Source: https://patents.google.com/patent/JP6254600B2/en
Timestamp: 2019-12-13 09:48:48
Document Index: 124107933

Matched Legal Cases: ['Application No. 61', 'Application No. 61', 'Application No. 13', 'Application No. 13', 'Application No. 60', 'Application No. 60', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 60', 'Application No. 13', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 11', 'Application No. 60', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 11', 'Application No. 12', 'Application No. 11', 'Application No. 60', 'Application No. 13', 'Application No. 11', 'Application No. 11', 'Application No. 60', 'Application No. 60', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 11', 'Application No. 12', 'Application No. 11', 'Application No. 60', 'Application No. 13', 'Application No. 13', 'Application No. 13', 'Application No. 11', 'Application No. 11', 'Application No. 60', 'Application No. 10', 'Application No. 60', 'art 90', 'art 924']

JP6254600B2 - Particle accelerator - Google Patents
Particle accelerator Download PDF
JP6254600B2
JP6254600B2 JP2015534729A JP2015534729A JP6254600B2 JP 6254600 B2 JP6254600 B2 JP 6254600B2 JP 2015534729 A JP2015534729 A JP 2015534729A JP 2015534729 A JP2015534729 A JP 2015534729A JP 6254600 B2 JP6254600 B2 JP 6254600B2
JP2015534729A
JP2015532510A (en
ゲリット・タウンゼント・ツワート
ケネス・ピー・ガル
ヤン・ファン・デル・ラーン
チャールズ・ディー・オニール・サード
ケン・ヨシキ・フランツェン
2012-09-28 Priority to US201261707572P priority Critical
2012-09-28 Priority to US61/707,572 priority
2013-09-27 Application filed by メビオン・メディカル・システムズ・インコーポレーテッド filed Critical メビオン・メディカル・システムズ・インコーポレーテッド
2013-09-27 Priority to PCT/US2013/062120 priority patent/WO2014052722A2/en
2015-11-09 Publication of JP2015532510A publication Critical patent/JP2015532510A/en
2017-12-27 Publication of JP6254600B2 publication Critical patent/JP6254600B2/en
CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority to US Provisional Application No. 61 / 707,572, filed Sep. 28, 2012. The contents of US Provisional Application No. 61 / 707,572 are hereby incorporated by reference into the present disclosure.
The present disclosure relates generally to focusing a particle beam in a synchrocyclotron using a magnetic field flutter.
Particle therapy systems use an accelerator to generate a particle beam for treating pain, such as a tumor. In operation, particles are accelerated along a trajectory in the cavity in the presence of a magnetic field and are extracted from the cavity through an extraction channel. One example of an accelerator that can be used in a particle therapy system is a synchrocyclotron.
In the synchrocyclotron, an ionized gas (for example, hydrogen) is used to generate a plasma column. An RF voltage is applied to extract particles from the plasma column, and a magnetic field is applied to maintain these particles of increasing energy and increasing radius in a spiral trajectory until reaching the extraction region. When accelerating particles from the plasma column, the RF voltage is swept over a range of frequencies to account for relativistic effects on the particles (eg, increasing particle mass).
US Patent Application No. 13 / 907,601 US patent application Ser. No. 11 / 948,662 US patent application Ser. No. 11 / 948,359 US Pat. No. 7,728,311 US patent application Ser. No. 12 / 275,103 US Patent Application No. 13 / 916,401 US Provisional Application No. 60 / 760,788, Name “High-Field Superducting Synchronic Clotron” US patent application Ser. No. 11 / 463,402, entitled “Magnet Structure For Particle Acceleration” US Provisional Application No. 60 / 850,565, name “Cryogenetic Vacuum Break Pneumatic Thermal Coupler” US Provisional Application No. 61 / 707,466, name "CONTROLLING INTENTITY OF A PARTICULE BEAM" US Provisional Application No. 61 / 707,515, Name “ADJUSTING ENERGY OF A PARTICLE BEAM” US Provisional Application No. 61 / 707,548, Name “ADJUSTING COIL POSITION” US Provisional Application No. 61 / 707,590, Name “MAGNETIC FIELD REGENERATOR” US Provisional Application No. 61 / 707,704, name “FOCUSING A PARTICULE BEAM” US Provisional Application No. 61 / 707,624, name “CONTROLLING PARTIC THERAPY” US Provisional Application No. 61 / 707,645, name “CONTROL SYSTEM FOR A PARTICLE ACCELERATOR” US Provisional Application No. 60 / 991,454 US Patent No. 8,003,964 US Pat. No. 7,208,748 US Pat. No. 7,402,963 US Patent Application No. 13 / 148,000 US patent application Ser. No. 11 / 937,573 US patent application Ser. No. 11 / 187,633, entitled “A Programmable Radio Frequency Waveform Generator for a Synchronotron” US Provisional Application No. 60 / 590,089 US patent application Ser. No. 10 / 949,734, entitled “A Programmable Particle Scatterer for Radiation Therapy Beam Formation” US Provisional Application No. 60 / 590,088
An exemplary particle accelerator is a voltage source for sweeping radio frequency (RF) voltage within a cavity to accelerate the particles from the plasma column, where the particles accelerated from the plasma column are in orbit within the cavity. Has a magnetic field that causes the magnetic field to move, the magnetic field having a magnetic flux that bows at the edge of the cavity, and a magnetic field that causes a magnetic field bump in the cavity, thereby accelerating the continuous trajectory of particles accelerated from the plasma column. A regenerator that changes and ultimately causes the particles to be output to the extraction point, arranged at a radius that is within the cavity relative to the plasma column, and of this radius within the cavity Nearby ferromagnetic devices, each ferromagnetic device providing a magnetic field bump, and the ferromagnetic device adjacent to the regenerator can include a ferromagnetic device spaced in space from the regenerator . This exemplary particle accelerator may include one or more of the following features, alone or in combination.
The combination of space, regenerator, and ferromagnetic device generates a magnetic field variation having a component that is at an angle to the particle trajectory, offsetting at least a portion of the vertical focusing reduction caused by the magnetic field bumps. The magnetic field is at least 4 Tesla and the magnetic field bumps generated by the regenerator can be up to 2 Tesla. The particle accelerator may be a synchrocyclotron.
There may be only two ferromagnetic devices, one on each side of the regenerator. There may be more than two ferromagnetic devices within the same radius with respect to the plasma column. There may be a plurality of ferromagnetic devices at each of a plurality of radii relative to the plasma column.
In some examples, the ferromagnetic device generates a magnetic field flutter that includes an azimuth average normalized magnetic field change rate between 0.25% and 20%.
An exemplary proton therapy system can include the particle accelerator described above and a gantry to which the particle accelerator is attached. The gantry is rotatable with respect to the patient position. Protons are substantially output directly from the synchrocyclotron to the patient location. The particle accelerator may be a synchrocyclotron.
An exemplary particle accelerator is a voltage source for sweeping radio frequency (RF) voltage within a cavity to accelerate the particles from the plasma column, where the particles accelerated from the plasma column orbit in the cavity. The magnetic field includes a voltage source having a magnetic field that causes movement, the magnetic field having a magnetic flux that is substantially linear throughout the cavity. The cavity includes alternating regions of a first magnetic field and a second magnetic field, wherein the first magnetic field is different from the second magnetic field and has a magnetic variation having an angular component substantially perpendicular to the particle trajectory in the cavity. Produce. This exemplary particle accelerator may include one or more of the following features, alone or in combination.
The alternating regions can have different levels of ferromagnetic material. The alternating regions can include regions of ferromagnetic material and regions that do not include ferromagnetic material. The alternating regions may be pie-shaped, each having one point on the plasma column and an edge on the edge of the cavity. The alternating regions may have a windmill shape, each with one point on the plasma column and an edge on the edge of the cavity.
The cavity can be defined by a magnetic structure. The alternating regions can include alternating regions that are vertically aligned, one of which is connected to the first magnetic structure and the other is connected to the second magnetic structure.
Magnetic fluctuations can cause particles to focus vertically on orbits in the cavity. The particle accelerator may be a synchrocyclotron.
The alternating region of the first magnetic field and the second magnetic field includes a magnetic field flutter, which includes an azimuth average normalized magnetic field change rate between 0.25% and 20%.
Each exemplary particle accelerator can include a magnetic structure that defines a cavity in which the particles are accelerated, and the particles are output as a particle beam having an energy selected from a range of energies. .
An exemplary proton therapy system includes the aforementioned particle accelerator and a gantry to which the particle accelerator is attached. The gantry is rotatable with respect to the patient position. Protons are substantially output directly from the particle accelerator to the patient location. The particle accelerator may be a synchrocyclotron.
Combining two or more of the features described in this disclosure, including those described in the Summary of the Invention section, forms an embodiment not specifically described herein. can do.
Instructions stored in one or more non-transitory machine-readable storage media and executable on one or more processing devices are control of various systems described herein, or portions thereof. Can be implemented via a computer program product. The systems, or portions thereof described herein may include an apparatus, method, and the like that may include one or more processing devices and memory for storing executable instructions that implement control of the described functions. Or it may be implemented as an electronic system.
1 is a perspective view of an exemplary treatment system. FIG. FIG. 2 is an exploded perspective view of components of an exemplary synchrocyclotron. 1 is a cross-sectional view of an exemplary synchrocyclotron. 1 is a cross-sectional view of an exemplary synchrocyclotron. 1 is a cross-sectional view of an exemplary synchrocyclotron. 1 is a perspective view of an exemplary synchrocyclotron. FIG. 2 is a cross-sectional view of an exemplary reverse bobbin and a portion of a winding. FIG. 1 is a cross-sectional view of an exemplary cable-in-channel composite conductor. 1 is a cross-sectional view of an exemplary ion source. FIG. 5 is a perspective view of an exemplary dee plate and an exemplary dummy dee. 1 is a perspective view of an exemplary vault. FIG. 1 is a perspective view of an exemplary treatment room with a vault. FIG. FIG. 3 shows a patient next to an exemplary particle accelerator. FIG. 6 shows a patient positioned in an exemplary internal gantry within a treatment room. FIG. 3 is a top view of an exemplary acceleration cavity and extraction channel. It is a graph which shows the radial direction distance from a magnetic field intensity | strength versus a plasma column with the figure of the one part cross section of the exemplary low-temperature holding apparatus of a superconducting magnet. FIG. 3 is a top view of an exemplary acceleration cavity and extraction channel showing a trajectory that moves to enter the extraction channel. 2 is a top view of an exemplary acceleration cavity and regenerator showing magnetic field lines in the cavity. FIG. FIG. 3 is a cutaway side view of an acceleration cavity of a particle accelerator having magnetic field lines bent in a bow. It is a top view of the acceleration cavity which accommodates a flutter brick in the outer periphery of a cavity. FIG. 6 is a top view of an acceleration cavity that accommodates flutter bricks on the outer periphery of the cavity in different radial arrangements. FIG. 4 is a cutaway side view of an acceleration cavity of a particle accelerator having linear magnetic field lines. FIG. 6 is a top view of a flutter guiding structure having a pie shape and having magnetic hills and valleys. It is a top view of the flutter guidance structure which has a magnetic hill and a valley which has a windmill shape. It is a notch side view of a part of a multilayer flutter guiding structure. 1 is a conceptual diagram of an exemplary particle therapy system that can use a variable energy particle accelerator. FIG. 6 is an exemplary graph showing energy and current for magnetic field and distance variations in a particle accelerator. FIG. 4 is a side view of an exemplary structure for sweeping voltage over a definite frequency range for each energy level of a particle beam and changing the frequency range as the particle beam energy changes. 1 is an exploded perspective view of an exemplary magnet system that may be used with a variable energy particle accelerator. FIG.
