JP2005230561A - Radiotherapy apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiotherapy apparatus which can perform secure and safe irradiation based on accurate alignment by executing alignment and irradiation in parallel. <P>SOLUTION: This radiotherapy apparatus to perform therapy by exposing an affected part to radiation is equipped with an imaging means (10) to image the affected part, a positioning means (23, 25) to position an irradiation field based on the imaging result obtained by the imaging means (10), and irradiating means (10, 26, 27) to expose the irradiation field positioned by the positioning means (23, 25) to a predetermined dose of radiation for a predetermined time. The imaging means (10) is integrated with the irradiating means (10). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a radiotherapy apparatus that performs treatment by irradiating an affected area with radiation.

  Traditionally, radiation therapy has been performed using an electronic linac (linear accelerator). The problems that arise when performing this radiation treatment are the absorbed dose in the abnormal tissue to be treated and the adverse effect on the normal tissue. In order to reliably treat the abnormal tissue, it is necessary to reliably inject a lethal dose into the abnormal tissue. However, when irradiation is simply performed, side effects are given to surrounding normal tissues.

  For example, the lethal dose of hepatoma that is an abnormal tissue is 60 Gray, whereas the lethal dose of normal liver tissue around the hepatoma is 40 Gray. For this reason, ingenuity to reduce radiation damage in normal tissues has been devised, such as rotation irradiation, multiportal irradiation, or conformal irradiation that adjusts the shape of the collimator according to the shape of the affected part (conformal irradiation). .

  However, even if any of the above-described devices are used, the irradiation field positioning accuracy of the radiotherapy apparatus cannot be ensured, and a sufficient therapeutic effect has not been achieved. In addition, the following five points cause the irradiation field positioning accuracy to deteriorate.

(1) Deviation of reference coordinates between a diagnostic apparatus such as an X-ray CT apparatus and an MRI apparatus used for diagnosis and position determination of an affected area and a treatment irradiation apparatus.

(2) The diagnostic device and the treatment irradiation device both use a bed to support the patient, but the positional relationship between the bed and the patient is ambiguous.

(3) Changes in the position of the affected area due to patient breathing.

(4) Change in the position of the affected area during multiple irradiations.

(5) Irradiation penumbra based on the size of the source.

  For example, a gamma knife used for treating a small area of a patient's head mechanically fixes a positioning frame to the patient's skull, and uses a diagnostic imaging apparatus and a treatment irradiation apparatus with the frame as a reference. At the same time, the irradiation penumbra is minimized based on the size of the radiation source peculiar to gamma rays by dividing one radiation source into many small dose sources. This solves each of the above problems and achieves high treatment results.

  However, the gamma knife cannot be applied to a part where the frame cannot be mounted, such as the chest and abdomen, and even if an accurate reference coordinate can be set, it cannot cope with a change in the position of the affected part due to patient breathing. In order to correct such a change in the position of the affected part due to respiration, various respiratory synchronization devices have been developed and evaluated. However, each device adopts a method that estimates the position of the affected area based on changes in the physical shape of the patient due to patient breathing, and there is a problem with positioning correction accuracy in terms of individual differences of patients and uniformity of respiratory motion. There is.

  An object of the present invention is to provide a radiotherapy apparatus capable of performing reliable and safe irradiation based on an accurate aim by performing aiming and irradiation in parallel.

  In order to solve the above problems and achieve the object, the radiotherapy apparatus of the present invention is configured as follows.

  The radiotherapy apparatus according to the present invention is an radiotherapy apparatus that performs treatment by irradiating an affected area with radiation. Imaging means for imaging the affected area, and positioning means for positioning an irradiation field based on an imaging result of the imaging means And an irradiating means for irradiating a predetermined dose to the irradiation field positioned by the positioning means for a predetermined time, and the imaging means and the irradiating means are integrated.

  As a result of taking the above-mentioned means, the following operation occurs.

  In the radiotherapy apparatus of the present invention, the imaging means for imaging the affected part and the irradiation means for irradiating the positioned irradiation field with a predetermined dose for a predetermined time are integrated. Therefore, the imaging means and the irradiation means Therefore, the patient can stop breathing without moving the patient in a short time, and can irradiate the affected area with a large dose. And the movement of an affected part and irradiation position shift resulting from a patient's respiration can be eliminated. In addition, it is possible to eliminate a positional shift such as a change in the position of the affected part due to multiple divided irradiations.

