Source: http://www.google.com/patents/US20100060209?dq=5708422
Timestamp: 2014-04-19 12:12:55
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Matched Legal Cases: ['application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61', 'application No. 61']

Patent US20100060209 - Rf accelerator method and apparatus used in conjunction with a charged ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsThe invention comprises a radio-frequency accelerator method and apparatus used in conjunction with multi-axis charged particle radiation therapy of cancerous tumors. An RF synthesizer provides a low voltage RF signal, that is synchronized to the period of circulation of protons in the proton beam path,...http://www.google.com/patents/US20100060209?utm_source=gb-gplus-sharePatent US20100060209 - Rf accelerator method and apparatus used in conjunction with a charged particle cancer therapy systemAdvanced Patent SearchPublication numberUS20100060209 A1Publication typeApplicationApplication numberUS 12/619,278Publication dateMar 11, 2010Filing dateNov 16, 2009Priority dateMay 22, 2008Also published asUS8373146Publication number12619278, 619278, US 2010/0060209 A1, US 2010/060209 A1, US 20100060209 A1, US 20100060209A1, US 2010060209 A1, US 2010060209A1, US-A1-20100060209, US-A1-2010060209, US2010/0060209A1, US2010/060209A1, US20100060209 A1, US20100060209A1, US2010060209 A1, US2010060209A1InventorsVladimir BalakinOriginal AssigneeVladimir BalakinExport CitationBiBTeX, EndNote, RefManPatent Citations (2), Referenced by (3), Classifications (8), Legal Events (1) External Links: USPTO, USPTO Assignment, EspacenetRf accelerator method and apparatus used in conjunction with a charged particle cancer therapy systemUS 20100060209 A1Abstract The invention comprises a radio-frequency accelerator method and apparatus used in conjunction with multi-axis charged particle radiation therapy of cancerous tumors. An RF synthesizer provides a low voltage RF signal, that is synchronized to the period of circulation of protons in the proton beam path, to a set of integrated microcircuits, loops, and coils where the coils circumferentially enclose the proton beam path in a synchrotron. The integrated components combine to provide an accelerating voltage to the protons in the proton beam path in a size compressed and price reduced format. The integrated RF-amplifier microcircuit/accelerating coil system is operable from about 1 MHz, for a low energy proton beam, to about 15 MHz, for a high energy proton beam.
1. An apparatus for accelerating a charged particle, comprising:
through turning sections, wherein each of said turning sections comprises a plurality of bending magnets;
an accelerator system, said accelerator system comprising:
a set of at least five coils, each of said coils circumferentially surrounding a section of said charged particle circulation beam path;
a set of at least five wire loops;
a set of at least five microcircuits, each of said microcircuits integrated to one of said loops, wherein each of said loops completes at least one turn about at least one of said coils; and
a radio-frequency synthesizer configured to send a low voltage signal to each of said microcircuits, each of said microcircuits amplifying said low voltage signal yielding an acceleration voltage.
2. The apparatus of claim 1, wherein said low voltage signal further comprises synchronization with a period of circulation of the charged particle in said charged particle circulation beam path.
3. The apparatus of claim 1, wherein said coils comprise a ferrite material, wherein each of said microcircuits integrated to said loops comprises an integration circuit.
4. The apparatus of claim 1, said radio-frequency amplifier configured to operate with impedance and/or resistance operable at frequencies above about ten megahertz.
5. The apparatus of claim 1, wherein at least one of said bending magnets further comprises:
a first focusing edge; and a second focusing edge, wherein said at least one of said bending magnets terminates on opposite sides with said first focusing edge and said second focusing edge, wherein a first plane established by said first focusing edge intersects a plane established by said second focusing edge beyond said center of said synchrotron, wherein each of said first focusing edge and said second focusing edge bend the charged particle toward said center of said synchrotron. 6. The apparatus of claim 1, wherein at least two of said plurality of bending magnets further comprise a magnetic field focusing section, said focusing section comprising:
a geometry tapering from a first cross-sectional area to a second cross-sectional area, said second cross-sectional area comprising less than two-thirds of an area of said first cross-sectional area, said first cross-sectional area parallel said second cross-sectional area, said second cross-sectional area proximate said charged particle beam path, wherein during use a magnetic field concentrates in density from said first cross-sectional area to said second-cross-sectional area. 7. The apparatus of claim 1, wherein at least one of said turning sections comprises at least four bending magnets, said four bending magnets comprising at least eight edge focusing surfaces, wherein geometry of said edge focusing surfaces focuses the charged particles in said charged particle circulation beam path during use.
8. The apparatus of claim 1, wherein each of said turning sections turns the charged particles by about ninety degrees.
9. The apparatus of claim 1, wherein at least one of said bending magnets comprises a tapered core, said tapered core comprising a first cross-section distance at least one and a half times longer than a second cross-section distance, said second cross-section distance proximate a gap, said gap having a surface polish of less than about ten microns roughness, said charged particle circulation beam path running through said gap.
10. The apparatus of claim 1, wherein a number of said turning sections comprises exactly four turning sections, wherein each of said four turning sections turns the charged particle circulation beam path about ninety degrees, said synchrotron capable of accelerating the charged particles to at least 300 MeV.
a gap, said charged particle beam path running through said gap, and a core, wherein said core terminates at said gap with a surface comprising a finish of less than about ten microns polish. 14. The apparatus of claim 13, further comprising:
a winding coil winding about said core; and a correction coil winding about said core, wherein said correction coil operates at less than three percent of a power of said winding coil. 15. The apparatus of claim 14, further comprising:
an extraction control algorithm, said extraction control algorithm receiving input generated by a current originating at an extraction foil, said extraction foil proximate said charged particle circulation beam path, said extraction control algorithm comparing a feedback input to an irradiation plan, said extraction control algorithm adjusting a radio-frequency field in a radio-frequency cavity system. 16. The apparatus of claim 1, further comprising:
a winding coil, wherein a winding turn in said winding coil wraps around at least two of said bending magnets, wherein said winding turn does not occupy space directly between said at least two of said bending magnets. 17. The apparatus of claim 1, wherein said circulation beam path comprises a length of less than about sixty meters, wherein a number of said straight sections equals a number of said turning sections.
an extraction foil, said extraction foil proximate said charged particle beam path in said synchrotron, wherein during extraction the charged particles strike said extraction foil generating a current, said current used in controlling said intensity. 19. The apparatus of claim 18, wherein a first level of said intensity is used when energy levels of the charged particles reach a distal region of the tumor during each of said at least five irradiation positions, wherein a second level of said intensity is used when energy levels of the charged particles reach an ingress region of the tumor during said each of said at least five irradiation positions, wherein said first intensity is greater than said second intensity.
20. A method for accelerating charged particles, comprising:
accelerating charged particles with a synchrotron, said synchrotron comprising:
applying an acceleration voltage to the charged particles, said acceleration voltage controlled with a radio-frequency synthesizer sending a low voltage signal to each of said microcircuits, each of said microcircuits amplifying said low voltage signal yielding said acceleration voltage. 21. The method of claim 20, further comprising the steps of:
controlling a magnetic field in at least one of said bending magnets, said at least one of said bending magnets comprising:
a tapered iron based core adjacent a gap, said core comprising a surface polish of less than about ten microns roughness; and
a first cross-sectional distance of said iron based core forming an edge of said gap,
a second cross-sectional distance of said iron based core not in contact with said gap, wherein said second cross-sectional distance is at least fifty percent larger than said first cross-sectional distance, said first cross-sectional distance running parallel said second cross-sectional distance.