Overview This document describes an example of a particle accelerator for use in an exemplary system, such as a proton or ion therapy system. The system includes a particle accelerator mounted on a gantry--in this example, a synchrocyclotron. The gantry allows the accelerator to rotate around the patient's position, as described in detail below. In some embodiments, the gantry is made of steel and has two legs that are rotatably mounted on each of two bearings disposed on both sides of the patient. The particle accelerator is supported by a steel truss that is long enough to straddle the treatment area on which the patient lies, and the steel truss is stably attached at both ends to the rotating legs of the gantry. As a result of the rotation of the gantry around the patient, the particle accelerator also rotates.
In one exemplary embodiment, the particle accelerator (eg, synchrocyclotron) includes a cryostat that holds a superconducting coil for conducting a current that generates a magnetic field (B). In this example, the cryostat uses liquid helium (He) to maintain the coil at a superconducting temperature, eg, 4 ° Kelvin (K). The magnetic yoke is adjacent to (eg, around) the cryostat and defines a cavity in which particles are accelerated. The magnetic field in the cavity (referred to as the “background magnetic field”) is at least 4 Tesla, 5 Tesla, or 6 Tesla and may be larger (eg, 8 Tesla, 8.5 Tesla, 9 Tesla, 9.5 Tesla, 10 Tesla, 10.5 Tesla, or more). The cryostat is attached to the magnetic yoke through a strap or the like.
In this exemplary embodiment, the particle accelerator includes a particle source (eg, a Penning ion gauge--PIG source) to provide a plasma column to the cavity. Hydrogen gas is ionized to generate a plasma column. The voltage source applies a radio frequency (RF) voltage to the cavity to accelerate the particles from the plasma column. As indicated, in this example, the particle accelerator is a synchrocyclotron. Thus, when extracting particles from the plasma column, the RF voltage is swept over a range of frequencies to account for relativistic effects on the particles (eg, increasing particle mass). Due to the magnetic field generated by the coil, the particles accelerated from the plasma column are accelerated on the orbit in the cavity. A magnetic field regenerator ("regenerator") is located near the outer edge of the cavity and in this arrangement adjusts the existing magnetic field, thereby positioning the continuous trajectory of particles accelerated from the plasma column (e.g. , Pitch and angle) and eventually the particles are output to the extraction channel through the yoke. The regenerator increases the magnetic field at a point in the cavity (eg, creating a magnetic field “bump” in the area of the cavity), which causes each continuous trajectory of the particle at that point to be at the point of entry of the extraction channel. Outward, it can precess until it reaches the withdrawal channel. Typically, magnetic field bumps are between 0.5 Tesla and 2 Tesla, but magnetic field bumps may be larger or smaller than these values in different systems. The extraction channel receives the accelerated particles from the plasma column and outputs the received particles from the cavity.
In some embodiments, the regenerator is a single ferromagnetic device configured to generate magnetic field bumps having a specific size and shape. A single ferromagnetic device can be a single adjacent or physically connected structure, or two vertically aligned but separated by an empty space through which magnetic flux passes. There may be non-physically connected ferromagnetic structures (eg, one on each yoke). Vertical alignment may include alignment between yokes, including all or part of a properly aligned ferromagnetic structure that is not connected.
Because the magnetic field in the cavity is high (eg, at least 4 Tesla), a relatively high magnetic field gradient can occur when the magnetic field crosses the coil. In this example, the magnetic field decreases from about 9 Tesla at the center of the cavity (approximately the plasma column location) to about 0 when traversing the superconducting coil and to about -2 Tesla on the opposite side of the superconducting coil. In addition, the magnetic field lines bend outwardly at the edge of the cavity. The amount of bending increases from the center of the cavity (approximately the location of the particle source) where the bending is about zero (ie, the magnetic field lines are substantially linear).
A magnetic field that bows at the edge of the cavity causes vertical focusing (also called “weak focusing”) on the particle beam, particularly at the edge of the cavity where bending is most noticeable. Vertical focusing occurs when a particle attempts to deviate from its trajectory by moving up or down along a bowed field line. As a result of the bowing of the magnetic field lines, particles that are going to travel upwards or downwards face a magnetic force that is opposite to the direction they are traveling. As a result, it is difficult for the particles to deviate far from the mid-orbital plane, resulting in a trajectory that is vertically focused.
The magnetic field bumps generated by the regenerator can hinder the vertical focusing generated as described above. For example, a magnetic field bump can cancel or move the field line curvature, at least where it is placed, thereby preventing vertical focusing. A “flutter brick” can be added to each side of the regenerator with approximately the same radial arrangement of the regenerator (although not necessarily exactly the same) to restore the vertical focusing hindered by the regenerator ( The radial arrangement is the distance measured relative to the plasma column in the center of the cavity). A space (or air gap) is between each flutter brick and the regenerator.
In some embodiments, the flutter brick is a ferromagnetic device that introduces magnetic field fluctuations (referred to as “magnetic flutter” or simply “flutter”) into the magnetic field at approximately the radial position of the flutter brick and regenerator. is there. Flutter results from azimuthal changes in adjacent magnetic fields generated by magnetic “hills” and “valleys”, which are regions of higher and lower magnetic fields, respectively. In this example, the flutter brick and regenerator constitute a hill, while the empty space between each flutter brick and regenerator constitutes a valley. Due to the magnetic field difference between the hills and valleys, adequate perturbation of the magnetic field lines is adequate so that the resulting magnetic field lines have a sufficient radial component at an angle to the particle beam and cause vertical focusing. Occurs in the radial region.
In some embodiments, each flutter brick is a single ferromagnetic device configured to generate magnetic field bumps having a specific size and shape. In the present invention, a single ferromagnetic device can be a single adjacent or physically connected structure, or two vertically aligned but empty spaces through which magnetic flux passes. May be non-physically connected ferromagnetic structures separated by (eg, one on each yoke). In the present invention, vertical alignment includes alignment between yokes and includes any suitably aligned whole or part of a ferromagnetic structure.
In some embodiments, there are only two flutter bricks, one on each radially adjacent side of the regenerator. In other embodiments, the series of flutter bricks can be in one or more radial arrangements relative to the plasma column. For example, at each of the Nth (N> 1) radii, there may be a series of flutter bricks around all or part of the cavity perimeter, each pair of flutter bricks corresponding to a lower magnetic field or other Separated by appropriate areas. These spaces may be approximately the same size, larger or smaller than the corresponding flutter brick, depending on the desired magnetic effect.
In an alternative embodiment, the magnetic field in the cavity can be controlled to reduce bending in the cavity. This can be done, for example, by changing the cross-sectional shape of the magnetic yoke that defines the cavity. As such, as explained above, there may be little or no vertical focusing inherently generated by the background magnetic field. However, magnetic flutter can be used to cause vertical focusing of the particle beam. For example, flutter bricks of the type described above can be placed at various radial locations within the cavity. Alternatively, a magnetic hill / valley arrangement can be realized in the cavity. In an exemplary embodiment, each part (hill or valley) of this arrangement may be pie-shaped, each part having a point on the plasma column and an edge on the edge of the cavity. Alternatively, each part (hill or valley) of this arrangement may be windmill shaped, each part having a point on the plasma column and an edge on the edge of the cavity. Other shapes can also be used. Similarly, variations of these shapes can also be used.
By maintaining the magnetic field lines substantially linear throughout the cavity, it may be possible to reduce the radius of the cavity. In some embodiments, the radius can be reduced, for example, by more than 10%, resulting in a more compact particle accelerator. Furthermore, in embodiments where the magnetic field is bowed at the edge of the cavity, the RF voltage must be swept to compensate for the decreasing magnetic field caused by vertical focusing. In embodiments where a magnetic flutter is used to provide vertical focusing, the RF sweep may only follow the increase in particle mass, so less RF sweep is needed in terms of range and / or size.
The features described herein are used in a single particle accelerator, and any two or more of these features can be combined in a single particle accelerator. The particle accelerator can be used for any type of medical or non-medical application. An example of a particle therapy system in which the aforementioned features can be used is presented below.
Exemplary Particle Therapy System As depicted in FIG. 1, the charged particle beam therapy system 500 includes a beam generating particle accelerator 502, where the weight and size of the beam generating particle accelerator 502 is determined by the output of the beam generating particle accelerator 502. Is sized to be attachable to a rotating gantry 504 having a directed output in a state oriented in a linear direction (ie substantially directly) from the accelerator housing to the patient 50.
In some embodiments, the steel gantry 504 has two legs 508, 510 that are two bearings 512, 514 disposed on opposite sides of the patient, respectively. It is attached to rotate. The beam-generating particle accelerator 502 is long enough to straddle the treatment area 518 on which the patient lies (which allows a tall person to rotate completely in space with the patient's desired target area maintained on the beam line. Is supported by a steel truss 516 (eg, twice the height of the tall human being) and is securely attached to the rotating leg of the gantry at both ends.
In some embodiments, the rotation of the gantry 504 is limited to a range 520 of less than 360 °, eg, about 180 °, so that the floor 522 extends from the wall of the vault 524 housing the treatment system to the interior of the patient treatment area. Can be extended. Further, by limiting the rotation range 520 of the gantry 504, it is possible to reduce the required thickness of some of the walls for shielding people outside the patient treatment area from radiation. If the rotation range 520 of the gantry 504 is 180 °, it is sufficient to accommodate all treatment approach angles, but it is advantageous to increase the range of movement. For example, even if the rotation range 520 is 180 ° to 330 °, a clearance with respect to a floor area for treatment can still be secured.
The horizontal axis of rotation 532 of the gantry 504 is located nominally 1 meter above the floor where the patient and therapist interact with the treatment system. This floor is positioned about 3 meters above the bottom floor of vault 524 that shields charged particle beam therapy system 500. The beam generating particle accelerator 502 can be swiveled below the raised floor to irradiate the treatment beam from below the rotation axis. The patient couch moves and rotates in a horizontal plane that is substantially parallel to the rotational axis 532 of the gantry 504. Such a configuration allows the couch to rotate over a range 534 of about 270 ° in the horizontal plane. The combination of the gantry 504 and patient rotation ranges 520, 534 and degrees of freedom allows the therapist to select virtually any approach angle for the beam. If necessary, by placing the patient on the couch in the opposite orientation, all possible angles are available.
In some embodiments, the beam generating particle accelerator 502 utilizes a synchrocyclotron having an ultra high field superconducting magnetic structure. Since the radius of curvature of a charged particle having a predetermined kinetic energy decreases in direct proportion to the increase in the magnetic field applied to the charged particle, the use of an ultrahigh magnetic field superconducting magnetic structure makes the accelerator small and Can be lightweight. The synchrocyclotron uses a magnetic field whose rotation angle is uniform and whose strength decreases as the radius increases. Since such a magnetic field shape is realized regardless of the size of the magnetic field, the upper limit on the strength of the magnetic field that can be used in the synchrocyclotron (and hence the resulting particle energy at a fixed radius) is theoretically Does not exist above.
