creates a pseudo-fluoroscopic X-ray image by placing a three-dimensional image of the patient 9 in a virtual space that is the same as the actual fluoroscopic X-ray imaging system and performing projection processing.

Here, the 3D image information contains information that indicates the shape and electron density of the patient on a voxel-by-voxel basis. By setting a threshold for the voxel values in advance, it is possible to distinguish between high-density materials, such as bone layers, and low-density materials, such as air, lung fields, or soft tissue.

The pseudo-perspective X-ray image creation unit 21 obtains a three-dimensional image of a target structure by extracting a structure contained in the human body and used for positioning (hereinafter also referred to as a positioning target structure or target structure) from the three-dimensional image based on the density of the target structure, and creates a pseudo-perspective X-ray image by projecting the three-dimensional image of the target structure onto a specified surface.

The ROI drawing unit 22 allows the user to draw on the screen the area to be used for alignment on the pseudo-fluoroscopic X-ray image as an ROI. The ROI that the user draws here may be one that is relatively easy to create and that includes the area of the structure to be positioned.

The edge enhancement processing unit 23 applies edge enhancement processing to the fluoroscopic X-ray image and the pseudo-fluoroscopic X-ray image.

The edge-enhanced ROI creation unit 24 creates an edge-enhanced ROI using the edge-enhanced pseudo-fluoroscopic X-ray image and the drawn ROI. This edge-enhanced ROI is relatively precise and follows the contour of the structure to be used for alignment.

The image matching unit 25 performs image matching between the fluoroscopic X-ray image and the pseudo fluoroscopic X-ray image only in the portion included in the edge enhancement ROI, and calculates the displacement amount of six degrees of freedom required to match the patient's position in both images. The displacement amount calculated here is used by the patient positioning device 20 to control the bed control device 15 to move the bed 7.

The patient positioning device 20 is composed of a device capable of various information processing, for example an information processing device such as a computer. The information processing device has a processing element, a storage medium, and a communication interface, and further has an input unit such as a mouse and a keyboard, and a display unit such as a display, as necessary.

The computing element may be, for example, a CPU (Central Processing Unit) or an FPGA (Field-Programmable Gate Array).

The storage medium may be, for example, a magnetic storage medium such as a hard disk drive (HDD), or a semiconductor storage medium such as a random access memory (RAM), a read only memory (ROM), or a solid state drive (SSD). In addition, a combination of an optical disk such as a digital versatile disk (DVD) and an optical disk drive may also be used as a storage medium. Furthermore, other well-known storage media such as magnetic tape media may also be used as a storage medium.

The storage medium stores programs such as firmware. When the operation of the patient positioning device 20 starts (for example, when the power is turned on), the computing element reads the programs from the storage medium and executes them to realize each of the sections 21 to 25 of the patient positioning device 20 and execute a series of controls over the entire device. In addition to the programs, the storage medium also stores data and the like required for each process of the patient positioning device 20.

In addition, the patient positioning device 20 of this embodiment may be configured using so-called cloud computing, in which the information processing devices are configured to be able to communicate via a communication network.

In the particle beam therapy system A of this embodiment, an edge-enhanced ROI is created in advance before patient positioning for particle beam therapy. The patient positioning method of this embodiment will be described below with reference to Figures 2 to 6.

Figure 2 is a flowchart of the edge-enhanced ROI creation process. The edge-enhanced ROI creation process is a series of steps to create an edge-enhanced ROI.

Figure 3 shows the images and ROIs used sequentially in the edge-enhanced ROI creation process. Note that for ease of explanation, only a pseudo-fluoroscopic X-ray image from one direction is shown in Figure 3, but in reality, there are pseudo-fluoroscopic X-ray images from two directions, and it is assumed that the edge-enhanced ROI creation process is applied to images from each direction.