controlling energy of the charged particles during an extraction phase of the charged particles from said synchrotron; and controlling intensity of the charged particles during said extraction phase of the charged particles from said synchrotron. 23. The method of claim 20, further comprising the steps of:
increasing intensity of the charged particles when charged particle delivery efficiency increases; and decreasing said intensity of the charged particles when said charged particle delivery efficiency decreases, wherein said charged particle delivery efficiency comprises a measure of relative energy delivered to the tumor versus surrounding healthy tissue. 24. A method for controlling energy of charged particles deliverable to a tumor of a patient, comprising the steps of:
controlling energy of the charged particles in a synchrotron, said synchrotron comprising an accelerator system, said accelerator system comprising:
a set of at least ten wire loops; and
using a radio-frequency synthesizer, sending a low voltage signal to each of said microcircuits, each of said microcircuits amplifying said low voltage signal yielding an acceleration voltage applied to the charged particles. 25. The method of claim 24, further comprising the step of:
increasing intensity of the charged particles when targeting a distal portion of the tumor, wherein said distal portion of said tumor changes with rotation of the patient on a platform rotating to as least ten distinct rotational positions in a period of less than one minute during irradiation of the tumor by the charged particles. 26. The method of claim 24, further comprising the steps of:
varying intensity of the charged particles dependent upon efficiency of delivery of energy of the charged particles within the tumor versus delivery of energy of the charged particles to healthy tissue of the patient. 27. The method of claim 24, further comprising the step of:
dynamically timing delivery of the charged particles at a set point in at least three sequential respiration cycles, wherein each of three sequential respiration cycles comprise a separate length of time. 28. The method of claim 24, further comprising the step of:
terminating the charged particle beam path in a distal region of the tumor for each of at least five irradiation positions, wherein the distal region comprises a furthest point of entry of the charged particles into the patient. Description
U.S. provisional patent application No. 61/055,395 filed May 22, 2008; U.S. provisional patent application No. 61/137,574 filed Aug. 1, 2008; U.S. provisional patent application No. 61/192,245 filed Sep. 17, 2008; U.S. provisional patent application No. 61/055,409 filed May 22, 2008; U.S. provisional patent application No. 61/203,308 filed Dec. 22, 2008; U.S. provisional patent application No. 61/188,407 filed Aug. 11, 2008; U.S. provisional patent application No. 61/188,406 filed Aug. 11, 2008; U.S. provisional patent application No. 61/189,815 filed Aug. 25, 2008; U.S. provisional patent application No. 61/201,731 filed Dec. 15, 2008; U.S. provisional patent application No. 61/205,362 filed Jan. 12, 2009; U.S. provisional patent application No. 61/134,717 filed Jul. 14, 2008; U.S. provisional patent application No. 61/134,707 filed Jul. 14, 2008; U.S. provisional patent application No. 61/201,732 filed Dec. 15, 2008; U.S. provisional patent application No. 61/198,509 filed Nov. 7, 2008; U.S. provisional patent application No. 61/134,718 filed Jul. 14, 2008; U.S. provisional patent application No. 61/190,613 filed Sep. 2, 2008; U.S. provisional patent application No. 61/191,043 filed Sep. 8, 2008; U.S. provisional patent application No. 61/192,237 filed Sep. 17, 2008; U.S. provisional patent application No. 61/201,728 filed Dec. 15, 2008; U.S. provisional patent application No. 61/190,546 filed Sep. 2, 2008; U.S. provisional patent application No. 61/189,017 filed Aug. 15, 2008; U.S. provisional patent application No. 61/198,248 filed Nov. 5, 2008; U.S. provisional patent application No. 61/198,508 filed Nov. 7, 2008; U.S. provisional patent application No. 61/197,971 filed Nov. 3, 2008; U.S. provisional patent application No. 61/199,405 filed Nov. 17, 2008; U.S. provisional patent application No. 61/199,403 filed Nov. 17, 2008; and U.S. provisional patent application No. 61/199,404 filed Nov. 17, 2008; claims the benefit of U.S. provisional patent application No. 61/209,529 filed Mar. 9, 2009; claims the benefit of U.S. provisional patent application No. 61/208,182 filed Feb. 23, 2009; claims the benefit of U.S. provisional patent application No. 61/208,971 filed Mar. 3, 2009; claims the benefit of U.S. provisional patent application No. 61/270,298, filed Jul. 7, 2009; and claims priority to PCT patent application serial No.: PCT/RU2009/00015, filed Mar. 4, 2009, all of which are incorporated herein in their entirety by this reference thereto. BACKGROUND OF THE INVENTION 1. Field of the Invention
This invention relates generally to treatment of solid cancers. More particularly, the invention relates to a radio-frequency (RF) accelerator system used in conjunction with charged particle cancer therapy beam injection, acceleration, extraction, and/or targeting methods and apparatus.
Cancer Treatment Proton therapy systems typically include: a beam generator, an accelerator, and a beam transport system to move the resulting accelerated protons to a plurality of treatment rooms where the protons are delivered to a tumor in a patient's body.
Patient Positioning Y. Nagamine, et. al. �Patient Positioning Device and Patient Positioning Method�, U.S. Pat. No. 7,212,609 (May 1, 2007) and Y. Nagamine, et. al. �Patient Positioning Device and Patient Positioning Method�, U.S. Pat. No. 7,212,608 (May 1, 2007) describe a patient positioning system that compares a comparison area of a reference X-ray image and a current X-ray image of a current patient location using pattern matching.
Problem There exists in the art of particle beam therapy of cancerous tumors a need for an accurate and efficient RF accelerator system used in conjunction with a negative ion beam source, synchrotron, and/or target method apparatus. Further, there exists a need in the art to control the charged particle cancer therapy system in terms of specified energy, intensity, and/or timing of charged particle delivery relative to a patient position. Still further, there exists a need for efficient, precise, and/or accurate noninvasive, in-vivo treatment of a solid cancerous tumor with minimization of damage to surrounding healthy tissue in a patient.
SUMMARY OF THE INVENTION The invention comprises a proton radio-frequency accelerator system used as part charged particle cancer therapy beam system.
FIG. 7A illustrates a negative ion beam path vacuum system, FIG. 7B illustrates a support layer, and FIG. 7C illustrates a foil;
FIG. 17 illustrates an RF accelerator;
FIG. 18 illustrates an RF accelerator element;
FIG. 19 illustrates a magnetic field control system;
FIG. 20 illustrates a charged particle extraction and intensity control system;
FIG. 21 illustrates a patient positioning system from: (A) a front view and (B) a top view;
FIG. 22 illustrates multi-dimensional scanning of a charged particle beam spot scanning system operating on: (A) a 2-D slice or (B) a 3-D volume of a tumor;
FIG. 23 illustrates an electron gun source used in generating X-rays coupled with a particle beam therapy system;
FIG. 24 illustrates an X-ray source proximate a particle beam path;
FIG. 25 illustrates an expanded X-ray beam path;
FIG. 26 provides an example of a patient positioning system;
FIG. 27 illustrates a head restraint system; and
FIG. 28 illustrates hand and head supports.
DETAILED DESCRIPTION OF THE INVENTION The invention relates generally to treatment of solid cancers. More particularly, the invention relates to a radio-frequency accelerator operating to enhance accuracy and efficiency of a synchrotron, used in conjunction with charged particle cancer therapy beam injection, acceleration, extraction, and/or targeting methods and apparatus.
Novel design features of a synchrotron are described. Particularly, a negative ion beam source with novel features in the negative ion source, ion source vacuum system, ion beam focusing lens, and tandem accelerator are described. Additionally, turning magnets, edge focusing magnets, magnetic field concentration magnets, winding and correction coils, flat magnetic field incident surfaces, and extraction elements are described that minimize the overall size of the synchrotron, provide a tightly controlled proton beam, directly reduce the size of required magnetic fields, directly reduce required operating power, and allow continual acceleration of protons in a synchrotron even during a process of extracting protons from the synchrotron. The ion beam source system and synchrotron are preferably computer integrated with a patient imagnig system and a patient interface including respiration monitoring sensors and patient positioning elements.
Used in conjunction with the injection, acceleration, synchrotron, and targeting systems, an imaging system, positioning system, and respiration sensors are described. Particularly, a negative ion beam source, ion beam focusing system, tandem accelerator, and negative ion beam vacuum system are described. Further, intensity control of a charged particle beam acceleration, extraction, and/or targeting method and apparatus used in conjunction with charged particle beam radiation therapy of cancerous tumors is described. More particularly, intensity and energy control of a charged particle stream of a synchrotron is described where the synchrotron includes any of: turning magnets, edge focusing magnets, concentrating magnetic field magnets, winding and control coils, and extraction elements. The synchrotron control elements allow tight control of the charged particle beam, which compliments the tight control of patient positioning to yield efficient treatment of a solid tumor with reduced tissue damage to surrounding healthy tissue. In addition, the system reduces the overall size of the synchrotron, provides a tightly controlled proton beam, directly reduces the size of required magnetic fields, directly reduces required operating power, and allows continual acceleration of protons in a synchrotron even during a process of extracting protons from the synchrotron.
Charged Particle Beam Therapy Throughout this document, a charged particle beam therapy system, such as a proton beam, hydrogen ion beam, or carbon ion beam, is described. Herein, the charged particle beam therapy system is described using a proton beam. However, the aspects taught and described in terms of a proton beam are not intended to be limiting to that of a proton beam and are illustrative of a charged particle beam system. Any of the techniques described herein are equally applicable to any charged particle beam system.
Synchrotron Herein, the term synchrotron is used to refer to a system maintaining the charged particle beam in a circulating path; however, cyclotrons are alternatively used, albeit with their inherent limitations of energy, intensity, and extraction control. Further, the charged particle beam is referred to herein as circulating along a circulating path about a central point of the synchrotron. The circulating path is alternatively referred to as an orbiting path; however, the orbiting path does not refer to a perfect circle or ellipse, rather it refers to cycling of the protons around a central point or region.