  According to the radiotherapy apparatus of the present invention, effective irradiation of an organ from the chest to the abdomen, which is difficult to position accurately because the patient moves by breathing, can be reliably and safely performed with an accurate aim. The Moreover, it can apply as an alternative treatment apparatus also about the site | parts conventionally treated with the gamma knife etc., such as a head.

  FIGS. 1A and 1B are cross-sectional views showing a schematic configuration of an imaging / irradiation unit 10 that is a central part in the radiotherapy apparatus according to the embodiment of the present invention, and FIG. (B) is a front view.

  1A and 1B, the accelerator 1 includes an electron gun 11, a focusing coil 12, a traveling wave type acceleration tube 13, and an X-ray conversion target / collimator 14. The electron gun 11 is attached to the upper end portion of the traveling wave type acceleration tube 13, and the X-ray conversion target / collimator 14 is attached to the lower end portion of the traveling wave type acceleration tube 13. Further, the focusing coil 12 is installed so as to surround the traveling wave type acceleration tube 13. Further, a dummy load 15 is attached to the lower part of the traveling wave type acceleration tube 13, and an acceleration microwave input port 16 is attached to the upper part of the traveling wave type acceleration tube 13.

  A bed 2 is installed below the accelerator 1, and a patient 4 lies on the bed 2. Further, an imaging sensor array 3 is installed below the bed 2. The accelerator 1 and the imaging sensor array 3 are integrated on the beam axis a. The acceleration voltage of the electron gun 11 when an acceleration microwave is applied to the accelerator 1 from the input port 16 is set to 100 kV to 150 kV.

  When acceleration microwaves are not applied to the accelerator 1, that is, during X-ray CT imaging, the electron beam output from the electron gun 11 travels without accelerating in the magnetic field of the focusing coil 12. Then, it is converted to X-rays by the X-ray conversion target 14 and becomes an X-ray source for X-ray CT imaging. The amount of electron beam current output from the electron gun 11 is controlled by the electron gun grid voltage. The imaging X-rays output from the X-ray conversion target 14 pass through the patient 4 on the bed 2 and then are received by the imaging sensor array 3 installed facing the X-ray conversion target 14. As described above, the accelerator 1 and the imaging sensor array 3 are integrated on the beam axis a, and rotate around the patient 4 about the rotation axis b. With this rotation, imaging can be performed from a plurality of directions within a range of a semicircular circle of about 180 degrees.

  The bed 2 to which the patient 4 is fixed is movable in the directions of arrows c (front and rear), arrows d (up and down) and arrows e (left and right) based on a predetermined operation by the operator. The entire irradiation field is imaged along with the movement, and tomography and grasping of the entire irradiation field are performed. Thereafter, the bed 2 to which the patient 4 is fixed is moved again, and the irradiation target is controlled to be positioned on the rotation axis b of the accelerator 1.

  Next, imaging near the irradiation target is performed at high speed, and after the operator confirms the aim, treatment irradiation is performed. At the time of this irradiation, electrons are accelerated by inputting an acceleration microwave from the input port 16 of the traveling wave type acceleration tube 13, the electrons hit the X-ray conversion target 14 with an energy of 6 MeV to 16 MeV, and the X of the same energy. Converted to a line. This X-ray is irradiated to the affected part of the patient 4 as therapeutic radiation. At that time, the irradiation dose is monitored by the imaging sensor array 3. The acceleration energy of electrons is controlled to an optimum value according to the irradiation field depth. The acceleration energy is controlled by the amount of electron beam current and the acceleration microwave power. Thereby, an optimal irradiation dose is irradiated to an affected part.

  The process from imaging to irradiation for aiming as described above is defined as one irradiation, and this one irradiation is completed within 20 seconds. During this time, the patient 4 intentionally stops breathing to prevent the irradiation target from moving due to breathing. By rotating the accelerator 1 about the rotation axis b and changing the irradiation direction, irradiation can be performed from a plurality of directions within a range of a semicircular circle of about 180 degrees with respect to one irradiation target. When a slight misalignment due to the patient's breathing occurs during the period when the accelerator 1 rotates, the correction is performed by the operator moving the bed 2 based on a predetermined operation.

  FIG. 2 is a block diagram showing the configuration of the control system of the radiotherapy apparatus. Hereinafter, the operation of the control system will be described with reference to FIG. An imaging / irradiation unit 10 in FIG. 2 is a central part of the radiotherapy apparatus, and includes the accelerator 1, the bed 2, and the imaging sensor array 3 shown in FIG.

