JP5222566B2 - Laminated body irradiation system and particle beam therapy system using the same - Google Patents

Description

  The present invention relates to a stacked body irradiation system for three-dimensionally irradiating a diseased part with a particle beam of carbon, neon or the like for treatment of cancer, malignant tumor, and the like, and a particle beam therapy apparatus using the same.

  In order to irradiate the affected area with an appropriate dose of particle beam for the treatment of cancer, malignant tumors, etc., so-called multilayered body irradiation is performed to match the irradiation area of the particle beam with the shape of the affected area existing three-dimensionally. It is necessary to go and improve the originality. To that end, the multi-leaf collimator shape (leaf position) is set appropriately, and the irradiation dose in the horizontal direction (on the surface of the irradiation field) so that a uniform dose is administered to the entire affected area. It is important to make the spatial distribution of the irradiation dose in the vertical direction (depth direction) as uniform as possible.

  Here, there is a wobbling method as a method for making the dose distribution of the planar irradiation field irradiated to the affected area uniform (see, for example, Patent Documents 1 to 4). In this wobbling method, the direction of the magnetic field of a pair of wobbler electromagnets is arranged so as to be orthogonal to each other, and the wobbler electromagnets are excited by flowing currents having the same period and 90 degrees in phase to each wobbler electromagnet. Thereby, the particle beam emitted from the accelerator is swirled and deflected in a direction perpendicular to the traveling direction by the magnetic field of the wobbler electromagnet. As a result, as shown in FIG. 16, the particle beam draws a circular orbit S at a constant period Tw (hereinafter, the time required to draw one orbit of the orbit S is referred to as a wobbler period Tw). ). At this time, when the scattering angle scattered by the scatterer provided in the middle of the irradiation path of the particle beam and the radius R of the circular orbit S are set optimally, as shown in FIG. Since the two particle beam distributions P1 and P2 overlap, the radial dose distribution P0 is flat within a plane including the orbiting center O. Therefore, if the particle beam is irradiated along the circular orbit S and a perfect circle for one round is drawn, the dose distribution on the surface of the irradiation field becomes uniform.

  On the other hand, in order to make the dose distribution in the vertical direction (depth direction) uniform, conventionally, as shown in FIG. 18, the particles in each layer in the depth direction correspond to the size L in the depth direction of the affected part. While changing the irradiation energy of the line by the range shifter and moving the extended Bragg peaks D1, D2,... Along the depth direction, the irradiation dose is increased at the deep position of the affected area, and the irradiation dose gradually increases as the depth becomes shallower. Try to reduce it. That is, the extended Bragg peaks D1, D2,... Are moved along the depth direction of the affected part, and the irradiation dose is adjusted according to the level of irradiation, so that the extended Bragg peaks D1, D2,. The dose distribution Dt becomes flat corresponding to the size L in the depth direction of the affected area.

  In this case, a large particle beam irradiation dose at the deep layer position is proportional to the long particle beam irradiation time if the particle beam intensity in each layer is the same. The number of times (hereinafter referred to as the number of times around the wobbler) is increased. In other words, the number of times of wobbler per layer decreases as the level of irradiation progresses (the irradiation region becomes shallower).

JP 2006-288875 A JP 2001-326098 A JP 2000-331799 A JP-A-2005-103255

  By the way, in the conventional lamination original body irradiation as described in each of the above Patent Documents 1 to 4, the timing of the emission and stop of the particle beam from the accelerator such as the synchrotron, that is, the irradiation period of the particle beam is a wobbler cycle. It was unrelated to Tw. That is, as shown in FIG. 19, the excitation signals of a pair of wobbler electromagnets have a fixed relationship such that their phases are different from each other by 90 degrees, but the wobbler period Tw is used to obtain a predetermined irradiation dose. It is set regardless of the irradiation period Tb of the time-divided particle beam.

  On the other hand, in the layered product irradiation method, the particle beam irradiation is terminated when the irradiation dose set in advance for each layer is reached. At this time, if the wobbler period Tw is set regardless of the particle beam irradiation period Tb as described above, the emission of the particle beam from the accelerator stops before the particle beam goes around the orbit, and the An unirradiated region where no particle beam is irradiated is generated on a part of the surface.

