JPH07194591A - CR image pickup device for radiation treatment planning - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a CR image capturing apparatus for a radiation treatment plan, which irradiates X-rays from various directions of a subject to capture a CR image of a region necessary for the radiation treatment plan. [Structure] An X-ray tube 3 and an X-ray detector 4 are rotatably attached to an opening 2 of a gantry 1 while facing each other. The top plate 13 on which the subject M is placed slides in the opening 2 and is reciprocated. The control unit first arranges the X-ray tube at the arrangement angle θ ₁ set from the setting board, and
3 is moved to take a CR image of an area within the set imaging width from the setting board. Thereafter, similarly, the X-ray tube 3 is arranged at θ ₂ and X-rays are irradiated to capture a CR image having an imaging width, and the X-ray tube 3 is arranged at θ ₃ , θ ₄ , and θ ₅ , respectively, and X A CR image having an imaging width is sequentially captured by irradiating a line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CR image pickup apparatus for a radiation treatment plan for obtaining information useful in a radiation treatment plan such as a dose distribution in the body of a subject and a positional relationship of organs.

[0002]

2. Description of the Related Art An X-ray tube provided with a collimator for adjusting an opening angle of X-ray irradiation and an X-ray irradiation thickness and an X-ray detector are opposed to each other and attached to an opening to detect the X-ray tube and the X-ray. A gantry that rotates in synchronization with the instrument and a subject on which a subject is placed, and a reciprocating movement of the imaging position of the subject with respect to the imaging center of the X-ray tube and the X-ray detector in the opening of the gantry. A diagnostic CR (Computed Radiogr) using an X-ray CT system equipped with
aphy, also called "scout view")
It is controlled and implemented as follows.

That is, the X-ray tube is positioned above the subject on the top plate, and one end of a predetermined imaging region (for example, between the neck and the knee) is attached to the X-ray tube and the X-ray detector. While moving the top plate 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 as to displace the imaging position of the subject from one end side to the other end side of the imaging region, and a CR image in the imaging region is captured.

[0004]

However, the conventional example having such a structure has the following problems. That is, when performing a radiation treatment plan, it is only necessary to obtain information (a dose distribution, a positional relationship between organs, and the like) of a region near the tumor, which is a target of radiation treatment. Therefore, if the above-mentioned diagnostic CR image is taken in order to make a radiation treatment plan, C including an unnecessary area in the radiation treatment plan will be obtained.
Since the R image is captured, there is a problem that the subject is irradiated with unnecessary X-rays.

Further, in the case of capturing a diagnostic CR image, only a CR image obtained by irradiating an X-ray from above the subject is obtained. However, a CR image viewed from the irradiation direction of X-rays irradiated to the subject at the time of radiotherapy, that is, a CR image obtained by irradiating X-rays from the irradiation direction of the X-ray at the time of radiotherapy, is This information is useful when making a treatment plan, but when capturing a diagnostic CR image, such C
There is a problem that an R image cannot be obtained.

The present invention has been made in view of the above circumstances, and is obtained by irradiating an area required for radiation treatment planning with X-rays from various directions of a subject.
It is an object of the present invention to provide a CR image capturing device for radiotherapy planning capable of capturing an R image.

[0007]

The present invention has the following constitution in order to achieve such an object. That is, the invention according to claim 1 is (a) an X provided with a collimator for adjusting the opening angle of the irradiation X-ray and the X-ray irradiation thickness.
The tube and the X-ray detector are opposed to each other and attached to the opening,
A gantry that rotates the X-ray tube and the X-ray detector in synchronism with each other, and (b) a subject is placed on the gantry, and an imaging center of the X-ray tube and the X-ray detector in an opening of the gantry. On the other hand, a top plate that reciprocates the imaging position of the subject,
(C) setting means for setting an imaging width including a specific part of the subject and an arrangement angle of the X-ray tube with respect to the subject; and (d) an X-ray tube having the arrangement angle set by the setting means. To rotate the X-ray tube and the X-ray detector so that one end side of the imaging width set by the setting means is positioned at the imaging center of the X-ray tube and the X-ray detector. While moving the top plate and irradiating X-rays from the X-ray tube arranged at the arrangement angle, the top plate is displaced from the one end side to the other end side of the imaging width of the subject. And a control means for performing control to move a lens to capture a CR (scout view) image of an area within the set imaging width.

