Particle beam treatment system with solenoid magnets

Abstract

A particle beam treatment system having a beam generation unit for generating a beam of charged particles, in particular ions, preferably protons, and having a beam guidance system. The generic beam guidance system takes up less space but can provide comparable or even improved beam properties because, in part, the beam guidance system seen in the direction of the beam of charged particles and behind the beam generation unit has at least one solenoid magnet as a beam shaping unit, and the at least one solenoid magnet of the beam guidance system is a superconducting solenoid magnet.

Claims

1. A particle beam treatment system comprising: a beam generation unit for generating a beam of charged particles, in particular ions, preferably protons, and a beam guidance system, wherein the beam guidance system seen in the direction of the beam of charged particles behind the beam generation unit has at least one solenoid magnet as a beam shaping unit, and the at least one solenoid magnet of the beam guidance system is a superconducting solenoid magnet.

2. A particle beam treatment system according to claim 1, wherein at least one solenoid magnet of the beam guidance system is provided directly behind the beam generation unit.

3. A particle beam treatment system according to claim 1, wherein the beam guidance system has an energy correction unit for adjusting the energy of the charged particles of the beam of charged particles and at least one solenoid magnet of the beam guidance system seen in the direction of the beam of charged particles is provided between the beam generation unit and the energy correction unit and/or at least one solenoid magnet of the beam guidance system seen in the direction of the beam of charged particles is provided behind the energy correction unit.

4. A particle beam treatment system according to claim 1, wherein the beam guidance system has at least two solenoid magnets seen in the direction of the beam of charged particles behind the beam generation unit.

5. A particle beam treatment system according to claim 1, wherein at least one solenoid magnet is designed as a cylindrical coil running in a substantially linear direction.

6. A particle beam treatment system according to claim 1, wherein the windings of at least one solenoid magnet run substantially perpendicularly to the beam of charged particles.

7. A particle beam treatment system according to claim 1, wherein at least one solenoid magnet generates at least in sections a substantially homogenous magnetic field.

8. A particle beam treatment system according to claim 1, wherein the magnetic field of a first solenoid magnet is in the range of 1 tesla to 10 tesla and the magnetic field of a second solenoid magnet is in the range of 5 tesla to 20 tesla.

9. A particle beam treatment system according to claim 1, wherein the particle beam treatment system is configured so that at least one solenoid magnet in the case of differing energies of the charged particles of the beam of charged particles generates a substantially constant magnetic field.

10. A particle beam treatment system according to claim 1, wherein a first solenoid magnet has an entry opening and/or exit opening of between 10 mm and 50 mm and a second solenoid magnet has an entry opening and/or exit opening of between 30 mm and 70 mm.

11. A particle beam treatment system according to claim 1, wherein the beam guidance system has an immovable section and a movable section.

12. A particle beam treatment system according to claim 11, wherein the at least one solenoid magnet is provided in the immovable section of the beam guidance system.

13. A particle beam treatment system according to claim 1, wherein the beam guidance system has at least one magnetic beam deflection unit in the movable section of the beam guidance system.

14. A particle beam treatment system according to claim 13, wherein at least one solenoid magnet seen in the direction of the beam of charged particles is disposed before the at least one magnetic beam deflection unit.

15. A particle beam treatment system according to claim 1, wherein the beam guidance system has at least one additional magnetic beam shaping unit in the form of a quadrupole magnet.

16. A method, carried out with a particle beam treatment system according to claim 1, comprising the steps of: generating a beam of charged particles with the beam generation unit, and guiding the beam of charged particles by means of the beam guidance system.

17. A particle beam treatment system according to claim 8, wherein the magnetic field of the first solenoid magnet is in the range of 4 tesla to 8 tesla and the magnetic field of a second solenoid magnet is in the range of 8 tesla to 15 tesla.

18. A particle beam treatment system according to claim 10, wherein a first solenoid magnet has an entry opening and/or exit opening of between 20 mm and 40 mm and a second solenoid magnet has an entry opening and/or exit opening of between 40 mm and 60 mm.