Ion Beam Generation System An ion beam generation system generates a negative ion beam, such as a hydrogen anion or H− beam; preferably focuses the negative ion beam; converts the negative ion beam to a positive ion beam, such as a proton or H+ beam; and injects the positive ion beam into the synchrotron 130. Portions of the ion beam path are preferably under partial vacuum. Each of these systems are further described, infra.
Still referring to FIG. 3, the first partial vacuum system 330 is an enclosed system running from the hydrogen gas inlet port 312 to the tandem accelerator 390 foil 395. The foil 395 is sealed directly or indirectly to the edges of the vacuum tube 320 providing for a higher pressure, such as about 10−5 torr, to be maintained on the first partial vacuum system 330 side of the foil 395 and a lower pressure, such as about 10−' torr, to be maintained on the synchrotron side of the foil 390. By only pumping first partial vacuum system 330 and by only semi-continuously operating the ion beam source vacuum based on sensor readings, the lifetime of the semi-continuously operating pump is extended. The sensor readings are further described, infra.
Still referring to FIG. 3, the ion beam focusing system 350 includes two or more electrodes where one electrode of each electrode pair partially obstructs the ion beam path with conductive paths 372, such as a conductive mesh. In the illustrated example, two ion beam focusing system sections are illustrated, a two electrode ion focusing section 360 and a three electrode ion focusing section 370. In a given electrode pair, electric field lines, running between the conductive mesh of a first electrode and a second electrode, provide inward forces focusing the negative ion beam. Multiple such electrode pairs provide multiple negative ion beam focusing regions. Preferably the two electrode ion focusing section 360, first three electrode ion focusing section 370, and a second three electrode ion focusing section are placed after the negative ion source and before the tandem accelerator and/or cover a space of about 0.5, 1, or 2 meters along the ion beam path 319. Ion beam focusing systems are further described, infra.
Negative Ion Source An example of the negative ion source 310 is further described herein. Referring now to FIG. 4, a cross-section of an exemplary negative ion source system 400 is provided. The negative ion beam 319 is created in multiple stages. During a first stage, hydrogen gas is injected into a chamber. During a second stage, a negative ion is created by application of a first high voltage pulse, which creates a plasma about the hydrogen gas to create negative ions. During a third stage, a magnetic field filter is applied to components of the plasma. During a fourth stage, the negative ions are extracted from a low temperature plasma region, on the opposite side of the magnetic field barrier, by application of a second high voltage pulse. Each of the four stages are further described, infra. While the chamber is illustrated as a cross-section of a cylinder, the cylinder is exemplary only and any geometry applies to the magnetic loop containment walls, described infra.
Ion Beam Focusing System Referring now to FIG. 5, the ion beam focusing system 350 is further described. In this example, three electrodes are used. In this example, the first electrode 510 and third electrode 530 are both negatively charged and each is a ring electrode circumferentially enclosing or at least partially enclosing the negative ion beam path 319. The second electrode 520 is positively charged and is also a ring electrode circumferentially enclosing the negative ion beam path. In addition, the second electrode includes one or more conducting paths 372 running through the negative ion beam path 319. For example, the conducting paths are a wire mesh, a conducting grid, or a series of substantially parallel conducting lines running across the second electrode. In use, electric field lines run from the conducting paths of the positively charged electrode to the negatively charged electrodes. For example, in use the electric field lines 540 run from the conducting paths 372 in the negative ion beam path 319 to the negatively charged electrodes 510, 530. Two ray trace lines 550, 560 of the negative ion beam path are used to illustrate focusing forces. In the first ray trace line 550, the negative ion beam encounters a first electric field line at point M. Negatively charged ions in the negative ion beam 550 encounter forces running up the electric field line 571, illustrated with an x-axis component vector 572. The x-axis component force vectors 572 alters the trajectory of the first ray trace line to a inward focused vector 552, which encounters a second electric field line at point N. Again, the negative ion beam 552 encounters forces running up the electric field line 573, illustrated as having an inward force vector with an x-axis component 574, which alters the inward focused vector 552 to a more inward focused vector 554. Similarly, in the second ray trace line 560, the negative ion beam encounters a first electric field line at point O. Negatively charged ions in the negative ion beam encounter forces running up the electric field line 575, illustrated as having a force vector with an x-axis force 576. The inward force vectors 576 alters the trajectory of the second ray trace line 560 to an inward focused vector 562, which encounters a second electric field line at point P. Again, the negative ion beam encounters forces running up the electric field line 577, illustrated as having force vector with an x-axis component 578, which alters the inward focused vector 562 to a more inward focused vector 564. The net result is a focusing effect on the negative ion beam. Each of the force vectors 572, 574, 576, 578 optionally has x and/or y force vector components resulting in a 3-dimensional focusing of the negative ion beam path. Naturally, the force vectors are illustrative in nature, many electric field lines are encountered, and the focusing effect is observed at each encounter resulting in integral focusing. The example is used to illustrate the focusing effect.
Still referring to FIG. 5, optionally any number of electrodes are used, such as 2, 3, 4, 5, 6, 7, 8, or 9 electrodes, to focus the negative ion beam path where every other electrode, in a given focusing section, is either positively or negatively charged. For example, three focusing sections are optionally used. In the first ion focusing section 360, a pair of electrodes are used where the first electrode encountered along the negative ion beam path is negatively charged and the second electrode is positively charged, resulting in focusing of the negative ion beam path. In the second ion focusing section 370, two pairs of electrodes are used, where a common positively charged electrode with a conductive mesh running through the negatively ion beam path 319 is used. Thus, in the second ion focusing section 370, the first electrode encountered along the negative ion beam path is negatively charged and the second electrode is positively charged, resulting in focusing of the negative ion beam path. Further, in the second ion focusing section, moving along the negative ion beam path, a second focusing effect is observed between the second positively charged electrode and a third negatively charged electrode. In this example, a third ion focusing section 380 is used that again has three electrodes, which acts in the fashion of the second ion focusing section, describe supra.
In an example of a two electrode negative beam ion focusing system having a first cross-sectional diameter, d1, the negative ions are focused using the two electrode system to a second cross-sectional diameter, d2, where d1>d2. Similarly, an example of a three electrode negative beam ion focusing system having a first cross-sectional diameter, d1, the negative ions are focused using the three electrode system to a third cross-sectional diameter, d3, where d1>d3. For like potentials on the electrodes, the three electrode system provides tighter or stronger focusing compared to the two-electrode system, d3<d2.
Tandem Accelerator Referring now to FIG. 7A, the tandem accelerator 390 is further described.
The tandem accelerator accelerates ions using a series of electrodes 710, 711, 712, 713, 714, 715. For example, negative ions, such as H−, in the negative ion beam path are accelerated using a series of electrodes having progressively higher voltages relative to the voltage of the extraction electrode 426, or third electrode 426, of the negative ion beam source 310. For instance, the tandem accelerator 390 optionally has electrodes ranging from the 25 kV of the extraction electrode 426 to about 525 kV near the foil 395 in the tandem accelerator 390. Upon passing through the foil, the negative ion, H−, loses two electrons to yield a proton, H+, according to equation 1.
H − →H ++2e − (eq. 1)
Circulating System A synchrotron 130 preferably comprises a combination of straight sections 910 and ion beam turning sections 920. Hence, the circulating path of the protons is not circular in a synchrotron, but is rather a polygon with rounded corners.
T   F   E = N   T   S * M N   T   S * F   E M eq .  3 where TFE is the number of total focusing edges, NTS is the number of turning sections, M is the number of magnets, and FE is the number of focusing edges. Naturally, not all magnets are necessarily beveled and some magnets are optionally beveled on only one edge.
The winding and/or correction coils correct 1, 2, 3, or 4 turning magnets, and preferably correct a magnetic field generated by two turning magnets. A winding or correction coil covering multiple magnets reduces space between magnets as fewer winding or correction coil ends are required, which occupy space. One correction coil 1610 optionally winds around a single turning magnet or an optional correction coil 1620 wraps around two or more tuning magnets.
Referring now to FIGS. 17 and 18, the accelerator system 270, such as a radio-frequency (RF) accelerator system, is further described. The accelerator includes a series of coils 1710-1719, such as iron or ferrite coils, each circumferentially enclosing the vacuum system 320 through which the proton beam 264 passes in the synchrotron 130. Referring now to FIG. 18, the first coil 1710 is further described. A loop of standard wire 1730 completes at least one turn about the first coil 1710. The loop attaches to a microcircuit 1720. Referring again to FIG. 17, an RF synthesizer 1740, which is preferably connected to the main controller 110, provides a low voltage RF signal that is synchronized to the period of circulation of protons in the proton beam path 264. The RF synthesizer 1740, microcircuit 1720, loop 1730, and coil 1710 combine to provide an accelerating voltage to the protons in the proton beam path 264. For example, the RF synthesizer 1740 sends a signal to the microcircuit 1720, which amplifies the low voltage RF signal and yields an acceleration voltage, such as about 10 volts. The actual acceleration voltage for a single microcircuit/loop/coil combination is about 5, 10, 15, or 20 volts, but is preferably about 10 volts. Preferably, the RF-amplifier microcircuit and accelerating coil are integrated.