  In particular, in the multilayer body irradiation, as described above, the number of wobbler per layer gradually decreases as the irradiation layer progresses (the irradiation region becomes shallower), so that the particle beam is in the middle of the circular orbit. When the irradiation is stopped, a portion where several portions where the particle beam irradiation is lost overlaps, and the dose distribution in the depth direction becomes extremely non-uniform.

  The present invention has been made to solve the above problems, and in the irradiation of the layered product, the number of occurrences of the irradiation deficient region in any layer regardless of the timing of stopping the particle beam emission from the accelerator. To provide a layered body irradiation system capable of making irradiation dose distribution even more uniform than in the past, and a particle beam therapy apparatus using the same With the goal.

In order to achieve the above object, in the present invention, an accelerator for accelerating a particle beam generated from an ion source, and an irradiation head for irradiating an irradiated body with the particle beam accelerated by the accelerator, The ion source, the accelerator, and an irradiation controller that controls the irradiation head to perform the irradiation of the layered original body, the irradiation head includes a wobbler electromagnet for deflection scanning of the particle beam, and the irradiation controller includes: The following configuration is adopted in a system that deflects and scans particle beams by controlling excitation of the wobbler electromagnet.

That is, in the present invention, the irradiation controller controls the excitation of the Wabler electromagnet so as to draw a circular trajectory of a one-stroke writing so that the particle beam starts from the starting point and returns to the starting point, and outputs from the accelerator before irradiation. The total irradiation period of the particle beam is set for each layer of the layered body irradiation so that the particle beam becomes an integral multiple of the wobbler period required for the particle beam to go around the orbit.

According to the present invention, when performing layered body irradiation, the particle beam starts from the starting point and draws a circular trajectory of a single stroke so that it returns to the starting point, and the total irradiation of the particle beam output from the accelerator before irradiation The period is set for each layer of the layered body irradiation so that the particle beam is an integral multiple of the wobbler period required for the particle beam to make one round of the orbit, so there is a lack of irradiation on the final orbit of each layer. This can be avoided reliably. That is, regardless of the timing of starting / stopping the particle beam emission, it is possible to realize the layered body irradiation in which the dose distribution that does not always cause the irradiation deficient region in each layer is made uniform. Further, when the output beam of the accelerator is a pulsed beam, a dose distribution that does not cause an irradiation deficient region is obtained in the irradiation period of each irradiated pulse beam except for the final orbit of each layer.

  Therefore, if this multi-layered body irradiation system is applied to a particle beam therapy system, the particle beam irradiation control becomes simple, the possibility of erroneous irradiation can be reduced, and highly accurate particle beam therapy is performed. Is possible.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing the overall configuration of a particle beam therapy system to which the layered body irradiation system according to Embodiment 1 of the present invention is applied, and FIG. 2 is an irradiation head that irradiates the irradiated body with the particle beam of the apparatus. It is a block diagram which shows the principal part of the irradiation control means which performs irradiation control of particle beam.

  The particle beam therapy system according to Embodiment 1 is accelerated by an ion source 1 for generating a particle beam, a synchrotron accelerator 2a as a main accelerator for accelerating the particle beam generated from the ion source 1, and a synchrotron accelerator 2a. The irradiation head 4 that irradiates the affected particle beam toward the affected part 3a, which is an irradiation body of the patient 3, and the irradiation control means 5 that controls the irradiation of the particle beam are mainly configured.

  Between the ion source 1 and the synchrotron accelerator 2a, a pre-accelerator 6 that preliminarily accelerates the particle beam generated by the ion source 1 before being introduced into the synchrotron accelerator 2a, and the synchrotron accelerator 2a Between the irradiation head 4, a beam transport system 7 for guiding the particle beam from the synchrotron accelerator 2 a to the irradiation head 4 is provided.

  The synchrotron accelerator 2a emits a particle beam with a pulse width (beam spill length) Tb longer than the wobbler period Tw by turning on / off a gate that leads to the beam transport system 7 under the control of an accelerator system controller 8 described later. It is supposed to be.