In the presence of a very high magnetic field, a superconductor loses its superconducting properties. In order to realize a very high magnetic field, a winding made of a high-performance superconducting wire is used.
A superconductor generally needs to be cooled to a low temperature state where its superconducting properties can be obtained. In some embodiments described herein, a refrigerator is utilized to cool the superconducting coil windings to a temperature near absolute zero. By utilizing a refrigerator, complexity and cost are reduced.
The synchrocyclotron is supported on the gantry so that the beam is generated directly on the patient. The gantry can rotate the cyclotron about a horizontal axis of rotation that includes a point in the patient's body or a point in the vicinity of the patient (isocenter 540). A split truss that is parallel to the horizontal axis of rotation supports the cyclotron on both sides.
Since the rotation range of the gantry is limited, the patient support area can be accommodated in a wide area centered on the isocenter. Since the floor can be extended over a wide range about the isocenter, the patient support base moves relative to the vertical axis 542 passing through the isocenter and rotates about the vertical axis 542 The beam can be directed at any angle toward any part of the patient by a combination of rotation of the gantry and movement and rotation of the patient support. The two gantry arms are separated by more than twice the height of the tall patient so that the couch carrying the patient can rotate and translate in a horizontal plane located above the elevated floor. .
By limiting the rotation angle of the gantry, the thickness of at least one of the walls surrounding the treatment room can be reduced. A thick wall, typically made of concrete, protects people outside the treatment room from radiation. The downstream wall for blocking the proton beam may be about twice as thick as the opposite wall of the treatment room to provide an equivalent level of protection. By limiting the rotation of the gantry, the treatment room can be set lower than the earth grade on three sides, while the occupied area can be adjacent to the thinnest wall so that the treatment room is built. Cost can be reduced.
In the exemplary embodiment shown in FIG. 1, the superconducting synchrocyclotron 502 operates at a peak magnetic field of 8.8 Tesla in the synchrocyclotron pole gap. The synchrocyclotron generates a proton beam having an energy of 250 MeV. In other examples, the field strength can be in the range of 4 to 20 or 6 to 20 Tesla, and the proton energy can be in the range of 150 to 300 MeV.
Although the radiotherapy system described in this example is used for proton radiotherapy, the same principles and details can be applied in similar systems for use in heavy ion (ion) therapy systems.
As shown in FIGS. 2, 3, 4, 5, and 6, an exemplary synchrocyclotron 10 (eg, 502 in FIG. 1) includes a magnet system 12 that houses a particle source 90, a high frequency A drive system 91 and a beam extraction system 38 are included. The magnetic field established by the magnet system is internally generated using a combination of a split pair of annular superconducting coils 40, 42 and a pair of shaped ferromagnetic (eg, low carbon steel) pole faces 44, 46. It has an appropriate shape to maintain the focus of the existing proton beam.
The two superconducting magnetic coils are centered on the common axis 47 and are arranged along the axis in a spaced manner. As shown in FIGS. 7 and 8, the coil is a 0.8 mm diameter Nb 3 Sn based superconducting wire 48 (initially surrounded by a copper sheath) arranged in a twisted cable in-channel conductor configuration. With a niobium tin core). After the seven individual wires have been combined into a cable, they are heated, causing a reaction that forms a wire-like final (brittle) superconductor. After the material has reacted, the wire is soldered into a copper channel (outer diameter 3.18 × 2.54 mm and inner diameter 2.08 × 2.08 mm) and insulator 52 (in this example, a fiberglass woven fabric) Covered with. It is then wound into a copper channel coil that houses the wire 53, which has a rectangular cross section of 8.55 cm × 19.02 cm, has 26 layers, and has 49 turns per layer. . The wound coil is then vacuum impregnated with an epoxy compound. The completed coil is mounted on an annular stainless steel reverse bobbin 56. A heater blanket 55 is spaced into the layers of the winding to protect the assembly when a magnet quench occurs.
The entire coil is then covered with a copper plate to provide thermal conductivity and mechanical stability and then housed in an additional epoxy layer. Pre-compression of the coil can be performed by heating a stainless steel reverse bobbin and fitting the coil into the reverse bobbin. The inner diameter of the reverse bobbin is selected so that when the entire mass is cooled to 4K, the reverse bobbin remains in contact with the coil, resulting in some degree of compression. This can be achieved by heating the stainless steel reverse bobbin to about 50 ° C. and fitting the coil at a Kelvin temperature of 100 degrees.
The coil geometry is maintained by mounting the coil in a rectangular reverse bobbin 56 and providing a restoring force 60 that acts against the forces that cause distortion when the coil is energized. As shown in FIG. 5, the coil position is maintained relative to the magnet yoke and cryostat using a set of hot-cold support straps 402, 404, 406. By supporting the cold mass with a thin strap, the heat leakage imparted to the cold mass by the rigid support system is reduced. The strap is configured to withstand the changing gravity applied to the coil when the gantry is rotated with the magnet mounted. They withstand the combined effect of gravity and the large eccentric force produced by the coil when it is perturbed from a perfectly symmetrical position with respect to the magnetic yoke. In addition, in some embodiments, the link serves to reduce the dynamic force applied to the coil as the gantry accelerates and decelerates when the position changes. Each hot-cold support includes one S2 glass fiber link and one carbon fiber link. The carbon fiber link is supported on pins between the hot yoke and intermediate temperature (50-70K), and the S2 glass fiber link 408 is supported on the intermediate temperature pins and pins attached to the cold mass. Each link has a length of 5 cm (between the pin center and the pin center) and a width of 17 mm. The link thickness is 9 mm. Each pin is made from high-strength stainless steel and has a diameter of 40 mm.
Referring to FIG. 3, the field strength profile as a function of radius is largely determined by the choice of coil geometry and pole face shape, and the pole faces 44, 46 of the permeable yoke material are The undulations can be tuned to fine-tune the shape of the to ensure that the particle beam converges during acceleration.
The superconducting coil, except for a limited set of support points 71, 73, is a coil assembly (coil and bobbin) inside an evacuated annular aluminum or stainless steel cryostat 70 that provides free space around the coil structure. ) Is maintained at a temperature close to absolute zero (eg, about 4 Kelvin). In an alternative version (FIG. 4), the outer wall of the cryostat is made of low carbon steel and can provide an additional return magnetic path for the magnetic field.
In some embodiments, temperatures near absolute zero are achieved and maintained using one single stage Gifford McMahon refrigerator and three two-stage Gifford McMahon refrigerators. Each two-stage refrigerator has a second stage cold end attached to a condenser that recondenses helium vapor to liquid helium. Compressed helium is supplied from the compressor to the head of the refrigerator. The single stage Gifford McMahon refrigerator is configured to cool high temperature (eg, 50-70 Kelvin) leads that supply current to the superconducting winding.
In some embodiments, temperatures near absolute zero are achieved and maintained using two Gifford McMahon refrigerators 72, 74 located at different locations on the coil assembly. Each refrigerator has a cold end 76 that contacts the coil assembly. Compressed helium is supplied from the compressor 80 to the head 78 of the refrigerator. The other two Gifford McMahon refrigerators 77, 79 are configured to cool high temperature (eg, 60-80 Kelvin) leads that supply current to the superconducting winding.
The coil assembly and cryostat are mounted in two halves 81, 83 of a pillbox shaped magnet yoke 82 and are completely enclosed. In this example, the inner diameter of the coil assembly is approximately 74.6 cm. The iron yoke 82 provides a path for the return magnetic flux 84 and magnetically shields the volume 86 between the pole faces 44 and 46 to prevent external magnetic influences from perturbing the shape of the magnetic field in the volume. The yoke also serves to reduce stray magnetic fields near the accelerator. In some embodiments, the synchrocyclotron may have an active feedback system that reduces stray fields. An example of an active feedback system is described in US patent application Ser. No. 13 / 907,601 filed May 31, 2013, the contents of which are incorporated herein by reference. In an active feedback system, the relatively large magnetic yoke described herein is replaced with a smaller magnetic structure called a pole piece. The superconducting coil conducts current on the opposite side of the main coil described herein and provides magnetic feedback, thereby reducing stray fields.
As shown in FIGS. 3 and 9, the synchrocyclotron includes a penning ion gauge type particle source 90 disposed near the geometric center 92 of the magnetic structure 82. The particle source is as described below, or the particle source is of the type described in US patent application Ser. No. 11 / 948,662, which is incorporated herein by reference. It's okay.
The particle source 90 is supplied from a hydrogen supply unit 99 through a gas pipe 101 and a pipe 194 for delivering gaseous hydrogen. Electrical cable 94 carries current from current source 95 and stimulates the emission of electrons from cathodes 192 and 190 aligned in the direction of magnetic field 200.
In some embodiments, the gas in gas tube 101 may include a mixture of hydrogen and one or more types of other gases. For example, the mixture may include one or more of hydrogen and a noble gas such as helium, neon, argon, krypton, xenon, and / or radon (the mixture is not limited to use with a noble gas). In some embodiments, the mixture may be a mixture of hydrogen and helium. For example, the mixture can contain about 75% or more hydrogen and about 25% or less helium (which can include residual gases). In another example, the mixture can contain about 90% or more hydrogen and about 10% or less helium (which can include residual gases). For example, hydrogen / helium mixtures are> 95% / <5%,> 90% / <10%,> 85% / <15%,> 80% / <20%,> 75% / <20%, etc. Any of
Possible benefits of using a noble gas (or other gas) in combination with hydrogen in the particle source are increased beam intensity, increased cathode life, and increased beam power continuity.
In this example, the emitted electrons ionize the gas exiting through a small hole from the tube 194 and take one semicircle (dee) that occupies half of the space surrounded by the magnet structure and one dummy dee plate 102. Shape) A supply portion of positive ions (protons) accelerated by the high-frequency plate 100 is formed. In the case of a blocked particle source (an example of which is described in US patent application Ser. No. 11 / 948,662), all (or a substantial portion) of the tube containing the plasma is removed in the acceleration region, Thereby, ions can be accelerated at a higher speed in a relatively high magnetic field.
As shown in FIG. 10, the deeplate 100 is hollow with two semicircular surfaces 103, 105 surrounding a space 107 where protons are accelerated in half of the rotation around the space enclosed by the magnet structure. It is a metal structure. A duct 109 that opens into the space 107 extends through the yoke to an external location where the vacuum pump 111 can be attached, thereby allowing the space 107 and the rest of the space in the vacuum chamber 119 where acceleration takes place. To a vacuum. The dummy dee 102 includes rectangular metal rings that are spaced apart near the exposed edges of the dee plate. The dummy dee is grounded to the vacuum chamber and the magnetic yoke. The deeplate 100 is driven by a high-frequency signal applied to the end portion of the high-frequency transmission path, and generates an electric field in the space 107. The radio frequency electric field is varied with time as the accelerated particle beam increases the distance from the geometric center. The high frequency electric field is described in US patent application Ser. No. 11 / 948,359, the content of which is incorporated herein by reference, “Matching A Resonant Frequency Of A Resonant Cavity To A Frequency Of Input Voltage”. Can be controlled.
