JP2003010346A - X-ray simulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the radiation dose to a patient when preparing a treatment plan and to align the garget position of irradiation and the reference point of equipment. SOLUTION: An X-ray tube 12 and an FPD 13 for detecting X-rays are provided across the patient 11 placed on a top plate 10, and a X-ray fluoroscopic image obtained by the FPD 13 is displayed on a monitor 28. First, the X-ray fluoroscopic image is obtained by X-ray irradiation for a short time and a stuff indicates an irradiation target position from an input part while looking at the image. A processing control part 20 calculates the positional deviation between the target position and a reference position equivalent to an isocentre as the different of the vertical/horizontal address of the FPD 13 and additionally converts the difference into a moving distance in the x and y directions of the top plate 10. A photographing control part 20a controls a top plate driving part 24 based on this information to move the top plate 10 so as to match the target position with the reference point, and afterwards photographs the X-ray fluoroscopic image for target collation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray simulator for capturing an X-ray fluoroscopic image for aiming verification, which is used when aiming radiation to be irradiated on a subject during radiotherapy.

[0002]

2. Description of the Related Art As one of the methods for treating malignant tumors such as cancer, radiation therapy is generally performed by irradiating a lesion in a patient's body with radiation such as high-energy X-rays and γ-rays of ⁶⁰ Co from outside the body. ing. In the case of radiotherapy, not only is the therapeutic effect not effective unless the radiation hits the lesion area properly,
If the radiation hits a normal part other than the lesion, normal living tissue may be destroyed. Therefore, a treatment plan that determines the appropriate radiation aim (irradiation range and direction) prior to treatment is called a radiation treatment device. Planning is performed using another X-ray simulator. In such a treatment plan, an X-ray for aiming and matching captured by an X-ray simulator is used.
The fluoroscopic image is finally recorded, and when the radiotherapy is performed, the radiation to be irradiated on the patient is aimed according to the X-ray fluoroscopic image for aiming verification. In general, an isocenter that can be confirmed as an intersection of laser beams emitted from a laser projector or the like installed on the ceiling or wall of a treatment room is used as a reference point for irradiation of radiation.

FIG. 7 shows a schematic configuration diagram of a conventional X-ray simulator used for making such a treatment plan, and FIG. 8 shows a front view of a main part thereof. In this X-ray simulator, an X-ray tube 42 for X-ray irradiation and an image intensifier (I • I) tube 43 for detecting an X-ray fluoroscopic image are opposed to each other with a patient 41 on a top plate 40 interposed therebetween. The X-ray tube 42 and the I / I tube 43 are rotated around the body axis C of the patient 41 while keeping the facing relationship with each other as the rotation body 44 rotates. It is like this. Further, the cassette 46 having the film loaded therein has a photographing position in front of the I / I tube 43 and a retracted position (reference numeral 4) indicated by a two-dot chain line in the drawing.
6 ') is reciprocally moved by the cassette moving mechanism 45. The output of the I / I tube 43 is image-processed by a signal processing unit (not shown) and
An X-ray fluoroscopic image based on the X-ray detection signal output from the I / I tube 43 is displayed on the screen of a monitor (not shown).

A general work procedure for making a treatment plan in the above configuration is as follows. First, cassette 4
With the 6 placed in the retreat position 46 ', X-rays are radiated from directly above the patient 41 lying on the top 40 as shown in FIGS. 7 and 8 and detected by the I / I tube 43. The X-ray fluoroscopic image is displayed on the monitor. Persons in charge such as planners (planners) and radiologists decide the irradiation plan while looking at this image, and according to the decided plan, move the top 40 back and forth so that the target position of the radiation irradiation comes to the isocenter which is the reference point. Move to the left or right (in the horizontal plane) to perform alignment in the horizontal plane. Then, the rotating body 44 is rotated about 90 ° to rotate the X-ray tube 4
The irradiation X-rays from 2 are made to strike from the lateral direction of the patient 41, and the top plate 40 is moved up and down and back and forth while performing the X-ray fluoroscopic imaging in the lateral direction in the same procedure as above, so that Align. When the alignment is completed, the rotator 44 is rotated to the angle at which the radiation treatment is actually performed, the cassette 46 is moved to the imaging position, and X
An X-ray fluoroscopic image is printed on the film loaded in the cassette 46 by irradiating a ray to obtain an X-ray fluoroscopic photograph for irradiation aiming.