  On the other hand, the irradiation head 4 includes a deflection electromagnet 41 for deflecting the particle beam transported by the beam transport system 7 toward the patient, a pair of wobbler electromagnets 42a and 42b for deflecting and scanning the particle beam, and a particle beam having a predetermined particle beam. Scattering body 43 that scatters to have a divergence angle, ridge filter 44 for expanding the energy width of the particle beam, range shifter 45 for changing the irradiation energy of the particle beam according to the depth position of the affected part 3a, particle beam A dose monitor 46 for monitoring the irradiation dose of the patient, a multi-leaf collimator 47 for defining the irradiation field of the particle beam according to the size of the affected part 3a, and a patient collimator 48 for edge enhancement that further regulates the irradiation field of the affected part 3a They are arranged sequentially along the line trajectory.

  In this case, the pair of wobbler electromagnets 42a and 42b are arranged so that the magnetic fields are orthogonal to each other in a plane orthogonal to the particle beam orbit. In the multileaf collimator 47, as shown in FIG. 3, the leaf 47a is set so as to match the shape of the affected part 3a, and thereby the planar irradiation field A of the particle beam is defined.

  The irradiation control means 5 comprises a control computer, for example, and controls the accelerator system control unit 8 and the irradiation head 4 for controlling the operations of the ion source 1, the pre-stage accelerator 6, the synchrotron accelerator 2 a, and the beam transport system 7. The irradiation head controller 9 and the irradiation system controller 10 that controls both the controllers 8 and 9 in a coordinated manner as a whole.

  Then, the irradiation head controller 9 controls the wobbler electromagnets 42a and 42b by individually controlling the wobbler electromagnets 42a and 42b, thereby deflecting and scanning the particle beam. It has a wobbler power supply control unit 92 and a range shifter control unit 93 that controls the range shifter 45 so that the irradiation energy of the particle beam is changed according to the dimension of the affected part in the depth direction. Further, the irradiation dose monitor value by the dose monitor 46 is taken into the irradiation system controller 10.

  Next, the control operation in the case of irradiating the particle body with the particle beam in the particle beam therapy system having the above configuration will be described.

  Information related to the particle beam characteristics necessary for the irradiation of the layered original body, such as the pulse width of the particle beam, the pulse height, the number of pulses for each layer (irradiation dose), the beam spill length Tb, and the wobbler cycle Tw. Set the input. Among these pieces of input information, the irradiation system controller 10 sends information related to the control of the accelerator system to the accelerator system control unit 8 and information related to the control of the irradiation head 4 to the irradiation head control unit 9.

  Here, the particle beam generated by the ion source 1 is preliminarily accelerated by the pre-stage accelerator 6, and further accelerated by the synchrotron accelerator 2a which is the main accelerator, and emitted as a particle beam for treatment irradiation. Is guided to the irradiation head 4 via the beam transport system 7. In this case, the energy intensity of the particle beam is basically set by the accelerator system control unit 8 controlling the synchrotron accelerator 2a.

  The particle beam guided to the irradiation head 4 is deflected in the direction of the irradiation point by the deflection electromagnet 41 of the irradiation head 4 and then deflected and scanned by the wobbler electromagnets 42a and 42b. Further, the particle beam is scattered so as to have a predetermined divergence angle when irradiated with the scatterer 43, and then the energy width of the particle beam is expanded by the ridge filter 44, and then the kinetic energy of the particle beam is reduced by the range shifter 45. Shifted to a value. Further, the irradiation dose is monitored by the dose monitor 46, and the irradiation area is limited by the multi-leaf collimator 47, and the affected part 3a is irradiated three-dimensionally.

  At this time, as shown in FIG. 4, the wobbler power supply control unit 92 has a sinusoidal waveform in which the excitation currents supplied from the wobbler power supplies 91 a and 91 b to the wobbler electromagnets 42 a and 42 b are in the same cycle and the phases are shifted by 90 degrees. Thus, the particle beam is deflected and scanned so as to draw a circular orbit S in a plane perpendicular to the traveling direction. At that time, if the scattering angle scattered by the scatterer 43 and the radius R of the circular orbit S are optimally set and a circle for one round is drawn, the circle center O on the circular orbit S as shown in FIG. Two particle beam distributions P1 and P2 facing each other through each other overlap, and the radial dose distribution P0 in the plane becomes flat. FIG. 5 illustrates the principle of forming a flat dose distribution by a wobbling operation by replacing the two-dimensional problem with the one-dimensional problem. The two-dimensional dose distribution P0 becomes flat by the sum.

