EP2652746A1

EP2652746A1 - Chromatic energy filter

Info

Publication number: EP2652746A1
Application number: EP11804662.2A
Authority: EP
Inventors: Ingo Hofmann
Original assignee: GSI Helmholtzzentrum fuer Schwerionenforschung GmbH
Current assignee: GSI Helmholtzzentrum fuer Schwerionenforschung GmbH
Priority date: 2010-12-13
Filing date: 2011-12-09
Publication date: 2013-10-23
Also published as: DE102010061178A1; US9390824B2; WO2012080118A1; US20130256556A1

Abstract

The invention relates to an energy filter device (1, 23) for particle beams (3) of charged particles (3), comprising at least one focusing device (12, 20, 27, 28, 29) and at least one radiation separation device (15, 17, 25, 30, 37). The at least one focusing device (12, 20, 27, 28, 29) is thereby implemented as an energy-dependent focusing device (12, 20, 27, 28, 29).

Description

Chromatic energy filter

The invention relates to an energy filter device for radiation, in particular an energy filter device for particle radiation of preferably charged particles, which has at least one focusing device and at least one radiation separation device. Furthermore, the invention relates to a particle radiation source, in particular a particle radiation source for the provision of particle radiation with specific energies, which has at least one target device, in particular at least one laser target device, and at least one energy filter device. Furthermore, the invention relates to a method for the energy-dependent filtering of radiation, in particular particle radiation of preferably charged particles. Moreover, the invention relates to the use of an energy-dependent focusing device for the energy-dependent filtering of radiation, in particular of particle radiation. In many fields, there is sometimes a need in the art to pass only certain portions of the signal through one signal, but to separate other portions of the signal from the signal. Such devices are commonly referred to as filters.

For example, it is sometimes necessary to allow only a certain energy range through the filter to pass through from an input radiation having a broad energy spectrum, but to split off other energy regions of the radiation to be processed (such as "radiation") Frequency filters are also mentioned in part, whereby the energy of radiation can be converted into a frequency by means of the so-called De Broglie relationship, and vice versa.This not only applies to photon radiation but also to particulate radiation (also called corpuscular radiation) ).

Particularly in the particle accelerator technique, it proves to be necessary on a regular basis to pass certain energy ranges through an energy filter while other energy ranges are to be filtered out by the filter. This applies not only to uncharged particles, but above all to charged particles (for example, electrons, protons and heavy ions, or more generally charged and / or uncharged leptons and / or hadrons). In the meantime, the particle accelerator technique has evolved from pure (basic) research and is now routinely used in some areas. Purely by way of example, electron welding methods, but in particular also the medical application of particle radiation, such as in cancer therapy, are mentioned. Particularly in cancer therapy, ions, especially heavy ions (for example carbon ions, oxygen ions, neon ions, nitrogen ions) have NEN and the like) proved to be extremely advantageous, since such heavy ions have a pronounced Bragg peak, and it is thus possible to introduce a specific radiation dose focused not only in an xy direction, but the dose entry to a certain depth range (z-direction) to limit.

So far, such particle beams (ie, in particular heavy ion particle beams) are typically produced for use using linear accelerators, particle cyclotrons and / or particle synchotrons. However, the apparatus required of such particle synchotrons is relatively large, so that efforts are underway to reduce the effort. In addition, particle beams generated by linear accelerators, cyclotrons and synchotrons, respectively, have certain physical disadvantages. Furthermore, such accelerators are very large in relation to the amount of particles produced and are less energy-efficient, which results in correspondingly high installation and operating costs.

A proposal for an alternative generation possibility of particle beams, in particular heavy ion particle beams, consists in the generation of the particle beams by means of laser. A high-energy laser is directed onto a thin foil. The actual acceleration process of the ions takes place immediately behind the thin film which is irradiated on the front side by the laser light with extremely high power density (typically in the range of 10 ²¹ watt / cm ² ). The thermal energy deposited thereby in the film causes the acceleration of the ions by thermal motion effects.

Particularly in the case of this proposed accelerator concept, ions which, unlike the properties of particle synchotrons or linear accelerators, occur, are liberated from an essentially punctiform starting position in the shape of a bündel to the outside. About that In addition, a very wide range of different particle energies occurs. It is therefore desirable to focus the angularly fanned out radiation bundle and also to filter out the usable energies. It would also be particularly preferred in particular if the filtering were variable in order to be able to realize a depth modulation in the irradiation of material (for example tissue of a patient) in a simple manner.

