JP2817609B2 - Radiation treatment planning image imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiotherapy planning image capturing apparatus for obtaining information useful in radiotherapy planning, such as, for example, the dose distribution in the body of a subject and the positional relationship of organs.

[0002]

2. Description of the Related Art An X-ray tube provided with a collimator for regulating an opening angle of an irradiated X-ray and an X-ray irradiation thickness, and an X-ray detector are attached to an opening so as to face each other. A gantry that rotates in synchronization with the detector and a subject are placed,
A diagnostic CR (Computed Radio) using an X-ray CT apparatus including an X-ray tube in an opening of a gantry and a top plate for reciprocating an imaging position of a subject with respect to an imaging center of an X-ray detector.
The imaging of an image (also referred to as “graphy,” also referred to as “scout view”) is controlled and performed as follows.

That is, an X-ray tube is positioned above a subject on a tabletop, and one end of a predetermined imaging region (for example, from the neck to the knee) is positioned between the X-ray tube and the X-ray detector. While moving the couchtop so that it is located at the imaging center of, while irradiating X-rays from the X-ray tube located above the subject,
The top plate is moved so that the imaging position of the subject is displaced from one end to the other end of the imaging region, and a CR image in the imaging region is captured.

[0004]

However, the prior art having such a structure has the following problems. That is, in the imaging of the diagnostic CR image, only a CR image obtained by irradiating X-rays from above the subject is obtained. However, the CR image viewed from the irradiation direction of the X-ray irradiating the subject during the radiation treatment, that is,
A CR image or the like obtained by irradiating the subject with X-rays from the X-ray irradiation direction at the time of radiation treatment is useful information when performing a radiation treatment plan.
There is a problem in that it is not possible to obtain useful information such as a CR image when planning a radiation treatment.

[0005] The present invention has been made in view of such circumstances, and C regions obtained by irradiating X-rays from various directions on a subject to a region necessary for a radiation treatment plan.
It is an object of the present invention to provide a radiotherapy planning image capturing apparatus capable of obtaining useful information for radiotherapy planning including an R image.

[0006]

The present invention has the following configuration to achieve the above object. That is, according to the first aspect of the present invention, (1-a) an X-ray tube provided with a collimator for regulating an opening angle of an irradiated X-ray and an X-ray irradiation thickness is opposed to an X-ray detector. A gantry that is attached to an opening and rotates the X-ray tube and the X-ray detector in synchronization with each other; (1-b) a subject is placed on the gantry, and the X-ray tube in the opening of the gantry and the gantry (1-c) rotating the X-ray tube and the X-ray detector with respect to the imaging center of the X-ray detector to reciprocate the imaging position of the subject; An arrangement angle adjusting means for adjusting an arrangement angle of the X-ray tube with respect to a mounted subject to an arbitrary arrangement angle; and (1-d) the gantry in a body axis direction of the subject mounted on the top plate. Gantry tilting means for tilting
(1-e) an imaging width including a specific portion of the subject placed on the top, an arrangement angle of the X-ray tube with respect to the subject placed on the top, a tilt angle of the gantry, And setting means for setting a plurality of X-ray tube arrangement angles, (1-f) display means for displaying a captured image, and (1-g) display means for displaying on the display means. CR
(Scout view) designating means for designating a CT scan position with respect to the image; (1-h) positioning the X-ray tube at the arrangement angle set by the setting means, and using the tilt angle set by the setting means While tilting the country, in this state, while irradiating X-rays from the X-ray tube, the top plate is displaced from one end of the set imaging width to the other end of the imaging position of the subject. The X-ray tube is moved and controlled to capture a CR image of an area within the set imaging width. When a plurality of arrangement angles of the X-ray tube are set, the X-ray tube of the set X-ray tube is set. The control for each arrangement angle is performed continuously, and the captured CR image is displayed on the display means, and the CT scan position designated by the designation means is taken in the CR image displayed on the display means. , Designated CT scan Wherein the catcher down position and the X-ray tube X
The table is moved so as to be positioned at the imaging center of the line detector, a CT slice image at a designated CT scan position is captured, and the captured CT slice image is displayed together with the captured CR image with the display means. And control means for controlling to display the designated CT scan position on the displayed CR image.

According to a second aspect of the present invention, there is provided a radiotherapy planning image capturing apparatus according to the first aspect.
X-ray focus changing means for changing the distance between the X-ray tube attached to the gantry and the subject on the tabletop, wherein the setting means is configured to perform imaging including a specific portion of the sample placed on the tabletop. The width and the X with respect to the subject placed on the top plate
In addition to setting the arrangement angle of the ray tube and the tilt angle of the gantry, the distance between the X-ray tube and the subject can also be set. And a control for adjusting a distance between the X-ray tube and the subject to a set distance set by the setting means.