According to a second aspect of the invention, in the CR image pickup apparatus for radiation treatment planning according to the first aspect, the distance between the X-ray tube attached to the gantry and the subject on the top plate is set. An X-ray focus changing means for changing the
The setting means can also set the distance between the X-ray tube and the subject, and the control means drives the X-ray focal point changing means to drive the X-ray tube and the subject. A CR image of an area within the set imaging width is taken while irradiating an X-ray from an X-ray tube arranged at an arrangement angle by adjusting the distance between the specimen and the set distance set by the setting means. To do.

[0009]

The operation of the invention described in claim 1 is as follows. The operator uses the setting means to specify a specific part of the subject (for example,
An imaging width including a tumor that is symmetrical to the radiation treatment) and an arrangement angle of the X-ray tube with respect to the subject (for example, an angle according to the irradiation direction of the X-ray to the subject during the radiation treatment) are set. The control means rotates the X-ray tube and the X-ray detector in the gantry so as to position the X-ray tube at the arrangement angle set by the setting means, and X-rays one end side of the imaging width set by the setting means. The top plate on which the subject is placed is moved so as to be located at the imaging center of the tube and the X-ray detector, and the imaging position of the subject while irradiating X-rays from the X-ray tube arranged at the arrangement angle. The top plate is moved so as to be displaced from one end side to the other end side of the imaging width, and a CR image of a region within the set imaging width is controlled to be captured.

According to the second aspect of the invention, in addition to the imaging width including the specific portion of the subject and the arrangement angle of the X-ray tube with respect to the subject, the operator determines that the X-ray tube is used. The distance to the subject is also set. This distance is, for example, an irradiation distance of an X-ray that is irradiated to a tumor or the like (symmetry of radiation treatment) in the subject during radiotherapy (an X-ray generator that generates therapeutic X-rays with the tumor or the like in the subject). (Distance between and).

Then, the control means positions the X-ray tube at the arrangement angle set by the setting means, and positions one end side of the imaging width set by the setting means at the imaging center of the X-ray tube and the X-ray detector. As described above, the top plate on which the subject is placed is moved, and further the X-ray focal point changing means is driven to adjust the distance between the X-ray tube and the subject to the set distance set by the setting means. Then, while irradiating the X-ray from the X-ray tube which is arranged at the arrangement angle and whose distance to the subject is adjusted to the set distance,
The top plate is moved so as to displace the imaging position of the subject from one end side to the other end side of the imaging width, and control is performed so as to capture a CR image of an area within the set imaging width.

By thus controlling and capturing a CR image, a CR image irradiated with X-rays can be obtained according to the irradiation distance of the X-rays irradiated to the subject during radiation therapy. Information useful for radiation therapy planning such as dose distribution in the body according to conditions can be obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing the configuration of a radiotherapy planning CR image pickup apparatus according to the first embodiment of the present invention.
2 is a side view showing the relationship between the subject and the gantry on the top plate, FIG. 3 is a plan view showing the positional relationship between the subject, the gantry, and the laser marker on the top plate, and FIG. 4 is an X-ray. It is a figure for demonstrating the structure of the angle detection mechanism which detects the arrangement | positioning angle of a pipe. This first embodiment device corresponds to the invention described in claim 1.

1 and 2, reference numeral 1 indicates a gantry.
An X-ray tube 3 and an X-ray detector 4 are rotatably attached to the opening 2 of the gantry 1 while facing each other. A collimator 5 is attached to the X-ray tube 3, and the spread angle α of the X-ray emitted from the X-ray tube 3 (see FIG. 2).
And irradiation X-ray thickness t (see FIG. 1) are adjustable. In addition, the X-ray tube 3 and the X-ray detector 4 include a rotating frame 6
Are linked to. The rotating frame 6 is configured to be rotated by a motor 7 provided inside the gantry 1. By rotating the line frame 6 in the forward and reverse directions, the X-ray tube 3 and the X-ray detector 4 are rotated in the opening 2 while facing each other. The rotation control of the motor 7 is performed by the control unit 21 described later.

