JP2009072287A - Particle beam irradiation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a particle beam irradiation apparatus achieving the simplification of the whole apparatus which easily responds to affected areas having various profiles. <P>SOLUTION: The irradiation apparatus includes a shielding leaf plate group 400 wherein a plurality of pairs of shielding leaf plates 400a and 400b that are movable in a first direction perpendicular to the beam advancing direction and faces each other in the first direction are arranged in a second direction perpendicular to the beam advancing direction, an attenuating leaf plate group 401 arranged immediately on the downstream side of the beam advancing direction right under the shielding leaf plate group 400 wherein a plurality of pairs of attenuating leaf plates 401a and 401b that are movable in the first direction and facing each other in the first direction are arranged in the second direction and the plurality of pairs of attenuating leaf plates 401a and 401b are arranged along the beam advancing direction in a plurality of steps, and a leaf plate driving mechanism that adjusts the arrangement of the shielding leaf plates 400a and 400b and the attenuating leaf plates 401a and 401b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a particle beam irradiation apparatus that shapes and irradiates a particle beam.

  Radiation therapy that irradiates an affected area such as a tumor with radiation (for example, X-rays, charged particle beam, etc.) is occupying an important position in cancer therapy because it does not directly hurt the patient. For example, the dose distribution in the patient's body when irradiated with X-rays is the largest near the body surface and attenuates as the depth increases. On the other hand, for example, when a charged particle beam such as a proton beam or a carbon beam is irradiated, the dose distribution in the patient's body shows a Bragg peak just before stopping, and is low in other regions. That is, the charged particle beam is excellent in that the dose can be concentrated on the affected area. Therefore, in recent years, particle beam therapy systems using charged particle beams are becoming widespread.

  In the particle beam therapy system, for example, a charged particle beam accelerated by an accelerator such as a synchrotron is output from an irradiation apparatus to irradiate an affected area of a patient. Irradiation devices can be broadly divided into a passive irradiation method in which a charged particle beam is scattered and expanded in the radial direction, and then cut into an affected part shape and irradiated, and a scanning irradiation method in which a thin charged particle beam is irradiated along the affected part shape. Are known.

  The passive irradiation type irradiation apparatus includes, for example, a first scatterer, a second scatterer, a ridge filter, a range shifter, a patient collimator, and a patient bolus in the order along the beam traveling direction. The first scatterer is composed of a plate member made of a material such as tungsten, for example, and expands the beam in the radial direction while making the radial dose distribution of the beam a normal distribution. The second scatterer has a double ring structure composed of, for example, a central disk portion made of a similar material and an outer ring portion made of a material such as a resin, and the beam radial dose distribution is made uniform. While expanding the beam in the radial direction. The ridge filter has a plurality of wedge-shaped structures, and widens the energy distribution width of the beam to expand the depth of arrival of the beam in the patient body in the depth direction. The range shifter is composed of a plurality of acrylic plates having different thicknesses, and selects an acrylic plate that allows the beam to pass through, adjusts the energy of the beam, and adjusts the arrival depth of the beam. The patient collimator is composed of a shield having a through hole corresponding to the shape of the affected part in the lateral direction (in other words, the shape in the direction perpendicular to the beam traveling direction), and shapes the irradiation field of the beam. The patient bolus is composed of a resin block body that has been excavated in accordance with the depth shape of the affected part, and shapes the distribution shape of the beam arrival depth in the patient body.

  By the way, since the above-mentioned patient collimator must be manufactured every time corresponding to the different shape of the affected part in the lateral direction, there arises a problem that not only the cost is high but also the handling in the case of disposal is difficult. Therefore, for example, a multi-leaf collimator has been proposed in which a plurality of pairs of shielding leaf plates facing each other in one direction perpendicular to the beam traveling direction are arranged in another direction perpendicular to the beam traveling direction ( For example, see Patent Document 1). Since this multi-leaf collimator sets the irradiation field of the beam by adjusting the facing distance between each pair of shielding leaf plates, it can cope with the lateral shape of the affected area.