Still referring to FIG. 17, the integrated RF-amplifier microcircuit and accelerating coil presented in FIG. 18 is repeated, as illustrated as the set of coils 1711-1719 surrounding the vacuum tube 320. For example, the RF-synthesizer 1740 under main controller 130 direction, sends an RF-signal to the microcircuits 1720-1729 connected to coils 1710-1719, respectively. Each of the microcircuit/loop/coil combinations generate a proton accelerating voltage, such as about 10 volts each. Hence, a set of five microcircuit/loop/coil combinations generate about 50 volts for proton acceleration. Preferably about 5 to 20 microcircuit/loop/coil combinations are used and more preferably about 9 or 10 microcircuit/loop/coil combinations are used in the accelerator system 270.
As a further clarifying example, the RF synthesizer 1740 sends an RF-signal, with a period equal to a period of circulation of a proton about the synchrotron 130, to a set of ten microcircuit/loop/coil combinations, which results in about 100 volts for acceleration of the protons in the proton beam path 264. The 100 volts is generated at a range of frequencies, such as at about 1 MHz for a low energy proton beam to about 15 MHz for a high energy proton beam. The RF-signal is optionally set at an integer multiple of a period of circulation of the proton about the synchrotron circulating path. Each of the microcircuit/loop/coil combinations are optionally independently controlled in terms of acceleration voltage and frequency.
Integration of the RF-amplifier microcircuit and accelerating coil, in each microcircuit/loop/coil combination, results in three considerable advantages. First, for synchrotrons, the prior art does not use microcircuits integrated with the accelerating coils but rather uses a set of long cables to provide power to a corresponding set of coils. The long cables have an impedance/resistance, which is problematic for high frequency RF control. As a result, the prior art system is not operable at high frequencies, such as above about 10 MHz. The integrated RF-amplifier microcircuit/accelerating coil system is operable at above about 10 MHz and even 15 MHz where the impedance and/or resistance of the long cables in the prior art systems results in poor control or failure in proton acceleration. Second, the long cable system, operating at lower frequencies, costs about $50,000 and the integrated microcircuit system costs about $1000, which is 50 times less expensive. Third, the microcircuit/loop/coil combinations in conjunction with the RF-amplifier system results in a compact small power consumption design allowing production and use of a proton cancer therapy system is a small space, as described supra, and in a cost effective manner.
Referring now to FIG. 19, an example is used to clarify the magnetic field control using a feedback loop 1900 to change delivery times and/or periods of proton pulse delivery. In one case, a respiratory sensor 1910 senses the respiration cycle of the subject. The respiratory sensor sends the information to an algorithm in a magnetic field controller 1920, typically via the patient interface module 150 and/or via the main controller 110 or a subcomponent thereof. The algorithm predicts and/or measures when the subject is at a particular point in the respiration cycle, such as at the bottom of a breath. Magnetic field sensors 1930 are used as input to the magnetic field controller, which controls a magnet power supply 1940 for a given magnetic field 1950, such as within a first turning magnet 1010 of a synchrotron 130. The control feedback loop is thus used to dial the synchrotron to a selected energy level and deliver protons with the desired energy at a selected point in time, such as at the bottom of the breath. More particularly, the main controller injects protons into the synchrotron and accelerates the protons in a manner that combined with extraction delivers the protons to the tumor at a selected point in the respiration cycle. Intensity of the proton beam is also selectable and controllable by the main controller at this stage. The feedback control to the correction coils allows rapid selection of energy levels of the synchrotron that are tied to the patient's respiration cycle. This system is in stark contrast to a system where the current is stabilized and the synchrotron deliver pulses with a period, such as 10 or 20 cycles per second with a fixed period.
Flat Gap Surface While the gap surface is described in terms of the first turning magnet 1010, the discussion applies to each of the turning magnets in the synchrotron. Similarly, while the gap 1110 surface is described in terms of the magnetic field incident surface 1270, the discussion additionally optionally applies to the magnetic field exiting surface 1280.
Proton Beam Extraction Referring now to FIG. 20, an exemplary proton extraction process from the synchrotron 130 is illustrated. For clarity, FIG. 20 removes elements represented in FIG. 2, such as the turning magnets, which allows for greater clarity of presentation of the proton beam path as a function of time. Generally, protons are extracted from the synchrotron 130 by slowing the protons. As described, supra, the protons were initially accelerated in a circulating path 264, which is maintained with a plurality of main bending magnets 250. The circulating path is referred to herein as an original central beamline 264. The protons repeatedly cycle around a central point in the synchrotron 280. The proton path traverses through a radio frequency (RF) cavity system 2010. To initiate extraction, an RF field is applied across a first blade 2012 and a second blade 2014, in the RF cavity system 2010. The first blade 2012 and second blade 2014 are referred to herein as a first pair of blades.
In the proton extraction process, an RF voltage is applied across the first pair of blades, where the first blade 2012 of the first pair of blades is on one side of the circulating proton beam path 264 and the second blade 2014 of the first pair of blades is on an opposite side of the circulating proton beam path 264. The applied RF field applies energy to the circulating charged-particle beam. The applied RF field alters the orbiting or circulating beam path slightly of the protons from the original central beamline 264 to an altered circulating beam path 265. Upon a second pass of the protons through the RF cavity system, the RF field further moves the protons off of the original proton beamline 264. For example, if the original beamline is considered as a circular path, then the altered beamline is slightly elliptical. The applied RF field is timed to apply outward or inward movement to a given band of protons circulating in the synchrotron accelerator. Each orbit of the protons is slightly more off axis compared to the original circulating beam path 264. Successive passes of the protons through the RF cavity system are forced further and further from the original central beamline 264 by altering the direction and/or intensity of the RF field with each successive pass of the proton beam through the RF field.
With a sufficient sine wave betatron amplitude, the altered circulating beam path 265 touches or traverses a material 2030, such as a foil or a sheet of foil. The foil is preferably a lightweight material, such as beryllium, a lithium hydride, a carbon sheet, or a material of low nuclear charge. A material of low nuclear charge is a material composed of atoms consisting essentially of atoms having six or fewer protons. The foil is preferably about 10 to 150 microns thick, is more preferably 30 to 100 microns thick, and is still more preferably about forty to sixty microns thick. In one example, the foil is beryllium with a thickness of about fifty microns. When the protons traverse through the foil, energy of the protons is lost and the speed of the protons is reduced. Typically, a current is also generated, described infra. Protons moving at a slower speed travel in the synchrotron with a reduced radius of curvature 266 compared to either the original central beamline 264 or the altered circulating path 265. The reduced radius of curvature 266 path is also referred to herein as a path having a smaller diameter of trajectory or a path having protons with reduced energy. The reduced radius of curvature 266 is typically about two millimeters less than a radius of curvature of the last pass of the protons along the altered proton beam path 265.
The thickness of the material 2030 is optionally adjusted to created a change in the radius of curvature, such as about �, 1, 2, 3, or 4 mm less than the last pass of the protons 265 or original radius of curvature 264. Protons moving with the smaller radius of curvature travel between a second pair of blades. In one case, the second pair of blades is physically distinct and/or are separated from the first pair of blades. In a second case, one of the first pair of blades is also a member of the second pair of blades. For example, the second pair of blades is the second blade 2014 and a third blade 2016 in the RF cavity system 2010. A high voltage DC signal, such as about 1 to 5 kV, is then applied across the second pair of blades, which directs the protons out of the synchrotron through an extraction magnet 292, such as a Lamberson extraction magnet, into a transport path 268.
Charged Particle Beam Intensity Control Control of applied field, such as a radio-frequency (RF) field, frequency and magnitude in the RF cavity system 2010 allows for intensity control of the extracted proton beam, where intensity is extracted proton flux per unit time or the number of protons extracted as a function of time.
Referring still to FIG. 20, when protons in the proton beam hit the material 2030 electrons are given off resulting in a current. The resulting current is converted to a voltage and is used as part of a ion beam intensity monitoring system or as part of an ion beam feedback loop for controlling beam intensity. The voltage is optionally measured and sent to the main controller 110 or to a controller subsystem 2040. More particularly, when protons in the charged particle beam path pass through the material 2030, some of the protons lose a small fraction of their energy, such as about one-tenth of a percent, which results in a secondary electron. That is, protons in the charged particle beam push some electrons when passing through material 2030 giving the electrons enough energy to cause secondary emission. The resulting electron flow results in a current or signal that is proportional to the number of protons going through the target material 2030. The resulting current is preferably converted to voltage and amplified. The resulting signal is referred to as a measured intensity signal.