The angle of rotation between the X-ray tube 3 and the X-ray detector 4 is detected by an angle detection mechanism. This angle detection mechanism, as shown in FIG.
, And a transmission type optical sensor 9 which detects the number of the holes 8 that have passed during rotation of the rotary frame 6 and outputs a pulse signal each time the holes 8 pass. It consists of and. For example, the state in which the X-ray tube 1 is at the uppermost position (the state shown in FIG. 2) is the reference position (the angle at this time is “0 °”).
Then, when the rotary 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 corresponds to the rotation angle of the X-ray tube 3 (or X-ray detector 4) with respect to the reference position (1 ° /
1 pulse). Note that, for example, when the rotation frame 6 is rotated clockwise in FIG. 2 as a forward rotation and the rotation angle of the X-ray tube 3 is recognized as an absolute angle of 0 ° to 359 °, the rotation frame 6 is rotated. The rotation angle of the X-ray tube 3 can be detected by the rotation direction (the rotation direction of the motor 7) and the number of pulse signals. For example, when 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 °”. When the rotation frame 6 is rotated counterclockwise 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 “330 °”. Can be detected. Further, in order to position the X-ray tube 1 at the reference position, a light shield plate 10 is attached to the outer periphery of the rotary frame 6 facing the X-ray tube 3, and the light shield plate 10 measures the second transmission type optical sensor 11. When the light is blocked, the rotation of the motor 7 is stopped. An output signal from the second optical sensor 11 is given to a control unit 21 described later, and is controlled by the control unit 21 to position the X-ray tube 3 at the reference position. Further, the output pulse signal from the optical sensor 9 of the angle detection mechanism is also given to the control unit 21, and the control unit 21 uses the pulse signal for the control of arranging the X-ray tube 3 at the set angle as described later. There is.

Returning to FIG. 1 and FIG. 2, a vertically movable base 12 is installed near the gantry 1. This base 1
A top plate 13 on which the subject M is placed is mounted on the gantry 1 on the upper surface 2.
It is attached so as to be able to reciprocate while sliding inside the opening 2. That is, by reciprocating the top plate 13 on which the subject M is placed, the imaging position of the subject M on the top plate 13 is reciprocated with respect to the imaging centers of the X-ray tube 3 and the X-ray detector 4. It becomes possible. The reciprocating movement of the top plate 13 is performed by the motor 14 installed in the base 12.
The rotation is performed in the forward and reverse directions. Also, this motor 1
The rotation control of No. 4 is performed by the control unit 21 described later.

In the vicinity of the gantry 1 on the side where the subject M is inserted into the opening 2 of the gantry 1, as shown in FIG. 3, a laser for irradiating the subject M on the top plate 13 with laser light. A marker 15 is installed. The laser marker 15 indicates the image pickup position of the subject M as described below.
This is for performing alignment when the radiation tube 3 and the X-ray detector 4 are positioned at the imaging center.

In FIG. 1, reference numeral 20 indicates a setting panel equipped with switches for inputting various data, an instruction switch and the like. From this 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 symmetrical to radiation treatment is present).
And an arrangement angle θ of the X-ray tube 3 with respect to the subject M (for example, an angle according to the irradiation direction of X-rays to the subject M during radiotherapy) is set as shown in FIG. 5B. It In addition,
The arrangement angle θ is configured so that a plurality (for example, five) can be set, and the arrangement angles θ are configured to be set by the above-mentioned absolute angle. The setting board 20 is also configured to be provided with an instruction to start imaging, an instruction to align imaging, an instruction to position a CT slice, and the like. The setting board 20 corresponds to the setting means in the invention described in claim 1.