  Moreover, since the above-mentioned patient bolus must be manufactured every time corresponding to the depth shape of a different affected part, the subject that not only the cost becomes high but the handling in the case of discarding becomes difficult arises. Therefore, for example, a multi-leaf bolus (slide bolus mechanism) in which a plurality of pairs of attenuation leaf plates (plate boluses) movable in a direction perpendicular to each other and perpendicular to the beam traveling direction are provided along the beam traveling direction. ) Has been proposed (see, for example, Patent Document 2). This multi-leaf bolus adjusts the position of the attenuation leaf plate to set the distribution shape of the depth of reach of the beam in the patient's body, so that it can cope with the depth shape of the affected area.

JP 2002-224230 A Japanese Patent Laid-Open No. 2001-276240 (FIG. 15)

However, there are the following problems in the above-described prior art.
That is, the multi-leaf collimator and the multi-leaf bolus are completely separate structures, and their structures (specifically, the shape of the leaf plate, the moving direction, the driving mechanism, etc.) are completely different. Therefore, when the irradiation apparatus is provided with the multi-leaf collimator and the multi-leaf bolus, there arises a problem that the entire apparatus becomes complicated.

  An object of the present invention is to provide an irradiation apparatus that can easily deal with different shapes of affected parts and can simplify the entire apparatus.

  In order to achieve the above object, according to the present invention, in a particle beam irradiation apparatus that shapes and irradiates a charged particle beam, the particle beam irradiation apparatus can move in the first direction perpendicular to the traveling direction of the beam. A shielding leaf plate group in which a plurality of pairs of shielding leaf plates opposed to each other are arranged in a second direction perpendicular to the beam traveling direction, and the first leaf while being movable in the first direction. A plurality of pairs of attenuating leaf plates disposed opposite to each other in the direction, and a plurality of pairs of attenuating leaf plates are provided along the beam traveling direction; An attenuating leaf plate group disposed immediately downstream of the group in the beam traveling direction; a first leaf plate driving mechanism for adjusting the arrangement of the shielding leaf plate to set the irradiation field of the beam; Beam arrival at the object And a second leaf plate drive mechanism for adjusting each arrangement of the attenuating leaf plate in order to set the degree of distribution shape.

  According to the present invention, the entire apparatus can be simplified while being easily adaptable to different affected part shapes.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing the overall configuration of a particle beam therapy system including an embodiment of the irradiation apparatus of the present invention. FIG. 2 is a schematic diagram showing the configuration of the emission nozzle in the irradiation apparatus of the present embodiment.

  In these FIG. 1 and FIG. 2, the particle beam therapy system is based on the control of the control device 121. The charged particle beam (proton beam in this embodiment) accelerated by the charged particle beam generator 100 is a rotary irradiation device 113. And irradiates the affected area of the patient 17 fixed to the treatment bed 18.

  The charged particle beam generator 100 includes an ion generator 102, a pre-stage accelerator 103, and a synchrotron 101.

  The ion generator 102 generates negative hydrogen ions from an ion source (not shown) of hydrogen molecules in response to a command from the controller 121, and electrostatically accelerates the generated negative hydrogen ions to, for example, 50 keV. The light is emitted to the front stage accelerator 103. The front stage accelerator 103 is, for example, a tandem electrostatic accelerator with a terminal voltage of 2.5 MeV, and accelerates negative hydrogen ions from the ion generator 102 to 2.5 MeV in response to a command from the control device 121. Exit.

  The synchrotron 101 includes an injector 104 that receives the beam from the pre-accelerator 103, a plurality (eight in FIG. 1) of bending electromagnets 106 that bend the beam trajectory, and a plurality of beams that control the betatron oscillation of the beam (FIG. 1). 8) quadrupole electromagnets 107, a high-frequency accelerating cavity 110 that gives energy to the beam, that is, accelerates the beam, and a high-frequency applying device for emission that increases the betatron oscillation of the beam by applying a high-frequency electromagnetic field to the beam. 109, a plurality of (four in FIG. 1) hexapole electromagnets 108 for exciting resonance during beam emission, and an exit deflector 105 for emitting the beam. In addition, in accordance with a command from the control device 121, a power supply device 111 is provided to control currents supplied to the deflection electromagnet 106, the quadrupole electromagnet 107, the high frequency acceleration cavity 110, the high frequency application device 109, and the hexapole electromagnet 108, respectively. Yes.

