JPH07255715A - Radiation treatment planning device - Google Patents

Abstract

PURPOSE:To enable an operator to make a high-accuracy treatment plan by assigning an irradiation field and isocenter on scannoimages, aligning the reconstitution center of the reconstituted image matched with the plane passing this isocenter and commanding the scan for obtaining the image along the aligned reconstitution center. CONSTITUTION:The scannoimages of an examinee P are photographed and the irradiation field enclosing the lesion is assigned on the scannoimages displayed on a display 47 from an input device 48 and the isocenter corresponding to the center of rotation at the time of a radiation treatment is assigned at the time of the treatment planning. A control section 40 makes the scan planning around the isocenter and executes the scan and its reconstitution by driving a bed control section 41 and a stand control section 42 along the planned data. This control section makes the radiation treatment planning as to setting of an irradiation method, fine adjustment of the irradiation field, check of linea cones, etc., in accordance with the resulted reconstitution images and uses this planning to the subsequent treatment by a radiation treatment device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation treatment planning apparatus, and more particularly to a radiation treatment planning apparatus for planning a radiation treatment using a tomographic image obtained from an X-ray CT apparatus, an MRI apparatus or the like.

[0002]

2. Description of the Related Art Conventionally, radiotherapy for irradiating a lesion such as cancer with radiation has been performed in a clinical setting, and its effectiveness has been confirmed.

A linear accelerator is generally used as a radiation treatment apparatus for performing this radiation treatment. This linear accelerator irradiates the affected area of a patient lying on a treatment table with radiation (X-rays) generated by applying an accelerated electron beam to a target from the irradiation device main body side.

In order to carry out treatment using such a radiation treatment apparatus, various preparatory work is required in advance. The first step is to acquire an image of the diseased part by, for example, an X-ray CT scanner. Then, in the second stage, the position, size, shape, number, etc. of the affected area are accurately grasped by using the image, and the position of the isocenter and the dose distribution,
After selecting the irradiation method (field of view, angle, number of portals, etc.), determine whether or not the affected area can be accurately irradiated. Furthermore, in the third stage, isocenter setting using the X-ray simulator, dose distribution, and irradiation conditions are used to set the isocenter, patient positioning by fluoroscopy, body surface marking (isocenter, irradiation field), and simulation using the determined irradiation method are performed. Be seen.

When the simulation is completed in this manner, thereafter, the treatment with the radiation treatment apparatus is usually performed after an appropriate period. Prior to this treatment, the irradiation field is collated with the fluoroscopic image for collation, the patient is positioned by the isocenter mark among the body surface marks attached to the patient, and the irradiation range of the collimator is set by the irradiation field mark. After this, the actual radiation treatment is performed according to the determined irradiation method.

[0006] In recent years, while various approaches to cancer treatment have been made, the significance of radiotherapy as a root treatment method and palliative therapy has been reexamined, and more accurate positioning of affected areas, more detailed treatment plan, and higher treatment. Accurate treatment is being demanded.

Under the present circumstances, when making a treatment plan, a scanogram of a subject and an axial image reconstructed in advance are generally used. That is, the irradiation field for the lesion (target) was determined by the scanogram, and the pyramid was confirmed by the axial image.

[0008]

However, in the conventional treatment planning method using the scano image and the axial image, the already scanned image (axial image) is used for the treatment plan, and therefore the isocenter should be set. A CT image including an appropriate position of a lesion may not be included in the scanned image group. In such a case, the rescan is forced to be performed, a lot of time is spent on the treatment planning, and the burden on the operator and the patient is increased.

Further, even when a CT image including such an appropriate position is present in the scanned image group, the reconstruction center position and the position where the isocenter should be set do not necessarily match, and the slice thickness is multi. The width of each leaf of the leaf-shaped collimator hardly matches, and it was difficult to obtain a high-quality image along the radiation path desired in the treatment plan.