In response to an instruction to start imaging from the setting board 20, the control section 21 follows the data set from the setting board 20 and controls the drive of the motors 7 and 14 so as to pick up a CR image and the X, as described later. The X-ray irradiation from the X-ray tube 3 is controlled, the image processing unit 22 is controlled, and the like. In addition, the control unit 21 performs control for capturing a CT slice image at the set CT scan position and the obtained C
It is also configured to perform control such as clearly indicating the positional relationship between the R image and the CT slice image. The control unit 21
It corresponds to the control means in the invention described in claim 1.

The image processing unit 22, under the control of the control unit 21, performs a process of reconstructing a CR image or a CT image based on the detection data detected by the X-ray detector 4. The image reconstructed by the image processing unit 22 is controlled by the control unit 21 and displayed on the monitor 23.

Next, the operation of the above-described first embodiment apparatus will be described with reference to FIG.
Will be described with reference to the flowchart of FIG.

Before starting the processing of the flow chart of FIG. 6, the operator operates the setting board 20 to pick up the imaging width HW and the X-ray tube 3.
The arrangement angle θ of is set. Note that the following operation will be described assuming that the X-ray tube 3 is arranged at _five angles θ ₁ to θ ₅ shown in FIG. 7.

First, when the operator gives an instruction to start imaging from the setting panel 20, the control section 21 causes the top plate 13 on which the subject M is placed to be inserted into the opening 2 of the gantry 1. The motor 14 is driven so as to move to (step S
1, S2).

At this time, from the laser marker 15,
Laser light is radiated toward the subject M, and the irradiation position of this laser light moves from the head of the subject M toward the legs as the top plate 13 moves. While observing the irradiation position of the laser light, the operator gives an imaging position adjustment instruction from the setting panel 20 when the laser light irradiates the specific portion TP of the subject M. The specific portion TP is
For example, it is determined before the operator diagnoses a diagnostic CR image or CT image captured in advance and executes this process.

When this instruction is given, the control section 21
The top plate 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 the distance L is based on the imaging width HW. The distance (L + HW / 2) for moving the end portion on the platform 12 side to the image pickup center is specified because the image pickup width HW is set. On the other hand, since the moving distance of the top plate 13 can be controlled by the rotation speed of the motor 14, the control unit 21 controls the top plate 13 to (L + HW /
The motor 14 may be drive-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 the center, and for example, the length between the specific portion TP and the end of the imaging width on the gantry 1 side, and the specific portion TP and the base 12 side. The length between the imaging width and the end may be set differently from the setting panel 20. In this case, the control unit 21 may control the top plate 13 to move by a length obtained by adding the length L 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 base 12 side is positioned at the imaging center, the control unit 21 controls the number of the set arrangement angles θ _{1 to} θ ₅ of the X-ray tube 3 (in this case, 5). ) Times, the following steps S4 to S6 are repeated (step S7) to capture a CR image in a state where the X-ray tube 3 is arranged at each arrangement angle θ _{1 to} θ ₅ .

In step S4, the control unit 21 controls the rotary frame 6 to position the X-ray tube 3 at the set arrangement angle.
To rotate. That is, the control unit 21 controls the first CR
When capturing an image, the X-ray tube 3 is controlled to be positioned at the set first arrangement angle θ ₁ , and the second C
When capturing the R image, the X-ray tube 3 is controlled to be positioned at the set second arrangement angle θ ₂ , and thereafter, when capturing the fifth CR image, it is set. The X-ray tube 3 is controlled to be positioned at the fifth arrangement angle θ ₅ . 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 flowchart of FIG. 6 is started. Therefore, as shown in FIG. 7, when capturing the first CR image, θ ₁ is set to “0.
Therefore, the control unit 21 does not rotate the rotating armpit 6. When capturing the second CR image, θ ₂
Is 45 °, the control unit 21 drives the motor 7 to rotate the rotary frame 6 in the forward direction (clockwise),
The pulse signal given 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 the third CR image is captured, θ ₃ is “90 °”, and when the second CR image is captured, the X-ray tube 3 is “4”.
Since it is arranged at the position of "5 °", the motor 7 is driven so as to rotate the rotary frame 6 in the positive direction, and the count number of the pulse signal given from the optical sensor 9 of the angle detection mechanism is "45" ( 90-45), the motor 7
To 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 image pickup position of the subject M on the top plate 13 is set to the image pickup width HW.
The top plate 13 is moved by HW so as to be displaced from the end side on the base 12 side to the other end side, and based on the data detected by the X-ray detector 4, the image processing unit 22 sets The monitor 23 reconstructs the CR image of the region within the captured imaging width HW.
To display. The CR image obtained on the first sheet is shown in Fig. 9 (a).
As shown in, the X-ray tube 3 is imaged by irradiating X-rays in a state of being arranged at the set arrangement angle θ ₁ .
The CR images obtained on the second to fifth sheets are shown in FIG.
As shown in (e), the arrangement angle θ at which the X-ray tube 3 is set
_The images are obtained by irradiating X-rays in the state of being respectively arranged in _{2 to} θ ₅ . The obtained CR images are reduced in size on the monitor 23 and displayed in a multi-display. Also,
This display control is performed by the control unit 21.