  On the other hand, the accelerator system control unit 8 turns on / off the gate that leads to the beam transport system 7 of the synchrotron accelerator 2a, so that the particle beam follows the circular orbit S as shown in FIGS. 6 (a) and 6 (b). The light is emitted in a time-sharing manner with a pulse width (beam spill length) Tb longer than the wobbler period Tw required for one round.

  At that time, as shown in FIG. 4, the accelerator system control unit 8 makes the irradiation period (beam spill length) Tb of each pulse of the particle beam an integral multiple of the wobbler period Tw, that is, Tb = n · Tw (however, The emission start / stop timing is controlled so that n is an integer. Therefore, in the irradiation period Tb of each pulse of the particle beam, the emission is always stopped at the point of returning from the irradiation start point to the irradiation start point after n turns on the circular orbit. In other words, the particle beam is always deflected and scanned so as to draw a perfect circle along the circular orbit regardless of the timing of stopping the emission of the particle beam, except for the irradiation period of the last one pulse of particle beam in each layer. , Not interrupted on the way. For this reason, it is possible to reliably avoid the occurrence of an irradiation deficient portion on the circular orbit S during the irradiation period Tb of each pulse of the particle beam. In fact, the particle beam always circulates if the particle beam current (proportional to the number of particles per unit time) is controlled based on the number of particles scheduled to be irradiated on each layer during the irradiation period of the last pulse in each layer. Deflection scanning is performed so as to draw a perfect circle along the trajectory, so that it is not interrupted. As a result, there is an effect that a more uniform dose distribution can be obtained.

  Moreover, since the value of the irradiation dose by the dose monitor 46 is taken into the irradiation system controller 10, the accelerator system control unit 8 sequentially reaches the predetermined number of pulses (irradiation dose) for each layer. The number of pulses of the line is changed, and control is performed so that the number of pulses per layer decreases as the irradiation region becomes shallower. Therefore, the irradiation dose per layer decreases as the irradiation region becomes shallower.

  Further, the range shifter control unit 93 controls the range shifter 45 to change the irradiation energy of the particle beam for each layer corresponding to the depth L of the affected part. Thereby, the extended Bragg peaks D1, D2,... Are moved along the depth direction. In this way, in addition to controlling the irradiation dose for each layer in the depth direction of the affected area, the extended Bragg peaks D1, D2,... Are moved along the depth direction of the affected area. As shown in FIG. 5, the entire dose distribution Dt obtained by integrating the extended Bragg peaks D1, D2,... For each layer is made uniform over the depth L in the depth direction of the affected area.

  In the multilayer body irradiation, as described above, the number of wobbler per layer gradually decreases as the irradiation layer advances (the irradiation region becomes shallower). Since the irradiation is not stopped or can be stopped only once, the frequency of occurrence of a portion where several portions where the particle beam irradiation is missing is overlapped as in the past is extremely high. It is possible to reduce the number of layers, and to achieve layered body irradiation that always has a uniform dose distribution. In addition, since it is not necessary to match the timing of the exciting currents of the wobbler electromagnets 42a and 42b with the timing of emission / stop of the particle beam by the synchrotron accelerator 2a, the particle beam irradiation control is simplified.

Embodiment 2. FIG.
FIG. 8 is a block diagram showing a main part of an irradiation head for irradiating a particle beam toward an irradiated object and an irradiation control means for controlling irradiation of the particle beam in the particle beam therapy system according to Embodiment 2 of the present invention. . Components corresponding to or corresponding to those of the first embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals.

  In the first embodiment, the synchrotron accelerator 2a that emits a particle beam in a pulse shape is used as the main accelerator. In the second embodiment, a cyclotron accelerator 2b that emits a particle beam continuously is used. It is intended to carry out layered product irradiation.

  In this case, as shown in FIG. 9, by changing the beam current intensity of the ion source 1 by the accelerator system control unit 8, a particle beam having a predetermined particle beam intensity preset for each layer from the cyclotron accelerator 2b. It is being pulled out.

In addition, at that time, the accelerator system controller 8 controls the ion source 1 and sets the particle beam irradiation period for each layer to be an integral multiple of the wobbler period. That is, if the irradiation period of the particle beam of an i-th layer is Tbi and the wobbler period is Tw,
Tbi = ni · Tw (1)
(Where ni is an integer set in the i-th layer).