19. A particle beam treatment system according to claim 11, wherein the movable section is rotatable.

20. The method according to claim 16, wherein the beam of charged particles includes protons.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0105] The figures show as follows:

[0106] FIG. 1 shows a schematic sectional view of an embodiment of a particle beam treatment system with an embodiment of a beam guidance system according to the present invention;

[0107] FIG. 2 shows a schematic sectional view of a further embodiment of the movable section of a beam guidance system;

[0108] FIG. 3 shows a schematic sectional view of an embodiment of an energy correction unit.

DETAILED DESCRIPTION OF THE INVENTION

[0109] FIG. 1 shows a schematic sectional view of an embodiment of a particle beam treatment system 1 with an embodiment of a beam guidance systems 2. The particle beam treatment system comprises a beam generation unit 4 for generating a beam of charged particles 6, which in particular can be protons. The beam of charged particles 6 is guided by the beam guidance system 2 to a treatment site 7. The beam guidance system 2 has a section 8 that is moveable, in this case rotatable through 360, and a section 10 that is immovable. The rotatable section 8 can for example be built as a supporting frame in the form of a gantry (not shown).

[0110] The beam generation unit 4 is in this case a cyclotron, that is to say an accelerator device which generates the beam of charged particles 6 with constant energy. The beam generation unit 4 emits charged particles with a constant kinetic energy, for example 210 MeV, 215 MeV or 250 MeV. It has been shown that by means of charged particles with a kinetic energy of approximately 207 MeV approximately 95%, and by means of charged particles with a kinetic energy of approximately 198 MeV still approximately 90%, of the patients to be treated can be treated.

[0111] The beam of charged particles runs initially in the direction of the arrow 12 along an original axis 14 of the beam of charged particles 6.

[0112] In the direction 12 of the beam of charged particles 6 seen behind the beam generation unit 4 a first superconducting solenoid magnet 16a is provided as a beam shaping unit. In this case the solenoid magnet 16a is provided directly behind the beam generation unit. Similarly, the solenoid magnet 16a is provided between the beam generation unit 4 and an energy correction unit 18. The magnetic field of the solenoid magnets 16a is in this case approximately 11.2 tesla. The entry opening and the exit opening of the solenoid magnet 16a are in this case approximately 30 mm. Depending on the construction of the particle beam treatment system and of the beam guidance system other magnetic field strengths and opening sizes may, however, be possible or necessary.

[0113] As a result of the solenoid magnet 16a improved mapping of the phase space emitted by the beam generation unit to the energy correction unit 18 disposed behind can be brought about, so that the beam quality and transmission of the beam of charged particles 6 up to the treatment site 7 can be increased.

[0114] The beam of charged particles 6 is then guided through the energy correction unit 18. The energy correction unit 18 allows an adjustment of the energy of the charged particles of the beam of charged particles 6. The energy correction unit is described in more detail in connection with FIG. 3.

[0115] The beam guidance system 2 also has, seen in the direction 12 of the beam of charged particles 6, directly after the energy correction unit 18 a collimator unit 20, which the beam of the charged particles 6 then passes through. The collimator unit comprises a screen, which takes the form of a circular block of material, and seen opposite to the direction 12 of the beam of charged particles 6, respectively, a tapered opening.

[0116] Seen further in the direction of 12 of the beam of charged particles 6 behind the energy correction unit 18 and the collimator unit 20 a second superconducting solenoid magnet 16b is provided as a beam shaping unit. The solenoid magnet 16b is provided between the energy correction unit 18 and the movable section 8 of the beam guidance system 2 and in particular before a first magnetic beam deflection unit 30a. The magnetic field of the solenoid magnet 16b is in this case approximately 6.16 tesla. The entry opening and the exit opening of the solenoid magnet 16b are in this case approximately 52 mm. Depending on the construction of the particle beam treatment system and of the beam guidance system other magnetic field strengths and opening sizes may, however, be possible or necessary.

[0117] As a result of the solenoid magnet 16b improved mapping of the phase space emitted by the energy correction unit 18 to a collimator unit 24 disposed behind (and thus in the movable section 8 of the beam guidance system 2) can be brought about, so that the beam quality and transmission of the beam of charged particles 6 up to the treatment site 7 can be increased.