It has been found that previous concepts for energy filtering radiation of particle radiation typically have greater deficiencies, especially when used in conjunction with laser target-film particle accelerators.

It is therefore the object of the invention to propose an energy filter device for radiation, in particular an energy filter device for particle radiation of preferably charged particles, which is improved over known energy filter devices. Another object of the invention is to propose a particle radiation source, in particular a particle radiation source for the provision of particle radiation with specific energies, which is improved over known particle radiation sources. A further object of the invention is to propose a method, which is improved over known methods, for the energy-dependent filtering of radiation, in particular of particle radiation, preferably of charged particles.

It is proposed to design an energy filter device for radiation, which has at least one focusing device and at least one radiation separating device, in such a way that the at least one focusing device is designed as an energy-dependent focusing device. The energy filter device for radiation may in particular be an energy filter device for particle radiation. your. The particle radiation may preferably be charged particles. The particles may in particular be charged and / or uncharged particles, such as charged / uncharged leptons and / or charged / uncharged hadrons. By way of example, electrons, protons, mesons, pions, neutrinos, antiprotons, ions and / or molecules, for example ions of hydrogen, helium, nitrogen, oxygen, carbon, neon, are to be mentioned at this point. Of course, it is also possible that a mixture of different ions and / or other particles, in particular the aforementioned particles, is used. The energy filter device can perform a filter function in any way. In particular, it is conceivable that only ions are transmitted in a certain energy interval. The energy interval may be closed on two sides, but may also be closed only on one side (that is, for example, such that only particles up to a certain energy or conversely particles above a certain energy are transmitted). It is also possible that not only ions in a specific energy range are transmitted, but conversely ions in a certain energy range are filtered out, while ions in all other particle energies are allowed to pass through. Of course, the filtering does not have to be limited to a single area, but several pass-through windows and / or blocking windows can also be provided. Furthermore, the filter curves may have a substantially arbitrary "shape." For example, these may be, for example, rectangular filter curves which may be "flattened" on one side and / or two sides and / or "smeared" In particular, it may also be a Gauss-shaped filter curve with a "flat top"("Fiat-Top"), mixed forms of different filter curves are of course also conceivable underneath a focusing device any devices which are at least temporarily and / or at least in some areas allow a certain merger (in particular in the sense of a converging lens). In particular, the focusing devices can make it possible to convert at least one specific part of a radiation consisting in particular of ions originating from a point source into a "parallel beam" and / or a "parallel beam" to a focal point (or to a plurality of points) Focus points). In particular, this also includes the possibility that the radiation emanating from a point source is diffracted such that it is focused onto another focal point (or to several focal points). As already mentioned, this bundling effect does not necessarily have to be "complete", but can in particular be limited to specific energy ranges, to certain local areas of the focusing device and the like ) for different energies and / or for different spatial areas, and / or that no focusing effect is possible in certain spatial areas and / or at certain energies This may be a "split operation", the way in which the two (or more) portions are directed in different directions. Likewise, it is also conceivable that the two (or more) different subregions are attenuated to different degrees (attenuated) (including the possibility that subregions are virtually not attenuated, while other subregions are weakened almost completely or to a negligible level ). Of course, another treatment is to be considered, such as the conduction of a specific frequency range in a Frequenzvervielfacherbereich or der- same. An energy-dependent focusing device is to be understood in particular as meaning that the focusing for different energy sources The radiation is done in different ways. This can - in the sense of the above explanations - be understood to the effect that, for example, a focus for different energies at different locations (possibly also at several locations) takes place. It is also possible that, in particular for certain energy ranges, no focusing takes place, whereas for other energy ranges such a focusing takes place or can take place. By means of the proposed "combination effect" of focusing on the one hand and energy-dependent focussing on the other hand, it is possible to focus both the radiation and a filtering process by resorting to the same components (or by resorting to some - possibly jointly formed - subcomponents) On the other hand, the lower number of components both energy can be saved, and typically (unwanted) aberrations can be reduced.Furthermore, as a rule, the overall size of the device can also be significantly reduced The focusing effect of the energy-dependent focusing device can optionally be termed - as an analogue to the optics - by the term "chromatic focusing" or "chromatic aberration." The already mentioned "Ko Combination effect "proves particularly in connection with components in which both" effects "must be used as particularly advantageous. Purely example, here are laser-target particle accelerator call, in which on the one hand, a focus of the radiant emitted from a point source particle radiation is required, in particular to realize an effective yield of the radiation generated by the laser target particle accelerator (and thus an acceptable On the other hand, to carry out an energy filtering, since with such laser-target accelerators functionally due to an extremely wide energy dispersion is available. It is proposed to form the energy filter device with exactly one and / or with exactly two beam separation devices. Initial calculations have surprisingly shown that for both a filter that passes only energies above or below a certain limit energy (where the transition at the boundary energy can be "fluent") and energy filter devices that have one or more energy ranges By means of the small number of radiation separation devices, the complexity, the size and the costs for the energy filter device can be reduced, and in addition, a single, possibly also two radiation separation devices are sufficient for the task to be performed As a rule, a smaller number of components (in particular of radiation separation devices) typically leads to an improved output quality of the filtered radiation, since typically fewer defect quantities are included in the "processing" of the radiation n. Accordingly, such a structure may prove to be particularly advantageous. Furthermore, it is proposed that at least one variable radiation separation device and / or at least one displaceably arranged radiation separation device be / is provided in the energy filter device. A displaceability of the radiation separation device may in particular be a displacement in the direction of the "optical axis" of the energy filter device, which is particularly advantageous because different "focusing points" can be approached by such a longitudinal displacement, and thus different energies or energies Energy ranges can be selected. As a result, it is possible that with the energy filter device also comparatively fast and uncomplicated energy variation is possible. Such an energy variation is, for example, Herten scanning process in material processing and / or in medical application (for example in tumor therapy) required. But it is also possible that the longitudinal adjustment is used to that, for example, variations in the control of the focusing device (for example, power fluctuations) can be at least partially compensated. This too can prove advantageous. Additionally or alternatively, it is of course also possible to move the radiation separation device in other directions (that is to say in particular in the x-direction or in the y-direction), whereby optionally also rotations of the radiation separation device may be advantageous. In a variable radiation separation device, the length and / or the diameter of the radiation separation device (in particular if it has a radiation separation effect due to "mechanical shaping") can be advantageously changed, for example by enlarging the aperture (diameter) of a radiation separation device In addition or as an alternative, however, it is also conceivable that such an enlargement or reduction of the aperture (or due to some other change) of the radiation separation device results in a displacement of the radiation separation device and / or a change of another component, such as, in particular, the focusing device, is at least partially compensated for. Such a structure can also predefine the flexibility and applicability of the energy filter increase significantly. In particular when a plurality of variable and / or displaceably arranged radiation separation devices are provided, it is also possible to realize a change of the radiation fraction (number of particles) transmitted through the energy filter device by a mutually adapted change of at least two radiation separation devices. This is possible in particular without the energy selection necessarily being changed substantially. Usually, For example, a simultaneous, matched constriction of two radiation separation devices (for example, pinhole and / or other apertures) cause a reduction in the number of transmitted particles. It is possible that a change in the initial divergence (in particular by reduction of the initial divergence) and / or a change in the beam spot size at the output of the energy filter device (and thus possibly the actual target volume of a body to be irradiated) may occur. However, such effects may be counteracted if necessary by adding and / or adapting other components (such as a scattering film).

