JP2848347B2 - Radiation treatment planning system - Google Patents

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 system, and more particularly to a radiation treatment planning system in which it is easy to compare an irradiation field created by a CT apparatus at the stage of treatment planning with an irradiation field set by the treatment apparatus at the time of treatment. The present invention relates to a radiation treatment planning system capable of quantitatively evaluating a shift between irradiation fields.

[0002]

2. Description of the Related Art Radiation therapy, which is an effective method for treating tumors in the human body, is important in that radiation is focused on the tumor and that radiation is not irradiated to parts other than the tumor. It is to be. In accordance with such importance, a radiation treatment planning system has been devised for examining how to irradiate an affected part and treat it. In conventional radiation therapy, CT (Computed
By looking at the scout view, which is an image of the front of the patient taken by a Tomography device, it was possible to confirm whether the irradiation field (the area to be treated) was accurate.

[0003] However, even if the treatment plan is accurately made by the radiation treatment planning system, the patient must move from the bed of the CT apparatus to the bed of the treatment apparatus in order to receive treatment, and the treatment beam is not necessarily provided. There was no guarantee that the field created during the planning phase would be irradiated. Therefore,
At the treatment planning stage, the irradiation field size and position are projected and marked on the patient's skin surface by a device called a CT simulator,
It has been proposed that the treatment apparatus also has a light emitting function to improve the positioning accuracy by aligning the mark with the mark on the patient's skin surface (for example, Japanese Patent Application Laid-Open No. 63-29483).
No. 9).

[0004]

However, the conventional radiation treatment planning system has a problem that it is difficult to compare the irradiation field scheduled to be treated set at the treatment planning stage with the irradiation field actually treated. . In other words, the scout view taken at the treatment planning stage and the linac graph taken at the time of treatment are output in the form of a film, so these films are arranged side by side on the shouch casten and compared. This is because the scales of the graphics do not match.

In addition, the conventional radiation treatment planning system has a problem in that it is not possible to quantitatively compare the irradiation field scheduled to be treated set at the treatment planning stage with the irradiation field actually treated. In other words, in the conventional radiation treatment planning system, in order to quantitatively compare the irradiation fields, it is necessary to manually perform the alignment and the grasp of the positional relationship between the two films arranged on the Schaukasten. This is because measurement errors tend to occur there, so that only inaccurate information can be obtained. The present invention has been made in order to solve the above-described problems, and it is easy to compare a treatment-scheduled irradiation field set in a treatment planning stage with an actually treated irradiation field, and to reduce a shift between these irradiation fields. An object of the present invention is to provide a radiation treatment planning system that can be quantitatively evaluated.

[0006]

According to the present invention, a CT image taken by a CT apparatus, an X-ray transmission image serving as a scout view, and a linac graph taken by a radiotherapy apparatus are provided. An output device for displaying an X-ray transmission image, and an arithmetic device for creating a scout view in which an irradiation field to be treated is drawn from a CT image and displaying the scout view and linacography on the same screen of the output device And By displaying the scout view and the linac graph on the same screen of the output device at the same time, the scout view and the linac graph can be compared on the screen.

According to a second aspect of the present invention, there is provided an input device for designating a point on an image for each of the scout view and linacography images displayed on the output device. A coordinate value deviation between a scout view and a designated point of the linac graph is calculated, a statistical calculation such as an average and deviation of the deviation is performed, and the calculation results are displayed on an output device. By providing an input device for designating a point on an image in this manner, each point of the irradiation field in the scout view and linac graph can be designated as the designated point, and the arithmetic unit can designate the scout view and the linac graph. The deviation of the coordinate values between the points is calculated, and statistical calculation such as the average and deviation of the deviation is performed. According to a third aspect of the present invention, the calculating means causes the output device to display a calculation result of the deviation of the coordinate values as a graph.

[0008]

FIG. 1 is a block diagram of a radiation treatment planning system according to a first embodiment of the present invention. In radiotherapy, a CT image is first captured by a CT device. This CR image 13 is, as shown in FIG.
An X-ray fluoroscopic image of the front of the patient is taken by moving the X-ray source 11 of the CT apparatus in a direction parallel to the body axis Z of the patient 12, and is a kind of scout view. continue,
In order to capture a CT image which is a cross-sectional image perpendicular to the body axis Z of the patient 12, the bed (not shown) on which the patient 12 is laid is rotated in a direction parallel to the body axis Z while rotating the X-ray source 11 around the patient 12. Move to

In FIG. 2, the X-ray fluoroscopic image projected on the virtual X-ray film 14 is described as a CR image 13, but the actual CR image and CT image are stored as image data in the image data storage device 1. Is stored. That is, an X-ray detector (not shown) is arranged below the bed, and the X-ray transmitted through the patient 12 is detected by the detector, and the transmitted X-ray intensity is converted into an electric signal by the detector. Then, the electric signal is converted into image data by a processing circuit (not shown) and stored in the image data storage device 1 as image data.