[0005]

As described above, in the conventional X-ray simulator, since it is necessary to perform the position adjustment manually while looking at the X-ray fluoroscopic image displayed on the monitor, it takes time to perform the position adjustment. However, since the patient is continuously irradiated with X-rays during that time, the patient's exposure dose increases accordingly. Further, since the position adjustment is performed manually, it takes time to finely adjust the position, resulting in poor work efficiency. Also,
To some extent, it is difficult to quickly perform delicate position adjustments without gaining experience, and work efficiency depends largely on the skill level of the person in charge. In addition, it can be said that the time-consuming alignment requires psychological and physical pain for the patient.

The present invention has been made to solve such a problem, and an object thereof is to significantly reduce the time required for fluoroscopic imaging when planning a treatment plan. An object of the present invention is to provide an X-ray simulator that can reduce the radiation dose to a patient and easily perform delicate positioning in a short time.

[0007]

DISCLOSURE OF THE INVENTION The present invention, which has been made to solve the above-mentioned problems, provides an X for aiming reference, which is referred to when aiming radiation to be irradiated on a subject during radiation treatment.
In an X-ray simulator for capturing a fluoroscopic image, a) X-ray irradiating means for irradiating an object placed on a top plate with X-rays, and b) said X-ray irradiating means with the object being sandwiched therebetween. X-ray detecting means arranged so as to face each other and having minute X-ray detecting elements arranged two-dimensionally, and c) the X-rays when the X-ray irradiating means irradiates the subject with X-rays. Image display means for displaying an X-ray fluoroscopic image taken by the detection means;
d) input means for designating a target position for radiation aiming on the X-ray fluoroscopic image displayed on the image display means, and e) positional deviation between the target position designated by the input means and a reference point for aiming. And a deviation amount calculating means for calculating as a separation distance of the top plate or information corresponding thereto.

That is, in the X-ray simulator according to the present invention, the alignment is performed in the following procedure. First, an X-ray irradiating unit irradiates a subject (for example, a person to be treated) with X-rays, and at that time, an X imaged by the X-ray detecting unit.
The fluoroscopic image is captured and displayed on the image display means. If a sufficiently clear image is obtained, X from the X-ray irradiation means
The line irradiation is stopped. The person in charge designates a target position for aiming at the time of subsequent radiation treatment by the input means while looking at this X-ray fluoroscopic image (still image). Although various methods can be used for this instruction, one of the simplest methods is
One is to display a pointer over the X-ray fluoroscopic image, move the pointer to a desired position on the image using a pointing device such as a mouse, and click at that position.
It is advisable to perform tapping operation etc. and input the confirmation of the position. Reference point (eg isocenter) on X-ray fluoroscopic image
Since the X-ray detection means causes almost no image distortion, the deviation amount calculation means determines the coordinate position of the reference position based on the coordinate position of the reference point and the coordinate information corresponding to the input target position. The position shift amount can be calculated.

After the shift amount is obtained in this way, the shift amount may be displayed by a numerical value or the like, and a person in charge may manually move the top plate so as to correct the position shift. However, it is preferable that the position shift is automatically corrected. That is, in the X-ray simulator according to the present invention, the top driving means for moving the top and the target position coincides with the reference point of aiming based on the information calculated by the deviation amount calculating means. A control unit for controlling the top driving unit may be further provided.