As the beam emerges from the centrally located particle source to clear the particle source structure and begin to spiral outward, a high voltage difference is required on the high frequency plate. 20,000 V is applied to the high frequency plate. In some versions, 8,000 to 20,000 volts can be applied to the radio frequency plate. In order to reduce the power required to drive this high voltage, the magnet structure is configured to reduce the capacitance between the high frequency plate and ground. This is done by forming holes with sufficient spacing from the high frequency structure to the outer yoke and the cryostat housing to ensure sufficient space between the pole faces.
This high voltage alternating potential that drives the deeplate is swept to a lower frequency in the acceleration cycle, taking into account the increasing relativistic mass of the protons and the decreasing magnetic field. The dummy dee is at ground potential along with the vacuum chamber wall and does not require a hollow semi-cylindrical structure. Other plate configurations can also be used, such as multiple pairs of accelerating electrodes driven at different phases or multiples of the fundamental frequency. The RF structure can be tuned to keep Q high in the required frequency sweep, for example by using rotating capacitors with rotating and stationary blades that mesh with each other. With each blade engagement, the capacitance increases and thus the resonant frequency of the RF structure decreases. The blade can be shaped into a shape that provides the exact frequency sweep required. The drive motor for the rotating capacitor can be phase locked to the RF generator for precise control. A group of particles is accelerated for each meshing of the rotating condenser blades.
The vacuum chamber 119 in which acceleration takes place is a generally cylindrical vessel with a thin center and thick edges. The vacuum chamber contains the RF plate and particle source and is evacuated by the vacuum pump 111. By maintaining a high vacuum, it is ensured that the accelerating ions are not lost in collision with gas molecules, allowing the RF voltage to be kept at a higher level without causing an arc ground fault.
Protons traverse a generally helical orbital path starting from a particle source. In each half of the spiral path, protons gain energy as they pass through the RF electric field in space 107. As the ion gains energy, the radius of the central trajectory of each successive loop of the helical path becomes larger than the previous loop until the loop radius reaches the maximum radius of the pole face. At that position, the magnetic field and electric field perturbations direct the ions into the region where the magnetic field decreases rapidly, and the ions exit the region of high magnetic field and are passed through a vacuum tube 38, referred to herein as an extraction channel, of the cyclotron. Get out of York. A magnetic regenerator can be used to change the magnetic field perturbation to determine the orientation of the ions. Ions exiting the cyclotron have a tendency to disperse upon entering a region of significantly reduced magnetic field that exists in the room around the cyclotron. Beam shaping elements 107, 109 in the extraction channel 38 redirect the ions so that the ions remain in a linear beam state with limited spatial spread.
The magnetic field in the pole gap needs to have several characteristics that maintain the beam in the vacuum chamber when accelerating. The magnetic field index n is given by the formula n = − (r / B) dB / dr
And must be kept positive to maintain this “weak” focusing. Here, r is the radius of the beam and B is the magnetic field. In addition, the magnetic field index, it is necessary to be maintained below 0.2, it is in this value, because the period of radial vibration and the vertical vibration of the beam coincides with the resonance of vr = 2v z is there. The betatron frequency is defined by v r = (1-n) 1/2 and v z = n 1/2 . The ferromagnetic pole face is designed to shape the magnetic field generated by the coil such that the magnetic field index n remains positive at the smallest diameter consistent with a 250 MeV beam within a given magnetic field and is less than 0.2. Is done.
As the beam exits the extraction channel, the beam is passed through a beam forming system 125 (FIG. 5) that can be programmably controlled to form the desired combination of scattering angle and range modulation for the beam. The beam forming system 125 may be used with the inner gantry 601 (FIG. 14) to direct the beam to the patient.
In operation, the plate absorbs energy from the applied high frequency field as a result of conduction resistance along the surface of the plate. This energy appears as heat and is removed from the plate using a water-cooled line 108 that releases heat into the heat exchanger 113 (FIG. 3).
The stray magnetic field emanating from the cyclotron is limited by both the pillbox magnet yoke (which also acts as a shield) and another magnetic shield 114. Another magnetic shield includes a layer 117 of ferromagnetic material (eg, steel or iron) surrounding the pillbox yoke, separated by a space 116. This configuration, including a yoke, space, and shield sandwich, forms a suitable shield against a given leakage field at a lower weight.
As described above, the gantry 504 rotates the synchrocyclotron around the horizontal rotation axis 532. Truss structure 516 has two generally parallel spans 580, 582. The synchrocyclotron is disposed approximately at the center between the legs 508 and 510 and between the spans 580 and 582. The gantry is balanced for rotation about the bearings 512, 514 by utilizing counterweights 122, 124 attached to the ends of the legs 508, 510 opposite the truss.
The gantry 504 is rotationally driven by an electric motor, and the electric motor is attached to at least one leg of the gantry 504 and is connected to the bearing housing via a drive gear. The rotational position of the gantry 504 is derived from a signal provided by a shaft angle encoder incorporated in the drive motor and drive gear of the gantry 504.
At the location where the ion beam exits the cyclotron, the beam forming system 125 operates on the ion beam to impart characteristics suitable for patient treatment to the ion beam. For example, by diffusing the beam and changing the penetration depth of the beam, the beam can be emitted uniformly with respect to a predetermined target volume. The beam forming system may comprise passive scattering elements in addition to the active scanning elements.
All active systems of the synchrocyclotron (eg current-driven superconducting coils, RF-driven plates, vacuum pumps for vacuum acceleration chambers, vacuum pumps for superconducting coil cooling chambers, current-driven particle sources, hydrogen gas sources And RF plate cooling device) by means of electronics (not shown) for controlling a suitable synchrocyclotron, including for example one or more computers programmed with a suitable program to implement the control effectively Be controlled.
The gantry, patient support, active beam shaping element, and synchrocyclotron are controlled to perform a treatment session by electronics (not shown) for controlling the appropriate treatment.
As shown in FIGS. 1, 11, and 12, the bearings 512, 514 of the gantry 504 are supported by the walls of the cyclotron vault 524. The gantry 504 can pivot the cyclotron over a 180 ° (or more than 180 °) rotation range 520 including the patient's upper, lateral, and lower positions. The vault 524 has a height sufficient to allow the gantry 504 to pass at the upper and lower end points of the gantry 504 movement. The maze 146 with the walls 148, 150 on the sides serves as an entrance / exit route for therapists and patients. Since at least one wall 152 is not in the range of direct proton beam irradiation from the cyclotron, the wall can be made relatively thin and still exhibit a shielding function. The other three side walls 154, 156, 150/148 of the treatment room need to be shielded relatively tightly and are embedded in a fill (not shown). The required thickness of the side walls 154, 156, 158 is reduced because the soil itself can serve part of the necessary shielding.
As shown in FIGS. 12 and 13, the treatment room 160 is configured in the vault 524 for safety and aesthetic reasons. The treatment room 160 can be passed from the walls 154, 156, 150 and the base 162 of the containment chamber so that a swiveling gantry can be passed and to maximize the extent of the treatment room floor area 164. It is formed as a cantilever beam toward the inside of the space formed between the leg portions 508 and 510 of 504. Periodic maintenance of the beam generating particle accelerator 502 can be performed in the space below the high floor. When the beam generating particle accelerator 502 is rotated to a position below the gantry 504, the entire accelerator is accessible in a space separated from the treatment area. The power source, the cooling device, the vacuum pump, and other support devices are disposed below the raised floor in the separated space. The patient support 170 is attachable to the interior of the treatment room 160 in a variety of ways that can move the support up and down and rotate and move the patient to various positions and orientations.
In the system 602 depicted in FIG. 14, a beam generating particle accelerator of the type described herein is attached to a rotating gantry 605, in this embodiment a synchrocyclotron 604. The rotating gantry 605 is of the type described herein and can rotate angularly about the patient support 606. This feature allows the synchrocyclotron 604 to directly irradiate the patient with a particle beam from various angles. For example, as shown in FIG. 14, when the synchrocyclotron 604 is positioned above the patient support 606, the particle beam is directed downward toward the patient. Alternatively, if the synchrocyclotron 604 is located below the patient support 606, the particle beam is directed upward toward the patient. In the sense that no intermediate beam routing mechanism is required, the particle beam is applied directly to the patient. The present invention provides an intermediate beam routing mechanism in that the shaping or sizing mechanism does not change the beam path, but determines the beam size and / or shape while maintaining the same and general beam trajectory. Is different from the molding or sizing mechanism.
Further details regarding exemplary embodiments of the system described above are disclosed in US Pat. No. 7,728,311 and US patent application Ser. No. 12 / 275,103. The contents of these patent documents are incorporated herein by reference. In some embodiments, the synchrocyclotron may be a variable energy device described below and in US patent application Ser. No. 13 / 916,401. The contents of this patent document are incorporated herein by reference.
Illustrative Example FIG. 15 shows a top view of a portion of a cavity 700 where particles are accelerated in orbit (eg, in an outward spiral orbit). A particle source 701, an example of which is described above, is disposed approximately in the center of the cavity. Charged particles (eg, protons or ions) are extracted from the plasma column generated by the particle source 701. The charged particles accelerate outward in the trajectory toward the magnetic regenerator 702 and finally reach the magnetic regenerator 702. In this exemplary embodiment, regenerator 702 is a single ferromagnetic device made from, for example, steel, iron, or other types of ferromagnetic materials. The regenerator 702 can include a portion connected to each half of the respective magnetic yoke. The regenerator 702 changes the background magnetic field that causes acceleration on the outward trajectory. In this example, the regenerator 702 causes the magnetic field to bump by increasing its magnetic field, eg, by strengthening the magnetic field at that location. Bumps in the background magnetic field affect the particle trajectory in such a way that the trajectory is pulled out and moved outward toward the channel 703. Eventually, the trajectory enters and exits the withdrawal channel 703.
More specifically, the particle beam trajectory approaches and interacts with the regenerator 702. As a result of the increase in the magnetic field, the particle beam then turns slightly and precesses into the extraction channel instead of being circular. FIG. 16 shows the magnetic field (B) plotted against the radius (r) for the particle source 702. In this example, B varies from about 9 Tesla (T) to about -2T, as shown in FIG. In other examples, the magnetic field may vary from about 4T, 5T, 6T, 7T, 8T, 8.5T, 9.5T, 10T, 105T, etc. to -2T or other values. In this example, 9T appears at about the center of cavity 700. The polarity of the magnetic field changes after the magnetic field crosses the superconducting coil, resulting in about -2T outside the coil and eventually decreasing to about zero. Magnetic field bump 705 occurs at the point of the regenerator. FIG. 16 also shows a magnetic field plot for a cross-section 706 of a bobbin 706 having a draw channel 703 between two superconducting coils 709, 710.