As shown in FIG. 2, first, the pseudo-fluoroscopic X-ray image creation unit 21 of the patient positioning device 20 creates a pseudo-fluoroscopic X-ray image (Step 100). At this time, the pseudo-fluoroscopic X-ray image creation unit 21 creates a pseudo-fluoroscopic X-ray image 200 of only the structure 50 to be positioned by performing a projection process with an image in which information other than the structure 50 to be positioned is excluded from the three-dimensional image of the patient. The three-dimensional image of the patient is usually a CT image. The structure 50 to be positioned is usually a bone. For example, when the three-dimensional image is a CT image, the three-dimensional image information stores a CT value that is correlated with electron density information. When the three-dimensional image is a CT image, a method of excluding information other than the structure 50 to be positioned from the three-dimensional image information of the patient may be used in which a predetermined threshold value is set for the CT value, the CT value of each voxel is compared with the threshold value, and voxels with a CT value equal to or less than the threshold value are excluded.

Next, the edge enhancement processing unit 23 applies processing for enhancing edges to the pseudo-transparent X-ray image 200 of only the structure 50 to be positioned, thereby creating an edge-enhanced pseudo-transparent X-ray image 201 (Step 101). The edge enhancement processing is not particularly limited, but for example, a differential filter may be applied to each of the vertical and horizontal directions as a general edge enhancement filter. A Prewitte filter or a Sobel filter may be used as a differential filter. Alternatively, the edge enhancement processing may be performed using other filters. Furthermore, the edge enhancement processing may be performed by combining multiple filters.

Next, the ROI drawing unit 22 sets an area on the edge-emphasized pseudo-fluoroscopic X-ray image 201 where a structure to be used for positioning exists as the ROI 300 based on the user's operation (Step 102). As a method of setting the ROI 300, the ROI drawing unit 22 displays the edge-emphasized pseudo-fluoroscopic X-ray image 201 on a screen, has the user fill in the area to be the ROI 300 by operating a mouse or the like, and sets the filled area as the ROI 300. Alternatively, the ROI drawing unit 22 displays the edge-emphasized pseudo-fluoroscopic X-ray image 201 on a screen, has the user select a position within the area to be the ROI 300 by operating a mouse or the like, and sets an area within a predetermined distance from the selected position as the ROI 300. Another method is for the ROI drawing unit 22 to display the edge-enhanced pseudo-fluoroscopic X-ray image 201 on the screen, have the user select a position within the region to be used as the ROI 300 by using a mouse or other means, and set a continuous region having pixel values within a certain range from the pixel value of the selected position as the ROI 300.

The ROI drawing unit 22 displays the ROI 300 created by the user's drawing on the screen, superimposed on the edge-enhanced pseudo-fluoroscopic X-ray image 201.

Here, as an example, we will explain the ROI setting process, which automatically extracts an area having pixel values similar to those of a position selected by the user as the ROI 300.

Figure 4 is a flowchart of the ROI setting process. Figure 5 is a diagram showing how the ROI 300 is searched for in the ROI setting process.

First, the ROI drawing unit 22 displays an edge-enhanced pseudo-fluoroscopic X-ray image on the screen, allows the user to select a position included in the ROI region on the screen by clicking, and acquires information indicating the selected position (Step 200). Next, as shown in FIG. 5, the ROI drawing unit 22 sets the position selected by the user as a reference position 60, and sets the pixel value of that position as a reference pixel value (Step 201). In FIG. 5, the pixel at the reference position 60 is surrounded by a thick line.

Next, the ROI drawing unit 22 sets the pixel values of the pixels in eight directions around the pixel at the reference position 60 as a search pixel 61 (Step 202), as shown in FIG. 5. In FIG. 5, the search pixel 61 is represented by hatching with diagonal lines slanting downward to the right.

Next, the ROI drawing unit 22 selects one pixel from the set search pixels and obtains the pixel value of that pixel (Step 203). Furthermore, the ROI drawing unit 22 determines whether the pixel value of the selected search pixel is within a predetermined pixel value range from the reference pixel value (Step 204). The pixel value range here is a value set in advance by the user, and is a setting value that sets the range of pixel values above and below the reference pixel value that are to be included in the ROI.

If the determination in step 204 is Yes, the ROI drawing unit 22 decides to include the currently selected search pixel in the ROI area, and sets the position of that pixel as a new reference position (step 205). In FIG. 5, pixels determined to be ROI are represented by hatching with diagonal lines slanting upward to the right. After that, the process returns to step 202, and pixel values in the surrounding eight directions are again set as search pixels with respect to the new reference position, and the process proceeds to steps 203 and 204.