[0008]

The operation of the first aspect of the invention is as follows. The operator uses the setting unit to specify a specific part of the subject (for example,
The imaging width including the tumor to be subjected to radiation treatment, etc., and the arrangement angle of the X-ray tube with respect to the subject (for example, the irradiation direction of the X-ray irradiating the subject during radiation treatment around the body axis of the subject) Angle) and a tilt angle of the gantry (for example, an angle corresponding to the direction of irradiation of the subject in the body axis direction of X-rays to be applied to the subject during radiation treatment). The operator sets a plurality of X-ray tube arrangement angles as necessary.

The control means controls the arrangement angle adjusting means so as to position the X-ray tube at the arrangement angle set by the setting means, rotates the X-ray tube and the X-ray detector in the gantry, and sets the setting means. The gantry tilting means is controlled so that the gantry is tilted at the tilt angle set in the above. And
In this state, the control unit moves the top plate so that the imaging position of the subject is displaced from one end to the other end of the set imaging width while irradiating X-rays from the X-ray tube. X is controlled so as to capture a CR image of an area within the set imaging width, and X
A CR image viewed from a direction in which X-rays are emitted is taken from the arrangement angle of the tube.

When a plurality of X-ray tube arrangement angles are set, the control means continuously performs the control for each of the set X-ray tube arrangement angles, and sets the set X-ray tube.
A plurality of CR images as viewed from the direction in which X-rays are radiated are taken from each arrangement angle of the tube.

The control means displays a plurality of captured CR images on the display means. The surgeon looks at the CR image displayed on the display means, and specifies the CT scan position from the specifying means for the displayed CR image. The control means captures the designated scan position, moves the tabletop so that the designated CT scan position is located at the imaging center of the X-ray tube and the X-ray detector, and moves the CT at the designated CT scan position. Capture a slice image. Then, the captured CT slice image is displayed on the display unit together with the already captured CR image as described above, and the CT scan position is displayed on the displayed CR image.

According to the second aspect of the present invention, the operator uses the setting means to set an imaging width including a specific portion of the subject placed on the top plate and the subject placed on the top plate. In addition to setting the arrangement angle of the X-ray tube and the tilt angle of the gantry, the distance between the X-ray tube and the subject is also set. This distance is, for example, the irradiation distance of X-rays that are irradiated to a tumor or the like (a target of radiation treatment) in a subject during radiotherapy (an X-ray generator that generates X-rays for treatment with a tumor or the like in the subject). Is set in accordance with the distance between.

The control means also controls the distance between the X-ray tube and the subject to be adjusted to the set distance set by the setting means when the CR image is picked up. I do.

By performing the above-described control to capture a CR image, a CR image obtained by irradiating the subject with X-rays in accordance with the irradiation distance of the irradiated X-rays to the subject during radiotherapy can be obtained. Useful information for radiation treatment planning, such as dose distribution in the body according to conditions, can be obtained.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. First, prior to describing an embodiment of the present invention, the configuration and operation of a radiation treatment planning image capturing apparatus, which is a basis for describing the embodiment of the present invention, will be described.
FIG. 1 is a front view showing a configuration of a radiotherapy planning image capturing apparatus which is a basis for explaining an embodiment of the present invention. FIG. 2 shows a relationship between a subject on a top plate and a gantry. FIG. 3 is a plan view showing a positional relationship between a subject, a gantry, and a laser marker on a top plate, and FIG. 4 is for explaining a configuration of an angle detection mechanism for detecting an arrangement angle of an X-ray tube. FIG.

1 and 2, reference numeral 1 denotes a gantry.
An X-ray tube 3 and an X-ray detector 4 are rotatably attached to the opening 2 of the gantry 1 in a state where they face each other. The X-ray tube 3 is provided with a collimator 5, and the opening angle α of the X-ray emitted from the X-ray tube 3 (see FIG. 2) and the thickness t of the irradiated X-ray (see FIG. 1) are regulated. It is configured to be. The X-ray tube 3 and the X-ray detector 4 are connected to a rotating frame 6. The rotating frame 6 is configured to be rotated by a motor 7 provided in the gantry 1.
By rotating the rotating frame 6 in the forward and reverse directions, the X-ray tube 3 is rotated.
The X-ray detector 4 and the X-ray detector 4 are rotated in the opening 2 in a state where they face each other. The rotation of the motor 7 is controlled by a control unit 21 described later.