[0118] Both the first solenoid magnet 16a and the second solenoid magnet 16b, for example, take the form of a cylindrical coil running in a linear direction and generate in the area of the beam of charged particles 6 a substantially homogenous magnetic field. The particle beam treatment system 1 is advantageously configured so that the solenoid magnets 16a, 16b independently of the energy of the charged particles of the beam of charged particles 6 generate a substantially constant magnetic field, so that complex energy-based control of the solenoid magnet 16a, 16b can be dispensed with.

[0119] After the second solenoid magnet 16b seen in the direction of 12 of the beam of charged particles 6, the beam guidance system 2 has a drift distance 22. The drift distance 22 has no magnetic units, such as magnetic beam deflection units or magnetic beam shaping units. In the area of the drift distance 22 a shield, for example a concrete shield (not shown) can be provided. In addition, in the area of the drift distance 22 measuring devices such as beam monitors (not shown) can be provided.

[0120] The beam of charged particles 6 can pass through the section of the energy correction unit 18, the collimator unit 20 and/or the drift distance 22 of the beam guidance system 2, in a vacuum, which improves the beam properties and the transmission in this section.

[0121] The elements of the beam guidance system 2 described above are disposed in the immovable section 10 of the beam guidance system 2. To be able to irradiate the treatment site 7 from as many angles as possible, the rotatable section 8 is provided. The axis of rotation of the supporting frame (not shown) coincides with the original axis 14 of the beam of charged particles 6.

[0122] In the rotatable section 8 the beam guidance system first has a collimator unit 24. As a result of the collimator unit 24 the phase space of the beam of charged particles can be defined. The collimator unit 24 is designed here as a screen, in this case as a block of material with a rectangular opening 26. The geometry of the opening 26 is variable in both directions transversally to the beam of charged particles 6, to allow flexible tailoring of the beam properties.

[0123] Then an optional beam monitor 28 is provided, in order to check the beam properties. Additionally, or alternatively, the beam monitor can also be provided at other points of the beam guidance system 2.

[0124] Then, for guiding the beam of charged particles 6, the beam guidance system 2 has several, in this case four, magnetic beam deflection units 30a, 30b, 30c, 30d designed as magnetic dipoles. The magnetic beam deflection units 30a, 30b, 30c, 30d each have an entry side 32a, 32b, 32c, 32d for entry of the beam of charged particles 6 from an entry direction into the respective magnetic beam deflection unit. The magnetic beam deflection units 30a, 30b, 30c, 30d also each have an exit side 34a, 34b, 34c, 34d for the emergence of the beam of charged particles 6 in an exit direction from the magnetic beam deflection unit 30a, 30b, 30c, 30d. The entry sides 32a, 32b, 32c, 32d are in each case designed to be parallel to the respective exit side 34a, 34b, 34c, 34d. Here the magnetic beam deflection units 30a, 30b, 30c, 30d are in each case provided for deflecting the beam of charged particles 6 in the beam guidance system 2, so that the respective entry side 32a, 32b, 32c, 32d lies oblique to the respective entry direction of the beam of charged particles 6 and the respective exit side 34a, 34b, 34c, 34d oblique to the respective exit direction of the beam of charged particles 6. Here the magnetic beam deflection units 30a, 30b, 30c, 30d are in this case provided for deflecting the beam of charged particles 6 in the beam guidance system 2, so that the entry direction and the exit direction at each beam deflection unit 30a, 30b, 30c, 30d are at an angle of 45 to each other. The beam deflection units 30a, 30b, 30c, 30d here are positioned symmetrically in the beam of charged particles, that is to say that the angle between entry direction and entry side 32a, 32b, 32c, 32d and the angle between exit direction and exit side 34a, 34b, 34c, 34d are in each case identical for the individual beam deflection units 30a, 30b, 30c, 30d.

[0125] The beam of charged particles 6 is deflected by the first beam deflection unit 30a away from the original axis 14 of the beam of charged particles. The beam of charged particles 6 is deflected by the second beam deflection unit 30b back towards the original axis 14 and then runs parallel to the original axis 14 of the beam of charged particles 6. Then the beam of charged particles 6 is deflected by the third and the fourth beam deflection units 30c, 30d similarly back towards the original axis 14, so that the beam of charged particles 6 after the last beam deflection unit 30d is running perpendicularly to the original axis 14 of the beam of charged particles 6 and crosses the original axis 14.