FIG. 18 shows the magnetic effect of the regenerator. More specifically, as shown in FIG. 18, the regenerator 702 generates a magnetic field represented by magnetic field lines 750. The magnetic field lines 750 cause a magnetic local defect 753 in the background magnetic field. This local defect is also shown in FIG. More specifically, as pointed out above, FIG. 16 shows a magnetic field bump 705 (eg, 0.5T to 2T) generated by the regenerator 702 with a corresponding local defect 753 in the background magnetic field. It is shown. As shown, the local defect 753 is relatively small compared to the background magnetic field. As such, its effect on orbital precession is relatively small. As a result, a single regenerator can be used that has characteristics similar to those described herein.
As shown in FIG. 17, the regenerator 702 causes a change in the angle 780 and pitch 781 of the trajectory 710 to cause movement to the extraction channel 703. At the point of the extraction channel, the strength of the magnetic field is low enough to allow the particle beam to enter and travel through the extraction channel. As also shown in FIG. 15, extraction channel 703 performs various additions and / or subtractions to the dipole field, and various magnetic structures 711 for directing the incoming particle beam through extraction channel 703 to the beam shaping element. To accommodate.
As described above, the magnetic field bumps generated by the regenerator 702 can prevent vertical focusing caused by bowing (or other distortion) of the magnetic field lines in the cavity 700. In this regard, FIG. 19 shows a cross section of the cavity 700 and the magnetic field lines 800 between the yokes. As shown, the magnetic field lines 800 gradually bow toward the edge of the cavity, with the most notable bends being seen at the edges. As explained above, this bowing causes vertical focusing, which is prevented by the regenerator. In other embodiments, different types of field line distortions can also cause vertical focusing and can be prevented by the operation of the regenerator or similar device.
Two or more flutter bricks can be incorporated into the cavity 700 and positioned relative to the regenerator to cause vertical focusing within the cavity. In the example of FIG. 15, there are two flutter bricks 802 and 803, one on each side of the regenerator 702. As shown in FIG. 15, there is a space (or air gap) between each flutter brick and the regenerator. The combination of space, regenerator and flutter brick generates a magnetic field variation with one or more components at the appropriate angle to the particle trajectory, causing vertical focusing. In some embodiments, the combination of space, regenerator, and flutter brick can be structured to generate an appropriate amount of focusing in the vertical direction. For example, in some embodiments, the amount of vertical focusing provided by this combination is sufficient to compensate for or exceed the total amount of vertical focusing caused by the regenerator. It may be.
The example of FIG. 15 shows only two flutter bricks in a radial arrangement close to (but not identical to) the radial arrangement of the regenerator. In an exemplary embodiment, the magnetic field flutter defined by the azimuth average normalized magnetic field change rate is between 0.25% and 20%. In other embodiments, more than two flutter bricks can be added to the radial arrangement. For example, there can be flutter bricks separated by a suitable space around the entire circumference of the cavity. For example, FIG. 20 shows a flutter brick 810 and a space 811 around the outer periphery of the cavity 812 in the radial arrangement 815. In other examples, there can be flutter bricks in different radial arrangements and multiple radial arrangements. For example, as shown in FIG. 21, there may be flutter bricks in the radial arrangements 815, 816, and 817, and there is an appropriate space between the flutter bricks in each radial arrangement. Although FIG. 21 shows flutter bricks around the entire perimeter of the cavity in each radial arrangement, this need not be the case. Rather, the flutter brick may occupy only a portion of the outer periphery in the radial arrangement, as in the embodiment of FIG.
In the embodiment described above, the ferromagnetic device is used as a flutter brick separated by space. As explained above, each flutter brick may be a single ferromagnetic device configured to generate magnetic field bumps having a particular size and shape. A single ferromagnetic device can be a single adjacent or physically connected structure, or two vertically aligned but empty spaces or other materials through which magnetic flux passes May be non-physically connected ferromagnetic structures separated by (eg, one on each yoke). Vertical alignment may include alignment between other magnetic structures, such as yokes or pole pieces, and includes any suitably aligned whole or part of the ferromagnetic structure.
The aforementioned configuration of flutter bricks, space, and regenerators results in a hill / valley configuration that generates the appropriate level of magnetic field variation. In some embodiments, the “valley” region need not be realized using an empty space, but rather has a different size and / or shape (eg, short, high, thin, thick) than the flutter brick. Use a ferromagnetic structure that is made of the same material (slim, wide, etc.) or that is the same or different size than the flutter brick, but has different ferromagnetic properties than the flutter brick Can be realized. Use any suitable combination of ferromagnetic material, non-ferromagnetic material, active coil, and empty space to generate the appropriate magnetic field fluctuations that cause the type of vertical focusing described above Can be made.
In this regard, although the flutter bricks shown in the figures are of approximately the same size and shape, the size and / or shape can be different in either the same radial configuration or different radial configurations. Furthermore, the number of flutter bricks for each radial arrangement can vary for each radius. Generally speaking, the number and configuration of flutter bricks can be set to produce an appropriate level of vertical focusing throughout the cavity, if desired.
In other examples, the cavity can be controlled to reduce or minimize the amount of bending (or other distortion) in the medium magnetic field. For example, the shape of the yoke 819 (or other magnetic structure) on the surface facing the magnetic cavity may be as shown in FIG. In this configuration, the magnetic field lines 820 in the cavity 822 are substantially linear throughout the cavity, even at the edge of the cavity (in other embodiments, the magnetic field lines are bowed). Linear field lines have several advantages in particle accelerators. For example, as described above, by maintaining the magnetic field lines substantially linear throughout the cavity, it is possible to reduce the radius of the cavity without significantly degrading performance. Also, since the RF sweep may only follow the increase in particle mass, less RF sweep is required with respect to range and / or size. However, keeping the magnetic field lines substantially linear throughout the cavity also reduces the vertical focusing that would otherwise result from the bowing of the magnetic field lines, as described above, or Eliminated.
Flutter can be used to provide vertical focusing in embodiments where the magnetic field lines are substantially linear throughout the cavity. For example, flutter bricks form magnetic hills and valleys used to generate flutter, with appropriate space or other structures, as shown in FIGS. 15, 20, and 21. Can be incorporated for. As explained above, flutter bricks are introduced in one or more radial arrangements and may or may not traverse the entire outer periphery of the cavity in each radial arrangement. In this example, the region of magnetic variation (eg, magnetic hills and valleys) uses any one or more of the configurations described above or described elsewhere herein. Can be generated.
In other examples, flutter can be generated using continuous regions having different ferromagnetic properties. For example, FIG. 23 shows a structure 822 that can be incorporated into a resonant cavity of a particle accelerator to generate flutter and thereby focus the particle beam vertically. The structure 822 includes a region 824 having a high magnetic field and a region 825 having a low magnetic field. “High” in the present invention simply means higher than the “low” magnetic field in the low magnetic field region, and neither “high” nor “low” is intended to imply any absolute or specific value. .
In this embodiment, each region is pie-shaped and the focal point or center point is approximately at the center of the cavity (where the plasma column is located), but this need not be the case in all embodiments. The edge of each pie-shaped region roughly corresponds to the outer edge of the cavity, but this need not be the case in all embodiments. The regions of high and low magnetic fields may alternate and have any of the characteristics described herein. For example, these are ferromagnetic devices and empty spaces, which are different materials (eg, ferromagnetic and non-ferromagnetic materials), which are different amounts of ferromagnetic material (eg, Iron, steel, etc.). Also, although the figure shows that the high and low field regions are approximately the same size, this need not be the case. These regions can have different sizes. Similarly, different regions of the same type may have different sizes, and there may be different numbers of regions in different embodiments. All this depends on the amount and shape of flutter desired in the particle accelerator. The resonant (acceleration) cavity can accommodate a single structure 822 or a plurality of such vertically aligned such structures 822. In the case of multiple structures, each structure 822 may be connected to a yoke or another location.
As shown in FIG. 24, in an alternative embodiment, the structure 830 that can be incorporated into the resonant cavity of the particle accelerator to generate flutter and thereby focus the particle beam vertically has a windmill shape. Good thing. All properties and variations associated with the pie-shaped structure 822 of FIG. 23 apply equally to the windmill-shaped structure of FIG. For example, the structure 830 includes a region 831 having a high magnetic field and a region 832 having a low magnetic field. As mentioned above, “high” in the present invention simply means higher than the “low” magnetic field in the low magnetic field region, and “high” or “low” implies any absolute or specific value. Not intended.
Either one or both of the structures 822 and 830 can be incorporated into the embodiments of FIGS. 15, 21, and 22 to generate flutter or increase flutter bricks and flutter provided by space. Please note that.
In some embodiments, the flutter guidance structure can have different levels of hills and valleys. For example, as represented in FIG. 25 which is a side view of such a structure, it has a valley 835 that does not contain ferromagnetic material, a first hill 836 having a first height, and a second height. There is a second hill 837. The second hill 837, due to its height, contains a stronger ferromagnetic material than the first hill 836, which contains a stronger ferromagnetic material than the valley 835. Such a configuration may be incorporated into a configuration similar to the structure of FIGS. 23 and 24, respectively. Similarly, flutter guiding structures are not limited to use with two or three levels (eg, amounts) of ferromagnetic material, but rather an appropriate number of levels of ferromagnetic material and / or different types. Can incorporate any material.
Variable Energy Particle Accelerator The particle accelerator used in the exemplary particle therapy system described herein may be a variable energy particle accelerator.
The energy of the extracted particle beam (particle beam output from the accelerator) can affect the use of the particle beam during treatment. In some machines, the energy of the particle beam (or particles in the particle beam) does not increase after extraction. However, energy can be reduced based on the need for treatment after withdrawal and before treatment. As depicted in FIG. 26, an exemplary treatment system 910 includes an accelerator 912, eg, a synchrocyclotron, from which a particle (eg, proton) beam 914 having variable energy is extracted and a target volume 924 of the body 922. Is irradiated. Where appropriate, one or more additional devices, such as a scanning unit 916 or scattering unit 916, one or more monitoring units 918, and an energy degrader 920, are placed along the illumination direction 928. These devices block the cross section of the extracted beam 914 and change one or more characteristics of the therapeutic extracted beam.
A target volume (irradiation target) irradiated with a particle beam for treatment typically has a three-dimensional configuration. In some examples, in order to perform the treatment, the target volume is divided into several layers along the direction of irradiation of the particle beam so that irradiation is performed layer by layer. For some types of particles, such as protons, the penetration depth in the target volume (or the layer that the beam reaches) is determined solely by the energy of the particle beam. A particle beam of a given energy does not reach substantially beyond the corresponding penetration depth for that energy. In order to move the beam irradiation from one layer of the target volume to the other, the energy of the particle beam is changed.
In the example shown in FIG. 26, the target volume 924 is divided into nine layers 926a to 926i along the irradiation direction 928. In the exemplary process, irradiation begins at the deepest layer 926i, proceeds progressively one layer at a time to the shallower layer, and ends at the shallowest layer 926a. Prior to application to the body 922, the energy of the particle beam 914 is substantially desired by the particle beam without penetrating further into the body or target volume, eg, layers 926e-926i, or even deeper into the body. Layer, for example, a level that can be stopped at layer 926d. In some examples, the desired energy of the particle beam 914 decreases as the treatment layer becomes shallower with respect to particle acceleration. In some examples, the difference in beam energy for treating adjacent layers of the target volume 924 is from about 3 MeV to about 100 MeV, eg, from about 10 MeV to about 80 MeV, although other differences may be, for example, layers Depending on the thickness and the characteristics of the beam.