The amplified signal or measured intensity signal resulting from the protons passing through the material 2030 is preferably used in controlling the intensity of the extracted protons. For example, the measured intensity signal is compared to a goal signal, which is predetermined in an irradiation of the tumor plan. The difference between the measured intensity signal and the planned for goal signal is calculated. The difference is used as a control to the RF generator. Hence, the measured flow of current resulting from the protons passing through the material 2030 is used as a control in the RF generator to increase or decrease the number of protons undergoing betatron oscillation and striking the material 2030. Hence, the voltage determined off of the material 2030 is used as a measure of the orbital path and is used as a feedback control to control the RF cavity system. Alternatively, the measured intensity signal is not used in the feedback control and is just used as a monitor of the intensity of the extracted protons.
As described, supra, the photons striking the material 2030 is a step in the extraction of the protons from the synchrotron 130. Hence, the measured intensity signal is used to change the number of protons per unit time being extracted, which is referred to as intensity of the proton beam. The intensity of the proton beam is thus under algorithm control. Further, the intensity of the proton beam is controlled separately from the velocity of the protons in the synchrotron 130. Hence, intensity of the protons extracted and the energy of the protons extracted are independently variable.
For example, protons initially move at an equilibrium trajectory in the synchrotron 130. An RF field is used to excite the protons into a betatron oscillation. In one case, the frequency of the protons orbit is about 10 MHz. In one example, in about one millisecond or after about 10,000 orbits, the first protons hit an outer edge of the target material 130. The specific frequency is dependent upon the period of the orbit. Upon hitting the material 130, the protons push electrons through the foil to produce a current. The current is converted to voltage and amplified to yield a measured intensity signal. The measured intensity signal is used as a feedback input to control the applied RF magnitude, RF frequency, or RF field. Preferably, the measured intensity signal is compared to a target signal and a measure of the difference between the measured intensity signal and target signal is used to adjust the applied RF field in the RF cavity system 2010 in the extraction system to control the intensity of the protons in the extraction step. Stated again, the signal resulting from the protons striking and/or passing through the material 130 is used as an input in RF field modulation. An increase in the magnitude of the RF modulation results in protons hitting the foil or material 130 sooner. By increasing the RF, more protons are pushed into the foil, which results in an increased intensity, or more protons per unit time, of protons extracted from the synchrotron 130.
In another example, a detector 2050 external to the synchrotron 130 is used to determine the flux of protons extracted from the synchrotron and a signal from the external detector is used to alter the RF field or RF modulation in the RF cavity system 2010. Here the external detector generates an external signal, which is used in a manner similar to the measured intensity signal, described in the preceding paragraphs.
Patient Positioning Referring now to FIG. 21, the patient is preferably positioned on or within a patient positioning system 2110 of the patient interface module 150. The patient positioning system 2110 is used to translate the patient and/or rotate the patient into a zone where the proton beam can scan the tumor using a scanning system 140 or proton targeting system, described infra. Essentially, the patient positioning system 2110 performs large movements of the patient to place the tumor near the center of a proton beam path 268 and the proton scanning or targeting system 140 performs fine movements of the momentary beam position 269 in targeting the tumor 2120. To illustrate, FIG. 21 shows the momentary proton beam position 269 and a range of scannable positions 2140 using the proton scanning or targeting system 140, where the scannable positions 2140 are about the tumor 2120 of the patient 2130. This illustratively shows that the y-axis movement of the patient occurs on a scale of the body, such as adjustment of about 1, 2, 3, or 4 feet, while the scannable region of the proton beam 268 covers a portion of the body, such as a region of about 1, 2, 4, 6, 8, 10, or 12 inches. The patient positioning system and its rotation and/or translation of the patient combines with the proton targeting system to yield precise and/or accurate delivery of the protons to the tumor.
Referring still to FIG. 21, the patient positioning system 2110 optionally includes a bottom unit 2112 and a top unit 2114, such as discs or a platform. Referring now to FIG. 21A, the patient positioning unit 2110 is preferably y-axis adjustable 2116 to allow vertical shifting of the patient relative to the proton therapy beam 268. Preferably, the vertical motion of the patient positioning unit 2110 is about 10, 20, 30, or 50 centimeters per minute. Referring now to FIG. 21B, the patient positioning unit 2110 is also preferably rotatable 2117 about a rotation axis, such as about the y-axis, to allow rotational control and positioning of the patient relative to the proton beam path 268. Preferably the rotational motion of the patient positioning unit 2110 is about 360 degrees per minute. Optionally, the patient positioning unit rotates about 45, 90, or 180 degrees. Optionally, the patient positioning unit 2110 rotates at a rate of about 45, 90, 180, 360, 720, or 1080 degrees per minute. The rotation of the positioning unit 2117 is illustrated about the rotation axis at two distinct times, t1 and t2. Protons are optionally delivered to the tumor 2120 at n times where each of the n times represent different directions of the incident proton beam 269 hitting the patient 2130 due to rotation of the patient 2117 about the rotation axis.
Preferably, the top and bottom units 2112, 2114 move together, such that they rotate at the same rates and translate in position at the same rates. Optionally, the top and bottom units 2112, 2114 are independently adjustable along the y-axis to allow a difference in distance between the top and bottom units 2112, 2114. Motors, power supplies, and mechanical assemblies for moving the top and bottom units 2112, 2114 are preferably located out of the proton beam path 269, such as below the bottom unit 2112 and/or above the top unit 2114. This is preferable as the patient positioning unit 2110 is preferably rotatable about 360 degrees and the motors, power supplies, and mechanical assemblies interfere with the protons if positioned in the proton beam path 269 Proton Beam Position Control Referring now to FIG. 22, a beam delivery and tissue volume scanning system is illustrated. Presently, the worldwide radiotherapy community uses a method of dose field forming using a pencil beam scanning system. In stark contrast, FIG. 22 illustrates a spot scanning system or tissue volume scanning system. In the tissue volume scanning system, the proton beam is controlled, in terms of transportation and distribution, using an inexpensive and precise scanning system. The scanning system is an active system, where the beam is focused into a spot focal point of about one-half, one, two, or three millimeters in diameter. The focal point is translated along two axes while simultaneously altering the applied energy of the proton beam, which effectively changes the third dimension of the focal point. The system is applicable in combination with the above described rotation of the body, which preferably occurs in-between individual moments or cycles of proton delivery to the tumor. Optionally, the rotation of the body by the above described system occurs continuously and simultaneously with proton delivery to the tumor.
For example, in the illustrated system in FIG. 22A, the spot is translated horizontally, is moved down a vertical, and is then back along the horizontal axis. In this example, current is used to control a vertical scanning system having at least one magnet. The applied current alters the magnetic field of the vertical scanning system to control the vertical deflection of the proton beam. Similarly, a horizontal scanning magnet system controls the horizontal deflection of the proton beam. The degree of transport along each axes is controlled to conform to the tumor cross-section at the given depth. The depth is controlled by changing the energy of the proton beam. For example, the proton beam energy is decreased, so as to define a new penetration depth, and the scanning process is repeated along the horizontal and vertical axes covering a new cross-sectional area of the tumor. Combined, the three axes of control allow scanning or movement of the proton beam focal point over the entire volume of the cancerous tumor. The time at each spot and the direction into the body for each spot is controlled to yield the desired radiation does at each sub-volume of the cancerous volume while distributing energy hitting outside of the tumor.
In FIG. 22A, the proton beam is illustrated along a z-axis controlled by the beam energy, the horizontal movement is along an x-axis, and the vertical direction is along a y-axis. The distance the protons move along the z-axis into the tissue, in this example, is controlled by the kinetic energy of the proton. This coordinate system is arbitrary and exemplary. The actual control of the proton beam is controlled in 3-dimensional space using two scanning magnet systems and by controlling the kinetic energy of the proton beam. The use of the extraction system, described supra, allows for different scanning patterns. Particularly, the system allows simultaneous adjustment of the x-, y-, and z-axes in the irradiation of the solid tumor. Stated again, instead of scanning along an x,y-plane and then adjusting energy of the protons, such as with a range modulation wheel, the system allows for moving along the z-axes while simultaneously adjusting the x- and or y-axes. Hence, rather than irradiating slices of the tumor, the tumor is optionally irradiated in three simultaneous dimensions. For example, the tumor is irradiated around an outer edge of the tumor in three dimensions. Then the tumor is irradiated around an outer edge of an internal section of the tumor. This process is repeated until the entire tumor is irradiated. The outer edge irradiation is preferably coupled with simultaneous rotation of the subject, such as about a vertical y-axis. This system allows for maximum efficiency of deposition of protons to the tumor, as defined using the Bragg peak, to the tumor itself with minimal delivery of proton energy to surrounding healthy tissue.