When attention is paid to the i-th layer in the depth direction of the affected area, the number of particle beams to be irradiated to the layer is Ni, the irradiation period of the particle beam to this layer is Tbi, and the ion source 1 required at this time If the beam current intensity Ii at
Ni = Tbi · Ii / Q ₀ (2)
(Where Q ₀ is the charge amount of electrons).

Therefore, from the above equations (1) and (2),
Ii = Ni · Q ₀ / (ni · Tw) (3)
It becomes.

That is, if the beam current intensity Ii of the ion source 1 is preset for each layer based on the equation (3), the number Ni of particle beams to be irradiated to each layer (that is, the irradiation dose to each layer) is set. The particle beam irradiation period Tbi can always be set to an integral multiple ni of the wobbler period Tw while ensuring appropriately. In this case, the number of particles Ni is determined in advance for each layer, and the charge amount Q ₀ of the particle beam is determined by the type of particle beam, and the beam current of the ion source 1 is usually 30 nA or less. The ni of each layer can be determined by the above (3) so that the beam setting current Ii falls within the range of several nA to 30 nA.

  Next, the control operation in the case of irradiating the particle body with the particle beam in the particle beam therapy system having the above configuration will be described.

  With respect to the irradiation system controller 10, the beam current intensity Ii of the ion source 1 in consideration of the particle beam intensity for each layer and the timing of starting / stopping the extraction of the particle beam for each layer ( Information related to the particle beam characteristics necessary for the irradiation of the layered original body such as the irradiation period Tbi) and the wobbler period Tw is input and set. Among these pieces of input information, the irradiation system controller 10 sends information related to the control of the accelerator system to the accelerator system control unit 8 and information related to the control of the irradiation head 4 to the irradiation head control unit 9.

  Since the accelerator system control unit 8 controls the beam current of the ion source 1 according to each layer, a particle beam having a particle beam intensity suitable for each layer is extracted from the cyclotron accelerator 2b. Then, the particle beam continuously emitted from the cyclotron accelerator 2 b is guided to the irradiation head 4. At this time, the wobbler power supply excites the wobbler electromagnets 42a and 42b under the control of the wobbler power supply control unit 92, so that the particle beam is deflected and scanned so as to draw a circular orbit in a plane perpendicular to the traveling direction.

  In this case, since the beam current intensity Ii of the ion source 1 is set in advance for each layer as in the above equation (3), the irradiation time Tbi of a certain i-th layer is just the wobbler period Tw of the wobbler electromagnets 42a and 42b. It corresponds to an integral multiple ni of. Accordingly, in the particle beam irradiation of a certain i-th layer, the irradiation dose monitored by the dose monitor 46 is preliminarily determined when the particle beam circulates on the circular orbit from the irradiation start point by ni times and returns to the irradiation start point. The set preset value is reached. In response to this, the irradiation system controller 10 informs the accelerator system control unit 8 accordingly, and the accelerator system control unit 8 stops the particle beam irradiation of the i-th layer. For this reason, even when a continuous beam is emitted from the cyclotron accelerator 2b, a more uniform dose distribution can be formed in the irradiation field.

  As in the first embodiment, the range shifter control unit 93 controls the range shifter 45 to change the irradiation energy of the particle beam for each layer corresponding to the depth L of the affected part. The extended Bragg peaks D1, D2,. In this way, in addition to controlling the irradiation dose for each layer in the depth direction of the affected area, the extended Bragg peaks D1, D2,... Are moved along the depth direction of the affected area. As shown in FIG. 4, the entire dose distribution Dt obtained by integrating the extended Bragg peaks D1, D2,... For each layer is made uniform over the depth L of the affected area.

  As described above, also in the second embodiment, since the irradiation time Tb of each layer is set to an integral multiple of the wobbler period Tw, the particle beam always circulates regardless of the timing of stopping the emission of the particle beam. Deflection scanning is performed so as to draw a perfect circle along the trajectory S, and there is no interruption on the way. For this reason, it is possible to reliably avoid the occurrence of an irradiation deficient portion on the final circular orbit S of each layer, and it is possible to realize stacked original body irradiation that always has a uniform dose distribution. Moreover, since it is not necessary to match the timing of the exciting currents of the wobbler electromagnets 42a and 42b with the timing of emission / stop of the particle beam of the ion source 1, the particle beam irradiation control is simplified.