Energy changes to treat different layers of the target volume 924 may be performed in the accelerator 912 in some embodiments so that no additional energy changes are required after the particle beam is extracted from the accelerator 912 ( For example, the energy can be changed on the accelerator side). Thus, the optional energy degrader 920 in the treatment system 10 can be excluded from the system. In some embodiments, the accelerator 912 can output a particle beam having an energy that varies between about 100 MeV and about 300 MeV, such as between about 115 MeV and about 250 MeV. The change may be continuous or discontinuous, for example, one step at a time. In some embodiments, continuous or non-continuous changes can occur at relatively high rates, for example, up to about 50 MeV per second or up to about 20 MeV per second. The non-continuous change can be performed one step at a time with a step size of about 10 MeV to about 90 MeV.
When irradiation with one layer is complete, the accelerator 912 can change the energy of the particle beam, for example within a few seconds or less than 1 second, to irradiate the next layer. In some examples, treatment of the target volume 924 can continue without substantial interruption or without any interruption. In some circumstances, the step size of the non-continuous energy change is selected to correspond to the difference in energy required to illuminate two adjacent layers of the target volume 924. For example, the step size may be the same as or a fraction of the energy difference.
In some embodiments, the accelerator 912 and the degrader 920 together change the energy of the beam 914. For example, coarse adjustment is performed by the accelerator 912 and fine adjustment is performed by the degrader 920, or vice versa. In this example, the accelerator 912 can output a particle beam that changes energy in a change step of about 10-80 MeV, and the degrader 920 adjusts the energy of the beam in a change step of about 2-10 MeV (eg, Reduced).
By reducing (or not using) an energy degrader, which may include a range adjuster, it is easier to maintain the characteristics and quality of the output beam from the accelerator, such as beam intensity. The control of the particle beam can be performed with an accelerator. Side effects, for example, side effects from neutrons that occur when the particle beam passes through the degrader 920 can be reduced or eliminated.
The energy of the particle beam 914 may be adjusted to treat another target volume 930 in another body or body portion 922 'after completion of treatment in the target volume 924. The target volumes 924, 930 may be in the same body (or patient) or may belong to different patients. The depth D of the target volume 930 from the surface of the body 922 ′ can be different from the depth of the target volume 924. Although some energy adjustment may be performed by the degrader 920, the degrader 912 only reduces the beam energy and cannot increase the beam energy.
In this regard, in some cases, the beam energy required to treat the target volume 930 is greater than the beam energy required to treat the target volume 924. In such a case, the accelerator 912 can increase the output beam energy after treating the target volume 924 and before treating the target volume 930. In other cases, the beam energy required to treat the target volume 930 is less than the beam energy required to treat the target volume 924. Although the degrader 920 can reduce energy, the accelerator 912 can be adjusted to output lower beam energy to reduce or eliminate the use of the degrader 920. The division of the target volume 924, 930 into several layers can be different or the same. Also, the target volume 930 can be treated in a manner similar to the treatment of the target volume 924, layer by layer.
Treatment of different target volumes 924, 930 for the same patient is substantially continuous, eg, the stop time is not longer than about 30 minutes for two volumes, eg, within 25 minutes, within 20 minutes, It may be within 15 minutes, within 10 minutes, within 5 minutes, or within 1 minute. As described herein, the accelerator 912 can be mounted on a movable gantry, and movement of the gantry can cause the accelerator to move toward different target volumes. In some situations, the accelerator 912 is making adjustments (such as moving the gantry) after the treatment system has completed treatment of the target volume 924 and before starting treatment of the target volume 930. The energy adjustment of the output beam 914 can be completed. After alignment of the accelerator and target volume 930 is performed, treatment can begin with the adjusted desired beam energy. Beam energy adjustments for different patients can also be completed relatively efficiently. In some examples, all adjustments including increasing / decreasing beam energy and / or moving the gantry are within about 30 minutes, eg, within about 25 minutes, within about 20 minutes, about 15 minutes. Within about 10 minutes, or within about 5 minutes.
In the same layer of the target volume, the irradiation dose is applied by using the scanning unit 916 to move the beam across the two-dimensional surface of the layer (also referred to as a scanning beam). Alternatively, the layer may be irradiated by passing a drawn beam (also referred to as a scattered beam) through one or more scatterers of the scattering unit 16.
Beam characteristics, such as energy and intensity, can be selected prior to treatment, or during treatment, such as an accelerator 912 and / or a scanning unit / scatterer 916, a degrader 920, and others not shown, It can be adjusted by controlling other devices. In this exemplary embodiment, similar to the exemplary embodiment described above, system 910 includes a controller 932, such as a computer, that communicates with one or more devices in the system. Control may be based on the results of monitoring performed by one or more monitors 918, such as monitoring of beam intensity, dose, beam placement within the target volume, and the like. Although the monitor 918 is illustrated as being between the device 916 and the degrader 920, one or more monitors can be placed in other suitable arrangements along the beam irradiation path. The controller 932 may also store treatment plans for one or more target volumes (same patient and / or different patients). The treatment plan is determined before treatment starts and may include parameters such as the shape of the target volume, the number of irradiated layers, the dose to each layer, the number of times each layer is irradiated. Adjustment of the beam characteristics within system 910 may be performed based on the treatment plan. Additional adjustments may be performed during treatment, for example, when deviations from the treatment plan are detected.
In some embodiments, the accelerator 912 is configured to change the energy of the output particle beam by changing the magnetic field in which the particle beam is accelerated. In one exemplary embodiment, one or more coil sets receive a varying current and generate a varying magnetic field in the cavity. In some examples, one coil set receives a fixed current, while one or more other coil sets receive a varying current such that the total current received by the coil set changes. In some embodiments, all coil sets are superconducting. In other embodiments, some coil sets, such as the set for fixed current, are superconducting, while other coil sets, such as one or more sets for varying current, are non-superconducting. In some examples, all coil sets are non-superconducting.
In general, the magnitude of the magnetic field can increase or decrease with the magnitude of the current. By adjusting the total current of the coil within a predetermined range, a magnetic field that changes within the corresponding predetermined range can be generated. In some examples, continuous adjustment of the current can cause a continuous variation of the magnetic field and a continuous variation of the output beam energy. Alternatively, if the current applied to the coil is adjusted non-continuously and stepwise, the magnetic field and output beam energy will also change accordingly (step-wise). By increasing or decreasing the magnetic field according to the current, the beam energy can be changed relatively accurately, but in some cases, fine adjustments other than the input current can be performed.
In some embodiments, to output a particle beam having variable energy, the accelerator 912 is configured to apply an RF voltage that sweeps across different frequency ranges, each range corresponding to a different output beam energy. The For example, if the accelerator 912 is configured to generate three different output beam energies, the RF voltage can be swept across three different frequency ranges. In another example, the RF voltage is swept over a continuously changing frequency range by responding to continuous beam energy changes. Different frequency ranges may have different lower frequency boundaries and / or upper frequency boundaries.
The extraction channel can be configured to accommodate different ranges of energy provided by the variable energy particle accelerator. Particle beams having different energies can be extracted from the accelerator 912 without changing the characteristics of the regenerator used to extract a particle beam having a single energy. In other embodiments, to accommodate for variable particle energy, the regenerator is moved to disturb (eg, vary) different particle trajectories as described above and / or iron rods (magnetic Shim) can be added or removed to change the magnetic field bump provided by the regenerator. More specifically, the different particle energies are typically in different particle trajectories within the cavity. By moving the regenerator as described herein, the particle trajectory is blocked with a specific energy, thereby ensuring the correct perturbation of that trajectory so that particles at a specific energy reach the extraction channel. It is possible to bring In some embodiments, regenerator movement (and / or magnetic shim addition / removal) is performed in real time to coincide with real time changes in particle beam energy output by the accelerator. In other embodiments, the particle energy is adjusted from treatment to treatment, and regenerator movement (and / or magnetic shim addition / removal) is performed prior to treatment. In either case, regenerator movement (and / or magnetic shim addition / removal) can be computer controlled. For example, the computer can control one or more motors that cause movement of the regenerator and / or magnetic shim.
In some embodiments, the regenerator is implemented using one or more magnetic shims that are controllable to move to the appropriate configuration.
In some embodiments, the structure 715 (described above) is controlled to accommodate different energy generated by the particle accelerator. For example, the structure 715 can be rotated to block a particle beam having a particular energy at an appropriate thickness. Thus, the structure 715 absorbs at least a portion of the energy of the particle beam, thereby allowing the particle beam to traverse the extraction channel as described above.
For example, Table 1 shows three exemplary energy levels at which the exemplary accelerator 912 can output a particle beam. The corresponding parameters for generating the three energy levels are also listed. In this regard, the magnet current refers to the total current applied to one or more coil sets within the accelerator 912, with the highest and lowest frequencies defining the range over which the RF voltage is swept, and “r” is , The radial distance from a location to the center of the cavity where the particles are accelerated.
Details that may be included in an exemplary particle accelerator that produces charged particles with variable energy are described below. The accelerator may be a synchrocyclotron and the particles may be protons. The particles are output as a pulsed beam. The energy of the beam output from the particle accelerator is varied during treatment of one target volume within the patient or between treatments of different target volumes of the same patient or different patients from one treatment to the next. be able to. In some embodiments, the accelerator settings are changed to change the beam energy when no beam (or particles) is output from the accelerator. The energy change may be continuous or discontinuous over a desired range.
As represented in the example shown in FIG. 1, a particle accelerator (synchrocyclotron 502), which may be a variable energy particle accelerator such as the accelerator 912 described above, is for a particle beam with variable energy. Can be configured. The range of the variable energy is about 200 MeV to about 300 MeV or more, for example, 200 MeV, about 205 MeV, about 210 MeV, about 215 MeV, about 220 MeV, about 225 MeV, about 230 MeV, about 235 MeV, about 240 MeV, about 245 MeV, about 250 MeV, about 255 MeV, about 255 MeV, The upper boundary can be about 260 MeV, about 265 MeV, about 270 MeV, about 275 MeV, about 280 MeV, about 285 MeV, about 290 MeV, about 295 MeV, or about 300 MeV or more. This range is from about 100 MeV or less to about 200 MeV, for example, about 100 MeV or less, about 105 MeV, about 110 MeV, about 115 MeV, about 120 MeV, about 125 MeV, about 130 MeV, about 135 MeV, about 140 MeV, about 145 MeV, about 150 MeV, about 155 MeV. , About 160 MeV, about 165 MeV, about 170 MeV, about 175 MeV, about 180 MeV, about 185 MeV, about 190 MeV, about 195 MeV, about 200 MeV.