Furthermore, it is proposed that in the energy filter device at least one focusing device is at least temporarily and / or at least partially formed as a magnetic field generating device, and in particular at least one preferably a plurality of magnetic dipole devices and / or at least one, preferably a plurality of magnetic quadrupole devices, more preferably a Diplett and / or a triplet and / or a quadruple and / or a multiplet of quadrupole devices and / or at least one, preferably a plurality of solenoid devices and / or at least one, preferably a plurality of Helmholtz coil devices and / or at least one, preferably a plurality to superconducting magnetic field generating devices and / or at least one, preferably a plurality of normal-conducting magnetic field generating devices. In particular, magnetic fields have proven to be particularly advantageous for the deflection of specially charged particles. Accordingly, the use of magnetic field generating devices proves to be advantageous. The explicitly mentioned devices have moreover proved to be suitable and, as a rule, also advantageous for the deflection of, in particular, charged particles. In particular, the use of quadrupole devices (in particular a plurality of quadrupole devices) advantageous if relatively small angular ranges are to be focused. Solenoid devices have proved to be particularly advantageous, in particular, when comparatively large angular ranges are to be focused. Typically, solenoid devices are typically elongate coil devices, often in the form of a type of air coil, which are "shot through" in the coil longitudinal direction by the particle beam As a rule, energy-dependent focussing devices can be formed using magnetic field generating devices, in particular using the magnetic field generating devices mentioned, in a particularly simple manner. The use of superconducting coils can prove to be particularly advantageous if comparatively strong magnetic fields are to be generated, which in particular compares should be constant. On the other hand, normally conducting magnetic field generating devices are particularly advantageous if the magnetic fields to be generated are to vary over a particularly wide range. Of course, a combination of superconducting and normal conducting magnetic field generating devices should also be considered, particularly such that a strong magnetic field (which is typically generated by the superconducting magnetic field generating device) is superimposed by a smaller, time varying magnetic field (typically generated by a normal conducting magnetic field generating device) and thereby "modulated".