Referring now to FIG. 22B, an example of a proton scanning or targeting system 140 used to direct the protons to the tumor with 4-dimensional scanning control is provided, where the 4-dimensional scanning control is along the x-, y-, and z-axes along with intensity control, as described supra. A fifth axis is time. Typically, charged particles traveling along the transport path 268 are directed through a first axis control element 142, such as a vertical control, and a second axis control element 144, such as a horizontal control and into a tumor 2120. As described, supra, the extraction system also allows for simultaneous variation in the z-axis. Further, as describe, supra, the intensity or dose of the extracted beam is optionally simultaneously and independently controlled and varied. Thus instead of irradiating a slice of the tumor, as in FIG. 22A, all four dimensions defining the targeting spot of the proton delivery in the tumor are simultaneously variable. The simultaneous variation of the proton delivery spot is illustrated in FIG. 22B by the spot delivery path 269. In the illustrated case, the protons are initially directed around an outer edge of the tumor and are then directed around an inner radius of the tumor. Combined with rotation of the subject about a vertical axis, a multi-field illumination process is used where a not yet irradiated portion of the tumor is preferably irradiated at the further distance of the tumor from the proton entry point into the body. This yields the greatest percentage of the proton delivery, as defined by the Bragg peak, into the tumor and minimizes damage to peripheral healthy tissue.
Imaging/X-Ray System Herein, an X-ray system is used to illustrate an imaging system.
Positioning An X-ray is preferably taken just before treating the subject to aid in patient positioning. For positioning purposes, an X-ray of a large body area is not needed. In one embodiment, an X-ray of only a local area is collected. When collecting an X-ray, the X-ray has an X-ray path. The proton beam has a proton beam path. Overlaying the X-ray path with the proton beam path is one method of aligning the proton beam to the tumor. However, this method involves putting the X-ray equipment into the proton beam path, taking the X-ray, and then moving the X-ray equipment out of the beam path. This process takes time. The elapsed time while the X-ray equipment moves has a couple of detrimental effects. First, during the time required to move the X-ray equipment, the body moves. The resulting movement decreases precision and/or accuracy of subsequent proton beam alignment to the tumor. Second, the time required to move the X-ray equipment is time that the proton beam therapy system is not in use, which decreases the total efficiency of the proton beam therapy system.
X-Ray Source Lifetime It is desirable to have components in the particle beam therapy system that require minimal or no maintenance over the lifetime of the particle beam therapy system. For example, it is desirable to equip the proton beam therapy system with an X-ray system having a long lifetime source, such as a lifetime of about 20 years.
Referring now to FIG. 23, an example of an X-ray generation device 2300 having an enhanced lifetime is provided. Electrons 2320 are generated at a cathode 2310, focused with a control electrode 2312, and accelerated with a series of accelerating electrodes 2340. The accelerated electrons 2350 impact an X-ray generation source 2348 resulting in generated X-rays that are then directed along an X-ray path 2470 to the subject 2130. The concentrating of the electrons from a first diameter 2315 to a second diameter 2316 allows the cathode to operate at a reduced temperature and still yield the necessary amplified level of electrons at the X-ray generation source 2348. In one example, the X-ray generation source is the anode coupled with the cathode 2310 and/or the X-ray generation source is substantially composed of tungsten.
Still referring to FIG. 23, a more detailed description of an exemplary X-ray generation device 2300 is described. An anode 2314/cathode 2310 pair is used to generated electrons. The electrons 2320 are generated at the cathode 2310 having a first diameter 2315, which is denoted d1. The control electrodes 2312 attract the generated electrons 2320. For example, if the cathode is held at about −150 kV and the control electrode is held at about −149 kV, then the generated electrons 2320 are attracted toward the control electrodes 2312 and focused. A series of accelerating electrodes 2340 are then used to accelerate the electrons into a substantially parallel path 2350 with a smaller diameter 2316, which is denoted d2. For example, with the cathode held at −150 kV, a first, second, third, and fourth accelerating electrodes 2342, 2344, 2346, 2348 are held at about −120, −90, −60, and −30 kV, respectively. If a thinner body part is to be analyzed, then the cathode 2310 is held at a smaller level, such as about −90 kV and the control electrode, first, second, third, and fourth electrode are each adjusted to lower levels. Generally, the voltage difference from the cathode to fourth electrode is less for a smaller negative voltage at the cathode and vise-versa. The accelerated electrons 2350 are optionally passed through a magnetic lens 2360 for adjustment of beam size, such as a cylindrical magnetic lens. The electrons are also optionally focused using quadrupole magnets 2370, which focus in one direction and defocus in another direction. The accelerated electrons 2350, which are now adjusted in beam size and focused strike an X-ray generation source 2348, such as tungsten, resulting in generated X-rays that pass through an optional blocker 2462 and proceed along an X-ray path 2370 to the subject. The X-ray generation source 2348 is optionally cooled with a cooling element 2349, such as water touching or thermally connected to a backside of the X-ray generation source 2348. The concentrating of the electrons from a first diameter 2315 to a second diameter 2316 allows the cathode to operate at a reduced temperature and still yield the necessary amplified level of electrons at the X-ray generation source 2348.
More generally, the X-ray generation device 2300 produces electrons having initial vectors. One or more of the control electrode 2312, accelerating electrodes 2340, magnetic lens 2360, and quadrupole magnets 2370 combine to alter the initial electron vectors into parallel vectors with a decreased cross-sectional area having a substantially parallel path, referred to as the accelerated electrons 2350. The process allows the X-ray generation device 2300 to operate at a lower temperature. Particularly, instead of using a cathode that is the size of the electron beam needed, a larger electrode is used and the resulting electrons 2320 are focused and/or concentrated into the required electron beam needed. As lifetime is roughly an inverse of current density, the concentration of the current density results in a larger lifetime of the X-ray generation device. A specific example is provided for clarity. If the cathode has a 15 mm radius or d1 is about 30 mm, then the area (π r2) is about 225 mm2 times pi. If the concentration of the electrons achieves a radius of 5 mm or d2 is about 10 mm, then the area (π r2) is about 25 mm2 times pi. The ratio of the two areas is about 9 (225π/25π). Thus, there is about 9 times less density of current at the larger cathode compared to the traditional cathode having an area of the desired electron beam. Hence, the lifetime of the larger cathode approximates 9 times the lifetime of the traditional cathode, though the actual current through the larger cathode and traditional cathode is about the same. Preferably, the area of the cathode 2310 is about 2, 4, 6, 8, 10, 15, 20, or 25 times that of the cross-sectional area of the substantially parallel electron beam 2350.
In another embodiment of the invention, the quadrupole magnets 2370 result in an oblong cross-sectional shape of the electron beam 2350. A projection of the oblong cross-sectional shape of the electron beam 2350 onto the X-ray generation source 2348 results in an X-ray beam that has a small spot in cross-sectional view, which is preferably substantially circular in cross-sectional shape, that is then passed through the patient 2330. The small spot is used to yield an X-ray having enhanced resolution at the patient.
Referring now to FIG. 24, in one embodiment, an X-ray is generated close to, but not in, the proton beam path. A proton beam therapy system and an X-ray system combination 2400 is illustrated in FIG. 24. The proton beam therapy system has a proton beam 268 in a transport system after the Lamberson extraction magnet 292 of the synchrotron 130. The proton beam is directed by the scanning/targeting/delivery system 140 to a tumor 2120 of a patient 2130. The X-ray system 2405 includes an electron beam source 2305 generating an electron beam 2350. The electron beam is directed to an X-ray generation source 2348, such as a piece of tungsten. Preferably, the tungsten X-ray source is located about 1, 2, 3, 5, 10, 15, or 20 millimeters from the proton beam path 268. When the electron beam 2350 hits the tungsten, X-rays are generated in all directions. X-rays are blocked with a port 2462 and are selected for an X-ray beam path 2470. The X-ray beam path 2470 and proton beam path 268 run substantially in parallel as they progress to the tumor 2120. The distance between the X-ray beam path 2470 and proton beam path 269 preferably diminishes to near zero and/or the X-ray beam path 2470 and proton beam path 269 overlap by the time they reach the tumor 2120. Simple geometry shows this to be the case given the long distance, of at least a meter, between the tungsten and the tumor 2120. The distance is illustrated as a gap 2480 in FIG. 24. The X-rays are detected at an X-ray detector 2490, which is used to form an image of the tumor 2120 and/or position of the patient 2130.