The present invention has been made in view of such a conventional situation, and makes it possible to make a more accurate treatment plan based on an image in which the position at which the isocenter should be set is re-emphasized. The main purpose is that. Also,
Another object is to be able to make a more accurate treatment plan based on an image in which the position where the isocenter is to be set and the width of each leaf of the multi-leaf collimator are emphasized.

[0011]

In order to solve the above-mentioned problems, according to claims 1 and 2 of the present invention, radiation treatment is performed based on an image obtained by irradiating a subject with X-rays. In a radiotherapy apparatus for planning, a means for picking up a scanogram of the subject, a means for designating an irradiation field and an isocenter on the scanogram, and a reconstruction center of a reconstructed image matched to a plane passing through the isocenter And a means for instructing a scan for obtaining the image along the combined reconstruction center.

According to a third aspect of the present invention, when a desired slice plane is aligned with a tilt angle of a radiation path from a radiation source with respect to a position in the irradiation field in the axial direction of the object apart from the isocenter. A means for calculating control data for the gantry and the bed and means for instructing a scan for obtaining the image according to the control data are added.

Further, according to claim 4 of the present invention, in a radiotherapy apparatus for planning a radiotherapy based on an image obtained by irradiating a subject with X-rays,
Means for capturing a scanogram of the subject, means for designating an irradiation field and an isocenter on the scanogram, means for aligning a reconstruction center with a plane passing through the isocenter, and the image according to the combined reconstruction center And a means for helical reconstruction.

According to claim 5 of the present invention,
In a radiation treatment apparatus for planning a radiation treatment by a radiation treatment apparatus equipped with a multi-leaf collimator based on an image obtained by irradiating a subject with X-rays, each pair of the multi-leaf collimators facing each other Means for calculating projection data on the cross section of the volume from the volume data of the volume whose collimator is in charge of opening and closing along the radiation path from the radiation source, and monitoring by superimposing the ray cone of the radiation path on the projection data. And means for displaying on.

According to a sixth aspect of the present invention, a means for adjusting the opening of the pyramid displayed on the monitor on the monitor is added.

[0016]

According to the present invention, images used for treatment planning are
Before the X-ray scan, a scan plan that considers the isocenter and the reconstruction center is made to perform an X-ray scan, and a CT image including the isocenter is obtained, and while the isocenter and the reconstruction center match, At a position away from the isocenter, the radiation path is tilted at the same angle as the radiation path for scanning, so that more accurate radiation treatment planning can be performed.

Further, according to the present invention, an image for each volume range in which each pair of leaves of the multi-leaf collimator is in charge of opening and closing can be displayed, and the leaf opening can be adjusted on the screen, which is highly convenient. Contribute to a more rapid and accurate treatment plan.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The entire radiotherapy system including the radiotherapy planning apparatus according to the first embodiment of the present invention will be described below with reference to FIGS.

This radiation treatment system, as shown in FIG. 1, is a CT system for radiation treatment planning as a radiation treatment planning device for consistently performing from image acquisition to treatment planning and alignment (simulation) during radiation treatment. 1 and a radiation treatment apparatus 2 for performing radiation treatment according to the treatment plan data planned and simulated by the radiation treatment planning CT system 1, and automatically controls a collimator described later, which is built in the radiation treatment apparatus 2. Therefore, the radiation treatment planning CT system 1 and the radiation treatment apparatus 2 are connected by a signal line 3 as a signal transmission line. In the middle of the signal line 3, a collation recording device 4 is inserted which allows the operator to finely adjust the opening of the collimator at the time of actual radiation treatment. Further, in the radiation treatment planning CT system 1, a treatment planning dedicated processing device 5 for performing specialized arithmetic processing such as radiation dose distribution calculation and a laser printer 6 for outputting plan data are transmitted via transmission lines 7 and 8. Each is connected.

Among these components, the CT system 1 for radiation treatment planning (hereinafter, simply referred to as "CT system") will be described first.