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

When step S7 is completed, ₅ images are taken with the X-ray tube 3 placed at each placement angle θ _{1 to} θ 5.
One CR image is obtained. This is shown in FIG. In the figure, symbols Z _{1 to} Z ₃ represent organs, and S ₁ and S ₂ represent tumors. These CR images G1 to G5 are obtained by irradiating the subject M with X-rays in the irradiation direction of the X-rays (angle of the X-ray tube 3) during the radiotherapy. Therefore, the surgeon is aware that the tumor S
In _1, the periphery of S _2, as viewed from a direction of irradiating the X-rays in the treatment, it is possible to know the positional relationship in the body of the dose distribution and the organ Z ₁ to Z _3, for proper radiation therapy planning be able to. It should be noted that in FIG. 10, a CR image of a region having an imaging width HW centered on the tumor S ₂ is captured.

Further, since the image pickup width HW sets the image pickup area including the specific portion TP, a CR image around the specific portion TP is always obtained, and the image pickup width HW sets the necessary area arbitrarily. Therefore, it is possible to avoid the inconvenience of performing unnecessary X-ray irradiation to the subject M as in the case of capturing a diagnostic CR image and making a radiation treatment plan.

In the above description, the five arrangement angles of the X-ray tube 3 are set, the X-rays are irradiated from five directions, and the five CRs are irradiated.
Although an image is taken, for example, if the irradiation direction of X-rays to the subject M when performing radiotherapy is only one direction, at least a CR image irradiated with X-rays from that direction may be obtained. , The X-ray tube 3 may be arranged at only one angle.

By the way, in this embodiment, in addition, in order to obtain data useful for the radiation treatment plan, the process of the following steps S8 to S10, that is, the position to be particularly examined in detail on the basis of each obtained CR image ( For example, tumor S ₁ ,
It is configured to perform processing such as capturing a CT slice image at a position where S ₂ exists).

First, the CT scan position set by the operator based on each obtained CR image is captured (step S
8). That is, the operator looks at each of the CR images G1 to G5 that are reduced and multi-displayed on the monitor 23, and designates the position for CT scanning from the setting panel 20 in order to obtain particularly detailed information. At this time, the operator sets an arbitrary CR image from each of the CR images G1 to G5 multi-displayed on the monitor 23.
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. Further, display control such as enlarged display of the CR image is performed by the control unit 21.

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

When the above step S7 is completed, the edge of the CR image width HW on the base 12 side is located at the center of the image, so that the LCT1 top plate 13 is first attached to the base 1.
Moving in two directions, the designated position CTP1 is positioned at the imaging center, and X-ray tube 3 and X
The first CT scan position CTP1 is obtained by rotating the line detector 4 around the subject M once and recombining the images by the image processing unit 22 based on the data detected by the X-ray detector 4.
To obtain a CT slice image. The captured CT slice image is controlled by the control unit 21 and displayed on the monitor 23.
Next, the top plate 13 is moved by the LCT 2 in the direction of the base 12, and a CT slice image at the second CT scan position CTP 2 is captured and displayed on the monitor 23.