According to this structure, the person in charge simply points the target position by the input means while looking at the X-ray fluoroscopic image displayed on the image display means, and the target position coincides with the isocenter, which is the reference point for treatment. The top plate automatically moves with the subject placed on it as described above. Therefore, for example, if the patient is then irradiated again with X-rays for a short time to capture an X-ray fluoroscopic image, an X-ray fluoroscopic image in which the target position matches the reference point can be obtained. Such an image may be printed on a film as usual, or may be stored in the form of digital data so that it can be drawn on a monitor screen as needed.

[0011]

According to the X-ray simulator of the present invention, it is necessary for a person such as a radiographing technician to manually control the movement of the tabletop so that the subject comes to a predetermined position while observing the X-ray fluoroscopic image. Disappears. Alternatively, even if the movement of the top is manually controlled, it is not necessary to control the movement while watching the X-ray fluoroscopic image taken in real time. Therefore, the time during which the subject is irradiated with X-rays is greatly shortened, and the dose to the subject is greatly reduced, and the influence on the body of the subject such as damage to normal living tissue is minimized. You can Further, since the X-ray fluoroscopic image for aiming verification can be easily taken in a short time, work efficiency is improved,
The psychological and physical burden on the subject is also reduced. Furthermore,
Since no skill is required for alignment during radiography, even an inexperienced person can surely take an X-ray fluoroscopic image according to the treatment plan, that is, the radiotherapy can be effectively performed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION X according to one embodiment of the present invention will be described below.
The line simulator will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of an X-ray simulator according to the present embodiment, and FIG. 2 is a front view of a main part centering on a gantry of the X-ray simulator according to the present embodiment.

In this X-ray simulator, an X-ray tube 12 and a two-dimensional X-ray sensor 13 are arranged to face each other with a top plate 10 on which a patient 11 as a subject is placed. Since the two-dimensional X-ray sensor 13 is a flat panel X-ray sensor,
Hereinafter referred to as "FPD". This FPD 13 is x in the figure
A predetermined number of minute X-ray detection elements are arranged in the axial and y-axis directions, and each X-ray detection element has a TF.
The read wirings are connected via T to the read wirings running in the vertical and horizontal directions, and the read wirings are connected to the horizontal read driving section or the vertical read driving section, respectively, and a read drive signal is supplied to the horizontal and vertical read driving sections. Addresses corresponding to the rows and columns are assigned to each X-ray detection element, and it is possible to read the signal of a specific X-ray detection element by designating the address. Here, for example, an FPD whose number of pixels (number of elements) is about 2000 × 2000 is used. The specific configuration of the FPD can be the one already described in Japanese Patent Application No. 9-324430 (JP-A No. 11-155851).

The X-ray tube 12 and the FPD 13 are supported by supporting arms 16 and 18 projecting in the horizontal direction from a rotating body 15 arranged in a standing posture on a ring type gantry 14 via guide arms 17 and 19, respectively. It is installed. The rotating body 15 is rotatable about a horizontal axis, and as shown in FIG. 2, the X-ray tube 12 and the FPD 13 maintain the facing arrangement state as the rotating body 15 rotates in the direction of the arrow M6. It is configured to rotate around the patient 11 as it is.
Further, the X-ray tube 12 and the FPD 13 are reciprocally movable in the longitudinal direction of the guide arms 17 and 19 (directions of arrows M4 and M5) for image magnification adjustment and the like.