[0126] As a result of the described development of the beam deflection units 30a, 30b, 30c, 30d improved beam properties can be achieved with a simultaneously more compact beam guidance system 2. This is attributed, inter alia, to the fact that the magnetic beam deflection units 30a, 30b, 30c, 30d can not only achieve a deflection of the beam of charged particles, but also a focusing of the beam of charged particles similar to a quadrupole magnet.

[0127] Here the magnetic beam deflection units 30a, 30b, 30c, 30d provided have a defocusing in a transversal direction (here, in the plane of projection) and a focusing in a direction perpendicular thereto. At this point the magnetic beam deflection units 30a, 30b, 30c, 30d have similar properties to quadrupole magnets, which similarly focus in a transversal direction and defocus in the direction perpendicular thereto. All four magnetic beam deflection units 30a, 30b, 30c, 30d therefore focus in just one direction (perpendicularly to the plane of projection). Of the seven quadrupole magnets 36a-36g provided (see below) therefore, five focus in the transversal direction in the plane of projection and only two in the direction perpendicular thereto. Thus overall sufficient focussing in both transversal coordinate directions is achieved. The result is that by focusing the dipoles in the y-direction therefore only two further quadrupoles with focusing in the same direction are necessary.

[0128] In addition, the manufacturing process for the beam deflection units 30a, 30b, 30c, 30d can be simplified as a result of the parallel entry and exit sides, since the iron core of the beam deflection units 30a, 30b, 30c, 30d can be made from parallel plates layered one on top of the other.

[0129] The beam guidance system 2 also has several, in this case seven, additional magnetic beam shaping units 36a, 36b, 36c, 36d, 36e, 36f, 36g in the form of quadrupole magnets. As a result of the beam shaping units 36a, 36b, 36c, 36d, 36e, 36f, 36g the beam property of the beam of charged particles 6 can be further improved. In particular, due, inter alia, to the solenoid magnets 16a, 16b and the beam deflection units 30a, 30b, 30c, 30d only a comparatively low number of additional beam shaping units 36a, 36b, 36c, 36d, 36e, 36f, 36g is necessary, to achieve good beam properties, allowing a compact beam guidance system 2.

[0130] Between the (seen in the direction 12 of the beam of charged particles 6) first magnetic beam deflection unit 30a and the second magnetic beam deflection unit 30b five additional beam shaping units 36a, 36b, 36c, 36d, 36e are provided. Between the second magnetic beam deflection unit 30b and the third magnetic beam deflection unit 30c a further two additional beam shaping units 36f, 36g are provided. The additional beam shaping units 36a, 36b, 36c, 36d, 36e, 36f, 36g in this case all have the same dimensions.

[0131] The beam guidance system 2 has, between the two magnetic beam deflection units 30b, 30c, a further collimator unit 38 in the form of a screen with a rectangular opening 40. The opening is variable in both directions transversal to the beam of charged particles 6, as a result of which shaping of the beam spot at the treatment site 7 can take place. It has been shown that between the beam deflection units 30b, 30c a comparatively large momentum dispersion dominates. This can be countered by providing the collimator unit 38, because the collimator unit 38 allows momentum selection for the beam of charged particles 6 at the treatment site 7.

[0132] In the beam guidance system 2 the beam monitors 42 and 44 are further provided. The beam monitor 42 is provided between the additional beam shaping units 36b and 36c. The beam monitor 44 is provided after the fourth beam deflection unit 30d and before the treatment centre 7.

[0133] Between the beam deflection unit 30c and the beam deflection unit 30d the beam guidance system also has a scanning magnet 46. The scanning magnet can be advantageously used at this position, since in this way at the treatment site a larger scanning range can be covered. With a system such as that previously proposed in 2005 by V. Anferov, for example, the beam can by way of example be moved so that at the treatment site an area of 210 mm175 mm can be covered, with a deflection angle of just 44 mrad in both coordinate directions. A further enlargement of the scanning range is possible. Since the beam deflection unit 30d must receive the charged particles 6 deflected by the scanning magnets 46, the beam deflection unit 30d can have a larger entry opening and/or exit opening than the other beam deflection units 30a, 30b, 30c. The beam deflection units 30a, 30b, 30c can be structurally identical.