In some examples, the change is discontinuous and the change step is about 10 MeV or less, about 15 MeV, about 20 MeV, about 25 MeV, about 30 MeV, about 35 MeV, about 40 MeV, about 45 MeV, about 50 MeV, about 55 MeV. , About 60 MeV, about 65 MeV, about 70 MeV, about 75 MeV, or about 80 MeV or more. The time required to change the energy by one step size is within 30 minutes, for example, within about 25 minutes, within about 20 minutes, within about 15 minutes, within about 10 minutes, within about 5 minutes, within about 1 minute, Or within about 30 seconds. In other examples, this change is continuous and the accelerator causes the energy of the particle beam to be relatively high, for example, up to about 50 MeV per second, up to about 45 MeV per second, up to about 40 MeV per second, up to about 35 MeV per second. Up to about 30 MeV per second, up to about 25 MeV per second, up to about 20 MeV per second, up to about 15 MeV per second, or up to about 10 MeV per second. The accelerator can be configured to adjust the particle energy both continuously and discontinuously. For example, a combination of continuous and non-continuous changes can be used to treat one target volume or to treat different target volumes. Flexible treatment plans and flexible treatments can be realized.
A particle accelerator that outputs a particle beam with variable energy can make irradiation treatment accurate and can reduce the number of additional devices (other than the accelerator) used in the treatment. For example, the use of a degrader to change the energy of the output particle beam can be reduced or not used. The properties of the particle beam, such as intensity, focus, etc. are controlled in the particle accelerator so that the particle beam can reach the target volume without substantial interruption from additional devices. A relatively high rate of change of beam energy can reduce treatment time and allow efficient use of the treatment system.
In some embodiments, an accelerator, such as the synchrocyclotron 502 of FIG. 1, accelerates the particle or particle beam to a variable energy level by changing the magnetic field in the accelerator, which is a coil to generate the magnetic field. Can be realized by changing the current applied to the. As shown in FIGS. 3, 4, 5, 6, and 7, the exemplary synchrocyclotron 10 (502 in FIG. 1) includes a magnet system that houses a particle source 90, a high frequency drive system 91. And a beam extraction system 38. FIG. 29 shows an example of a magnet system that can be used in a variable energy accelerator. In this exemplary embodiment, the magnetic field established by the magnet system 1012 varies from about 5% to about 35% of the maximum value of the magnetic field that the two coil sets 40a and 40b, 42a and 42b can generate. obtain. The magnetic field established by the magnet system is used to maintain the focus of the contained proton beam using a combination of two coil sets and a pair of shaped ferromagnetic (eg, low carbon steel) structures. It has a suitable shape, examples of which are presented above.
Each coil set may be a split pair of annular coils for receiving current. In some situations, both coil sets are superconducting. In other situations, only one coil set is superconducting and the other set is non-superconducting or normal conducting (as described further below). It is also possible for both coil sets to be non-superconducting. Superconductors suitable for use in coils include niobium 3 tin (Nb 3 Sn) and / or niobium titanium. Other normal conductors can include copper. An example of producing a coil set will be further described below.
The two coil sets can be electrically connected in series or in parallel. In some embodiments, the total current received by the two coil sets is from about 2 million amperes to about 10 million amperes, such as from about 2.5 million to about 7.5 million amperes, or from about 3.75 million amperes. May include up to 10,000 amperes. In some examples, one coil set is configured to receive a fixed (or constant) portion of the total variable current and the other coil set is configured to receive a variable portion of the total current. The total current in the two coil sets changes with changes in the current in one coil set. In other situations, the current applied to both coil sets can vary. The variable total current in the two coil sets can generate a magnetic field with a varying magnitude, which in turn changes the particle's acceleration path and generates particles with variable energy.
In general, the magnitude of the magnetic field generated by the coil can be increased or decreased depending on the magnitude of the total current applied to the coil. Based on this increase / decrease, in some embodiments, a linear change in magnetic field strength can be achieved by changing the total current of the coil set linearly. The total current can be adjusted relatively quickly, thereby adjusting the magnetic field and beam energy relatively quickly.
In the example reflected in Table 1 above, the ratio of the current value to the magnetic field value at the geometric center of the coil ring is 1990: 8.7 (approximately 228.7: 1), 1920: 8. 4 (about 228.6: 1), 1760: 7.9 (about 222.8: 1). Therefore, the magnitude of the magnetic field can be proportionally adjusted (based on the ratio) by adjusting the magnitude of the total current applied to the superconducting coil.
The increase or decrease of the magnetic field relative to the total current in the example of Table 1 is also shown in the plot of FIG. 27, where BZ is the magnetic field along the Z direction and R is the coil ring along the direction perpendicular to the Z direction. The radial distance measured from the geometric center. The magnetic field has a maximum at the geometric center and decreases as the distance R increases. Curves 1035, 1037 represent the magnetic field generated by the same coil set receiving different total currents, which are 1760 amps and 1990 amps, respectively. The corresponding energies of the extracted particles are 211 MeV and 250 MeV, respectively. The two curves 1035, 1037 have substantially the same shape, and different portions of the curves 1035, 1037 are substantially parallel. As a result, either curve 1035 or curve 1037 may be linearly shifted to substantially match the other curve, which increases or decreases with the total current applied to the coil set by the magnetic field. Show that you can.
In some embodiments, the increase or decrease of the magnetic field relative to the total current may not be complete. For example, the ratio between the magnetic field and the current calculated based on the example shown in Table 1 is not constant. Further, as shown in FIG. 27, even if one curve is shifted linearly, it cannot completely match the other curve. In some embodiments, the total current is applied to the coil set under the assumption that the increase or decrease is complete. The target magnetic field (under the assumption that the increase and decrease is complete) can be generated in addition to changing the coil characteristics, eg, geometry, to offset the increase and decrease imperfections. In one example, a rod (magnetic shim) of ferromagnetic material (eg, iron) can be inserted or removed from one or both of the magnetic structures. The characteristics of the coil can be changed relatively fast so that the speed of magnetic field adjustment is not substantially affected compared to the situation where the increase / decrease is complete and only the current needs to be adjusted. In the iron rod example, the rod can be added or removed on a time scale of seconds or minutes, eg, within 5 minutes, within 1 minute, less than 30 seconds, or less than 1 second.
In some embodiments, accelerator settings, such as the current applied to the coil set, can be selected based on a substantial increase or decrease of the magnetic field relative to the total current in the coil set.
In general, any combination of currents applied to two coil sets can be used to generate a total current that varies within a desired range. In one example, the coil sets 42a, 42b may be configured to receive a fixed current corresponding to the lower boundary of the desired range of magnetic fields. In the example shown in Table 1, the fixed current is 1760 amperes. In addition, the coil sets 40a, 40b can be configured to receive a variable current having an upper boundary corresponding to the difference between the upper and lower boundaries of the desired range of magnetic fields. In the example shown in Table 1, the coil sets 40a, 40b are configured to receive a current that varies between 0 and 230 amps.
In another example, the coil sets 42a, 42b may be configured to receive a fixed current corresponding to the upper boundary of the desired range of magnetic fields. In the example shown in Table 1, the fixed current is 1990 amps. In addition, the coil sets 40a, 40b can be configured to receive a variable current having an upper boundary corresponding to the difference between the lower and upper boundaries of the desired range of magnetic fields. In the example shown in Table 1, the coil sets 40a, 40b are configured to receive a current that varies between -230 amperes and 0 amperes.
The total variable magnetic field generated by the variable total current to accelerate the particles is greater than 4 Tesla, for example greater than 5 Tesla, greater than 6 Tesla, greater than 7 Tesla, greater than 8 Tesla, greater than 9 Tesla, or It may have a maximum size greater than 10 Tesla and up to about 20 Tesla or more, for example, up to about 18 Tesla, up to about 15 Tesla, or up to about 12 Tesla. In some embodiments, the change in total current in the coil set causes the magnetic field to vary from about 0.2 Tesla to about 4.2 Tesla or more, for example, from about 0.2 Tesla to about 1.4 Tesla or about 0.6. It can vary from Tesla to about 4.2 Tesla. In some situations, the amount of change in the magnetic field may be proportional to the maximum magnitude.
FIG. 28 illustrates an exemplary RF structure for sweeping voltage over the de-plate 100 over a constant RF frequency range for each energy level of the particle beam and changing the frequency range as the particle beam energy changes. Show. The semicircular surfaces 103 and 105 of the deeplate 100 are connected to the inner conductor 1300 and housed in the outer conductor 1302. A high voltage is applied to the deeplate 100 from a power source (not shown, eg, an oscillating voltage input) through a power coupling device 1304 that couples the power source to the inner conductor. In some embodiments, the coupling device 1304 is located on the inner conductor 1300 and provides power transfer from the power source to the deeplate 100. In addition, deeplate 100 is coupled to variable reactance elements 1306, 1308 to perform an RF frequency sweep for each particle energy level and to change the RF frequency range for different particle energy levels.
The variable reactance element 1306 may be a rotating capacitor having a plurality of blades 1310 that can be rotated by a motor (not shown). By engaging or disengaging the blade 1310 in each cycle of the RF sweep, the capacitance of the RF structure is changed, thus changing the resonant frequency of the RF structure. In some embodiments, the blades 1310 engage each other every quarter cycle of the motor. The capacitance of the RF structure increases and the resonance frequency decreases. This process is reversed when the blade 1310 is disengaged. As a result, the power required to generate the high voltage applied to the deeplate 103 and necessary to accelerate the beam can be greatly reduced. In some embodiments, the shape of the blade 1310 is machined to produce the necessary dependence of the resonant frequency on time.
The generation of the RF frequency is synchronized with the blade rotation by sensing the phase of the RF voltage within the resonator and maintaining an alternating voltage applied to the deeplate near the resonant frequency of the RF cavity. (The dummy dee is grounded but not shown in FIG. 28).
The variable reactance element 1308 may be a capacitor formed by the plate 1312 and the surface 1316 of the inner conductor 1300. The plate 1312 is movable along a direction 1314 toward or away from the surface 1316. The capacitance of the capacitor changes as the distance D between the plate 1312 and the surface 1316 changes. For each frequency range that is swept for one particle energy, the distance D is at a set point and the plate 1312 is moved in response to changes in the energy of the output beam to change the frequency range.
In some embodiments, inner conductor 1300 and outer conductor 1302 are formed from a metallic material, such as copper, aluminum, or silver. Blade 1310 and plate 1312 may also be formed from the same or different metal material as conductors 1300 and 1302. The coupling device 1304 can be a conductor. The variable reactance elements 1306, 1308 can have other forms and can be coupled to the deeplate 100 in other ways, thereby performing RF frequency sweeps and frequency range changes. In some embodiments, a single variable reactance element may be configured to perform the functions of both variable reactance elements 1306, 1308. In other embodiments, more than two variable reactance elements may be used.
Any of the features described herein can be configured for use with a variable energy particle accelerator, as described above.
In this regard, any two more of the foregoing embodiments can be used in any suitable combination in a suitable particle accelerator (eg, synchrocyclotron). Similarly, any two additional individual features of the above embodiments may be used in appropriate combinations.
The elements of the different embodiments described herein can also be combined to form other embodiments not specifically mentioned above. Elements may be removed from the processes, systems, devices, etc. described herein without adversely affecting their operation. Various separate elements can be combined into one or more individual elements to perform the functions described herein.
The exemplary embodiments described herein are not limited to use with the particle therapy system or with the exemplary particle therapy system described herein. Rather, the exemplary embodiment can be used in a suitable system that directs accelerated particles to the output.