When all the CT slice images (CT1, CT2) at the set CT scan position have been imaged, the monitor 23
The CT scan position is displayed on each CR image displayed on the screen (step S10). This is shown in FIG. Thus, by associating the positional relationship between each CR image and the obtained CT image, the dose distribution and the positional relationship of the organs can be known three-dimensionally, so that the operator can perform a more appropriate radiation treatment plan. It can be performed.

When performing the process of step S3, when the laser beam is emitted from the specific portion TP from the position where the subject M is placed on the top plate 13 (the initial position of the top plate 13) (position alignment). Top plate 13 by the time the instruction is given)
Is calculated in advance, and the movement amount, the set imaging width HW, and the arrangement angle θ (θ _{1 to} θ) of the X-ray tube 3 are set.
₅ )), the CT scan position (CTP1, CTP2, etc.) set in step S8, and the amount of movement of the tabletop at that time (L
(CT1, LCT2, etc.) is stored as a database for each subject M, so that 2 for the same subject can be stored.
When the CR image and the CT image are captured after the first time, the CR image and the CT image can be captured under the same conditions without performing a troublesome procedure such as data setting and alignment of the image capturing position. Therefore, it is convenient when performing continuous repeated radiotherapy for the same subject.

Further, the control unit 21 of the apparatus of the first embodiment is provided with a function of controlling to capture a CR image for diagnosis,
The diagnostic CR image may be captured and the radiotherapy CR image may be captured.

Next, a modification of the above-described first embodiment device will be described with reference to FIGS. 13 to 16. In this modified example, in addition to the configuration of the first embodiment described above, the gantry 1 is tilted in the body axis direction of the subject M on the top plate 13 so that a CR image can be captured. To do.

First, the configuration 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 this modification.
Is a cross-sectional view showing the configuration of the gantry support member and the gantry base viewed from the side surface (the side where the subject is inserted into the opening of the gantry). FIG. 15A is a side view of the gantry support member. FIG. 15 (b) is a front view of the support member of the gantry, FIG. 16 (a) is a plan view showing the structure of the gantry base, and FIG. 15 (b) is a plan view of FIG. 15 (a). 15A is a sectional view taken along the line AA, and FIG. 15C is a sectional view taken along the line BB of FIG.

As shown in FIG. 14, a semicircular support member 31 is attached to the bottom surface of the gantry 1 of this modification, and the support member 31 is provided with a rack 32 along the peripheral surface. Further, sled members 33 are attached to both sides of the support member 31. On the other hand, the gantry base 34 is provided with a recess 35 for accommodating the semicircular support member 31 attached to the gantry, and the recess 35 is provided with a rack provided on the semicircular support member 31. Groove 36 for accommodating 32 and arcuate groove 37 for accommodating sled member 33
Is provided. A pinion 38 that meshes with the rack 32 is provided near the center of the groove 36. The pinion 38 is rotated by a motor 39 provided inside the gantry base 34. Then, as shown in FIG. 14, the semicircular support member 31 of the gantry 1 is fitted into the recess 35 of the gantry base 34, the rack 32 is fitted into the groove 36 so that the pinion 38 is engaged, and the sled member 33 is fitted into the groove 36. 37 are slidably accommodated. At this time, the groove 37 is formed longer than the length of the sled 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 member 33 slides in the groove 37, and the gantry 1 is moved as shown in FIG. Then, the subject M is tilted in the body axis MJ direction. The drive control of the motor 39 is configured to be performed by the control unit 21.

Further, in this modification, from the setting board 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 in the first and second embodiments, the tilt angle of the gantry 1 can be set. As this tilt angle, the irradiation angle of the X-rays irradiated to the subject M during the radiotherapy with respect to the body axis direction is set.

The control unit 21 is the same as that of the first embodiment shown in FIG.
Between steps S3 and S4 in the flowchart of FIG. 3, the motor 37 is rotated to adjust the gantry 1 to the set tilt angle, and X-rays are irradiated from the set arrangement angle θ of the X-ray tube 3 to specify the tilt angle. A CR image of a region including the part TP within the imaging width HW is captured.