Furthermore, it may prove advantageous if a plurality of focusing devices and / or a plurality of magnetic field generating devices are provided in the energy filter device, wherein the Focusing devices and / or the magnetic field generating devices act at least partially and / or at least partially focusing in different directions. If a plurality of focusing devices or magnetic field generating devices is used, it may be possible to make a single focusing device / magnetic field generating device smaller or weaker and still achieve the desired overall effect in combination with other focusing devices / magnetic field generating devices. Moreover, by using a plurality of focusing devices and / or magnetic field generating devices, it is possible (in particular when using quadrupole devices) to effect a deflection in different directions, which in particular can also be focusing. In this way, for example, the entire xy plane can be focused on a point (possibly also on a straight line or the like), so that the overall acceptance of the device (or the total emittance of the finally generated beam having particles, preferably ions) can be significantly increased. The focusing must - as already mentioned - not necessarily be symmetrical (in particular rotationally symmetric). On the contrary, for example, an n-fold symmetry can be considered, in particular with n = 2, 3, 4, 5, 6, 7, 8 and the like. In principle, however, it is also possible to design the energy filter device in such a way that it only focuses in a single direction. Furthermore, it is preferred if, in the case of the energy filter device, the energy dependence is expressed at least temporarily and / or at least partially and / or at least partially as a shift of the focal point, in particular as a shift of the focal point in the longitudinal direction. Such a displacement of the focal point is particularly advantageous when using radiation separation devices, since these are comparatively simple Way "spatial resolution" (or "location-dependent") can be formed. The total cost of the energy filter device can then be particularly simple. In particular, it is possible, for example, for the radiation separation device to be designed as a simple boundary wall with a boundary edge. This is correspondingly easy.