The top plate 10 is constructed so as to be movable in three axial directions of x, y, and z, and is reciprocated within a predetermined range by a top plate drive unit 24 including a motor and the like (arrow M).
1, M2, M3 direction). At the center of control, a processing / control unit 20 functionally including an image pickup control unit 20a is installed. The photographing control unit 20a includes the X-axis driving unit 24, X
The irradiation control unit 23 that controls the X-ray irradiation from the radiation tube 12 and the rotation driving unit 25 that drives the rotating body 15 are collectively controlled. Further, the output of each X-ray detection element of the FPD 13 is converted into a digital value by the A / D conversion unit 22 via the data collection unit 21 and input to the processing / control unit 20. The processing / control unit 20 can be configured as a device dedicated to this X-ray simulator, but the same function can be realized by installing and executing predetermined software in a normal computer. This processing / control unit 20
A large-capacity storage device 26 for storing photographed X-ray fluoroscopic image data, a film recording unit 27 for printing the photographed X-ray fluoroscopic image on a film, an X-ray fluoroscopic image and other information are displayed. A monitor 28, an input unit 29 including a pointing device such as a keyboard and a mouse, and the like are connected.

In the same manner as in the conventional case, around the gantry 14, for example, the position setting of the patient 11 in the X-ray simulator and the setting position of the patient in the radiotherapy apparatus can be accurately aligned, for example, A three-reference-point plotting type positioning laser irradiation device is provided, and three cross lines are projected on the body surface of the patient 11 by the laser light from the laser irradiation device. That is,
Each intersection of these three cross lines is a reference point, and a point where all the intersections in the space coincide with each other is an isocenter serving as a reference for treatment.

Next, the operation of this X-ray simulator will be described with reference to FIG.
The procedure will be described according to the procedure for creating an X-ray fluoroscopic image for aiming verification shown in the flowchart in FIG. In addition, here, the person in charge such as a radiographing technician knows in advance the target position of radiation irradiation (center position of the irradiation region) in the body of the patient to be imaged based on instructions from a treatment planner such as a doctor. Be present. Of course, the treatment plan may be made while looking at the X-ray fluoroscopic image as described below.

First, the person in charge is placed on the top plate 10 of the patient 1
After placing 1 in the supine position, the top 10 is moved to the gantry 14 to set the patient 11 at a predetermined imaging position (step S1), and a predetermined operation is performed from the input unit 29 to start the imaging operation. Is instructed (step S2). In response to this instruction, the imaging control unit 20a drives the X-ray tube 12 via the irradiation control unit 23 in a state where the X-ray tube 12 is directly above the patient 11 and the FPD 13 is directly below as shown in FIG. Then, the X-ray is irradiated toward the patient 11 for a predetermined time (step S3). The signal output from the FPD 13 while the X-ray is being emitted passes through the data acquisition unit 21 and the A / D conversion unit 2
2 is input to each of the X-ray detection elements, converted into a digital value for each detection signal from each X-ray detection element, and sent to the processing / control unit 20. Then, it is stored in the storage device 26 as data constituting one X-ray fluoroscopic image. At the same time, the processing / control unit 20
In step S4, a predetermined image signal processing is performed, and the result is displayed on the screen of the monitor 28 as an X-ray fluoroscopic image (step S4).

At this time, for example, an X-ray fluoroscopic image as shown in FIG. 3 is displayed on the monitor 28. Here, a reference point S corresponding to the isocenter is displayed at the center of the X-ray fluoroscopic image. In FIG. 3, T is a target position which is the center of the irradiation range, and although it may happen to coincide with the reference point S, it usually exists at a position displaced from the reference point S. As described above, the person in charge recognizes which part is the target position on the X-ray fluoroscopic image of FIG.
An instruction of the target position is given while watching the X-ray fluoroscopic image above (step S5). As a method for this, a pointer that moves in conjunction with the operation of a mouse or the like is superimposed on the X-ray fluoroscopic image, the pointer is moved to a desired position, and then a click operation is performed to confirm the target position. You can take the way. Of course, various methods other than the above, such as a method of instructing a target position by touching a transparent touch panel provided on the screen of the monitor 28 with a finger or a pen, can be used.