  A signal S1a indicating an X-ray image acquired by the imaging sensor array 3 during X-ray CT imaging is input to the sensor array signal amplification / AD conversion unit 21, and is amplified and AD converted. Then, the signal S2 indicating the X-ray image output from the sensor array signal amplification / AD conversion unit 21 is input to the CT signal processing unit 22 and subjected to image processing based on a sensor array position signal S17 described later, and then a diagnostic image S3. Is output to the operator interface device 23. As a result, a diagnostic image is displayed on the display of the operator interface device 23 together with a position reference for imaging. On the other hand, the image output from the CT signal processing unit 22 is supplied to the dose management computer 24 as irradiation field data.

  The surgeon refers to the diagnostic image displayed on the display of the surgeon interface device 23 and performs a predetermined operation on the surgeon interface device 23, thereby giving an irradiation position (or observation) instruction to the system control device 25. A signal S6 for instructing treatment irradiation (or diagnosis irradiation) is output. The system control device 25 controls the entire control system based on the signal S6 input from the operator interface 23. The system controller 25 outputs an electron gun trigger / current / klystron trigger signal S7 to the klystron modulator / electron gun high voltage source 26. When the klystron modulator / electron gun high voltage source 26 receives the signal S7, it supplies the accelerator 1 with an electron gun acceleration voltage S8 of 100 kV to 150 kV and a grid voltage for electron beam current control, and a klystron amplifier 27 with a klystron acceleration voltage S9. Supply.

  Further, the system control device 25 outputs a klystron output command S10 to the klystron RF driver 28. The klystron RF driver 28 supplies the klystron RF source S11 to the klystron amplifier 27 based on the input klystron output command S10. As a result, the klystron amplifier 27 outputs an acceleration microwave to the input port 16 of the accelerator 1.

  The system control device 25 outputs a position setting command / accelerator position / bed position signal S12 to the drive control unit 29 together with the above operation. When the drive control unit 29 receives the position setting command / accelerator position / bed position signal S12 from the system control device 25, the drive control unit 29 receives the position signal S13 input from the accelerator / sensor array rotation drive mechanism 30 and the bed linear movement drive mechanism 31. Based on the position signal S14, the angle command S15 is output to the accelerator / sensor array rotation drive mechanism 30, and the bed position command S16 is output to the bed linear movement drive mechanism 31. Thereby, the accelerator / sensor array rotation drive mechanism 30 controls the rotation drive of the accelerator 1 and the sensor array 3, and the bed linear movement drive mechanism 31 controls the linear drive of the bed 2. The drive control unit 29 outputs a signal S17 indicating the position of the sensor array 3 to the CT signal processing unit 22 based on the position signal S13 input from the accelerator / sensor array rotation drive mechanism 30.

  On the other hand, the evacuation / cooling system control / interlock unit 32 controls the evacuation system 33 and the cooling system 34 connected to the accelerator 1 while monitoring the system control device 25, and interlock control related thereto. To do.

  When the therapeutic irradiation is performed, the signal S1b indicating the irradiation dose output from the sensor array 3 is input to the dose management computer 24 as the irradiation dose signal S4 via the sensor array signal amplification / AD conversion unit 21. In the dose management computer 24, based on the input irradiation dose signal S4, the integrated dose of the irradiation field, that is, the abnormal tissue and the integrated dose of the normal tissue around it are calculated, and the result is sent to the operator interface device 23 as a dose management graphic signal. Output as S5. The operator interface device 23 displays the irradiation field image in different colors on its own display based on the input dose management graphic signal S5. This display is referred to by the operator during treatment planning.

  In addition, this invention is not limited to the said embodiment, In the range which does not change a summary, it can implement suitably.

(Operational effects of the embodiment)
(1) Since the diagnostic imaging apparatus and the treatment irradiation apparatus are integrated, the problem of deviation of the reference axis between the diagnostic imaging apparatus and the treatment irradiation apparatus can be solved.

(2) Imaging / positioning and irradiation of the affected area from one direction without changing the patient's condition can be completed in a short time of about ten seconds, and one-way / one-time irradiation is completed while the patient stops breathing. Therefore, it is possible to eliminate the ambiguity of the positional relationship between the bed and the patient, the change of the affected part position / irradiation position accompanying the patient's breathing, and the affected part position change caused by the multiple divided irradiations. In order to solve these problems, a high-speed image signal processing device and an X-ray / electron beam irradiation device that can control the energy (radiation hardness) to an optimum value according to the irradiation field depth, which is a large dose, are adopted. doing.