On the other hand, if the determination in Step 204 is No, the ROI drawing unit 22 determines that the currently selected search pixel is outside the ROI (Step 206). In FIG. 5, pixels determined to be outside the ROI are represented by dotted hatching. Furthermore, the ROI drawing unit 22 determines whether or not it has been determined whether or not to include all search pixels in the ROI (Step 207).

If the determination in Step 207 is No, the ROI drawing unit 22 selects one search pixel that has not yet been determined, obtains the pixel value (Step 208), and returns to Step 204. On the other hand, if the determination in Step 207 is Yes, the ROI drawing unit 22 ends the ROI setting process.

Returning to FIG. 2, next, the edge-enhanced ROI creation unit 24 creates an edge-enhanced ROI 301 (Step 103). At this time, the edge-enhanced ROI creation unit 24 extracts a region that is included in the ROI 300 set by the user and that overlaps with the contour of the edge-enhanced structure in the edge-enhanced pseudo-fluoroscopic X-ray image 201, and sets the region obtained by expanding the overlapping contour by a certain width as the edge-enhanced ROI 301 (Step 103).

Here, the width by which the contour is expanded can be set to a value sufficient to include the correct position after alignment, taking into account the amount of displacement between the position at the start of alignment and the correct position after alignment. In an optimization calculation that uses the pseudo-fluoroscopic X-ray image and the fluoroscopic X-ray image to search for a position where the patient's position in both images coincides, if a narrow edge-enhanced ROI is set along the edge, the calculation using only the area included in the narrow ROI in both images will be very limited as an area for searching for an optimal solution, and therefore it may not be possible to arrive at a solution for the correct position. Therefore, it is advisable to expand the width set along the contour of the edge-enhanced ROI according to the amount of displacement between the start of alignment and the correct position.

When the edge-enhanced ROI creation unit 24 creates the edge-enhanced ROI 301, it displays it on the screen superimposed on the edge-enhanced pseudo-fluoroscopic X-ray image 201.

The edge-enhanced ROI 301 created through the above process is used for patient positioning calculations, which will be described later.

Figure 6 is a flowchart showing the patient positioning process. With reference to Figure 6, patient positioning using edge enhancement ROI 301 will be described.

First, when positioning the patient for particle beam therapy, the patient 9 is placed on the bed 7 in the setup position. The setup position is the position of the bed 7 for placing the patient 9 on the bed 7 and adjusting the patient 9 to an appropriate position on the bed 7. The position of the body surface of the patient 9 on the bed 7 is measured using an infrared laser installed in the treatment room, and the position is adjusted to reproduce the patient's position in the irradiation information created by the treatment planning device 10.

Then, the bed 7 carrying the patient 9 is moved toward the isocenter, which is the reference position for particle beam irradiation, by controlling the robot arm 8 via the bed control device 15 (Step 300). The bed 7 moves so that the positioning target structure 50 of the patient 9 is within the irradiation area formed by the flat panel detectors 5A and 5B and the X-ray tubes 6A and 6B in FIG. 1.

Then, a fluoroscopic X-ray image (Digital Radiography: DR) is acquired by the fluoroscopic X-ray imaging device 14 (Step 301).

Next, the initial values for a total of six degrees of freedom (three translational degrees of freedom and three rotational degrees of freedom) are set in the process of creating a DRR from the CT used when creating the treatment plan (Step 302).

Next, the DRR is created by projecting the 3D CT image onto a plane, assuming the same imaging system as the DR (step 303).

Next, the image matching unit 25 in the patient positioning device 20 calculates the degree of match between the DR and DRR images using information only within the edge-enhanced ROIs of both images (Step 304). As an index for measuring the degree of match, a commonly used normalized cross-correlation coefficient or mutual information may be used, or other indexes may be used.

Next, it is determined whether the calculated degree of agreement satisfies a preset convergence condition (Step 305). If the degree of agreement does not satisfy the convergence condition, a condition that satisfies the convergence condition (values for a total of six degrees of freedom: three translational degrees of freedom and three rotational degrees of freedom) is searched for by optimization processing. In the optimization processing, the values of the six degrees of freedom are updated (Step 306), and Steps 303 to 306 are repeated. Methods of multivariate optimization processing such as the six degrees of freedom in this embodiment include the downhill simplex method and Powell's method, which can be used in this embodiment. However, the optimization processing is not limited to these, and other methods may also be used.