Furthermore, it can prove to be advantageous if, in the energy filter device, at least one radiation separation device is formed at least partially and / or at least partially as a section-wise absorber device. Experience has shown that the energy ranges to be separated by the energy filter device are generally meaningless to use "on the spot." Accordingly, absorption ("elimination") of the corresponding energy ranges is particularly expedient, and moreover usually very easy to carry out (for example by simply providing a compact, radiopaque material). Such absorption may prove to be advantageous in particular in connection with a controlled change in the number of particles transmitted through the energy filter device. Furthermore, it can prove to be particularly advantageous if, in the energy filter device, the at least one radiation separation device is formed at least partially and / or at least partially as an aperture device and / or at least partially and / or at least partially as an axial absorber, wherein the at least one aperture device and or the at least one axial absorber device is at least partially and / or at least partially provided with obliquely-truncated surfaces and / or has at least partially and / or at least partially a frusto-conical and / or a double-cone-stump-like surface. An aperture device may in the simplest case be a type of hole formed in a compact material. It is not necessary that the hole size is variable - However, it is advantageous if this is made possible in particular by suitable design measures. An axial absorber device can be designed in particular in the form of a type of rod, which is arranged in particular in the middle of the optical axis. Preferably, the rod may have a frusto-conical shape. The (truncated cone shaped) rod can be used in particular to provide an (additional) attenuation for too high and / or too low energy ranges. Often, however, it can prove quite sufficient to provide a single aperture device to pass a particular energy slice and to attenuate the rest. It is only for the sake of completeness that it should be pointed out that, of course, completely different principles and / or shapes can be used. The term "obliquely-beam-optimized surface" is to be understood in particular as meaning a surface which is arranged at an angle and / or in a position such that a just-permissible particle beam (in particular maximum value and / or minimum value of particle energy) in one Type "parallel incidence" at least partially along the corresponding surface runs. This has the advantage that - if the particle beam exceeds the permissible limit value - it has to pass through a material over a particularly long distance, and accordingly is greatly attenuated. With such a training so a particularly sharp separation is usually possible. In addition or as an alternative, a particularly effective avoidance of "impurities" by secondary particles (for example, released photons, neutrons, electrons and the like) can be avoided by such a design, which is correspondingly advantageous Generally frusto-conical and / or double frustoconical surfaces, which can both confine a solid to the outside and confine a hollow body in a block of material (possibly also a combination thereof). Furthermore, it may be advantageous if the energy filter device has at least one radiation separation device, which is designed as a direction-dependent radiation separation device, in particular as an angle-direction-dependent radiation separation device. That is, a different energy firing width can be separated and / or transmitted (or attenuated) in different directions by the radiation separation device. This is possible, for example, by non-rotationally symmetric or non-rotationally symmetrical radiation separation devices. If, for example, the radiation separation device is designed as a diaphragm device, such a directional dependence can be formed in the form of a hole with a plurality of additional recesses pointing radially outwards. For example, one, two, three, four, five, six, seven, eight, nine, ten or more, preferably radially outwardly extending additional recesses to think. With such a directional dependency (which can usually also be partially eliminated again by subsequent components, in particular by one or more downstream scattering films), it is possible, in particular, for not only directional dependence to be generated but (finally) additionally or alternatively An additional energy lubrication can be realized, which can also be designed in particular so that there is a desired energy distribution. A particularly preferred energy distribution in this context is a Gaussian energy distribution, although other forms are conceivable and may also be advantageous. However, a gaussian superimposition usually has the advantage, in particular in medical applications, that such a superimposition of several gaussian curves within the framework of a scanning process (which in particular includes a depth scan) and the radiation entries superimposed here prove to be advantageous. Furthermore, it can prove to be advantageous if the energy filter device comprises at least one upstream radiation separation device, which in particular effects a radiation separation with respect to the solid angle region of the radiation entering the energy filter device. By means of such a radiation separation device, for example, a (usually unwanted) "bombardment" of parts of the focussing device (for example a solenoid) and the like can be effectively avoided, whereby secondary particles such as electrons, neutrons and the like can be avoided also damage to the corresponding, otherwise "bombarded" components avoidable.

It is furthermore advantageous if the energy filter device has at least one radiation scattering device, in particular for outgoing radiation, which is preferably designed as a scattering film device and / or if the energy filter device is provided with at least one downstream focusing device, in particular for the radiation emerging from the energy filter device. If a scattering foil device is used, unwanted spatial distributions (which are in particular non-symmetric or non-rotationally symmetrical) and / or undesired "energy edges" may be smeared, depending on the design (in particular with regard to material and / or material thickness) of the scattering foil Such a scattering film device can be provided in particular behind the last aperture of the energy filter device and / or at a sufficient distance (typically several centimeters) before the last aperture of the energy filter device possible that the exiting radiation is parallelized, which is usually particularly advantageous, especially especially if it has to be transported over a longer distance.

Furthermore, a particle radiation source is proposed which has at least one target device and an energy filter device of the aforementioned construction. In particular, the particle radiation source can be a particle radiation source for providing particle radiation with specific energies. The target device (in this case, for example, may be a target foil or the like) may in particular be a laser target device, that is to say a target device which is irradiated by a laser which is typically particularly strong. The resulting particle radiation source can then have the previously mentioned features, properties and advantages in at least an analogous manner. A development of the particle radiation source in the sense described above is of course possible.

Furthermore, a method for the energy-dependent filtering of radiation is proposed, in which the radiation is split using at least one energy-dependent focusing device and then separated by means of at least one radiation separation device radiation with a desired energy. The radiation may in particular be particle radiation, wherein the particles may be particularly preferably charged particles. The method has the advantages, properties and features already mentioned above in connection with the energy filter device, at least in analogy. In addition, the method can also be modified in the sense of the previous description. Finally, the use of an energy-dependent focusing device for the energy-dependent filtering of radiation, in particular that of particle radiation of preferably charged particles, wherein the radiation is split using the energy-dependent focussing device and then radiation with a desired energy is separated by means of at least one radiation separation device. Due to the proposed use, the properties, features and advantages already described above can be achieved, at least in analogy. Also, the proposed use in terms of the previous description, at least by analogy, be extended or modified.