  In the second embodiment, the particle beam blocking performed when the irradiation dose of each layer expires is performed by controlling the ion source 1, but in the middle of the beam transport system 7 from the cyclotron accelerator 2b to the irradiation head 4. It is also possible to block the particle beam by providing a kicker electromagnet or the like.

  In the above description, the case where ni in equation (3) is set to just an integer has been described, but actually, ni may not be strictly an integer. The reason is that the particle beam deflected and scanned by the wobbler electromagnets 42a and 42b has a sufficiently large spot size due to the scatterer 43 and the like, and therefore the particle beam distributions overlap without drawing a strict perfect circle. This is because the dose distribution in the radial direction is flat in the plane. Therefore, n may be a value approximated to an integer, and the same effect as described above can be obtained.

  Other configurations and operational effects are the same as those of the first embodiment, and thus detailed description thereof is omitted here.

Embodiment 3 FIG.
FIG. 12 is a block diagram showing a main part of an irradiation head for irradiating the irradiated body with a particle beam and an irradiation control means for controlling the irradiation of the particle beam in the particle beam therapy system according to Embodiment 3 of the present invention. . Components corresponding to or corresponding to those of the first embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals.

  In the first embodiment, the synchrotron accelerator 2a in which the particle beam is emitted with a pulse width (beam spill length) Tb longer than the wobbler period Tw is used. In the second embodiment, the cyclotron in which the particle beam is continuously emitted. Although the accelerator 2b is used, the linear accelerator 2c in which the particle beam is emitted with a pulse width Tq shorter than the wobbler period Tw is used in the third embodiment. In addition to the linear accelerator 2c, a synchrotron accelerator can be applied.

In this case, the number of pulses of the particle beam emitted from the linear accelerator 2c is changed for each layer by the accelerator system control unit 8 so that an appropriate irradiation dose is given to each layer. Moreover, at that time, as shown in FIG. 13, the irradiation period Tri in each layer is set so that an integral multiple of the particle beam pulse emission period Tp is an integral multiple of the wobbler period Tw. That is,
Tri = ki · Tp = ni · Tw (4)
(Where ki, ni are integers set in the i-th layer).

  Next, the control operation in the case of irradiating the particle body with the particle beam in the particle beam therapy system having the above configuration will be described.

  For the irradiation system controller 10, the irradiation period Tri for each layer, the pulse number ki of the particle beam pulse, the emission period Tp of the particle beam pulse, the pulse width Tq, and the pulse height so as to satisfy the relationship of the above equation (4) , Information regarding particle beam characteristics necessary for the irradiation of the layered original body such as the wobbler period Tw is input and set. Among these pieces of input information, the irradiation system controller 10 sends information related to the control of the accelerator system to the accelerator system control unit 8 and information related to the control of the irradiation head 4 to the irradiation head control unit 9.

  Since the accelerator system controller 8 controls the ion source 1 and the linear accelerator 2c according to each layer, a particle beam pulse having a shorter pulse width Tq than the wobbler period Tw is emitted from the linear accelerator 2c at a predetermined period Tp. Is done. Then, the particle beam pulse emitted from the linear accelerator 2 c is guided to the irradiation head 4. At this time, the wobbler power source excites the wobbler electromagnets 42a and 42b under the control of the wobbler power control unit 92, so that the particle beam pulse is deflected and scanned so as to draw a circular orbit S in a plane perpendicular to the traveling direction. The

  In this case, since the pulse width Tq of the particle beam pulse emitted from the linear accelerator 2c is shorter than the wobbler period Tw, the center point of the irradiation region P per pulse exists discretely along the circular orbit S. However, since the particle beam is scattered by the scatterer 43 or the like and has a sufficiently large spot size as shown in FIG. 14, if a circle for one round is drawn, the center of the circle on the orbit S Two particle beam distributions facing each other through O overlap, and the radial dose distribution in the plane becomes flat.