  The power supply device 111 controls the current supplied to the deflecting electromagnet 106, the quadrupole electromagnet 107, and the high-frequency acceleration cavity 110, thereby accelerating the beam while stably circling it, and setting the energy of the beam to a set value (in detail, The value is set to a plurality of levels corresponding to a plurality of layers obtained by dividing the affected part in the depth direction. Thereafter, by controlling the current supplied to the high-frequency applying device 109, the quadrupole electromagnet 107, and the hexapole electromagnet 107, the beam is emitted from the extraction deflector 105 to the beam transport system 112.

  The control device 121 determines the set value of the beam energy based on the depth position of the affected area input from the treatment planning device 120. In addition, the current values supplied to the deflection electromagnet 6, the quadrupole electromagnet 107, and the high-frequency acceleration cavity 110 necessary for accelerating the beam to the energy set value are calculated and stored in a storage device (not shown). ing. The current value for each device stored in the storage device is output to the power supply device 111 when the synchrotron 101 is accelerated or extracted.

  The rotary irradiation device 113 includes a gantry 116 to which a part of the beam transport system 112 and an emission nozzle 117 connected thereto are attached, and a motor 114 that rotationally drives the gantry 116 around a rotation shaft 115. It is possible to irradiate the affected part (in other words, the isocenter that is the intersection of the rotation axis 115 and the beam center axis 119 of the emission nozzle 117) from an arbitrary direction.

  The beam incident on the beam transport system 112 has its trajectory bent by a plurality (four in FIG. 1) of deflecting electromagnets 106, and betatron oscillation is adjusted by a plurality (five in FIG. 1) of quadrupole electromagnets 107. Guided to the exit nozzle 117.

  After the beam guided to the emission nozzle 117 passes through the vacuum window 2, the position of the beam is measured by the primary position monitor (profile monitor) 3. Thereafter, the beam passes through the first scatterer 4 and further passes through the second scatterer 6. The first scatterer 4 is made of a plate member made of a material such as tungsten, for example, and expands the beam in the radial direction while making the radial dose distribution of the beam a normal distribution. In the present embodiment, a plurality of (three in FIG. 2) first scatterers 4 having different thickness dimensions are arranged along the beam traveling direction, and any first scatterer 4 is placed at the beam passing position. A drive mechanism 5 is provided for placement. The second scatterer 6 has a double ring structure composed of, for example, a central disk portion made of a similar material and an outer ring portion made of a material such as a resin, and the radial dose distribution of the beam is uniform. And expanding the beam in the radial direction. In the present embodiment, a plurality of different types of second scatterers 6 are arranged on the rotary table 7, and the arbitrary second scatterers 6 are arranged at beam passing positions by the rotation of the rotary table 7. The

  The beam that has passed through the second scatterer 6 is measured by the primary dose monitor 8, passes through the ridge filter 9, and further passes through the range shifter 11. The ridge filter 9 has a plurality of wedge-shaped structures, and widens the energy distribution width of the beam to expand the reach depth of the beam in the body of the patient 17 in the depth direction. In the present embodiment, a plurality of ridge filters 9 having different shapes are arranged on the rotary table 10, and the arbitrary ridge filter 9 is arranged at a beam passing position by the rotation of the rotary table 10. The range shifter 11 is composed of a plurality of acrylic plates having different thicknesses, selects an acrylic plate that allows the beam to pass therethrough, adjusts the energy of the beam, and adjusts the reach depth of the beam. In the present embodiment, a plurality of (three in FIG. 2) range shifters 11 having different thickness dimensions are arranged along the beam traveling direction, and a driving mechanism for arranging an arbitrary range shifter 11 at a beam passing position. 12 is provided.