In the following the invention will be explained in more detail by means of advantageous embodiments and with reference to the accompanying drawings. The figures show:

Fig. 1: a first embodiment of a particle beam source in a schematic view;

2 shows a second embodiment of a particle beam source in a schematic view;

3 shows a typical transmission curve for the one shown in FIG

particle beam:

Fig. 4: a modified particle aperture for use in a

Particle beam source in a schematic plan view from the front;

Fig. 5: a typical energy distribution curve using the in

Fig. 4 shown particle aperture;

6 shows a possible embodiment for carrying out a

Energy selection process.

In Fig. 1, a particle beam source 2 is shown in a schematic plan view from the side. The particle beam source 2 serves to generate a (heavy) ion particle beam (output beam 16, for example Carbon ions), which is useful for use in a medical device for the irradiation of tumors. In order to meet the comparatively high requirements of medical applications, the particles 3 of the starting steel 16 released by the particle beam source 2 must satisfy comparatively high requirements. In particular, the released particle beam 16 must be substantially parallel, ie form a so-called "pencil beam" (pencil-thin particle beam 16). Moreover, the particles 3 contained in the particle beam 16 must lie in a comparatively narrow energy range.

The "classical" and currently most commonly used method of producing such a medical particle beam is to use linear accelerators, usually in combination with particle synchotrons, but such systems are relatively expensive, expensive, have high power consumption, and have In addition, a large volume, in particular a large volume, which must be shielded from the environment radiation technology to avoid pollution of the environment by particle radiation (especially neutrons and / or radioactive radiation).

In contrast, the particle beam source 2 is based on another principle of acceleration, namely the so-called laser-induced particle acceleration. The actual accelerator stage 4 (to the left in FIG. 1) has a very powerful high-power pulsed laser 5, which typically has a power density of approximately 10 ²¹ watt / cm ² . The laser beam 5 generated by the laser 5 is directed onto a target film 7. The laser beam 6 strikes the target film 7 in a small, substantially punctiform area (impact area 8). The actual acceleration zone 9, which is also essentially punctiform, lies on the side of the target foil 7 opposite the impact area 8, namely immediately adjacent to the target foil 7. Due to the laser bombardment, brought amount of energy, there is an extreme heating in the accelerator region 9, so that a divergent beam 10 is released from substantially point-shaped accelerator region 9. The diverging beam 10 is presently represented by four, symmetrically to the central axis 1 1 drawn line. The diverging beam has a substantially continuous intensity distribution, which decreases with increasing angle from the central axis 1 1. In addition to the angle broadening of the generated radiation beam 10, the released particles 3 located in the radiation beam 10 have a large energy variation. In the case of the abovementioned laser power, for example, particle energies in the interval between 0 MeV and 250 to 300 MeV are to be expected for protons.

In order to achieve the highest possible fluency (in other words, to "lose" as few particles as possible), the divergent beam 10 is focused by a solenoid coil 12. The solenoid 12 used is similar to a high intensity chromatic lens in terms of its deflection characteristics This means that particles 3 of different energy are focused at a different distance from the solenoid 12 (or from the target foil 7) to a focal point 13, 14. In FIG For illustration purposes, two foci 13 of particles having a "false" energy (more precisely, too low an energy) are shown, as well as a focal point 14 for particles having the "correct" energy.