If the degree of agreement satisfies the convergence condition in step 305, the bed control device 15 moves the bed 7 based on the obtained values of the six degrees of freedom (step 307). This makes it possible to move the patient from the current position to the position in the treatment plan and position him/her precisely.

This completes the patient positioning and the actual particle beam irradiation begins.

As described above, this embodiment makes it possible to perform accurate patient positioning without lengthy manual work or the need for additional imaging equipment.

More specifically, by creating an edge-enhanced ROI through computational processing as described above and using that edge-enhanced ROI to position the patient, it is possible to eliminate the need for long hours of manual labor or the need for additional imaging equipment, and by focusing on the periphery of the contour of the structure to be positioned, highly accurate positioning can be achieved through computational processing, even if structures not used for positioning overlap the structure to be positioned.

In this embodiment, as a method for eliminating portions that are not structures to be positioned from the 3D image information of the patient, voxels that are not structures to be positioned are eliminated by determining the CT value of each voxel in the CT image using a threshold value, but portions that are not structures to be positioned may be eliminated using other methods. For example, the user may spatially specify either or both of the adopted area and the excluded area in the 3D area of the CT image.

In addition, in this embodiment, the edge-enhanced ROI creation unit 24 may display an image of the overlapping portion where the edge and the ROI in the edge-enhanced pseudo-fluoroscopic X-ray image overlap on the screen, create an edge-enhanced ROI so as to include a portion in the ROI specified by a user operation, and create an indifferent region in the edge-enhanced ROI so as to include a portion specified by a user operation. In this case, the image matching unit 25 may calculate the amount of movement by performing a calculation in which a portion that is not the indifferent region in the edge enhancement is weighted higher than a portion of the indifferent region based on the fluoroscopic X-ray image, the pseudo-fluoroscopic X-ray image or the edge-enhanced pseudo-fluoroscopic X-ray image, the edge-enhanced ROI, and the indifferent region. The overlapping portion where the edge and the ROI overlap is displayed on the screen, an edge-enhanced ROI and an indifferent region are created from the overlapping portion by a user operation, and the indifferent region in the edge-enhanced ROI is weighted lower than other regions to calculate the amount of movement, so that it is possible to easily perform highly accurate positioning.

In addition, in this embodiment, the degree of match is calculated using only information within the edge enhancement ROI, but information outside the edge enhancement ROI may also be used if necessary. In that case, for example, a method can be considered in which weighting coefficients are set by assigning different weights to the inside and outside of the edge enhancement ROI so that information within the edge enhancement ROI is given more importance than information outside the ROI.

In addition, in this embodiment, an edge-enhancement ROI is applied to the original images of the acquired DR and the created DRR, and the patient positioning calculation process is performed using information only within the edge-enhancement ROI, but this is not limited to this. Calculation processing may also be performed using the edge-enhancement ROI on edge-enhancement images obtained by applying edge enhancement processing to the original images of the DR and DRR.

The above-described embodiments of the present invention are illustrative and are not intended to limit the scope of the present invention, and various modifications are included. For example, the above-described embodiments have been described in detail to provide an easy-to-understand explanation of the present invention, and are not necessarily limited to those having all of the configurations described.

It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace part of the configuration of each embodiment with another configuration.

In this embodiment, a particle beam therapy system is exemplified, but it may be a broader radiation therapy system. For example, the configuration and method for patient positioning exemplified in this embodiment are broadly applicable to radiation therapy systems. As an example, the accelerator 1 described in this embodiment may be an electron beam accelerator intended for therapeutic X-rays, or a particle beam accelerator such as a proton or carbon beam accelerator.

Furthermore, the above-mentioned configurations, functions, processing units, processing means, etc. may be realized in hardware, in part or in whole, for example by designing them as integrated circuits. Furthermore, the above-mentioned configurations, functions, etc. may be realized in software, by a processor interpreting and executing a program that realizes each function. Information on the programs, tables, files, etc. that realize each function can be stored in a memory, a recording device such as a hard disk or SSD, or a recording medium such as an IC card, SD card, or DVD.

In addition, the control lines and information lines shown are those considered necessary for the explanation, and not all control lines and information lines on the product are necessarily shown. In reality, it can be assumed that almost all components are interconnected.