The rotation angle between the X-ray tube 3 and the X-ray detector 4 is configured to be detected by an angle detection mechanism. As shown in FIG. 4, this angle detection mechanism
And a transmission optical sensor 9 for detecting the number of the holes 8 passed during rotation of the rotary frame 6 and outputting a pulse signal each time the hole 8 passes. It is composed of For example, the state where the X-ray tube 1 is at the uppermost position (the state shown in FIG. 2) is defined as a reference position (the angle at this time is “0 °”
When the rotating frame 6 is rotated from that state, the optical sensor 9 outputs pulse signals corresponding to the number of the holes 8 that have passed. The number of pulse signals is equal to the rotation angle of the X-ray tube 3 (or X-ray detector 4) with respect to the reference position (1 ° /
1 pulse). In addition, for example, when the rotation of the rotating frame 6 is rotated clockwise in FIG. 2 as normal rotation and the rotation angle of the X-ray tube 3 is recognized as an absolute angle of 0 ° to 359 °, The rotation angle of the X-ray tube 3 can be detected from the rotation direction (the rotation direction of the motor 7) and the number of the pulse signals. For example, if the rotating frame 6 is rotated clockwise from the state where the X-ray tube 3 is at the reference position and the number of pulse signals is “30”, the X-ray tube 3 has an absolute angle of “30 °”. From the state in which the X-ray tube 3 is at the reference position, the rotating frame 6 is rotated counterclockwise, and if the number of pulse signals is “30”, the X-ray tube 3 becomes “330 °” in absolute angle. "Can be detected. Further, in order to position the X-ray tube 1 at the reference position, a light-shielding plate 10 is attached to the outer periphery of the rotating frame 6 facing the X-ray tube 3, and the light-shielding plate 10 is used to measure the second transmission optical sensor 11 When the light is blocked, the rotation of the motor 7 is stopped. The output signal from the second optical sensor 11 is given to a control unit 21 described later, and the control unit 21 controls the X-ray tube 3 to be positioned at a reference position. An output pulse signal from the optical sensor 9 of the angle detection mechanism is also given to the control unit 21. The control unit 21 uses the pulse signal for controlling the X-ray tube 3 at a set angle as described later. I have. The angle detecting mechanism and the motor 7 constitute an arrangement angle adjusting means in the present invention.

Returning to FIGS. 1 and 2, a base 12 which can be moved up and down is installed near the gantry 1. As shown in FIG. This base 1
On top of the gantry 1, a table 13 on which the subject M is placed is placed.
Is mounted so as to be able to reciprocate while sliding within the opening 2 of the camera. That is, by reciprocating the top 13 on which the subject M is placed, the imaging position of the subject M on the top 13 is reciprocated with respect to the imaging center of the X-ray tube 3 and the X-ray detector 4. It is possible to do. The reciprocating movement of the top plate 13 is performed by the motor 1 installed in the base 12.
4 is performed by the forward and reverse rotation. The rotation of the motor 14 is controlled by a control unit 21 described later.

As shown in FIG. 3, near the gantry 1 on the side where the subject M is inserted into the opening 2 of the gantry 1, a laser for irradiating the subject M on the top plate 13 with a laser beam. A marker 15 is provided. This laser marker 15 is used to set the imaging position of the subject M as described below.
This is for positioning the X-ray detector 4 and the X-ray detector 4 when positioning them at the imaging center.

In FIG. 1, reference numeral 20 denotes a setting panel provided with a switch for inputting various data, an instruction switch, and the like. From the setting panel 20, for example, as shown in FIG. 5A, an imaging width HW centered on a specific portion TP of the subject M (for example, a position where a tumor to be subjected to radiation treatment is present).
5B, the arrangement angle θ of the X-ray tube 3 with respect to the subject M (for example, in the irradiation direction around the body axis of the subject M of X-rays that irradiate the subject M during radiation treatment). Corresponding angle) is set. The arrangement angles θ are configured so that a plurality (for example, five) can be set, and the arrangement angles θ are configured to be set by the above-described absolute angles. The setting panel 20 is also configured to give an imaging start instruction, an imaging position alignment instruction, designation of a CT slice position, and the like.

In response to an instruction to start imaging from the setting panel 20, the control unit 21 controls the driving of the motors 7 and 14 and X and the like so as to capture a CR image in accordance with the data set from the setting panel 20, as described later. It is configured to perform control of X-ray irradiation from the ray tube 3, control of the image processing unit 22, and the like. In addition, the control unit 21 controls the imaging of the CT slice image at the set CT scan position, and controls the obtained C slice image.
It is configured to perform control such as clarifying the positional relationship between the R image and the CT slice image.

The image processing unit 22 performs a process of reconstructing a CR image or a CT slice image based on the detection data detected by the X-ray detector 4 while being controlled by the control unit 21.
The image reconstructed by the image processing unit 22 is displayed on the monitor 23 under the control of the control unit 21. This monitor 23
This corresponds to the display means in the present invention.

Next, the operation of the above apparatus will be described with reference to the flowchart of FIG. 6 and each of FIGS. 7 to 12.

Before starting the processing of the flowchart of FIG. 6, the operator sets the imaging width HW and the X-ray tube 3 from the setting panel 20.
Is set in advance. The following operation will be described assuming that _five arrangement angles θ ₁ to θ ₅ shown in FIG. 7 are set as the arrangement angles of the X-ray tube 3.