This CT system 1 is constructed by applying a normal X-ray CT scanner, and as shown in FIG. 1, a gantry 11, a bed 12 and a control console 1 are provided.
3 is a device that is driven by the RR method, for example. On the upper surface of the bed 12, its longitudinal direction (Z axis (body axis) direction)
The top plate 12a is disposed in a slidably supported state, and the subject P is placed on the top surface of the top plate 12a. The top plate 12a is inserted into the diagnostic opening OP of the gantry 11 so as to be movable back and forth by driving a slide mechanism represented by an electric motor 13.

As shown in FIG. 2, the gantry 11 contains an X-ray tube 20 and an X-ray detector 21 which are opposed to each other with the subject P inserted in the opening OP interposed therebetween. The weak current signal corresponding to the transmitted X-ray detected by the X-ray detector 21 is converted into a digital amount by the data collection unit 22 and sent to the console 13. In FIG. 2, reference numeral 23 is a gantry 1.
The collimator and the filter in 1 are shown, and the code | symbol 24 has shown the X-ray fan.

Further, on the front side of the gantry 11, that is, inside the front cover 11a located on the bed 12 side,
Three positioning laser projectors 27a, 27b and 27c are provided which are activated when marking the isocenter.

The console 13 has a main control unit 40 that controls the entire CT system, and a bed control unit 41 and a gantry control unit 42 that operate in response to commands from the main control unit 40.
And are mutually connected via an internal bus. The main controller 40 is also provided with a high voltage generator 44 which is connected to an X-ray controller 43 outside the console and which operates in response to a drive signal from the X-ray controller 43. The high voltage generated by the high voltage generator 44 is supplied to the X-ray tube 20,
X-ray exposure is performed. Further, the console 13 receives an acquisition signal of the data acquisition unit 22, and reconstructs image data, an image reconstructing unit 45, an image memory 46 for storing the image data, a display 47 for displaying the reconstructed image, and an operator. Each have an input device 48 for giving a command to the main control unit 40. Each of the control units and the controllers 40 to 43 is equipped with a computer and operates based on a program stored in its memory in advance.

The internal bus of the console 13 is further connected to an extension board 48 for signal lines, and a projector controller 49 for controlling the marker irradiation positions of the projectors 27a to 27c is connected to the extension board 48 via a signal line 50. In addition, the continuous printer 6 and the collation recording device 4 are connected via signal lines 8 and 3. Position data of the isocenter of the subject is supplied to the projector controller 49 from the main controller 40. In response to this data supply, the projector controller 49 causes the projector controller 49 to illuminate the three projectors 27a to 27c. Each position is automatically controlled.

Next, the radiation treatment apparatus 2 will be described.

The radiation treatment apparatus 2 (hereinafter, simply referred to as "treatment apparatus") is a treatment apparatus that uses X-rays in this embodiment, and as shown in FIG. 1, a treatment table 50 on which a subject P is placed.
A pedestal 51 that is rotatable around the body axis (Z) direction of the subject P and a gantry support 52 that rotatably supports the pedestal 51 are provided with a console (not shown).

The treatment table 50 has a top plate 50a on its upper side. Since the height of the treatment table 50 can be adjusted by an internal drive mechanism, the top plate 50a can be moved up and down (Y-axis direction). In addition, the treatment table 50 can move the top plate 50a in a predetermined range in the longitudinal direction (Z direction) and the lateral direction (X direction) by driving another driving mechanism inside the treatment table 50, and another driving device. By operating the mechanism, it is possible to rotate the top support and rotate around the isocenter. The operation of these treatment tables 50 is necessary when positioning the subject P on the top plate 50a and irradiating the radiation, and is controlled by a control signal from the console.