The above disclosure includes the items listed below. However, the items included in this disclosure are not limited to those listed below.

(1) a pseudo-perspective X-ray image creation unit that acquires a three-dimensional image of a target structure, which is a structure contained in the human body and used for positioning, from a three-dimensional image used to create a treatment plan for irradiating a patient with a particle beam in particle beam therapy, by extracting the target structure based on the density of the target structure, and creates a pseudo-perspective X-ray image by projecting the three-dimensional image of the target structure onto a predetermined surface;
an edge enhancement processing unit that performs processing for enhancing edges on the pseudo fluoroscopic X-ray image to create an edge-enhanced pseudo fluoroscopic X-ray image;
a region of interest acquisition unit that acquires a first region of interest including a region of the target structure in the edge-enhanced pseudo-fluoroscopic X-ray image;
an edge-enhanced region-of-interest creating unit that creates a second region of interest including a contour of the target structure that appears as the edge in the edge-enhanced pseudo perspective X-ray image, based on the edge-enhanced pseudo perspective X-ray image and the first region of interest;
an image matching unit that calculates a movement amount for moving the bed based on a fluoroscopic X-ray image obtained by capturing an X-ray fluoroscopy of the patient placed on a bed, the pseudo fluoroscopic X-ray image or the edge-enhanced pseudo fluoroscopic X-ray image, and the second region of interest so that a position of the target structure in the fluoroscopic X-ray image coincides with a position of the target structure in the pseudo fluoroscopic X-ray image;
A positioning device having

This allows a precise second region of interest that includes the contour of the target structure to be created from a first region of interest that is relatively easy to create and includes the area of the target structure, and the amount of movement is calculated using this second region of interest, making it easy to perform accurate patient positioning.

(2) The positioning device according to (1) above, wherein the edge-enhanced region of interest creation unit creates the second region of interest so as to include an overlapping portion of the edge in the edge-enhanced pseudo-fluoroscopic X-ray image with the first region of interest. This allows the second region of interest to be created so as to include an overlapping portion of the edge in the edge-enhanced pseudo-fluoroscopic X-ray image with the first region of interest, making it easy to create the second region of interest.

(3) The positioning device according to (2) above, wherein the edge-enhanced region of interest creation unit sets the second region of interest to a strip-shaped region obtained by expanding a linear portion of the edge in the edge-enhanced pseudo-fluoroscopic X-ray image where the edge and the first region of interest overlap by a predetermined width. This allows the second region of interest to be created so as to include the portion of the edge in the edge-enhanced pseudo-fluoroscopic X-ray image where the edge and the first region of interest overlap, making it easy to create the second region of interest.

(4) The positioning device according to (1) above, wherein the region of interest acquisition unit displays the edge-enhanced pseudo-fluoroscopic X-ray image on a screen, extracts a continuous region including a position on the screen where a click operation was performed and having pixel values within a predetermined range from the pixel value of the position, and sets the region as the first region of interest. As a result, the edge-enhanced pseudo-fluoroscopic X-ray image is displayed on the screen, and a continuous region having pixel values within a predetermined range from the pixel value of the position on the screen where a click operation was performed is set as the first region of interest, making it possible to easily create the first region of interest by a click operation.

(5) The edge-enhanced region of interest creation unit displays on a screen an image of an overlapping portion where the edge in the edge-enhanced pseudo-fluoroscopic X-ray image and the first region of interest overlap, creates a second region of interest within the first region of interest so as to include a first designated portion designated by a first operation by the user, and creates a region of indifference within the second region of interest so as to include a second designated portion designated by a second operation by the user,

the image matching unit calculates the amount of movement by a calculation in which a portion of the second region of interest that is not the region of indifference is weighted higher than a portion of the region of indifference based on the fluoroscopic X-ray image, the pseudo fluoroscopic X-ray image or the edge-enhanced pseudo fluoroscopic X-ray image, the second region of interest, and the region of indifference.
The positioning device described in (1) above.

This allows the overlapping portion where the edge and the first region of interest overlap to be displayed on the screen, and a second region of interest and a region of indifference can be created from the overlapping portion through user operation, making it easy to create the second region of interest and the region of indifference.