[0134] Because the scanning magnet 46 is provided between the last and the penultimate (that is to say the third and fourth) beam deflection units 30c, 30d, this allows a larger scanning range at the treatment site 7.

[0135] It has been shown that a particularly compact beam guidance system 2 can be provided. The distance 50 from the beam generation unit 4 to the end of the energy correction unit 18 here is less than 2 m. The distance 52 from the end of the energy correction unit 18 to the treatment site 7 here is less than 10 m. Here the beam of charged particles 6 can be guided with the beam guidance system 2 over a distance 54 of less than 8 m from the direction 12 along the original axis 14 of the beam of charged particles 6 to the treatment site 7. Here the maximum distance 56 of the beam of charged particles 6 is less than 3 m from the original axis 14 of the beam of charged particles 6. Here the distance 58 of the second and third magnetic beam deflection units 30b, 30c is less than 15 m. Here the distance 60 of the last magnetic beam deflection unit 30d from the treatment site is less than 1 m, for example 0.991 m.

[0136] It is worth noting that the geometric dimensions refer to a beam of charged particles with a kinetic energy of approximately 210 MeV. If higher energies are used, the geometric dimensions are preferably multiplied by a factor. This geometric scaling factor is, for example, the precise ratio of the momentum of the higher energy protons (for example 245 MeV) to 210 MeV protons.

[0137] FIG. 2 is a schematic sectional view of a further embodiment of the movable section of a beam guidance system 2. The rotatable section 8 shown, of the beam guidance system 2 from FIG. 2, is similar to the rotatable section 8 of the beam guidance system 2 from FIG. 1. In this regard, for the same elements the same reference signs are used. Equally, reference is made to the statements on the beam guidance system 2 from FIG. 1. In particular, the rotatable section 8 can be provided instead of the rotatable section 8 in the beam guidance system 2. In the following only the differences from the beam guidance system 2 from FIG. 1 are considered.

[0138] The substantial difference between the beam guidance system 2 and the beam guidance system 2 is that the beam guidance system 2 does not have any collimator units 24, 38 in the rotatable section 8. This means in particular that the distance from the magnetic beam deflection units 30b, 30c can be shortened, so that the distance of these can be less than 1.2 m, in particular less than 1.1 m. The phase space selection in this case has already taken place before the beam of charged particles 6 enters the rotatable section 8.

[0139] FIG. 3 shows a schematic sectional view of an embodiment of an energy correction unit 18 in the form of a degrader, such as can, for example, be used in the beam guidance system 2 or 2. The energy correction unit 18 has a plurality of block-shaped energy correction elements 62a, 62b, 62c, 62d, 62e moveable transversally to the beam of charged particles 6 and two wedge-shaped energy correction elements 64a, 64b moveable transversally to the beam of charged particles 6.

[0140] The block-shaped energy correction elements 62a, 62b, 62c, 62d, 62e are moveable here along the arrow 66 perpendicularly to the beam of charged particles 6. This allows differing adjustments of the energy of the charged particles of the beam of charged particles 6, depending on which of the block-shaped energy correction elements 62a, 62b, 62c, 62d, 62e is pushed into the beam of charged particles. For this, the block-shaped energy correction elements 62a, 62b, 62c, 62d, 62e seen in the direction 12 of the beam of charged particles 6, can have different widenings. Here the block-shaped energy correction elements 62a, 62b, 62c, 62d, 62e provide a rough adjustment of the energy of the charged particles of the beam of charged particles 6, because the energy of the charged particles of the beam of charged particles 6 can be adjusted to discrete values by the block-shaped energy correction elements 62a, 62b, 62c, 62d, 62e.

[0141] The wedge-shaped energy correction elements 64a, 64b are similarly movable along the arrow 68 similarly perpendicularly to the beam of charged particles 6. The wedge-shaped energy correction elements 64a, 64b provide fine-tuning of the energy of the charged particles of the beam of charged particles 6 after the beam of charged particles 6 has been guided through one of the block-shaped energy correction elements 62a, 62b, 62c, 62d, 62e. The energy of the charged particles of the beam of charged particles 6 can be continuously adjusted by the wedge-shaped energy correction elements 64a, 64b within a certain range. By moving the wedge-shaped energy correction elements transversally to the beam of charged particles the widening of the wedge-shaped energy correction element 64a, 64b seen in the direction of the beam of charged particles 6 can be changed in the area of the beam of charged particles. The two wedge-shaped energy correction elements 64a, 64b are in this case disposed point-symmetrically to one another. The angled surfaces of the wedge-shaped energy correction elements 64a, 64b are turned towards one another. This arrangement means that an asymmetrical reduction of the energy over the transverse section of the beam of charged particles 6 can be avoided.