By thus controlling and capturing the CR image, 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 pickup is set to the body axis MJ.
It can be adjusted by the angle of rotation (the arrangement angle θ of the X-ray tube) and the angle of the body axis MJ direction (the tilt angle of the gantry 1). Therefore, it is possible to obtain a CR image irradiated with X-rays from a direction that more faithfully reproduces the X-ray irradiation direction at the time of radiotherapy, and thus it is possible to obtain more useful information in the radiotherapy plan.

Next, the configuration of the second embodiment device of the present invention will be described with reference to FIG. This second embodiment device corresponds to the invention described in claim 2. The apparatus of the second embodiment is characterized in that the distance between the X-ray tube 3 and the subject M on the top plate 13 can be arbitrarily changed in the first embodiment.

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 rotary frame 6. This moving mechanism is, for example, R in FIG.
It is configured by rotating a rack extending in the direction and a pinion meshing with the rack in the forward and reverse directions by a motor. The rotation of the motor is controlled by the control unit 21. The moving mechanism of the X-ray tube 3 corresponds to the X-ray focal point changing means in the invention of claim 2.

From the setting panel 20, the imaging width HW and the arrangement angle θ of the X-ray tube 3 described in the first and second embodiments are set.
In addition to (θ _{1 to} θ ₅ ), the X-ray focus of the X-ray tube 3 and the top plate 1
The distance SL to the specific part in the subject M on the upper part 3 can also be set. The distance SL is, for example, an irradiation distance of X-rays to be applied to a tumor or the like (symmetry of radiotherapy) in the subject M during radiotherapy, that is, a tumor in the subject M and a therapeutic X-ray are generated. The distance is set according to the distance (for example, 800 mm or 1000 mm) from the X-ray generator. In addition, the setting board 20 configured in this way
Corresponds to the setting means in the invention of claim 2.

The control unit 21 is the same as that of the first embodiment shown in FIG.
Between steps S3 and S4 in the flowchart of FIG. 6, the distance SL between the X-ray focal point of the X-ray tube 3 and the specific part of the subject M is set by rotating the motor of the moving mechanism of the X-ray tube. The set angle θ of the X-ray tube 3 adjusted to
X-ray is emitted from the image capturing width H centered on the specific portion TP.
A CR image of the area within W is taken. The control unit 21 that controls in this way corresponds to the control means in the invention of claim 2.

By thus controlling and capturing the CR image, the CR image is obtained by irradiating the subject M during radiation treatment with X-rays according to the irradiation distance from the angle around the body axis of the irradiation X-rays. be able to. Therefore, more useful information can be obtained for the radiation treatment plan such as the dose distribution in the body according to the conditions at the time of radiation treatment.

The configuration according to the modification of the first embodiment described above may be added to the second embodiment device. At this time, from the setting board 20, the imaging width HW, the arrangement angle θ (θ _{1 to} θ ₅ ) of the X-ray tube 3, the X-ray focal point of the X-ray tube 3, and the specific portion of the subject M on the top plate 13 are set. The distance SL between them and the tilt angle of the gantry 1 are set. Then, the control unit 21 sets X
Immediately before or after the distance between the X-ray tube 3 and the subject M is adjusted to the set distance SL, the motor 37 is rotated to adjust the tilting angle of the gantry 1, and then the set X-ray tube 3 is adjusted. X-rays are emitted from the arrangement angle θ, and a CR image of a region within the imaging width HW centered on the specific portion TP is captured. By thus controlling and capturing a CR image, the angle around the body axis and the body axis direction of the irradiation X-rays on the subject M during radiotherapy is adjusted, and the X-rays are irradiated according to the irradiation distance. Since the CR image can be obtained, more useful information can be obtained for the radiation treatment plan such as the dose distribution in the body and the positional relationship of the organs according to the conditions during the radiation treatment.