(6) The positioning device described in (1) above, wherein the region of interest acquisition unit displays the edge-enhanced pseudo-fluoroscopic X-ray image on a screen to prompt the user to draw the first region of interest, and displays the drawn first region of interest on the screen superimposed on the edge-enhanced pseudo-fluoroscopic X-ray image.

(7) The positioning device described in (6) above, in which the edge-enhanced region of interest creation unit creates the second region of interest and displays the second region of interest on the screen superimposed on the edge-enhanced pseudo-fluoroscopic X-ray image.

(8) A particle beam therapy system using a positioning device described in any one of (1) to (7) above.

(9) obtaining a three-dimensional image of a target structure, which is a structure contained in a human body and used for positioning, from a three-dimensional image used to create a treatment plan for irradiating a patient with a particle beam in particle beam therapy, based on the density of the target structure; and generating a pseudo-fluoroscopic X-ray image by projecting the three-dimensional image of the target structure onto a predetermined surface;
performing edge enhancement processing on the pseudo fluoroscopic X-ray image to generate an edge-enhanced pseudo fluoroscopic X-ray image;
obtaining a first region of interest including a region of the target structure in the edge-enhanced pseudo-fluoroscopic X-ray image;
creating a second region of interest based on the edge-enhanced pseudo-fluoroscopic X-ray image and the first region of interest, the second region of interest including a contour of the target structure that appears as the edge in the edge-enhanced pseudo-fluoroscopic X-ray image;
calculating a movement amount for moving the bed so that a position of the target structure in the fluoroscopic X-ray image coincides with a position of the target structure in the pseudo fluoroscopic X-ray image, based on a fluoroscopic X-ray image obtained by photographing the patient placed on a bed by X-ray fluoroscopy, the pseudo fluoroscopic X-ray image or the edge-enhanced pseudo fluoroscopic X-ray image, and the second region of interest;
Positioning method.

A...Particle beam therapy system, 1...Accelerator, 2...Beam transport device, 3...Gantry, 4...Irradiation nozzle, 5A...Planar detector, 5B...Planar detector, 6A...X-ray tube, 6B...X-ray tube, 7...Bed, 8...Robot arm, 9...Patient, 10...Treatment planning device, 11...Communication device, 12...Data server, 14...Fluoroscopy X-ray image capture device, 15...Bed control device, 20...Patient positioning device, 21...Pseudo fluoroscopy X-ray image creation unit, 22...ROI drawing unit, 23...Edge enhancement processing unit, 24...Edge-enhanced ROI creation unit, 25...Image matching unit, 50...Target structure, 60...Reference position, 61...Search pixel, 200...Pseudo fluoroscopy X-ray image, 201...Edge-enhanced pseudo fluoroscopy X-ray image, 301...Edge-enhanced ROI

Claims (8)