Referring now to FIG. 25, additional geometry of the electron beam path 2350 and X-ray beam path 2470 is illustrated. Particularly, the electron beam 2350 is shown as an expanded electron beam path 2352, 2354. Also, the X-ray beam path 2470 is shown as an expanded X-ray beam path 2472, 2474.
In this section an x-, y-, and z-axes coordinate system and rotation axis is used to describe the orientation of the patient relative to the proton beam. The z-axis represent travel of the proton beam, such as the depth of the proton beam into the patient. When looking at the patient down the z-axis of travel of the proton beam, the x-axis refers to moving left or right across the patient and the y-axis refers to movement up or down the patient. A first rotation axis is rotation of the patient about the y-axis and is referred to herein as a rotation axis, bottom unit 2112 rotation axis, or y-axis of rotation. In addition, tilt is rotation about the x-axis, yaw is rotation about the y-axis, and roll is rotation about the z-axis. In this coordinate system, the proton beam path 269 optionally runs in any direction. As an illustrative matter, the proton beam path running through a treatment room is described as running horizontally through the treatment room.
In this section, three examples of positioning systems 2600 are provided: (1) a semi-vertical partial immobilization system; (2) a sitting partial immobilization system; and (3) a laying position. Elements described for one immobilization system apply to other immobilization systems with small changes. For example, a head rest will adjust along one axis for a reclined position, along a second axis for a seated position, and along a third axis for a laying position. However, the headrest itself is similar for each immobilization position.
Vertical Patient Positioning/Immobilization The semi-vertical patient positioning system is preferably used in conjunction with proton therapy of tumors in the torso. The patient positioning and/or immobilization system controls and/or restricts movement of the patient during proton beam therapy. In a first partial immobilization embodiment, the patient is positioned in a semi-vertical position in a proton beam therapy system. As illustrated, the patient is reclining at an angle alpha, α, about 45 degrees off of the y-axis as defined by an axis running from head to foot of the patient. More generally, the patient is optionally completely standing in a vertical position of zero degrees off the of y-axis or is in a semi-vertical position alpha that is reclined about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, or 65 degrees off of the y-axis toward the z-axis.
Respiration control is optionally performed by using the video display. As the patient breathes, internal and external structures of the body move in both absolute terms and in relative terms. For example, the outside of the chest cavity and internal organs both have absolute movements with a breath. In addition, the relative position of an internal organ relative to another body component, such as an outer region of the body, a bone, support structure, or another organ, moves with each breath. Hence, for more accurate and precise tumor targeting, the proton beam is preferably delivered at point a in time where the position of the internal structure or tumor is well defined, such as at the bottom of each breath. The video display is used to help coordinate the proton beam delivery with the patient's respiration cycle. For example, the video display optionally displays to the patient a command, such as a hold breath statement, a breathe statement, a countdown indicating when a breath will next need to be held, or a countdown until breathing may resume.
Sitting Patient Positioning/Immobilization In a second partial immobilization embodiment, the patient is partially restrained in a seated position. The sitting restraint system has support structures that are similar to the support structures used in the semi-vertical positioning system, described supra with the exception that the seat support is replaced by a chair and the knee support is not required. The seated restraint system generally retains the adjustable support, rotation about the y-axis, camera, video, and respiration control parameters described in the semi-vertical embodiment, described supra.
Referring now to FIG. 26, a particular example of a sitting patient semi-immobilization system is provided. The sitting system is preferably used for treatment of head and neck tumors. As illustrated, the patient is positioned in a seated position on a chair 2610 for particle therapy. The patient is further immobilized using any of the: the head support 2640, the back support 2630, a hand support 2620, the knee support 2660, and the foot support 2670. The supports 2640, 2630, 2620, 2660, 2670 preferably have respective axes of adjustment 2642, 2632, 2622, 2662, 2672 as illustrated. The chair 2610 is either readily removed to allow for use of a different patient constraint system or adapts to a new patient position, such as the semi-vertical system.
Laying Patient Positioning/Immobilization In a third partial immobilization embodiment, the patient is partially restrained in a laying position. The laying restraint system has support structures that are similar to the support structures used in the sitting positioning system and semi-vertical positioning system, described supra. In the laying position, optional restraint, support, or partial immobilization elements include one or more of: the head support and the back, hip, and shoulder support. The supports preferably have respective axes of adjustment that are rotated as appropriate for a laying position of the patient. The laying position restraint system generally retains the adjustable supports, rotation about the y-axis, camera, video, and breath control parameters described in the semi-vertical embodiment, described supra.
Support System Elements Positioning constraints include all elements used to position the patient, such as those described in the semi-vertical positioning system, sitting positioning system, and laying positioning system. Preferably, positioning constraints or support system elements are aligned in positions that do not impede or overlap the proton beam path 269. However, in some instances the positioning constraints are in the proton beam path 269 during at least part of the time of treatment of the patient. For instance, a positioning constraint element may reside in the proton beam path 269 during part of a time period where the patient is rotated about the y-axis during treatment. In cases or time periods that the positioning constraints or support system elements are in the proton beam path, then an upward adjustment of proton beam energy is preferably applied that increases the proton beam energy to offset the positioning constraint element impedance of the proton beam. This time period and energy is a function of rotational orientation of the patient. In one case, the proton beam energy is increased by a separate measure of the positioning constraint element impedance determined during a reference scan of the positioning constraint system element or set of reference scans of the positioning constraint element as a function of rotation about the y-axis.
Referring now to FIG. 27 another example of a head support system is described for positioning and/or restricting movement of a human head 2102 during proton therapy of a solid tumor in the head or neck. In this system, the head is restrained using 1, 2, 3, 4, or more straps or belts, which are preferably connected or replaceably connected to a back of head support element 2710. In the example illustrated, a first strap 2720 pulls or positions the forehead to the head support element 2710, such as by running predominantly along the z-axis. Preferably a second strap 2730 works in conjunction with the first strap 2720 to prevent the head from undergoing tilt, yaw, roll or moving in terms of translational movement on the x-, y-, and z-axes coordinate system. The second strap 2730 is preferably attached or replaceable attached to the first strap 2720 at or about: (1) a forehead position 2732; (2) at a point on one or both sides of the head 2734; and/or (3) at or about a position of a support element 2736. A third strap 2740 preferably orientates the chin of the subject relative to the support element 2710 by running dominantly along the z-axis. A fourth strap 2750 preferably runs along a predominantly y- and z-axes to hold the chin relative to the head support element 2710 and/or proton beam path. The third 2740 strap preferably is attached to or is replaceably attached to the fourth strap 2750 during use at or about the patient's chin position 2742. The second strap 2730 optionally connects to the fourth strap 2750 at or about the support element 2710. The four straps 2720, 2730, 2740, 2750 are illustrative in pathway and interconnection. Any of the straps optionally hold the head along different paths around the head and connect to each other in separate fashion. Naturally, a given strap preferably runs around the head and not just on one side of the head. Any of the straps 2720, 2730, 2740, and 2750 are optionally used independently or in combinations or permutations with the other straps. The straps are optionally indirectly connected to each other via a support element, such as the head support element 2710. The straps are optionally attached to the head support element 2710 using hook and loop technology, a buckle, or fastener. Generally, the straps combine to control position, front-to-back movement of the head, side-to-side movement of the head, tilt, yaw, roll, and/or translational position of the head.
Referring now to FIG. 28, still another example of a head support system 2640 is described. The head support 2640 is preferably curved to fit a standard or child sized head. The head support 2640 is optionally adjustable along a head support axis 2642. Further, the head supports, like the other patient positioning constraints, is preferably made of a semi-rigid material, such as a low or high density foam, and has an optional covering, such as a plastic or leather.
Still referring to FIG. 28, an example of the arm support 2620 is further described. The arm support preferably has a left hand grip 2810 and a right hand grip 2820 used for aligning the upper body of the patient 2130 through the action of the patient 2130 gripping the left and right hand grips 2810, 2820 with the patient's hands 2134. The left and right hand grips 2810, 2820 are preferably connected to the arm support 2620 that supports the mass of the patient's arms. The left and right hand grips 2810, 2820 are preferably constructed using a semi-rigid material. The left and right hand grips 2810, 2820 are optionally molded to the patient's hands to aid in alignment. The left and right hand grips optionally have electrodes, as described supra.