When the target position is designated, the processing / control section 2
For 0, the positional deviation amount between the designated point and the reference point S is obtained as follows (step S6). That is, the position information in the X-ray fluoroscopic image displayed on the monitor 28 is
The position (that is, the vertical / horizontal address) of the X-ray detection element of the FPD 13 as shown in FIG. 5 is associated, and the position designated by the pointer on the image is the vertical / horizontal address of the X-ray detection element of the FPD 13. Is calculated as Since the vertical and horizontal addresses of the X-ray detection element corresponding to the reference point S are known, the amount of positional deviation between the target position T and the reference point S is FPD13.
Is calculated as a value (ΔX, ΔY) on the position coordinate (that is, address coordinate) of the X-ray detecting element. Furthermore, patient 11
Since the ratio of the size of the body surface of the FPD 13 to the size of the body surface of the FPD 13 is determined by the positions of the guide arms 17 and 19, the value on the position coordinate of the X-ray detection element of the FPD 13 is calculated by a predetermined conversion formula or X-axis, y using conversion table
It can be converted into the moving distance (dx, dy) of the top plate 10 in the axial direction.

After the above calculation, the imaging control unit 20a moves the top 10 on which the patient 11 is placed via the top driving unit 24.
Positional deviations are corrected by moving a predetermined distance (dx, dy) in each of the axis and y-axis directions (step S
7). After that, the X-ray tube 1 is again passed through the irradiation control unit 23.
The patient 11 is irradiated with X-rays for a predetermined time from 2 and the detection signal by the X-rays incident on the FPD 13 is sent to the processing / control unit 20 as before (step S8). As a result, the newly photographed X-ray fluoroscopic image is displayed on the monitor 28 (step S9). If the patient 11 does not move his / her body, the target position T and the reference point S in this X-ray fluoroscopic image match, that is, the target position T should come to the center of the X-ray fluoroscopic image. Therefore, the person in charge makes such a visual check (step S10), and if there is no problem, the process proceeds to step S11.

First shooting (steps S3, S4) and 2
If the patient 11 has moved his / her body significantly between the second imaging (steps S8 and S9), the target position T may deviate from the reference point S in the second X-ray imaging image. When the person in charge determines that there is such a deviation, the process returns to step S5, and the target position is again designated in the X-ray fluoroscopic image at that time, and the above operation is executed.

When the alignment by the X-ray irradiation from above is completed, the alignment by the X-ray irradiation from the side has not been performed yet, and therefore the process proceeds from step S11 to S12, and the person in charge makes a predetermined input from the input unit 29. Then, the rotating body 15 is rotated by 90 °, and the X-ray tube 12 and the FPD 13 are arranged at the position where X-rays are irradiated from right side of the patient 11. Then, the process returns to step S3, and the alignment on the vertical plane (zy plane) is executed by the same procedure as above. The X-ray fluoroscopic image at this time is as shown in FIG. Therefore, the target position T ′ is indicated on this image, and the top 10 is moved up and down (in the direction of arrow M3 in FIG. 2) and back and forth (FIG. 1) so that the target position T ′ coincides with the reference point S ′. Other mark in the middle M
1 direction). Then, when the target position T ′ coincides with the reference point S ′, the process proceeds to steps S10 → S11 → S13,
This time, the rotating body 15 is rotated so that the X-ray irradiation angle becomes the same as the radiation irradiation angle at the time of treatment, and the X-ray is irradiated in that state, whereby the X-ray fluoroscopic image obtained by the FPD 13 is used for aiming verification. Save as. In this way, a desired X-ray fluoroscopic image for aiming verification can be obtained.

It should be noted that the X-ray fluoroscopic image stored for irradiation verification is marked as necessary to show the region to be irradiated with radiation. for that purpose,
As described in Japanese Patent Application No. 9-324430, a frame body formed of a wire or the like that does not transmit X-rays is arranged between the X-ray tube 12 and the patient 11, and the projected image of the frame body is X-rayed. It is recommended that it be reflected in a fluoroscopic image.