  The beam that has passed through the range shifter 11 is the main part of this embodiment after the beam position is measured by the secondary position monitor (flatness monitor) 13 and the beam dose is measured by the secondary dose monitor 14. It is shaped by the multi-leaf collimator bolus 15 and irradiated to the affected part of the patient 17.

  The control device 121 receives detection signals from the primary position monitor 3 and the secondary position monitor 13 and determines whether or not the beam position deviation is within an allowable range. Further, detection signals from the primary dose monitor 8 and the secondary dose monitor 14 are input, and it is determined whether or not the beam dose has reached a target value or has not exceeded an allowable value. For example, when it is determined that the beam position deviation exceeds the allowable range or the beam dose exceeds the allowable value, the shutter mechanism 118 provided on the upstream side of the emission nozzle 117 is switched to the closed state, and the beam Stop the irradiation.

  FIG. 3 is a plan view showing a basic configuration of the multi-leaf collimator bolus 15, and FIG. 4 is a cross-sectional view taken along a section IV-IV in FIG. In FIG. 4, 301 is an affected area of the patient 17, and 302 is the body surface of the patient 17.

  3 and 4, the multi-leaf collimator bolus 15 is arranged immediately below the beam traveling direction with respect to the shielding leaf plate group 400 having a multi-leaf collimator function and the attenuation leaf plate group 400, and has a multi-leaf bolus function. A damping leaf group 401 having

  The shielding leaf plate group 400 includes a plurality of pairs of shielding leaf plates 400a and 400b formed of a material (for example, iron) that shields the charged particle beam. Specifically, the pair of shielding leaf plates 400a and 400b arranged to face each other while being movable in a first direction (left and right direction in FIG. 3) perpendicular to the beam traveling direction is set to be perpendicular to the beam traveling direction. Two or more are arrange | positioned in the direction of 2 (up-down direction in FIG. 3). Then, the arrangement of the shielding leaf plates 400a and 400b is adjusted by a leaf plate driving mechanism (details will be described later), and the facing distance (gap) in each pair of shielding leaf plates 400a and 400b is adjusted. Thereby, components other than the gap formed by the arrangement of the shielding leaf plates 400a and 400b in the beam reaching the shielding leaf plate group 400 are shielded, so that the beam irradiation field is set. As a result, it is possible to deal with the shape of the affected part in the lateral direction.

  The attenuation leaf plate group 401 includes a plurality of pairs of attenuation leaf plates 401a and 401b formed of a material (for example, resin) that attenuates the energy of the charged particle beam. Specifically, a plurality of pairs of attenuation leaf plates 401a and 401b that are arranged to face each other while being movable in the first direction are arranged in the second direction, and the plurality of pairs of attenuation leaf plates are arranged. For example, 401a and 401b are arranged in four stages along the beam traveling direction. The four-stage attenuation leaf plates 401a and 401b have the same dimensions in the width direction (up and down direction in FIG. 3) and in the length direction (left and right direction in FIG. 3). On the other hand, the attenuation leaf plates 401a and 401b in the first and second steps from the upstream side in the beam traveling direction have a smaller dimension in the thickness direction (vertical direction in FIG. 4) than the shielding leaf plates 400a and 400b, The attenuation leaf plates 401a and 401b in the third and fourth steps are smaller in the thickness direction than the attenuation leaf plates 401a and 401b in the first and second steps. The arrangement of the attenuation leaf plates 401a and 401b is adjusted by a leaf plate driving mechanism (details will be described later), and the thickness of the attenuation leaf plate 401a or 401b at each beam incident position (in other words, out of four stages) Are adjusted). As a result, among the beams that have passed through the gap of the shielding leaf plate group 400, the energy that has passed through the attenuation leaf plate 401a or 401b is attenuated according to the overlap thickness dimension, so that the beam inside the patient 17 body. The distribution shape of the reaching depth is set. As a result, it is possible to deal with the depth shape of the affected area.