First, when the start of imaging is instructed from the setting panel 20 by the operator, the control section 21 inserts the top 13 on which the subject M is placed into the opening 2 of the gantry 1. The motor 14 is driven to move the motor 14 (step S
1, S2).

At this time, from the laser marker 15,
The laser light is emitted toward the subject M, and the irradiation position of the laser light moves from the head of the subject M toward the foot as the top plate 13 moves. While observing the irradiation position of the laser beam, the surgeon gives an imaging position alignment instruction from the setting panel 20 when the laser beam irradiates the specific portion TP of the subject M. In addition, this specific site TP is
For example, it is determined before the operator diagnoses a diagnostic CR image, CT slice image, or the like that has been captured in advance, and performs this processing.

When this instruction is given, the control unit 21
The top 13 is moved so that the end of the imaging width HW on the base 12 side is located at the imaging center of the X-ray tube 3 and the X-ray detector 4 (Step S3). As shown in FIG. 8, the distance L between the position where the laser marker 15 irradiates the subject M and the imaging center is specified when the gantry 1 and the laser marker 15 are installed, and is based on the imaging width HW. The distance (L + HW / 2) for moving the end on the table 12 side to the imaging center is specified because the imaging width HW is set. On the other hand, the moving distance of the top 13 can be controlled by the number of rotations of the motor 14, so the control unit 21 sets the top 13 to (L + HW /
The drive of the motor 14 may be controlled so as to move the distance 2). The imaging width HW is not limited to the case where the specific portion TP is set as a center. For example, the length between the specific portion TP and the end of the imaging width on the gantry 1 side, and the length between the specific portion TP and the base 12 side It may be set from the setting panel 20 with a different length from the end of the imaging width. In this case, the control unit 21 controls the top plate 13 to move by a length obtained by adding the length between the specific portion TP and the end of the imaging width on the base 12 side and the above L. Good.

When the end of the imaging width HW on the side of the base 12 is positioned at the imaging center, the control unit 21 determines the number of set arrangement angles θ _{1 to} θ ₅ of the X-ray tube 3 ( ₅ in this case). ) times, repeat steps S4~S6 follows (step S7), and images the CR image in a state where the X-ray tube 3 is disposed in the arrangement angle theta ₁ through? _5.

In step S4, the control unit 21 controls the rotating frame 6 so that the X-ray tube 3 is positioned at the set arrangement angle.
To rotate. That is, the control unit 21 sets the first CR
When capturing an image, control is performed so that the X-ray tube 3 is positioned at the set first arrangement angle θ ₁ , and the second C
When imaging the R image is controlled so as to position the X-ray tube 3 to a second arrangement angle theta ₂ which is set, similarly hereinafter, when imaging the 5 th CR image is set the arrangement angle theta ₅ of the fifth controlled so as to position the X-ray tube 3. Note that the control unit 21 positions the X-ray tube 3 at the reference position (the position of the X-ray tube 3 shown in FIG. 2) before the start of the flowchart in FIG. Therefore, as shown in FIG. 7, when capturing the first CR image, θ ₁ is set to “0”.
° ”, the control unit 21 does not rotate the rotating frame 6. When capturing the second CR image, θ ₂
Is “45 °”, the control unit 21 drives the motor 7 to rotate the rotating frame 6 in the forward direction (clockwise),
The pulse signal supplied from the optical sensor 9 of the angle detection mechanism is counted, and when the counted number reaches “45”, the rotation of the motor 7 is stopped. Further, when capturing the third CR image, θ ₃ is “90 °”, and when capturing the second CR image, the X-ray tube 3 sets “4”.
5 ° ”, the motor 7 is driven to rotate the rotating frame 6 in the forward direction, and the count of the pulse signal given from the optical sensor 9 of the angle detection mechanism is“ 45 ”( 90-45), the motor 7
Stop the rotation of. Thereafter, similarly, the X-ray tube 3 is moved to each arrangement angle.

In step S5, X-rays are emitted from the X-ray tube 3, and the imaging position of the subject M on the table 13 is set to the imaging width HW.
The top plate 13 is moved by HW so as to be displaced from the end side of the base 12 side to the other end side, and the image processing unit 22 performs the setting based on the data detected by the X-ray detector 4. The CR image of the region within the captured imaging width HW is reconstructed, and the monitor 23
To be displayed. FIG. 9A shows the first CR image obtained.
As shown in the figure, the X-ray tube 3 is arranged at the set arrangement angle θ ₁ and is imaged by irradiating with X-rays, and each of the second to fifth CR images is obtained. Fig. 9 (b)
As shown in (e), the X-ray tube 3 is imaged by irradiating X-rays while being arranged at the set arrangement angles θ _{2 to} θ ₅ , respectively. Each of the obtained CR images is
The images are reduced and multi-displayed on the monitor 23. The display control is performed by the control unit 21.