On the other hand, the gantry 51 is provided with an irradiation head 51a for deflecting the accelerated electrons from the Claxtron to hit the target and irradiating the subject P with the X-ray beam generated from the target. The irradiation head 51a is provided with a collimator 55 that determines an irradiation field on the body surface of the subject P between a target, that is, a radiation source and an irradiation port. In this embodiment, the collimator 55 is a multi-leaf collimator (Multi-Leaf C
ollimator). That is, as shown in FIG. 3, two sets of leaf groups 56A and 56B, which are composed of a plurality of plate-shaped tungsten leaves 56 ... 56, are arranged to face each other with the X-ray path from the radiation source S interposed therebetween. , Leaf 56 ... 5
Each of 6 is a moving mechanism 57 whose main part is a lead screw.
57 allows the leaves to be independently driven in the length direction (Z direction). The moving mechanisms 57 ... 57 are driven according to a control signal supplied from the console, and the size and shape of the irradiation opening formed by the two leaf groups 56A and 56B (that is, the size of the irradiation field on the body surface). , Corresponding to the shape) can be changed in real time.

Further, the gantry support 52 can be rotated in the clockwise direction or the counterclockwise direction of the gantry 51 by the drive mechanism incorporated therein. The operation of this drive mechanism is performed based on a control signal from the console.

The console of the treatment apparatus 2 has a main control unit for managing the treatment apparatus 2 as a whole, a collimator control unit, and the like.

Next, the operation of the first embodiment will be described with reference to FIGS.
Will be explained.

The main control unit 40 of the CT system 1 carries out the processing shown in FIG. 4 when planning a treatment. First, step 60 in FIG.
In step 1, a command is issued to capture a scanogram of the subject P. Since this scanogram is displayed on the display 47 as shown in FIG. 5, for example, the irradiation field R surrounding the lesion on this scanogram is displayed.
F is designated from the input device 48 using ROI or the like. Similarly, the isocenter I / C corresponding to the rotation center at the time of radiotherapy is designated (at this time, the axial image is also added to determine the depth). The concept of the radiation field RF and the radiation source S of the isocenter I / C is shown in FIG.

Next, in step 61, a scan plan centering on the isocenter I / C is set up. That is,
As shown in FIG. 7, a radiation path To connecting the positions of the radiation source S and the isocenter I / C is determined, and the scan center Sc thereof is determined. An axis Q passing through the scan center Sc and orthogonal to the radiation path To is determined. Furthermore, FoV size,
The ranges FOV and SCN to be scanned and reconstructed are designated from the input device 48. When the coordinate axes and the range required for scanning are set in this way, specific scan plan information is obtained. First, the isocenter I / C can be located, and the reconstruction center Rc is located at the isocenter I / C along the radiation path To.
Make a scan plan (only the reconstruction position plan in the case of helical scan) so as to match the position of.
At a position away from the isocenter I / C in the body axis Z direction, a scan plan tilted along the radiation paths Tn ... Tn + m is prepared. For this tilt, as shown in FIG. 8, if a straight line SB is drawn with respect to the desired place B, Z
The top plate position is determined from the axis and the intersection ZB, and the angle θ becomes the tilt angle, whereby the control data of the gantry 11 and the top plate 12a are calculated.

When the scan plan is completed in this way,
In step 63, the bed control unit 41 and the gantry control unit 42 are driven in accordance with the planned data, and scanning and its reconstruction are performed. Then, in step 64, a radiation treatment plan such as the setting of the irradiation method, the fine adjustment of the irradiation field, and the confirmation of the pyramid is made based on the reconstructed image obtained as a result. This plan data is used for the subsequent treatment by the radiation treatment apparatus 2.

It should be noted that the scan may be performed only on the region of interest such as the end of the irradiation field or an important organ.
You may make it carry out at equal intervals. When performing at equal intervals, as shown in FIG. 9, a multileaf collimator 5 is used.
It is also possible to make a scan plan considering the thickness of each leaf 56 of 5 (for example, 1 cm on the body surface). That is, at the position of the isocenter I / C, this isocenter I / C
While matching C, leaf center and reconstruction center,
It adjusts the slice thickness to the leaf thickness (the slice thickness may be an integral multiple of the leaf thickness).

Further, when planning to irradiate radiation from the side of the subject, a scan plan and scan in which the gantry or bed is swung are performed.