[0142] The block-shaped energy correction elements 62a, 62b, 62c, 62d, 62e of the energy correction unit 18 are made of graphite and/or boron carbide. It is similarly conceivable, however, to provide block-shaped energy correction elements in different materials. The wedge-shaped energy correction elements 64a, 64b of the energy correction unit 18 are also made of graphite and/or of boron carbide. It is also conceivable here to provide wedge-shaped energy correction elements in different materials.

[0143] Due to the compactness of the energy correction unit 18 excessive expansion of the phase space of the beam of charged particles 6 can be avoided.

[0144] Seen in direction 12 of the beam of charged particles 6, behind the energy correction unit 18, a collimator 20 is provided. This can, for example, be the collimator shown in FIG. 1.

[0145] In summary, it is possible, using a smaller deflection angle, caused by the magnetic field of the scanning magnets 46, to achieve a large scanning range at the treatment site 7 and at the same time to keep down the distances of all magnetic elements from the axis of rotation 14.

[0146] The efficiency of the particle beam treatment system from FIG. 1 can be determined by means of more accurate Monte Carlo calculations. For example, the transmission efficiency at the treatment site 7 when decelerating an energy emitted by a cyclotron from 215 MeV to 70 MeV is still approximately 3.3%. This means that a cyclotron current of a few 10 nA is required in order to achieve a current of 1 nA at the treatment centre. For a deceleration to 90 MeV, the transmission when superconducting solenoid magnets are used is for example five times higher than when quadrupole magnets are used. The width of the beam spot here can be set at 3.6 mm (1) with a very low ellipticity (approximately 3-5%). The momentum width of the charged particles arriving at the treatment site 7 can be varied between 4 and 9 per thousand. At the same time, the size of the beam spot at the treatment site 7 is maintained. It has been shown that for a deceleration by the energy correction unit 18 to 90 MeV a transmission efficiency up to the treatment site of up to 10% can even be achieved.

[0147] For the above results it is assumed that the magnetic fields of the solenoid magnets are constant for particle energies of 70 MeV-200 MeV. The first solenoid 16a generates a magnetic field of 11.2 tesla with a cold bore of 30 mm. The second solenoid 16b generates a magnetic field of 6.16 tesla with a cold bore of 52 mm. The material of the energy correction unit 18 is assumed to be boron carbide. The magnetic fields of the quadrupole magnets scale for energies of 120 MeV with the average momentum of the decelerated beam.

[0148] The physical principles of the interaction between protons and matter and the programs used for calculating the properties of beam guidance systems are described in the following scientific reports: [0149] Particle Data Group, W.-M. Yao et al., The Review of Particle Physics, Journal of Physics G33 (2006) 1 and update 2008. [0150] Karl L. Brown, Sam K. Howry, TRANSPORT, A Computer Program for Designing Charged Particle Beam Transport Systems, SLAC Report No. 91 (1970), SLAC Report 91, Rev. 3 (1983) and later updates of the TRANSPORT program by U. Rohrer and others. [0151] U. Rohrer, PSI Graphic TURTLE Framework based on a CERN-SLAC-FERMILAB version by K. L. Brown et al., http://aea.web.psi.ch/Urs_Rohrer/MyWeb/turtle.htm. [0152] J. Drees, Passage of Protons through Thick Degraders, Cryoelectra Report September 2008.
The contents of these scientific reports are incorporated herein by reference in their entireties.

[0153] The principle of an x-y scanning magnet is described in the following scientific report: [0154] V. Anferov, Combined X-Y scanning magnet for conformal proton radiation therapy, Med. Phys. 32 (3), March 2005.
The contents of which are incorporated herein by reference in its entirety.

[0155] All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0156] The use of the terms a and an and the and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms comprising, having, including, and containing are to be construed as open-ended terms (i.e., meaning including, but not limited to,) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., such as) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0157] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.