When the imaging of one CR image in step S5 is completed, the end of the imaging width HW on the base 12 side is positioned at the imaging center for imaging of the next CR image. The top plate 13 is moved by HW in the reverse direction (step S6). Note that, also in the movement of the HW in steps S5 and S6, the control unit 21 controls the rotation speed of the motor 14 as described in step S3.

[0032] When the step S7 is completed, imaged the X-ray tube 3 while being disposed in the arrangement angle theta ₁ through? ₅ 5
One CR image is obtained. This is shown in FIG. In the figure, reference numeral Z ₁ to Z ₃ are the organs, S _1, S ₂ represents the tumor, respectively. These CR images G1 to G5 are the X-ray subject M irradiated to the subject M during the radiotherapy, respectively.
Are obtained by irradiating X-rays from the irradiation direction around the body axis (the angle of the X-ray tube 3). Therefore, the surgeon views the dose distribution in the body and the positional relationship between the organs Z _{1 to} Z ₃ around the tumors S ₁ and S _{2 to be} subjected to the radiation treatment, as viewed from the direction of X-ray irradiation during the treatment. Etc., so that an appropriate radiation treatment plan can be made. In FIG. 10,
CR image area on the image width HW around the tumor S ₂ is imaged.

In the above description, the arrangement angle of the X-ray tube 3 is 5
Individually, X-rays were emitted from five directions to capture five CR images. For example, the direction of X-ray irradiation on the subject M around the body axis of the subject M when performing radiation therapy Is only one direction, at least a CR image irradiated with X-rays from that direction can be obtained.
You only need to set the number.

By the way, in this apparatus, in order to obtain useful data for a radiotherapy plan, the processing in the following steps S8 to S10, that is, the position (for example, , Tumor S ₁ , S
It is configured to execute a process of capturing a CT slice image at (a certain position ₂ ).

First, the CT scan position set by the operator based on each of the obtained CR images is captured (step S).
8). In other words, the surgeon looks at each of the CR images G1 to G5 reduced and displayed on the monitor 23 and instructs from the setting panel 20 a position to perform a CT scan in order to obtain particularly detailed information. At this time, the operator sets an arbitrary CR image from the CR images G1 to G5 multi-displayed on the monitor 23 on the setting panel 2
The designated CR image is enlarged and displayed on the monitor 23 by designating from 0, and an arbitrary position on the CR image is designated from the setting panel 20. The control unit 21 captures the CT position on the CR image set by the operator. A plurality of CT scan positions can be designated. Display control such as an enlarged display of the CR image is performed by the control unit 21.

Next, the controller 21 captures a CT slice image at the set CT scan position (step S).
9). First, the amount of movement of the top 13 is specified based on the CT scan position set on the CR image. For example, as shown in FIG. 11, a length LCT1 from the end of the imaging width HW of the CR image on the base 12 side to the first CT scan position CTP1 set is obtained as follows. That is, C
Assuming that the number of pixels of the CR image from the end on the base 12 side of the imaging width HW of the R image to the first CT scan position CTP1 is GL, and the number of pixels of the CR image of the imaging width HW is GW, Since the actual length is (HW / GW), LCT1 is obtained by GL × (HW / GW). Similarly, the amount of movement LCT2 of the tabletop 2 from the first CT scan position CTP1 to the second CT scan position CTP2 is CTP
Based on the number of pixels GL2 of the CR image between 1 and CTP2 and the actual length per pixel (HW / GW), GL2 ×
(HW / GW).

When the above-described step S7 is completed, since the end of the CR image on the base 12 side of the imaging width HW is located at the imaging center, first, the top plate 13 is moved by the LCT1 and the base 1
In two directions, the designated position CTP1 is positioned at the center of the imaging, and the X-ray tubes 3 and X
The X-ray detector 4 makes one round around the subject M, and the image is re-combined by the image processing unit 22 based on the data detected by the X-ray detector 4, thereby obtaining the first CT scan position CTP1.
Is obtained. The captured CT slice image is displayed on the monitor 23 under the control of the control unit 21.
Next, the top plate 13 is moved in the direction of the base 12 by LCT2, and a CT slice image at the second CT scan position CTP2 is captured and displayed on the monitor 23.

When all the CT slice images (CT1, CT2) at the set CT scan position are captured, the monitor 23
The CT scan position is displayed on each CR image displayed in (1) (Step S10). This is shown in FIG. In this way, by associating the positional relationship between each CR image and the obtained CT scan image, the dose distribution and the positional relationship of the organs can be known three-dimensionally. You can make a plan.