A CT image is a large number of images obtained by continuously slicing a range including a lesion such as a tumor in a patient's body at a predetermined thickness. FIG. 3 shows an example of the CT image. CT images 21a-
In 22d, 22a to 22d are X-ray transmission images of the patient 12, and 23a to 23d are X-ray transmission images of lesions such as tumors.

The target drawing unit 6 in the arithmetic unit 2 specifies lesions 23a to 23d to be treated on each CT image stored in the image data storage device 1 as targets. Each CT image 21a to which a target is designated and drawn
Since 21d is a group of continuous slices having a parallel positional relationship to each other, an image as shown in FIG. 4A is obtained by arranging them along the body axis Z and projecting the image in the frontal direction of the patient. .

The image created by the target drawing unit 6 in this way is a scout view, and FIG.
The projected shape of the target shown in FIG. The scout view is stored in the image data storage device 1 as image data.

[0013] If considering the accuracy of treatment,
The treatment should be performed without moving the patient at the time when the irradiation field is determined in this way, but there is no device that combines the treatment device and the CT device, and the treatment is not always performed immediately after CT imaging. Therefore, the patient usually leaves the CT apparatus once, and after a while, sits on the bed of another treatment apparatus.

Therefore, after the treatment is planned, the irradiation field shape to be treated is projected onto the patient's body surface with a laser beam or the like, and a model of the irradiation field shape is created with a wire made of a radiopaque substance along the shape. The irradiation field shape is marked on the patient's body with ink or the like. Then, before the treatment, the model is placed on the body surface of the patient, and a fluoroscopic image of the front of the patient is taken by the treatment apparatus to align the mark with the ink, thereby adjusting the position of the irradiation field. Here, if the patient changes the position, the position of the irradiation field will shift even if the position is adjusted by marking or the like.

In the present embodiment, the following measures are taken in order to qualitatively / quantitatively evaluate the degree of the deviation. First, in a radiotherapy device such as a linac, X-rays are emitted to a patient 12 from an X-ray source 15 as shown in FIG. In FIG. 5 as well, the X-ray fluoroscopic image projected on the virtual X-ray film 17 is described as the linac graph 16 as in FIG. 2, but the actual linac graph stores image data as image data similarly to the CT image. Stored in the device 1.

Here, since the above-described radiopaque model is placed on the patient's skin, the photographed linacography shows an irradiation field formed by the model (this is referred to as an irradiation field 27). Appears. In the present embodiment,
The irradiation field in the treatment stage is set by such a model, but the X-ray generated by the X-ray source 15 may be controlled by an X-ray collimator so as to form the irradiation field, and the irradiation may be performed.

Next, the image display unit 7 in the arithmetic unit 2 outputs the scout view image data and the linac graphy image data stored in the image data storage device 1 to the output device 3.
Is converted to an image signal so that the image signal can be displayed. This allows
As shown in FIG. 6, the scout view 24 is displayed in a first work area 31 on the screen of the output device 3, and the linacography 26 is also displayed in a second work area 32 on the screen.

FIG. 7 shows only the two irradiation fields for explanation. Irradiation field 25 seen in scout view
Irradiation field 2 whose shape and position can be seen using linacography
If it matches the shape and position of 7, irradiation field 2 in the planning stage
5 is the same as the irradiation field 27 actually treated by receiving the radiation. The irradiation field 25 in the scout view 24 includes a1, b1, c1, d1, e1, f
Each point of 1, g1, h1, i1, j1, k1, and l1 is connected in this order.

Considering the position of each point, the irradiation field 27 in the linacography 26 corresponding to the irradiation field 25 becomes
a2, b2, c2, d2, e2, f2, g2, h2, i
2, j2, k2, and l2 are connected in this order. Using the input device 4 for designating a point on the screen, each of the points a1 to l1 of the irradiation field 25 and the irradiation field 2 corresponding thereto.
When each point of a2 to l2 of 7 is designated, the coordinate calculation unit 8 calculates
The coordinate value of the designated point is calculated from the information indicating the scale ratio attached to the image and the relative position on the screen.

The calculated coordinate values are stored in the data storage device 5. Next, the X coordinate of point a1 is Xa1, and the X coordinate of point a2 is X
Assuming that the coordinates are Xa2, a shift ΔX1 between the X coordinates of the point a1 and the point a2 is represented by (Xa1−Xa2). Also, point b1
Let Xb1 be the X coordinate of Xb1 and Xb2 be the X coordinate of point b2.
The difference ΔX2 between the X coordinates of the point b1 and the point b2 is (Xb1−Xb
It is represented by 2).

The difference ΔX3 between the points c1 and c2, and the points d1 and d2
ΔX4, the deviation ΔX5 between points e1 and e2, the points f1 and f
A deviation ΔX6, a deviation ΔX7 between points g1 and g2, a deviation ΔX8 between points h1 and h2, a deviation ΔX9 between points i1 and i2, a point j1
ΔX10 between points k1 and k2, ΔX11 between points k1 and k2,
The same applies to the deviation ΔX12 between the points l1 and l2.