As described above, by performing the scan in which the isocenter and the radiation angle are recognized, the slice center (further, the slice thickness) coincides with the isocenter and the leaf position (further, the leaf thickness) of the multi-leaf collimator, and the isocenter is reconstructed. It is possible to obtain an image with the configuration center. As a result, an image of the isocenter position and angle actually desired to be seen in the treatment plan can be quickly obtained, and more accurate plan can be performed.

The second embodiment of the present invention will be described with reference to FIGS. Since the hardware configuration of this embodiment is the same as that of the first embodiment, the description thereof will be omitted.

In the second embodiment, an image is obtained by helical reconstruction in consideration of isocenter I / C, and the main control unit 40 of the console 13 performs the processing shown in FIG.

That is, as in the first embodiment, a scan image is taken, and the isocenter I / C and the irradiation field RF are designated, and then the scan plan is entered (steps 60 to 6 in FIG. 4).
2), here, when the reconstruction center is designated to include an image having the same isocenter I / C, and the range of FoV: FoV is determined as shown in FIG.
Both ends of the scan are determined. That is, the irradiation field R in FIG.
Lines SA and AB connecting points A and B determined by the range of the body axis Z of F to the source S can be formed, and intersections C and D between the line segments SA and AB and the lower end of FoV can be formed. The area between C and D is recognized as the reconstruction area.

Then, based on the reconstruction conditions thus determined, reconstruction is carried out based on the projection data obtained by the helical scan to make a treatment plan.

As a result, as shown in FIG. 11, the portion corresponding to the irradiation range is reconstructed with the reconstruction center coinciding with the isocenter.

By thus providing a treatment plan having a reconstructing function with the isocenter as the reconstructing center, a more accurate plan can be achieved as in the first embodiment.

Next, a third embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. The hardware configuration of this embodiment is also the first
It is equivalent to that of the embodiment.

The third embodiment is suitable when volume data obtained by helical scanning or the like can be used, and the leaves 56 ... 56 of the multi-leaf type collimator 55.
Each volume of MPR (Multi-Pl
anar Reconstruction) is displayed, and at the same time, the leaf opening is also displayed.

MPR of the volume range in charge of this leaf
In order to perform the display, the main control unit 40 performs the processing shown in FIG. That is, the pair of leaves 56a and 56b selected by the input device (trackball, etc.) 48 in step 70 of FIG.
On the other hand, as shown in FIG. 13, a plane A passing through the center line CL of the leaf and the radiation source S is assumed. Then step 71
Then, the volume range RV in which the leaves 56a and 56b are in charge of opening and closing is calculated as shown in FIG. 14 based on the environmental data. Fig. 1 shows an example of the layout relationship between multiple pairs of assigned volume ranges.
5 shows. Next, in step 72, the volume data within the assigned volume range RV is added and projected onto the plane A. Further, in step 73, the projection data on the plane A (line cones (i.e., leaf openings) LN and LN indicating the irradiation range as MPR images IMPR and the leaf numbers a and b in charge are displayed as illustrated in FIG.

Further, when the MPR image IMPR is displayed, it is judged whether or not the current leaf opening is OK based on the operation information from the pointing device (mouse, light pen, etc.) of the input device, and the leaf is opened. When an operation for adjusting the opening is instructed, the leaf opening (the line cones LN, LN) is immediately adjusted based on the operation information. The above display and adjustment are performed for each pair of leaves (see FIG. 15).

As a result, the image of the volume range in charge of each leaf pair of the multi-leaf type collimator can be confirmed on the spot, and the leaf opening can be adjusted on the spot, so that an accurate and quick treatment plan can be made. Can help.

[0050]

As described above, according to the present invention, an image used for treatment planning is
An X-ray scan is made with a scan plan considering the isocenter and the reconstruction center, a CT image including the isocenter is obtained, and the isocenter and the reconstruction center coincide with each other, but at a position away from the isocenter, Since the scanning is performed by inclining the same angle as the radiation path, more accurate radiation treatment planning can be performed.