In performing the processing in step S3, when the laser beam is irradiated from the position where the subject M is placed on the top 13 (the initial position of the top 13) to the specific portion TP (position adjustment). By the time the instruction is given)
The amount of movement of the X-ray tube 3 is determined in advance, and the amount of movement and the set imaging width HW and the arrangement angle θ (θ _{1 to} θ
₅ ), the CT scan position (CTP1, CTP2, etc.) set in step S8, and the amount of movement (L
CT1, LCT2, etc.) are stored as a database for each subject M, so that 2
In the processing such as the imaging of the CR image and the CT scan image after the first time, the CR image and the CT scan image can be imaged under the same conditions without performing a complicated procedure such as data setting and alignment of the imaging position. . Therefore, it is convenient when performing continuous repetitive radiotherapy of the same subject.

The control unit 21 of this apparatus stores a diagnostic C
A function to perform control to capture an R image is added, and a diagnostic CR
It may be configured to be able to capture an image and a CR image for radiation therapy.

Next, the first embodiment of the present invention will be described. In addition to the above-described apparatus configuration, the first embodiment apparatus tilts the gantry 1 in the body axis direction of the subject M on the top plate 13 to irradiate the subject M with X-rays during radiation treatment. A function of irradiating X-rays from an angle corresponding to the irradiation direction in the body axis direction of M to capture a CR image is added. The first embodiment corresponds to the first aspect of the present invention.

First, the structure for tilting the gantry 1 is shown in FIG.
This will be described with reference to FIGS. FIG. 13 is a front view showing the tilting operation of the gantry of the first embodiment, and FIG. 14 is a gantry support member and a gantry base viewed from the side (the side where the subject is inserted into the opening of the gantry). 15A is a cross-sectional view of the gantry support member viewed from the side, FIG. 15B is a view of the gantry support member viewed from the front, and FIG. FIG. 16B is a plan view showing the configuration of the gantry base, and FIG.
16A is a cross-sectional view taken along the arrow A. FIG.
It is arrow sectional drawing.

As shown in the figure, a semi-circular support member 31 is attached to the bottom surface of the gantry 1 of the first embodiment, and the rack member 3 extends along the peripheral surface.
2 are provided, and a sled-shaped member 33 is attached to both sides of the support member 31. Meanwhile, gantry base 3
4 is provided with a concave portion 35 for accommodating a semicircular support member 31 attached to the gantry, and the concave portion 35 has a groove for accommodating the rack 32 provided on the semicircular support member 31. 36 and an arc-shaped groove 37 for accommodating the sled-shaped member 33. A pinion 38 meshing with the rack 32 is provided near the center of the groove 36. This pinion 38 is rotated by a motor 39 provided inside the gantry base 34. As shown in FIG. 14, the semicircular support member 31 of the gantry 1 is inserted into the recess 35 of the gantry base 34, the rack 32 is engaged with the groove 36 so as to mesh with the pinion 38, and the sled-shaped member 33 is inserted into the groove. 37 are slidably accommodated. At this time, the groove 37
Is formed longer than the length of the sled-shaped member 33. By rotating the motor 39 in the forward and reverse directions, the rack 32 slides in the groove 36, and accordingly, the sled-shaped member 33 slides in the groove 37, and the gantry 1 moves as shown in FIG. Is tilted in the body axis MJ direction of the subject M. In addition,
The drive control of the motor 39 is configured to be performed by the control unit 21.

In the first embodiment, the imaging width HW and the arrangement angle θ of the X-ray tube
In addition to (θ _{1 to} θ ₅ ), the tilt angle of the gantry 1 can be set. The tilt angle is determined by the X-ray subject M irradiated to the subject M during the radiation treatment.
The angle corresponding to the irradiation direction in the body axis MJ direction is set.
The setting panel 20 corresponds to the setting unit and the specifying unit according to the first aspect of the invention, and the control unit 21 corresponds to the control unit according to the first aspect of the invention.

The control unit 21 rotates the motor 39 between steps S3 and S4 in the flowchart of FIG. 6 to adjust the gantry 1 to the set tilt angle, and sets the set X-ray. X-rays are radiated from the arrangement angle θ of the tube 3 and CR of an area within the imaging width HW including the specific portion TP
Capture an image.

By capturing a CR image under such control, the position of the X-ray tube 3 with respect to the subject M, that is,
The irradiation direction of X-ray irradiation for CR image imaging
Around the body axis MJ (the X-ray tube arrangement angle θ) and the body axis M
It can be adjusted by the angle in the J direction (the tilt angle of the gantry 1). Therefore, a CR image irradiated with X-rays can be obtained from a direction that more faithfully reproduces the X-ray irradiation direction at the time of radiation treatment, so that more useful information can be obtained for a radiation treatment plan.

Next, the structure of the device which is the basis of the device according to the second embodiment of the present invention will be described with reference to FIG. The apparatus shown in FIG. 17 differs from the apparatus shown in FIG.
It is characterized in that the distance to the subject M can be arbitrarily changed.