Additional information regarding the design of an exemplary embodiment of a particle accelerator that can be used in a system as described herein is filed on Jan. 20, 2006, which is incorporated herein by reference. US Provisional Application No. 60 / 760,788, titled “High-Field Supersonic Synchronotron”, US Patent Application No. 11 / 463,402, filed August 9, 2006, “Magnet Structure For Particulate,” And US Provisional Application No. 60 / 850,565, filed Oct. 10, 2006, entitled “Cryogenetic Vacuum Break Thermal Coupler”.
The following applications are incorporated by reference into this application. United States provisional application, name “CONTROLLING INTENSITY OF A PARTICLE BEAM” (Application No. 61 / 707,466), US provisional application, name “ADJUSTING ENERGY OF A PARTICLE BEAM” (Application No. 61 / 707,515), United States provisional Application, name “ADJUSTING COIL POSITION” (Application No. 61 / 707,548), US provisional application, name “FOCUSING A PARTICLE BEAM USING MANETIC FIELD FLUTTER” (Application No. 61 / 707,572), US Provisional Application, No. 61 / 707,572 “MAGNETIC FIELD REGENERATOR” (Application No. 61 / 707,590), US provisional application, name “FOCUSING A PARTICLE” EAM "(Application No. 61 / 707,704), US Provisional Application, name" CONTROLLING PARTICLE THERAPY "(Application No. 61 / 707,624), and US Provisional Application, name" CONTROL SYSTEM FOR A PARTICLE ACCELERATOR "(Application) 61 / 707,645).
The following references are also incorporated into this application by reference. US Patent No. 7,728,311 issued on June 1, 2010; US Patent Application No. 11 / 948,359 filed on November 30, 2007; US filed on November 20, 2008 Patent Application No. 12 / 275,103, U.S. Patent Application No. 11 / 948,662 filed on November 30, 2007, U.S. Provisional Application No. 60 / 991,454 filed on Nov. 30, 2007, U.S. Patent No. 8,003,964 issued on August 23, 2011, U.S. Patent No. 7,208,748 issued on Apr. 24, 2007, issued on Jul. 22, 2008 U.S. Patent No. 7,402,963; U.S. Patent Application No. 13 / 148,000 filed on February 9, 2010; U.S. Patent Application No. 11 / 937,573 filed on November 9, 2007; US Provisional Application No. 11 / 187,633, filed July 21, 005, entitled “A Programmable Radio Frequency Generator for a Synchrony Clotron”, US Provisional Application No. 60 / 590,089, filed July 21, 2004 No. 10 / 949,734, filed September 24, 2004, “A Programmable Particle Scatterer For Radiation Therapy Formation”, and US Provisional Application No. 60 filed July 21, 2005. / 590,088.
Any feature of this application may be combined with one or more of the following suitable features. United States provisional application, name “CONTROLLING INTENSITY OF A PARTICLE BEAM” (Application No. 61 / 707,466), US provisional application, name “ADJUSTING ENERGY OF A PARTICLE BEAM” (Application No. 61 / 707,515), United States provisional Application, name “ADJUSTING COIL POSITION” (Application No. 61 / 707,548), US provisional application, name “FOCUSING A PARTICLE BEAM USING MANETIC FIELD FLUTTER” (Application No. 61 / 707,572), US Provisional Application, No. 61 / 707,572 “MAGNETIC FIELD REGENERATOR” (Application No. 61 / 707,590), US provisional application, name “FOCUSING A PARTICLE” EAM "(Application No. 61 / 707,704), US Provisional Application, name" CONTROLLING PARTICLE THERAPY "(Application No. 61 / 707,624), and US Provisional Application, name" CONTROL SYSTEM FOR A PARTICLE ACCELERATOR "(Application) 61 / 707,645), US Patent No. 7,728,311 issued on June 1, 2010, US Patent Application No. 11 / 948,359 filed on November 30, 2007, 2008. US Patent Application No. 12 / 275,103 filed on November 20, 2007, US Patent Application No. 11 / 948,662 filed on November 30, 2007, US Provisional Filed on November 30, 2007 US Patent Application No. 60 / 991,454, filed May 31, 2013 Application No. 13 / 907,601, U.S. Patent Application No. 13 / 916,401, filed June 12, 2013, U.S. Patent No. 8,003,964, issued August 23, 2011, 2007. United States Patent No. 7,208,748 issued on April 24, United States Patent No. 7,402,963 issued on July 22, 2008, United States Patent filed on February 9, 2010 Application No. 13 / 148,000, U.S. Patent Application No. 11 / 937,573, filed on Nov. 9, 2007, U.S. Patent Application No. 11 / 187,633, filed on Jul. 21, 2005, "A Programmable Radio Frequency Waveform Generator for a Synchrocyclotron", filed on July 21, 2004 U.S. Provisional Application No. 60 / 590,089, U.S. Patent Application No. 10 / 949,734, filed on September 24, 2004, entitled "A Programmable Particle Scatterer For Radiation Therapy Formation", and July 2005. US Provisional Application No. 60 / 590,088 filed on 21st.
No other document is incorporated by reference into this patent application, except the provisional application from which this patent application claims priority and the documents incorporated by reference above.
Other implementations not specifically described herein are within the scope of the following claims.
DESCRIPTION OF SYMBOLS 10 Synchrocyclotron 12 Magnet system 38 Beam extraction system 40 Annular superconducting coil 40a, 40b Coil set 42 Annular superconducting coil 42a, 42b Coil set 44 Magnetic pole surface 46 Magnetic pole surface 47 Common axis 48 Nb 3 Sn system superconducting wire 52 Insulator 53 Wire 55 Heater blanket 56 Annular stainless steel reverse bobbin, rectangular reverse bobbin 60 Restoring force 70 Low temperature holding tank 71 Support point 72 Gifford McMahon refrigerator 73 Support point 74 Gifford McMahon refrigerator 76 Low temperature end 77 Gifford McMahon refrigerator 78 Head 79 Gifford McMahon refrigerator 80 Compressor 81 Half 82 Magnet yoke, Iron yoke, Magnetic structure 83 Half 84 Return magnetic flux 86 Volume part 90 Particle source 91 High frequency drive system 92 Geometry Center 94 Electric cable 95 Current source 99 Hydrogen supply unit 100 D-plate 101 Gas pipe, gas pipe 102 Dummy de-plate 103, 105 Semi-circular surface 107 Space 108 Water-cooled pipe 109 Duct 111 Vacuum pump 113 Heat exchanger 114 Magnetic Shield 116 space 117 layer of ferromagnetic material (eg steel or iron) 119 vacuum chamber 122 counterweight 124 counterweight 125 beam forming system 146 maze 148 wall, side wall 150 wall, side wall 152 wall 154 wall, side wall 156 wall, side wall 160 treatment room 162 base 164 floor area 170 patient support 190 cathode 192 cathode 194 tube 200 magnetic field 402 hot-cold support strap 404 hot-cold support strap 406 hot-cold support strap 408 S2 glass Fiber link 500 Charged particle beam therapy system 502 Synchrocyclotron 504 Rotary gantry 508 Leg 510 Leg 512 Bearing 514 Bearing 516 Steel truss, truss structure 518 Treatment area 520 Range 522 Floor 524 Vault 532 Horizontal rotation axis 534 Range 540 Range 580 Span 582 Span 601 Inner gantry 602 System 604 Synchrocyclotron 605 Rotating gantry 606 Patient support 700 Cavity 701 Particle source 702 Magnetic field regenerator 703 Extraction channel 705 Magnetic field bump 706 Bobbin 706 Cross section 709, 710 Superconducting structure 711 Body 750 magnetic field lines 753 magnetic localized defect
780 Angle 781 Pitch 800 Magnetic field lines 802, 803 Flutter brick 810 Flutter brick 811 Space 812 Cavity 815, 816, 817 Radial arrangement 819 Yoke 822 Structure 824 High magnetic field 825 Low magnetic field 830 High magnetic field 831 High structure 831 Region with 832 Region with low magnetic field 835 Valley not containing ferromagnetic material 836 First hill 837 Second hill 910 Treatment system 912 Accelerator 914 Beam 916 Scan unit 916 Scatter unit 918 Monitor unit 920 Energy degrader 922 Body 922 'Body part 924 Target volume 926a-926i Layer 928 Irradiation direction 930 Target volume 932 Controller 1012 Magnet system 1035, 1037 1300 inner conductor 1302 outer conductor 1304 power coupling device 1306 variable reactance element 1310 blade 1312 plate 1314 direction 1316 surface
A magnetic structure defining a cavity in which particles are accelerated;
A voltage source for sweeping radio frequency (RF) voltage within the cavity to accelerate particles from a plasma column generated by a particle source, the cavity based at least in part on the magnetic structure A voltage source having a magnetic field, wherein the magnetic field moves particles accelerated from the plasma column in orbit within the cavity, and the magnetic field has a magnetic flux that bows at the edge of the cavity;
A regenerator that provides magnetic field bumps in the cavity, thereby changing the continuous trajectory of the particles accelerated from the plasma column, and finally allowing the particles to be output to a withdrawal point; A regenerator disposed at a radius in the cavity with respect to the plasma column;
A ferromagnetic device located near the radius in the cavity, each ferromagnetic device providing a magnetic field bump, wherein at least two ferromagnetic devices are adjacent to the sides of the regenerator at the same radius. The ferromagnetic device is spaced in space from the regenerator, and the ferromagnetic device is configured to at least partially restore vertical focusing of particles in an orbit blocked by the regenerator, A particle accelerator comprising a ferromagnetic device.
The combination of the space, the regenerator, and the ferromagnetic device generates a magnetic field variation having a component that is at an angle to the particle trajectory, offsetting at least a portion of the vertical focusing reduction caused by the magnetic field bumps. The particle accelerator of claim 1.
The particle accelerator of claim 1, wherein the magnetic field is at least 4 Tesla and the magnetic field bumps generated by the regenerator are at most 2 Tesla.
The particle accelerator of claim 1, wherein there are only two ferromagnetic devices, one on each side of the regenerator.
The particle accelerator of claim 1, wherein there are more than two ferromagnetic devices within the same radius with respect to the plasma column.
The particle accelerator of claim 1, wherein there are a plurality of ferromagnetic devices within each of a plurality of radii relative to the plasma column.
The particle accelerator of claim 1, wherein the particle accelerator is a synchrocyclotron.
The particle accelerator of claim 1;
A gantry attached to the particle accelerator and rotatable with respect to a patient position;
A proton therapy system in which protons are output substantially directly from the particle accelerator to the patient location.
The proton therapy system of claim 8, wherein the particle accelerator includes a synchrocyclotron.
The proton therapy system according to claim 9, wherein the magnetic field is 4 Tesla or more, and the synchrocyclotron is a variable energy particle accelerator.
The particle accelerator of claim 1, wherein the particles are output as a particle beam having an energy selected from a range of energies.
The particle accelerator of claim 1, wherein the ferromagnetic device produces a magnetic field flutter that includes an azimuth average normalized magnetic field change rate between 0.25% and 20%.
JP2015534729A 2012-09-28 2013-09-27 Particle accelerator Active JP6254600B2 (en)
US201261707572P true 2012-09-28 2012-09-28
US61/707,572 2012-09-28
PCT/US2013/062120 WO2014052722A2 (en) 2012-09-28 2013-09-27 Focusing a particle beam using magnetic field flutter
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