  In the present embodiment, the shielding leaf plates 400a and 400b and the attenuation leaf plates 401a and 401b at the respective stages have shapes in the direction perpendicular to the beam traveling direction (dimensions in the width direction and dimensions in the length direction). They are the same as each other. Further, the shielding leaf plates 400a and 400b and the attenuation leaf plates 401a and 401b at the respective stages are arranged so that the positions in the width direction are the same.

  FIG. 5 is a functional block diagram showing the configuration of the control system related to the multi-leaf collimator / bolus 15. In FIG. 5, for the sake of convenience, a drive mechanism for a plurality of pairs of shielding leaf plates 400a and 400b is representatively shown.

  In FIG. 5, a leaf that generates a driving force for moving the shielding leaf plate 400a (or 400b) as a driving mechanism of the shielding leaf plate 400a (or 400b, the same correspondence in parentheses hereinafter) of the multi-leaf collimator bolus 15 is used. A position drive actuator 402a (or 402b) and a drive force transmission / cutoff mechanism 403a (or 403b) that switches the transmission / cutoff state of drive force from the leaf position drive actuator 402a (or 402b) to the shielding leaf plate 400a (or 400b). ), A braking mechanism (not shown) for generating a braking force for braking the shielding leaf plate 400a (or 400b), and transmission / cutoff of the braking force from the braking mechanism to the shielding leaf plate 400a (or 400b) Braking force transmission / cutoff mechanism 405a (or 405b) for switching the state, Position for detecting the position of use leaf plate 400a and a (leaf position) detection mechanism 404 is provided.

  Then, for example, the driving force transmission / cut-off mechanism 403a (or 403b) is turned off, and the braking force transmission / cut-off mechanism 405a (or 405b) is put into the braking force transmission state, thereby the shielding leaf plate 400a ( Alternatively, the position 400b) is held. On the other hand, for example, by setting the driving force transmission state in the driving force transmission / cutoff mechanism 403a (or 403b) and the braking force transmission state in the braking force transmission / cutoff mechanism 405a (or 405b), the shielding leaf plate 400a ( Alternatively, the position 400b) is moved.

  The driving mechanism of the attenuation leaf plates 401a and 401b has the same configuration as the driving mechanism of the shielding leaf plates 400a and 400b, and a description thereof will be omitted.

  The treatment planning device 120 includes, for example, a computer, a plurality of display devices, an input device, and a patient database (note that the patient database may be a separate unit and connected via a network). It has a function to assist the treatment planning work performed by the doctor as a pre-stage. The details will be specifically described. For example, at the time of diagnosis before treatment, three-dimensional image data of a tumor in the body is acquired in advance by X-ray CT examination and MRI examination. The affected part image data is numbered for each patient, and is stored and managed as digital data in a patient database. The doctor obtains affected part image data by accessing the patient database, and slices the affected part image on the display device of the treatment planning apparatus 120 at a depth or a three-dimensional image obtained by viewing the affected part image from an arbitrary direction. The cross-sectional image is displayed (see FIG. 6). The doctor determines the irradiation contour in each irradiation slice based on these. The treatment planning apparatus 120 has a function of automatically determining the positions of the shielding leaf plates 400a and 400b based on the irradiation contour information, and superimposes the automatically determined positions of the shielding leaf plates 400a and 400b and the cross-sectional images. indicate. Further, it has a function of automatically determining the positions of the attenuation leaf plates 401a and 401b based on the three-dimensional shape data, and displays the automatically determined positions of the attenuation leaf plates 401a and 401b and a three-dimensional image. Based on the set position information of the leaf plates, the dose distribution in the body is simulated by calculation, and the calculation result is displayed on the display device. At this time, the irradiation parameters such as the irradiation dose and beam energy are given by the doctor, the simulation for several irradiation directions is performed, and the irradiation direction with the most suitable result is finally determined by the doctor. Selected. Note that the leaf plate setting position information and irradiation parameters are stored in the patient database as patient-specific treatment data.