The coordinate calculator 8 calculates the deviation ΔX of these X coordinates.
1 to ΔX12 are calculated. Then, the calculated X coordinate deviations ΔX1 to ΔX12 are stored in the storage device 5. Subsequently, the statistical calculation unit 9 calculates the average X of the deviation of the X coordinate as in the following equation.

[0023]

(Equation 1)

Further, the variance S of the deviation of the X coordinate is calculated as follows.

[0025]

(Equation 2)

The results of these statistical calculations are also stored in the data storage device 5. Further, a coordinate calculation unit 8, a statistical calculation unit 9
Performs the same calculation for the Y coordinate as for the X coordinate. Next, the calculation result display unit 10 generates an image signal so that the results calculated by the coordinate calculation unit 8 and the statistical calculation unit 9 can be displayed on the output device 3. Thus, the results calculated by the coordinate calculator 8 and the statistical calculator 9 are displayed on the calculation result display screen of the output device 3.

At this time, since the deviation of the coordinate values is displayed as a graph as shown in FIG. 8, the qualitative evaluation of the deviation can be performed more visually. In the example of FIG. 8, ΔX1, ΔX
2, ΔX11 and ΔX12 are large, and it can be seen that there is a possibility that the patient has shifted so that the patient rotates around the one closer to f2 or g2 with less shift during positioning. In addition, since the results calculated by the coordinate calculation unit 8 and the statistical calculation unit 9 are stored in the data storage device 5, it can be stored as information accompanying the treatment plan, and can be read when necessary.

[0028]

According to the present invention, the scout view and the linac graph can be compared on the screen by simultaneously displaying the scout view and the linac graph on the same screen of the output device. Can be obtained, and the irradiation field before and after treatment can be compared with reference to various data at the time of treatment planning. That is,
By displaying the scout view and linac graph within a narrow viewing angle, it is possible to visually grasp the shape of the entire irradiation field, and furthermore, it is possible to refer to necessary treatment plan data at any time by the treatment planning system. . As a result, it is possible to evaluate the treatment plan and the actual treatment itself without leaving the radiation treatment planning system. In addition, by displaying the scout view and the linac graph on an image instead of a conventional film, it is possible to make these scales coincide.

Further, by providing an input device for designating a point on an image, each point of the irradiation field in the scout view and linacography can be designated as a designated point, and the irradiation field in the treatment planning stage and the actual irradiation field can be designated. It is possible to quantitatively handle the position and shape of the irradiation field that has been treated in a timely manner. Furthermore, the arithmetic unit calculates the deviation of the coordinate values between the designated points of the scout view and the linac graph, and performs statistical calculation such as the average and deviation of the deviation, so that the irradiation field and the irradiation field at the treatment planning stage are actually calculated. The difference from the treated irradiation field can be quantitatively evaluated. As a result, information for specific and objective evaluation of the treatment planning system or the treatment itself can be provided.

Further, the calculation means displays the calculation result of the deviation of the coordinate values on the output device as a graph, so that the difference between the irradiation field at the treatment planning stage and the irradiation field actually treated can be more visually and qualitatively determined. Can be evaluated.

[Brief description of the drawings]

FIG. 1 is a block diagram of a radiation treatment planning system according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a state of imaging of a scout view by a CT apparatus.

FIG. 3 is a diagram showing an example of a CT image.

FIG. 4 is a diagram showing how a scout view in which an irradiation field to be treated is set is generated.

FIG. 5 is a diagram showing a state of imaging of linacography by the radiation therapy apparatus.

FIG. 6 is a diagram illustrating a scout view and a linac graph displayed on a screen of an output device.

FIG. 7 is a diagram showing irradiation fields in the scout view and linacography in FIG. 6;

FIG. 8 is a diagram illustrating a display example of a calculation result.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 image data storage device 2 arithmetic device 3 output device 4 input device 5 data storage device 6 target drawing unit 7 image display unit 8 coordinate calculation unit 9 statistical calculation Part, 10 ... calculation result display part.

Claims (3)

(57) [Claims] A CT image captured by a CT apparatus;
An output device for displaying an X-ray transmission image serving as a scout view and an X-ray transmission image serving as a linac graph taken by a radiotherapy apparatus, and creating the scout view in which an irradiation field to be treated is drawn from a CT image A radiotherapy planning system comprising: the scout view and an arithmetic unit for displaying the linac graph on the same screen of an output device. 2. The radiation treatment planning system according to claim 1, further comprising: an input device for designating a point on an image for each of the scout view and linacography images displayed on the output device, wherein the calculation is performed. The apparatus calculates the deviation of the coordinate values between the designated point of the scout view and the linac graph, performs statistical calculation such as the average and deviation of the deviation, and displays the calculation results on the output device. Characteristic radiation treatment planning system. 3. The radiation treatment planning system according to claim 2, wherein the calculation means causes the output device to display a calculation result of the deviation of the coordinate values as a graph.