(3) To prevent radiation damage, treatment irradiation is performed from several tens of directions, and a dose management computer is provided to perform three-dimensional dose management / treatment planning. As a result, radiation damage to normal tissue can be minimized and the necessary dose can be concentrated on the affected area. In addition, the dose management computer can perform radiation control of the affected area and surrounding tissues based on the irradiation field data and irradiation dose data from the imaging / irradiation section.

(4) By providing the radiation quality adjustment function so that the transmittance can be adjusted according to the irradiation depth, even if the affected area depth changes according to the irradiation direction, it is possible to ensure the quality of the radiation that is surely transmitted to the affected area.

(Summary of embodiment)
The configuration and operational effects shown in the embodiment are summarized as follows.

[1] The radiotherapy apparatus shown in the embodiment includes an imaging means (10) for imaging an affected area in the radiotherapy apparatus for performing treatment by irradiating the affected area with radiation, and the imaging means (10). Positioning means (23, 25) for positioning the irradiation field based on the imaging result of the above, and irradiation means (10, 26, 25) for irradiating the irradiation field positioned by the positioning means (23, 25) with a predetermined dose for a predetermined time 27), and the imaging means (10) and the irradiation means (10) are integrated.

  As described above, in the above radiotherapy apparatus, the imaging means (10) for imaging the affected part and the irradiation means (10) for irradiating the positioned irradiation field with a predetermined dose for a predetermined time are integrated. The reference axis shifts between the means of irradiation and the means for irradiation, and the patient can stop breathing without moving the patient in a short time, and the patient can irradiate the affected area with a large dose. It becomes. And the movement of an affected part and irradiation position shift resulting from a patient's respiration can be eliminated. In addition, it is possible to eliminate a positional shift such as a change in the position of the affected part due to multiple divided irradiations.

[2] The radiotherapy apparatus shown in the embodiment is the apparatus described in [1] above, and performs a plurality of imaging operations by the imaging unit (10) and irradiation units by the irradiation unit (10, 26, 27). Means (29, 30, 31) for rotationally driving the imaging means (10) and the irradiating means (10) so as to perform from the direction.

  As described above, in the above radiotherapy apparatus, the imaging means (10) and the irradiation means (10) are rotationally driven so as to perform imaging and irradiation from a plurality of directions. Yes. In addition, since continuous rotation irradiation is possible in a plurality of directions, radiation damage to areas other than the irradiation field can be prevented.

[3] The radiotherapy apparatus shown in the embodiment is the apparatus according to [1] or [2] above, and according to the depth of the irradiation field positioned by the positioning means (23, 25). And means (25, 26, 27) for controlling the dose irradiated by the irradiation means (10).

  As described above, in the radiotherapy apparatus, since the dose to be irradiated is controlled according to the depth of the positioned irradiation field, the dose necessary for the affected area is concentrated so as to minimize the radiation damage of the normal tissue. Can be irradiated.

It is sectional drawing which shows schematic structure of the center part in the radiotherapy apparatus which concerns on embodiment of this invention, (a) is a side view, (b) is a front view. The block diagram which shows the structure of the control system of the radiotherapy apparatus which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Imaging / irradiation part 1 ... Accelerator 11 ... Electron gun 12 ... Focusing coil 13 ... Traveling wave type acceleration tube 14 ... X-ray conversion target / collimator 15 ... Dummy load 16 ... Input port 2 ... Bed 3 ... Sensor array for imaging 4 ... Patient 21 ... Sensor array signal amplification / AD conversion unit 22 ... CT signal processing unit 23 ... Surgery interface device 24 ... Dose management computer 25 ... System controller 26 ... Klystron modulator / electron gun high voltage source 27 ... Klystron amplifier 28 ... Klystron RF driver 29 ... Drive control unit 30 ... Accelerator / sensor array rotation drive mechanism 31 ... Bed linear movement drive mechanism 32 ... Vacuum exhaust / cooling system control / interlock unit 33 ... Vacuum exhaust system 34 ... Cooling system a ... Beam shaft b …Axis of rotation

Claims (1)

In a radiotherapy device that performs treatment by irradiating the affected area with radiation,
Imaging means for imaging the affected area;
Positioning means for positioning the irradiation field based on the imaging result by the imaging means;
Irradiating means for irradiating a predetermined dose to the irradiation field positioned by the positioning means for a predetermined time, and
A radiotherapy apparatus in which the imaging unit and the irradiation unit are integrated.

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