  The control device 121 includes an input device and a display device as a user operation interface. The patient treatment data including the leaf plate setting position information determined by the treatment planning device 120 is acquired via the network, and is displayed on the display device so as to receive confirmation from the doctors. And according to the input of the treatment start by an input device, the leaf board movement start command is output to the collimator / bolus controller 16.

  The collimator / bolus controller 16 receives the set position information of the leaf plate from the control device 121 and stores it in a storage device (not shown). Then, control is performed by outputting a command signal to the leaf position driving actuator, the driving force transmission / cutoff mechanism, and the braking force transmission / cutoff mechanism so that the position of the leaf plate detected by the position detection mechanism becomes the set position. At this time, the position information and the driving state of the leaf plate are always transmitted to the control device 121 and displayed on the display device of the control device 121.

  As described above, in the irradiation apparatus 113 according to the present embodiment, the shielding leaf plate group 400 having a multi-leaf collimator function and the attenuation leaf plate group 400 are arranged immediately below the beam traveling direction and have a multi-leaf bolus function. A multi-leaf collimator bolus 15 having a damping leaf group 401 is provided. Thereby, it is possible to easily cope with the lateral shape and depth shape of different affected parts. Further, the shielding leaf plates 400a and 400b and the attenuation leaf plates 401a and 401b at the respective stages have the same width direction and the same moving direction, so that the structure is not complicated and the entire apparatus is simplified. Can be achieved.

  In the above-described embodiment, the shielding leaf plates 400a and 400b and the attenuation leaf plates 401a and 401b at the respective stages have the same width direction and the same position in the width direction. Although explained, it is not limited to this. That is, for example, at least one level of the attenuation leaf plate is different from the shielding leaf plate in the width direction position or the width direction position, so that the pair of shielding leaf plates and the pair of shielding leaf plates are adjacent to each other. You may arrange | position so that the slight clearance gap which arises between may be interrupted. In such a case, leakage of the beam from the gap between the shielding leaf plates can be suppressed.

It is the schematic showing the whole structure of the particle beam therapy system provided with one Embodiment of the irradiation apparatus of this invention. It is the schematic showing the structure of the emission nozzle in one Embodiment of the irradiation apparatus of this invention. It is a top view showing the basic composition of the multileaf collimator bolus which constitutes one embodiment of the irradiation device of the present invention. FIG. 4 is a sectional view taken along section IV-IV in FIG. 3. It is a functional block diagram showing the structure of the control system regarding the multileaf collimator bolus which comprises one Embodiment of the irradiation apparatus of this invention. It is a figure showing an affected part and the cross-sectional image which sliced it as an example.

Explanation of symbols

113 Irradiation device 400 Shielding leaf plate group 400a, 400b Shielding leaf plate 401 Damping leaf plate group 401a, 401b Shielding leaf plate 402a, 402b Leaf position actuator (first leaf plate driving mechanism)
403a, 403b Drive force transmission / cutoff mechanism (first leaf plate drive mechanism)
405a, 405b Braking force transmission / cutoff mechanism (first leaf plate drive mechanism)

Claims (1)

In a particle beam irradiation device that shapes and irradiates a charged particle beam,
A plurality of pairs of shielding leaf plates arranged in opposition to each other in the first direction while being movable in a first direction perpendicular to the beam traveling direction are arranged in a second direction perpendicular to the beam traveling direction. A set of shielding leaf plates,
A plurality of pairs of attenuating leaf plates that are arranged to face each other in the first direction while being movable in the first direction are arranged in the second direction, and the plurality of pairs of attenuating leaf plates are arranged on the beam. A plurality of stages along the traveling direction, and a damping leaf plate group disposed immediately below the shielding leaf plate group on the downstream side in the traveling direction of the beam,
A first leaf plate driving mechanism that adjusts the arrangement of the shielding leaf plates to set a beam irradiation field;
A particle beam irradiation apparatus comprising: a second leaf plate driving mechanism that adjusts an arrangement of the attenuation leaf plates in order to set a distribution shape of a beam arrival depth in an irradiation target.

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