Although not shown in FIG. 6, after the X-ray fluoroscopic image for aiming verification is acquired, the person in charge is
A reference point at which three lines projected to determine the isocenter intersect on the body surface of the patient 11 is marked on the body surface with ink or the like, and further, the frame body is formed on the body surface of the patient 11 by a visible light source. The image projected on is drawn as a line indicating the irradiation range. Such markings are used for positioning when radiotherapy is actually performed.

It should be noted that the above embodiment is merely an example of the present invention, and it is obvious that appropriate changes and modifications can be made within the scope of the present invention.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an X-ray simulator according to an embodiment of the present invention.

FIG. 2 is a front view of the main part centering on the gantry of the X-ray simulator according to the present embodiment.

FIG. 3 is a diagram showing an example of an X-ray fluoroscopic image on a horizontal plane.

FIG. 4 is a diagram showing an example of an X-ray fluoroscopic image on a vertical plane.

FIG. 5 is a schematic diagram showing an imaging state of an X-ray fluoroscopic image on the FPD.

FIG. 6 is a flowchart showing a procedure for creating an X-ray fluoroscopic image for aiming verification using the X-ray simulator of this embodiment.

FIG. 7 is an overall configuration diagram of a conventional X-ray simulator.

FIG. 8 is a front view of a main part of a conventional X-ray simulator.

[Explanation of symbols]

10 ... Top plate 11 ... Patient 12 ... X-ray tube 13 ... FPD 14 ... Gantry 15 ... Rotating body 16, 18 ... Support arm 17, 19 ... Guide arm 20 ... Processing / control unit 20a ... Shooting control unit 21 ... Data collection unit 22 ... A / D converter 23 ... Irradiation control unit 24 ... Top drive unit 25 ... Rotational drive 26 ... Storage device 27 ... Film recording section 28 ... Monitor 29 ... Input section

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G21K 5/02 G21K 5/02 RX (72) Inventor Takayuki Okamura 1st Nishinokyo Kuwabara-cho, Nakagyo-ku, Kyoto City Stock Company Shimadzu Corporation (72) Inventor Masahiro Kono 1 Nishinokyo Kuwahara-cho, Nakagyo-ku, Kyoto Shimadzu Co., Ltd. (72) Inventor Isao Nakata 1 Nishinokyo Kuwahara-cho, Nakagyo-ku, Kyoto Co. Ltd. Shimadzu, Inc. (72) Hiroshi Miyata F-term in Shimadzu Corporation, 1st Nishinokyo Kuwabara-cho, Nakagyo-ku, Kyoto (reference) 4C082 AA03 AC02 AE01 AG09 AG21 AJ05 AJ07 AN02 AP01 AR02 4C093 AA25 CA16 EB12 EB13 EB17 ED07 FA36 FA54 FB01 FG05 FG13

Claims (2)

[Claims] 1. An X-ray simulator for capturing an X-ray fluoroscopic image for aiming reference, which is referred to when aiming radiation to be irradiated on a subject at the time of radiotherapy, a) is placed on a top plate. An X-ray irradiating means for irradiating the subject with X-rays, and b) a micro X-ray detecting element arranged in a two-dimensional array and arranged so as to face the X-ray irradiating means with the subject interposed therebetween. X-ray detection means, c) image display means for displaying an X-ray fluoroscopic image photographed by the X-ray detection means when the subject is irradiated with X-rays by the X-ray irradiation means, and d) the image. Input means for designating a target position for radiation aiming on the X-ray fluoroscopic image displayed on the display means, and e) a displacement between the target position designated by the input means and a reference point for aiming is made on the top plate. Deviation distance calculating means for calculating as the separation distance or information equivalent thereto An X-ray simulator comprising: 2. A top driving means for moving the top,
The control means for controlling the top driving means so that the target position coincides with a reference point of aiming on the basis of the information calculated by the deviation amount calculating means, further comprising: The described X-ray simulator.