a pseudo-perspective X-ray image creation unit that acquires a three-dimensional image of a target structure by extracting a target structure, which is a structure contained in the human body and used for positioning, from a three-dimensional image used for creating a treatment plan for irradiating a patient with radiation in radiation therapy based on the density of the target structure, and creates a pseudo-perspective X-ray image by projecting the three-dimensional image of the target structure onto a predetermined surface;
an edge enhancement processing unit that performs processing for enhancing edges on the pseudo fluoroscopic X-ray image to create an edge-enhanced pseudo fluoroscopic X-ray image;
a region of interest acquisition unit that acquires a first region of interest including a region of the target structure in the edge-enhanced pseudo-fluoroscopic X-ray image;
an edge-enhanced region-of-interest creating unit that creates a second region of interest including a contour of the target structure that appears as the edge in the edge-enhanced pseudo perspective X-ray image, based on the edge-enhanced pseudo perspective X-ray image and the first region of interest;
an image matching unit that performs image matching between the fluoroscopic X-ray image and the pseudo fluoroscopic X-ray image or the edge-enhanced pseudo fluoroscopic X-ray image based on a fluoroscopic X-ray image of the patient placed on a bed taken by X-ray fluoroscopy, the pseudo fluoroscopic X-ray image or the edge-enhanced pseudo fluoroscopic X-ray image, and the second region of interest, thereby calculating an amount of movement for moving the bed so that a position of the target structure in the fluoroscopic X-ray image coincides with a position of the target structure in the pseudo fluoroscopic X-ray image;
having
the edge-enhanced region-of-interest creation unit displays on a screen an image of an overlapping portion where the edge in the edge-enhanced pseudo fluoroscopic X-ray image and the first region of interest overlap, creates a second region of interest within the first region of interest so as to include a first designated portion designated by a first operation by a user, and creates a region of indifference within the second region of interest so as to include a second designated portion designated by a second operation by the user;
the image matching unit calculates the amount of movement by a calculation in which a portion of the second region of interest that is not the region of indifference is weighted higher than a portion of the region of indifference based on the fluoroscopic X-ray image, the pseudo fluoroscopic X-ray image or the edge-enhanced pseudo fluoroscopic X-ray image, the second region of interest, and the region of indifference.
Positioning device. the edge-enhanced region-of-interest creation unit creates the second region of interest so as to include an overlapping portion of the edge in the edge-enhanced pseudo fluoroscopic X-ray image and the first region of interest.
The positioning device according to claim 1 . the edge-enhanced region-of-interest creation unit defines, as the second region of interest, a strip-shaped region obtained by expanding a linear portion where the edge and the first region of interest in the edge-enhanced pseudo fluoroscopic X-ray image overlap by a predetermined width;
The positioning device according to claim 2 . the region of interest acquisition unit displays the edge-enhanced pseudo-fluoroscopic X-ray image on a screen, extracts a continuous region including a position where a click operation has been performed on the screen and having pixel values within a predetermined range from a pixel value of the position, and defines the extracted region as the first region of interest.
The positioning device according to claim 1 . the region of interest acquisition unit displays the edge-enhanced pseudo fluoroscopic X-ray image on a screen to prompt a user to draw the first region of interest, and displays the drawn first region of interest on the screen in a state superimposed on the edge-enhanced pseudo fluoroscopic X-ray image.
The positioning device according to claim 1 . When the edge-enhanced region-of-interest creating unit creates the second region of interest, the edge-enhanced pseudo fluoroscopic X-ray image is displayed on a screen in a superimposed manner with the second region of interest.
The positioning device according to claim 1 . A radiotherapy system comprising a positioning device according to any one of claims 1 to 6 . A three-dimensional image of a target structure is obtained by extracting a target structure, which is a structure contained in a human body and used for positioning, from a three-dimensional image used for creating a treatment plan for irradiating a patient with radiation in radiation therapy, based on the density of the target structure, and creating a pseudo-fluoroscopic X-ray image by projecting the three-dimensional image of the target structure onto a predetermined surface;
performing edge enhancement processing on the pseudo fluoroscopic X-ray image to generate an edge-enhanced pseudo fluoroscopic X-ray image;
obtaining a first region of interest including a region of the target structure in the edge-enhanced pseudo-fluoroscopic X-ray image;
creating a second region of interest based on the edge-enhanced pseudo-fluoroscopic X-ray image and the first region of interest, the second region of interest including a contour of the target structure that appears as the edge in the edge-enhanced pseudo-fluoroscopic X-ray image;
a fluoroscopic X-ray image of the patient placed on a bed taken by X-ray fluoroscopy, the pseudo fluoroscopic X-ray image or the edge-enhanced pseudo fluoroscopic X-ray image, and the second region of interest, and by comparing the fluoroscopic X-ray image with the pseudo fluoroscopic X-ray image or the edge-enhanced pseudo fluoroscopic X-ray image, a movement amount for moving the bed is calculated so that a position of the target structure in the fluoroscopic X-ray image coincides with a position of the target structure in the pseudo fluoroscopic X-ray image;
In the positioning method,
displaying an image of an overlapping portion where the edge in the edge-enhanced pseudo fluoroscopic X-ray image and the first region of interest overlap on a screen, creating a second region of interest within the first region of interest so as to include a first designated portion designated by a first operation by a user, and creating a region of indifference within the second region of interest so as to include a second designated portion designated by a second operation by the user;
calculating the amount of movement by a calculation in which a portion of the second region of interest that is not the region of indifference is weighted higher than a portion of the region of indifference based on the fluoroscopic X-ray image, the pseudo fluoroscopic X-ray image or the edge-enhanced pseudo fluoroscopic X-ray image, the second region of interest, and the region of indifference;
Positioning method.

Images