Further, according to the present invention, an image for each volume range in which each pair of leaves of the multi-leaf collimator is in charge of opening and closing can be displayed and the leaf opening can be adjusted on the screen, which is highly convenient. Contribute to a more rapid and accurate treatment plan.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an example of a radiation treatment system to which a radiation treatment planning apparatus of the present invention is applied.

FIG. 2 is a block diagram of a CT system as a radiation treatment planning device.

FIG. 3 is a schematic perspective view of a multi-leaf type collimator mounted on the radiotherapy apparatus.

FIG. 4 is a flowchart of a treatment plan by the main control unit in the first embodiment.

FIG. 5 is a diagram illustrating a relationship between a scanogram, an isocenter, and an irradiation field.

FIG. 6 is a diagram exemplifying a relationship between a radiation source, an isocenter, and an irradiation field.

FIG. 7 is an explanatory diagram showing a slice example.

FIG. 8 is an explanatory diagram for obtaining a tilt angle of a gantry and a moving position of a top plate.

FIG. 9 is an explanatory diagram showing an example of slices in consideration of leaf thickness.

FIG. 10 is a diagram illustrating a range of helical reconstruction in the second embodiment.

FIG. 11 is an explanatory diagram of a slice example related to helical reconstruction.

FIG. 12 is a flowchart showing display of an MPR image for each leaf charge by the main control unit in the third embodiment.

FIG. 13 is a diagram illustrating a process of processing related to displaying an MPR image.

FIG. 14 is a diagram illustrating one process of processing related to display of an MPR image.

FIG. 15 is a diagram illustrating a volume range for each leaf charge in the third embodiment.

FIG. 16 is an image diagram showing a display example of an MPR image.

[Explanation of symbols]

 1 CT system (radiation treatment planning device) 2 Radiation device 40 Main control unit 41 Bed control unit 42 Frame control unit 45 Image reconstruction unit 46 Image memory 47 Display unit 48 Input unit 55 Collimator 56 Leaf P object

Claims (6)

[Claims] 1. A radiation treatment planning apparatus for making a radiation treatment plan based on an image obtained by exposing a subject to X-rays, and means for capturing a scanogram of the subject, and the scanogram. Means for designating the irradiation field and isocenter, means for aligning the reconstruction center of the reconstructed image that matches the plane passing through the isocenter, and commanding a scan for obtaining the image along the combined reconstruction center And a radiation treatment planning apparatus. 2. The radiation treatment planning device is a radiation treatment planning device for planning a radiation treatment by a radiation treatment device equipped with a multi-leaf type collimator, the slice thickness of the scan and the thickness of each leaf of the collimator. 2. The radiation treatment planning apparatus according to claim 1, further comprising means for instructing a scan that matches the height. 3. Control data of a gantry and a bed when a desired slice plane is aligned with a tilt angle of a radiation path from a radiation source with respect to a position in the irradiation field in the direction of an object body away from the isocenter. The radiation treatment planning apparatus according to claim 1, further comprising means and means for instructing a scan for obtaining the image according to the control data. 4. A radiotherapy apparatus for planning a radiotherapy based on an image obtained by irradiating a subject with X-rays, a means for picking up a scanogram of the subject, and a device for scanning the scanogram. Radiation therapy comprising means for designating an irradiation field and an isocenter, means for aligning a reconstruction center with a plane passing through the isocenter, and means for helically reconstructing the image according to the combined reconstruction center. Planning equipment. 5. A radiation treatment planning apparatus for planning a radiation treatment by a radiation treatment apparatus equipped with a multileaf collimator based on an image obtained by exposing a subject to X-rays, wherein the multileaf type is used. A means for calculating projection data on the cross section of the volume from the volume data of the volume for which each pair of collimators facing each other opens and closes along the radiation path from the radiation source, and a line of the radiation path for the projection data. A radiation treatment planning apparatus, comprising: a means for superimposing a cone and displaying it on a monitor. 6. The radiation treatment planning apparatus according to claim 5, further comprising means for adjusting the opening of the pyramid displayed on the monitor on the monitor.