  Further, as shown in the above equation (4), since the integral multiple of the particle beam pulse emission period Tp in each layer is set to be an integral multiple of the wobbler period Tw, for example, the irradiation time Tri of the i-th layer Corresponds to an integer multiple ni of the wobbler period Tw. For this reason, in the particle beam irradiation of the i-th layer, when the irradiation is stopped after returning from the irradiation start point to the irradiation start point after turning around the orbit on the circular orbit (that is, when the Tri period has elapsed). ), The particle beam pulse is irradiated ki times. Therefore, even when a particle beam pulse having a pulse width Tq shorter than the wobbler period Tw is emitted from the linear accelerator 2c, a uniform dose distribution can be formed in the irradiation field.

  As in the first embodiment, the range shifter control unit 93 controls the range shifter 45 to change the irradiation energy of the particle beam for each layer corresponding to the depth L of the affected part. As a result, as shown in FIG. 7 or FIG. 11, the dose distribution Dt obtained by integrating the extended Bragg peak for each layer is made uniform over the depth L of the affected area.

  As described above, in the third embodiment, even when the accelerator 2c that emits a particle beam having a pulse width Tq shorter than the wobbler period Tw is used, an irradiation deficient portion occurs on the final orbit of each layer. Can be reliably avoided, and it is possible to realize stacked original body irradiation having a uniform dose distribution at all times. Moreover, since it is not necessary to match the timing of the exciting currents of the wobbler electromagnets 42a and 42b with the timing of emission / stop of the particle beam of the ion source 1, the particle beam irradiation control is simplified.

  Other configurations and operational effects are the same as those of the first embodiment, and thus detailed description thereof is omitted here.

  In the first to third embodiments, the case where the dose distribution is made uniform by performing deflection scanning so that the particle beam draws a circular orbit on a plane by the excitation of the wobbler electromagnets 42a and 42b has been described. For example, as shown in FIG. 15, the dose distribution on a plane may be obtained by performing deflection scanning so as to draw a zigzag circular trajectory in which the particle beam starts from the start point and returns to the start point. Can be made uniform.

It is a block diagram which shows the whole structure of the particle beam therapy apparatus to which the lamination original body irradiation system in Embodiment 1 of this invention is applied. It is a block diagram which shows the principal part of the irradiation control means which performs irradiation control of the irradiation head and particle beam which irradiate the to-be-irradiated body with the particle beam of the apparatus. It is a top view of the multileaf collimator of the apparatus. It is a timing chart which shows the relationship between the wobbler exciting current in the same apparatus, extraction / stop of the particle beam by a synchrotron accelerator, and the irradiation period of a particle beam. In the same apparatus, it is a characteristic figure which shows the irradiation dose distribution of a radial direction in case a particle beam is deflected and scanned circularly on a plane by excitation of a wobbler electromagnet. It is a figure which shows the irradiation pattern of the particle beam in the case of performing a stack original body irradiation in the same apparatus. In the same apparatus, it is a figure which shows the absorption dose distribution after the expansion Bragg peak of each layer in laminated body irradiation, and all the layer irradiation. In the particle beam therapy system in Embodiment 2 of this invention, it is a block diagram which shows the principal part of the irradiation head which irradiates a particle beam toward a to-be-irradiated body, and the irradiation control means which controls irradiation of a particle beam. It is a figure which shows the irradiation pattern of the particle beam in the case of performing a stack original body irradiation in the same apparatus. It is a timing chart which shows the relationship between the wobbler exciting current in the same apparatus, extraction / stop of the particle beam by a synchrotron accelerator, and the irradiation period of a particle beam. In the same apparatus, it is a figure which shows the absorption dose distribution after the expansion Bragg peak of each layer in laminated body irradiation, and all the layer irradiation. In the particle beam therapy system in Embodiment 3 of this invention, it is a block diagram which shows the principal part of the irradiation head which irradiates a particle beam toward a to-be-irradiated body, and the irradiation control means which performs irradiation control of a particle beam. 4 is a timing chart showing a relationship between a wobbler excitation current, particle beam emission / stop by a synchrotron accelerator, and an irradiation period of a particle beam pulse in the apparatus. It is a characteristic view which shows the dose distribution of the irradiation area | region per pulse of the particle beam pulse generate | occur | produced in the same apparatus. It is explanatory drawing which shows a mode when a particle beam is deflected and scanned on a plane zigzag by excitation of a wobbler electromagnet. It is explanatory drawing which shows a mode in case a particle beam is deflected and scanned circularly on a plane by excitation of a wobbler electromagnet. It is a characteristic view which shows the irradiation dose distribution of a radial direction in case a particle beam is deflected and scanned circularly on a plane by excitation of a wobbler electromagnet. It is a figure which shows the expanded Bragg peak of each layer in lamination | stacking base body irradiation, and the absorbed dose distribution after all the layer irradiation. It is a timing chart which shows the relationship between the wobbler excitation current in the prior art, the extraction / stop of the particle beam by the synchrotron accelerator, and the irradiation period of the particle beam pulse.