More specifically, as shown in FIG. 17, the X-ray tube 3 (and the collimator 5) can be moved up and down with respect to the rotating frame 6. This moving mechanism is, for example, the R shown in FIG.
The rack is formed by rotating a rack extending in the direction and a pinion meshing with the rack in a forward and reverse direction by a motor. The rotation of the motor is controlled by the control unit 21.

Further, from the setting panel 20, in addition to the imaging width HW and the arrangement angle θ (θ _{1 to} θ ₅ ) of the X-ray tube 3 described above, the X-ray focal point of the X-ray tube 3 and the top 13 The distance SL to a specific part in the subject M above can be set. The distance SL is, for example, an irradiation distance of X-rays irradiated to a tumor or the like (a target of radiation treatment) in the subject M at the time of radiation treatment, that is, a distance between the tumor in the subject M and the treatment X-rays. Distance between the X-ray generator (for example,
(800 mm or 1000 mm).

The control unit 21 rotates the motor of the moving mechanism of the X-ray tube 3 between steps S3 and S4 in the flowchart of FIG. Distance S that sets the distance to the specific part
Is adjusted to L, X-rays are emitted from the set arrangement angle θ of the X-ray tube 3, and a CR image of an area within the imaging width HW centering on the specific portion TP is taken.

By capturing a CR image under such control, X-rays are irradiated according to the irradiation distance from the angle around the body axis of the subject M during the radiation treatment. A CR image can be obtained. Therefore, more useful information can be obtained for a radiation treatment plan, such as a dose distribution in the body according to the conditions at the time of radiation treatment.

As a second embodiment of the present invention, the structure shown in FIG. 17 for tilting the gantry 1 described in the first embodiment may be added. At this time, the setting panel 20
From the imaging width HW, the arrangement angle θ of the X-ray tube 3 (θ _{1 to} θ
₅ ) The distance SL between the X-ray focal point of the X-ray tube 3 and a specific part of the subject M on the top 13 and the tilt angle of the gantry 1 are set. Then, immediately before or immediately after adjusting the distance between the X-ray tube 3 and the subject M to the set distance SL, the control unit 21 adjusts the tilt angle of the gantry 1 by rotating the motor 37, X-rays are emitted from the set arrangement angle θ of the X-ray tube 3 to capture a CR image of a region within the imaging width HW centered on the specific portion TP. By controlling and imaging the CR image in this manner, the angle around the body axis and the body axis direction of the irradiation X-ray to the subject M during the radiotherapy is adjusted, and the X-ray is irradiated according to the irradiation distance. Since a CR image can be obtained, more useful information can be obtained for a radiation treatment plan, such as the dose distribution in the body and the positional relationship of organs according to the conditions during radiation treatment.

[0053]

As is apparent from the above description, according to the first aspect of the present invention, the imaging width including the specific portion of the subject, the arrangement angle of the X-ray tube with respect to the subject, and the tilting of the gantry The angle can be set, and the X-ray tube is arranged at the set arrangement angle, and the gantry is tilted at the set tilt angle to obtain a CR image of an area within the set imaging width. Therefore, the X-ray irradiation direction for CR image imaging can be adjusted by the angle around the body axis of the subject and the angle in the body axis direction, and the X-ray irradiation direction at the time of radiation treatment is reproduced more faithfully. A CR image irradiated with X-rays from a direction can be obtained, and useful information for planning radiotherapy can be obtained.

Further, since a plurality of X-ray tube arrangement angles can be set, it is possible to flexibly cope with a case of planning a radiotherapy in which the X-ray irradiation direction is performed from a plurality of directions during the radiotherapy. it can. In addition, when a plurality of X-ray tube arrangement angles are set, C
Since the imaging of the R image is continuously performed, a plurality of CR images from a plurality of X-ray irradiation directions can be sequentially and automatically obtained.

Further, C which is imaged and displayed on the display means
Specify the CT scan position for the R image, and
Since the CT slice image at the T-scan position is configured to be automatically captured, the surgeon can obtain a CT scan image of a part to be examined particularly in detail by looking at the captured CR image, More useful information can be obtained when planning radiation therapy.

Further, the captured CR image and CT slice image are displayed on the display means, and the displayed CR image displays the CT scan position. Therefore, the positional relationship between the CR image and the CT scan image is determined. Since it becomes clear and the dose distribution and the positional relationship of the organs can be known three-dimensionally, the operator can make a more appropriate radiation treatment plan.

According to the second aspect of the present invention, the distance between the X-ray tube and the subject can be further set, and the distance between the X-ray tube and the subject is set to the set distance. It is configured to capture a CR image adjusted to, so that a CR image irradiated with X-rays can be obtained according to the irradiation distance of the irradiated X-rays to the subject at the time of radiation treatment, and can be obtained according to the conditions at the time of radiation treatment. It is possible to obtain useful information for radiation treatment planning, such as dose distribution in the body.