Positioning System Computer Control One or more of the patient positioning unit components and/or one of more of the patient positioning constraints are preferably under computer control, where the computer control positioning devices, such as via a series of motors and drives, to reproducibly position the patient. For example, the patient is initially positioned and constrained by the patient positioning constraints. The position of each of the patient positioning constraints is recorded and saved by the main controller 110, by a sub-controller or the main controller 110, or by a separate computer controller. Then, medical devices are used to locate the tumor 2120 in the patient 2130 while the patient is in the orientation of final treatment. The imaging system 170 includes one or more of: MRI's, X-rays, CT's, proton beam tomography, and the like. Time optionally passes at this point where images from the imaging system 170 are analyzed and a proton therapy treatment plan 2060 is devised. The patient may exit the constraint system during this time period, which may be minutes, hours, or days. Upon return of the patient to the patient positioning unit, the computer can return the patient positioning constraints to the recorded positions. This system allows for rapid repositioning of the patient to the position used during imaging and development of the treatment plan 2060, which minimizes setup time of patient positioning and maximizes time that the charged particle beam system 100 is used for cancer treatment.
Patient Placement Preferably, the patient 2130 is aligned in the proton beam path 269 in a precise and accurate manner. Several placement systems are described. The patient placement systems are described using the laying positioning system, but are equally applicable to the semi-vertical and sitting positioning systems.
Monitoring Respiration Preferably, the patient's respiration or breathing pattern is monitored. When a subject, also referred to herein as a patient, is breathing many portions of the body move with each breath. For example, when a subject breathes the lungs move as do relative positions of organs within the body, such as the stomach, kidneys, liver, chest muscles, skin, heart, and lungs. Generally, most or all parts of the torso move with each breath. Indeed, the inventors have recognized that in addition to motion of the torso with each breath, various motion also exists in the head and limbs with each breath. Motion is to be considered in delivery of a proton dose to the body as the protons are preferentially delivered to the tumor and not to surrounding tissue. Motion thus results in an ambiguity in where the tumor resides relative to the beam path. To partially overcome this concern, protons are preferentially delivered at the same point in each of a series of respiration cycles.
Referring again to FIG. 27, an example of the thermal respiration monitoring system is provided. In the thermal respiration monitoring system, a sensor is placed by the nose and/or mouth of the patient. As the jaw of the patient is optionally constrained, as described supra, the thermal respiration monitoring system is preferably placed by the patient's nose exhalation path. To avoid steric interference of the thermal sensor system components with proton therapy, the thermal respiration monitoring system is preferably used when treating a tumor not located in the head or neck, such as a when treating a tumor in the torso or limbs. In the thermal monitoring system, a first thermal resistor 2770 is used to monitor the patient's respiration cycle and/or location in the patient's respiration cycle. Preferably, the first thermal resistor 2770 is placed by the patient's nose, such that the patient exhaling through their nose onto the first thermal resistor 2770 warms the first thermal resistor 2770 indicating an exhale. Preferably, a second thermal resistor 2760 operates as an environmental temperature sensor. The second thermal resistor 2760 is preferably placed out of the exhalation path of the patient but in the same local room environment as the first thermal resistor 2770. Generated signal, such as current from the thermal resistors 2770, 2760, is preferably converted to voltage and communicated with the main controller 110 or a sub-controller of the main controller. Preferably, the second thermal resistor 2760 is used to adjust for the environmental temperature fluctuation that is part of a signal of the first thermal resistor 2770, such as by calculating a difference between the values of the thermal resistors 2770, 2760 to yield a more accurate reading of the patient's respiration cycle.
Referring again to FIG. 26, an example of the force/pressure respiration monitoring system is provided. In the force respiration monitoring system, a sensor is placed by the torso. To avoid steric interference of the force sensor system components with proton therapy, the force respiration monitoring system is preferably used when treating a tumor located in the head, neck or limbs. In the force monitoring system, a belt or strap 2650 is placed around an area of the patient's torso that expands and contracts with each respiration cycle of the patient. The belt 2650 is preferably tight about the patient's chest and is flexible. A force meter 2652 is attached to the belt and senses the patients respiration pattern. The forces applied to the force meter 2652 correlate with periods of the respiration cycle. The signals from the force meter 2652 are preferably communicated with the main controller 110 or a sub-controller of the main controller.
Respiration Control Once the rhythmic pattern of the subject's respiration is determined, a signal is optionally delivered to the subject to more precisely control the breathing frequency. For example, a display screen is placed in front of the subject directing the subject when to hold their breath and when to breathe. Typically, a respiration control module uses input from one or more of the respiration sensors. For example, the input is used to determine when the next breath exhale is to complete. At the bottom of the breath, the control module displays a hold breath signal to the subject, such as on a monitor, via an oral signal, digitized and automatically generated voice command, or via a visual control signal. Preferably, a display monitor is positioned in front of the subject and the display monitor displays at least breathing commands to the subject. Typically, the subject is directed to hold their breath for a short period of time, such as about one-half, one, two, or three seconds. The period of time the subject is asked to hold their breath is less than about ten seconds. The period of time the breath is held is preferably synchronized to the delivery time of the proton beam to the tumor, which is about one-half, one, two, or three seconds. While delivery of the protons at the bottom of the breath is preferred, protons are optionally delivered at any point in the respiration cycle, such as upon full inhalation. Delivery at the top of the breath or when the patient is directed to inhale deeply and hold their breath by the respiration control module is optionally performed as at the top of the breath the chest cavity is largest and for some tumors the distance between the tumor and surrounding tissue is maximized or the surrounding tissue is rarefied as a result of the increased volume. Hence, protons hitting surrounding tissue is minimized. Optionally, the display screen tells the subject when they are about to be asked to hold their breath, such as with a 3, 2, 1, second countdown so that the subject is aware of the task they are about to be asked to perform.
A proton delivery control algorithm is used to synchronize delivery of the protons to the tumor within a given period of each breath, such as at the top or bottom of a breath when the subject is holding their breath. The proton delivery control algorithm is preferably integrated with the respiration control module. Thus, the proton delivery control algorithm knows when the subject is breathing, where in the respiration cycle the subject is, and/or when the subject is holding their breath. The proton delivery control algorithm controls when protons are injected and/or inflected into the synchrotron, when an RF signal is applied to induce an oscillation, as described supra, and when a DC voltage is applied to extract protons from the synchrotron, as described supra. Typically, the proton delivery control algorithm initiates proton inflection and subsequent RF induced oscillation before the subject is directed to hold their breath or before the identified period of the respiration cycle selected for a proton delivery time. In this manner, the proton delivery control algorithm can deliver protons at a selected period of the respiration cycle by simultaneously or nearly simultaneously delivering the high DC voltage to the second pair of plates, described supra, which results in extraction of the protons from the synchrotron and subsequent delivery to the subject at the selected time point. Since the period of acceleration of protons in the synchrotron is constant or known for a desired energy level of the proton beam, the proton delivery control algorithm is used to set an AC RF signal that matches the respiration cycle or directed respiration cycle of the subject.
Multi-Field Irradiation The 3-dimensional scanning system of the proton spot focal point, described supra, is preferably combined with a rotation/raster method. The method includes layer wise tumor irradiation from many directions. During a given irradiation slice, the proton beam energy is continuously changed according to the tissue's density in front of the tumor to result in the beam stopping point, defined by the Bragg peak, to always be inside the tumor and inside the irradiated slice. The novel method allows for irradiation from many directions, referred to herein as multi-field irradiation, to achieve the maximal effective dose at the tumor level while simultaneously significantly reducing possible side-effects on the surrounding healthy tissues in comparison with existing methods. Essentially, the multi-field irradiation system distributes dose-distribution at tissue depths not yet reaching the tumor.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS5917293 *Dec 9, 1996Jun 29, 1999Hitachi, Ltd.Radio-frequency accelerating system and ring type accelerator provided with the sameUS20090289194 *Apr 21, 2009Nov 26, 2009Hitachi, Ltd.Particle beam therapy system* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS8067748 *Jul 6, 2009Nov 29, 2011Vladimir BalakinCharged particle beam acceleration and extraction method and apparatus used in conjunction with a charged particle cancer therapy systemUS8637839Apr 6, 2011Jan 28, 2014Siemens AktiengesellschaftMethod for operating a particle therapy systemDE102010014002A1 *Apr 7, 2010Oct 13, 2011Siemens AktiengesellschaftVerfahren zum Betreiben einer Partikeltherapieanlage* Cited by examinerClassifications U.S. Classification315/505, 250/396.00RInternational ClassificationH05H9/00Cooperative ClassificationA61N2005/1087, H05H7/10, H05H13/04European ClassificationH05H7/10, H05H13/04Legal EventsDateCodeEventDescriptionJul 2, 2012ASAssignmentOwner name: WILMINGTON TRUST, NATIONAL ASSOCIATION (AS AGENT),Effective date: 20120626Free format text: SECURITY AGREEMENT;ASSIGNORS:PROTOM INTERNATIONAL INC.;PROTOM INTERNATIONAL LLC;BALAKIN, VLADIMIR;REEL/FRAME:028487/0065RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google