Explanation of symbols

1 ion source, 2a synchrotron accelerator, 2b cyclotron accelerator,
2c linear accelerator, 3a affected part (irradiated body), 4 irradiation head, 5 irradiation control means,
8 Accelerator system control unit, 9 Irradiation head control unit, 10 Irradiation system controller,
42a, 42b Wobbler electromagnet, 45 range shifter.

Claims (7)

An accelerator for accelerating the particle beam generated from the ion source, an irradiation head for irradiating the irradiated object with the particle beam accelerated by the accelerator, and controlling the ion source, the accelerator, and the irradiation head, An irradiation controller that performs body irradiation, the irradiation head has a wobbler electromagnet for particle beam deflection scanning, and the irradiation controller is a system that performs excitation control of the wobbler electromagnet to deflect and scan the particle beam. There,
The irradiation controller controls the excitation of the wobbler electromagnet so that the particle beam starts from the starting point and returns to the starting point, and controls all of the particle beams output from the accelerator before irradiation. A layered precursor irradiation system, wherein the irradiation period is set for each layer of the layered precursor irradiation so that the particle beam is an integral multiple of the wobbler period required for the particle beam to make a round of the orbit. The accelerator is an accelerator that emits particle beams with a pulse width longer than the wobbler period, and the irradiation controller changes the number of particle beams for each layer of the layered body irradiation by changing the number of particle beams. 2. The laminate source according to claim 1, wherein the irradiation dose of each layer in the depth direction is controlled, and the irradiation period of each pulse of the particle beam is controlled to be an integral multiple of the wobbler period. Body irradiation system. The accelerator is an accelerator that continuously emits a particle beam, and the irradiation controller controls the irradiation dose of each layer in the depth direction of the irradiated object by changing the particle beam intensity for each layer, 2. The layered product irradiation system according to claim 1, wherein the particle beam intensity is controlled for each layer so that the total irradiation period of the particle beam for each layer is an integral multiple of the wobbler period. An accelerator for accelerating the particle beam generated from the ion source, an irradiation head for irradiating the irradiated object with the particle beam accelerated by the accelerator, and controlling the ion source, the accelerator, and the irradiation head, An irradiation controller that performs body irradiation, the irradiation head has a wobbler electromagnet for particle beam deflection scanning, and the irradiation controller is a system that performs excitation control of the wobbler electromagnet to deflect and scan the particle beam. There,
The irradiation controller performs excitation control of the wobbler electromagnet so as to draw a circular orbit of one stroke so that the particle beam starts from the starting point and returns to the starting point, and the accelerator causes the particle beam to go around the orbiting circle. The irradiation controller emits the particle beam with a pulse width shorter than the wobbler cycle required for the irradiation, and the irradiation controller changes the number of pulse of the particle beam for each layer of the layered body irradiation. Laminate body irradiation characterized by controlling the irradiation dose of each layer in the depth direction and controlling the integral multiple of the emission period of each pulse of the particle beam to be an integral multiple of the wobbler period. system. In addition to controlling the irradiation dose of each layer in the depth direction of the irradiated object, the irradiation controller changes the irradiation energy of the particle beam for each layer, thereby changing the irradiation direction of the irradiated object in the depth direction. The layered product irradiation system according to any one of claims 1 to 4, wherein the dose distribution is controlled to be flat. 6. The layered product irradiation system according to claim 1, wherein the orbit of the one-stroke writing is a circular or zigzag orbit. A particle beam therapy system using the layered product irradiation system according to any one of claims 1 to 6.

Images