[Brief description of the drawings]

FIG. 1 is a front view showing a configuration of a radiotherapy planning image capturing apparatus which is a basis for describing an embodiment of the present invention.

FIG. 2 is a side view showing a relationship between a subject on a top plate and a gantry.

FIG. 3 is a plan view showing a positional relationship among a subject, a gantry, and a laser marker on a top plate.

FIG. 4 is a diagram illustrating a configuration of an angle detection mechanism that detects an arrangement angle of an X-ray tube.

FIG. 5 is a diagram for explaining an imaging width set from a setting panel and an arrangement angle of an X-ray tube.

FIG. 6 is a flowchart showing the operation of the apparatus of FIG. 1;

FIG. 7 is a diagram showing an example of an arrangement angle of an X-ray tube set from a setting panel.

FIG. 8 is a diagram for explaining a moving amount of a top plate when one end of an imaging width is positioned at an imaging center.

FIG. 9 is a diagram showing an X-ray irradiation direction when capturing a CR image.

FIG. 10 is a diagram showing an obtained CR image.

FIG. 11 is a diagram for explaining an amount of movement of a top plate when moving a CT scan position to an imaging center.

FIG. 12 is a diagram illustrating an obtained CT scan image and a CR image indicating an imaging position of the CT scan image.

FIG. 13 is a front view showing the tilting operation of the gantry in the first embodiment of the present invention.

FIG. 14 is a cross-sectional view showing a configuration of a gantry support member and a gantry base.

FIG. 15 is a diagram showing a configuration of a gantry support member and the like.

FIG. 16 is a diagram showing a configuration of a gantry base.

FIG. 17 is a diagram showing a configuration of an apparatus serving as a basis of a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Gantry 2 ... Gantry opening 3 ... X-ray tube 4 ... X-ray detector 5 ... Collimator 6 ... Rotating frame 7, 14 ... Motor 13 ... Top plate 20 ... Setting panel 21 ... Control part M ... Subject TP ... Specific site HW ... imaging width θ, θ _{1 to} θ ₅ ... X-ray tube arrangement angle CT1, CT2 ... CT scan position

Claims (2)

(57) [Claims] 1. An X-ray tube provided with a collimator for regulating an opening angle of an irradiated X-ray and an X-ray irradiation thickness.
A gantry for mounting the X-ray tube and the X-ray detector in synchronization with each other and mounting the X-ray tube and the X-ray detector in opposition to the X-ray detector; With respect to the imaging center of the X-ray tube and the X-ray detector in the unit,
A top board for reciprocating the imaging position of the subject; (1-
c) arrangement angle adjusting means for rotating the X-ray tube and the X-ray detector to adjust the arrangement angle of the X-ray tube with respect to the subject placed on the top plate to an arbitrary arrangement angle; (1
-D) gantry tilting means for tilting the gantry in the body axis direction of the subject placed on the top, and (1-e) an imaging width including a specific portion of the subject placed on the top When,
Setting means for setting an arrangement angle of the X-ray tube and a tilt angle of the gantry with respect to a subject mounted on the top plate, and a plurality of arrangement angles of the X-ray tube; 1-f) display means for displaying a captured image; (1-g) designation means for designating a CT scan position with respect to a CR (scout view) image displayed on the display means; ) While positioning the X-ray tube at the arrangement angle set by the setting means, tilting the country at the tilt angle set by the setting means, and in that state,
While irradiating X-rays from the X-ray tube, the top plate is moved so that the imaging position of the subject is displaced from one end to the other end of the set imaging width, and the set imaging width is set. Control to take a CR image of the area inside
When a plurality of arrangement angles of the X-ray tube are set, the control for each of the set arrangement angles of the X-ray tube is continuously performed, and the captured CR image is displayed on the display means,
A CT scan position designated by the designation means is taken into the CR image displayed on the display means, and the designated CT scan position is positioned at the imaging center of the X-ray tube and the X-ray detector. The top plate is moved to capture a CT slice image at a designated CT scan position, and the captured CT slice image is displayed on the display unit together with the captured CR image, and the displayed CR is displayed.
Control means for controlling the display of the designated CT scan position on an image. 2. The radiation imaging system according to claim 1, further comprising an X-ray focal point varying unit that varies a distance between an X-ray tube attached to the gantry and a subject on a top plate. The setting unit includes an imaging width including a specific portion of the subject mounted on the top, an arrangement angle of the X-ray tube with respect to the subject mounted on the top, and a tilt angle of the gantry. In addition to the setting, the distance between the X-ray tube and the subject can also be set, and the control unit determines the distance between the X-ray tube and the subject when capturing the CR image. And a control for adjusting the distance to the set distance set by the setting means.