[0052]

As is apparent from the above description, according to the invention described in claim 1, it is possible to set the imaging width including the specific portion of the subject and the arrangement angle of the X-ray tube with respect to the subject. Since the X-ray tube is arranged at the set arrangement angle to obtain the CR image of the region within the set imaging width, the X-ray is irradiated from the X-ray irradiation direction to the subject at the time of radiotherapy. It is possible to obtain a CR image and obtain useful information when planning radiation therapy, such as the dose distribution around a specific site that is symmetrical to radiation therapy and the positional relationship of organs.

Further, since the imaging width including the specific region can be set, a CR image only around the specific region can be obtained and unnecessary X-ray irradiation to the subject is not performed.

Further, according to the invention described in claim 2,
In addition to the imaging width including the specific region of the subject and the arrangement angle of the X-ray tube with respect to the subject, the distance between the X-ray tube and the subject is also set, and the distance between the X-ray tube and the subject is set. The imaging position of the subject is imaged while irradiating the X-ray from the X-ray tube which is adjusted to the set distance and is arranged at the arrangement angle and the distance to the subject is adjusted to the set distance. Since the top plate is moved so as to be displaced from one end side to the other end side of the width and the CR image of the region within the set imaging width is taken, irradiation of the subject at the time of radiation treatment is performed. A CR image irradiated with X-rays can be obtained according to the irradiation distance of X-rays, and useful information for a radiation treatment plan such as the dose distribution in the body according to the conditions at the time of radiation treatment can be obtained.

[Brief description of drawings]

FIG. 1 is a front view showing a configuration of a CR image capturing apparatus for radiation treatment planning according to a first 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 for explaining 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 and an arrangement angle of an X-ray tube set from a setting board.

FIG. 6 is a flowchart showing the operation of the apparatus of the embodiment.

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

FIG. 8 is a diagram for explaining the movement amount of the top plate when one end of the imaging width is positioned at the 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 the movement amount of the top plate when the CT scan position is moved to the imaging center.

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

FIG. 13 is a front view showing a tilting operation of the gantry in a modified example of the first embodiment device.

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

FIG. 15 is a view 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 a second embodiment device of the present invention.

[Explanation of symbols]

1 ... Gantry 2 ... Gantry opening 3 ... X-ray tube 4 ... X-ray detector 5 ... Collimator 6 ... Rotating frame 6 ... Rotating frame 7, 14 ... Motor 13 ... Top plate 20 ... Setting panel 21 ... Control unit M ... Subject TP ... Specific part HW ... Imaging width θ, θ _{1 to} θ ₅ ... X-ray tube arrangement angle

Claims (2)

[Claims] (A) An X-ray tube provided with a collimator for adjusting the opening angle of the irradiated X-rays and the X-ray irradiation thickness and an X-ray detector are opposed to each other and attached to the opening, and the X-rays are attached. A gantry that rotates the tube and the X-ray detector in synchronization with each other;
(B) A top plate on which a subject is placed and which reciprocates the imaging position of the subject with respect to the imaging center of the X-ray tube and the X-ray detector in the opening of the gantry; Setting means for setting an imaging width including a specific part of the subject and an arrangement angle of the X-ray tube with respect to the subject; and (d) positioning the X-ray tube at the arrangement angle set by the setting means. And rotating the X-ray tube and the X-ray detector so that one end side of the imaging width set by the setting means is positioned at the imaging center of the X-ray tube and the X-ray detector. While moving the X-ray from the X-ray tube arranged at the arrangement angle, the tabletop is moved so as to displace the imaging position of the subject from one end side to the other end side of the imaging width. The CR (scout view) image of the area within the set imaging width. Radiation therapy planning for CR image capturing apparatus characterized by comprising a control means for performing control to. 2. The CR for radiation treatment planning according to claim 1.
The image pickup apparatus includes an X-ray focal point changing means for changing the distance between the X-ray tube attached to the gantry and the subject on the top plate, and the setting means causes the X-ray tube and the subject to be connected to each other. The distance between the X-ray tube and the subject is set by the control unit by driving the X-ray focal point changing unit. While adjusting the distance and irradiating X-rays from the X-ray tube arranged at the arrangement angle, C of the area within the set imaging width
CR for radiation treatment planning characterized by capturing R image
Image pickup device.