1, the particles 3 running together in a "false" focal point coincide in a focal point 13 which lies on (or in) the axially arranged, rod-shaped absorber 15. Accordingly, the corresponding low-energy Particles 3 attenuated by the rod-shaped absorber 15 and thus A more advantageous embodiment results if the rod-shaped absorber 15 has a conical shape and thus has an obliquely-beam-optimized shape Furthermore, a pinhole 17 is provided with a centrally arranged round hole 18. Particles 3, the desired energy are focused by the solenoid 12 at a focal point 14 centered in the circular hole 18 of the aperture 17. Thus, the corresponding particles 3 (after having passed the rod-shaped absorber 15) can be substantially attenuated through the circular hole 18 The same applies to particles 3, which have a slightly different energy from the target energy, since the round hole 18 has a certain size, but particles which are above the upper limit energy meet for the most part to a range of Pinhole 17 on the outside de s edge hole 18 is located. Accordingly, such high-energy particles 3 are attenuated by the pinhole 17. The particles 3 (ie particles with a "correct" energy) passing through the pinhole 17 are directed behind the pinhole 17 onto a scattering foil 19. This typically consists of a plastic material and has a thickness of one to a few millimeters In addition, the scattering foil 19 also causes a certain, typically relatively small angular spread of the individual particle partial beams 3. Since the particles 3 leaving the scattering foil 19 have a certain (albeit comparatively small) spread, the filter curve is smeared. Having angular dispersion, the energy filter 1 is followed by yet another solenoid 20, which forms a thin, parallel particle beam 16 from the slightly divergent particle beam 3. In addition, a displacement of the pinhole 17th provided along the central axis 1 1 of the energy filter 1 (this can be realized for example by a linear motor or a stepper motor using a rack). The displaceability of the pinhole 17 is indicated by a displacement arrow 21. By shifting the pinhole 17, it is possible that the energy of the passing through the energy filter 1 passing particles 3 can be changed. Accordingly, the energy of the particle beam 6 leaving the energy filter 1 can be varied. Such a change in particle energy is required, for example, in order to be able to vary a depth variation of the Bragg peak in a target material (for example in a tissue). Additionally or alternatively, it is also possible to realize such an energy variation by changing the strength of the magnetic field in the solenoid 12. Incidentally, the scattering foil 19 can not only be provided essentially at the "end" of the energy filter 1 (as shown in FIG. 1), but also in front of the perforated plate 17. It is advisable to place between the pinhole 17 and an upstream scattering foil 19 a certain distance (typically several centimeters) so that the scattering caused by the scattering film 19 actually has a smoothing effect on the energy selection.

Furthermore, size change arrows 22 are shown in FIG. These symbolize that the size of the round hole 18 in the perforated plate 17 is variable. This can be realized, for example, in the manner of an iris diaphragm or the like. By changing the size of the round hole 18 in the pinhole 17, it is possible to increase or decrease the width of the filter curve (and thus the width of the interval of transmitted energies). In particular, it is thereby also possible for the relative width of the energy interval to be kept substantially constant in the event of a change in the transmitted energy level can. Such adjustment is typically desired in medical facilities.

Incidentally, it is also possible to provide a second pinhole, in particular in a lying between the target film 7 and the rod-shaped absorber 15 area. In particular, a second pinhole adjacent to and / or behind or within the solenoid coil 12 may be provided. In the presence of two pinhole diaphragms, a simultaneous variation in the size of both pinhole diaphragms allows a variation of the particle fraction passed through the energy filter 1, and thus an intensity variation of the particles 3 leaving the energy filter 1 (without substantially changing the energy range filtered out by the energy filter 1). , The output particle beam 16 generated and released by the particle beam source 2 can then be supplied in a manner known per se to a treatment room, in particular a patient (not shown) located in the treatment room. FIG. 2 shows a modified version of a particle beam source 24 compared to FIG. The difference consists essentially in the different structure of the energy filter 23.

First, analogously to the particle beam source 2 shown in FIG. 1, the laser beam 6 generated by a laser 5 is directed onto a target film 7, so that a diverging particle beam 10 with particles 3 of very different energies and output angles is produced.

The diverging particle beam 10 is first fed to a stopper block 25. This is a block of a good energy-absorbing material (for example, lead), which is centered on the midline never 1 1 has a frusto-conical recess 26. The recess is shaped so that an impact of particle radiation 3 on the surfaces of the (switched-on) solenoid assembly 27 is avoided. As a result, on the one hand the solenoid assembly 27 is spared, on the other hand the generation of secondary radiation (gamma radiation, electron radiation, neutron radiation and the like) is prevented. The frusto-conical recess 26 is shaped such that the cone tip would lie in the punctiform accelerator region 9. Accordingly, the surface of the recess 26 extends parallel to the particle beams 3 immediately adjacent to the surface of the recess 26. In other words, the recess 26 is slanted beam optimized. Particle beams 3 with a slightly smaller angle than the angle of the recess 26 pass through the stopper block 25 unhindered. By contrast, particle beams 3 with a slightly larger angle completely pass through the thickness of the stopper block 25 and are therefore sufficiently attenuated.

The solenoid assembly 27 in the present embodiment of the particulate filter 23 consists of a superconducting coil 28 and a normal-conducting coil 29. In the present case, the two coils 28, 29 of the Solenoidanord- tion 27 are arranged concentrically to each other. However, it would also be conceivable, for example, a serial arrangement in the direction of the central axis 1 1 of the energy filter 23. The superconducting solenoid 28 causes a strong, but constant magnetic field. With the help of the normal-conducting solenoid 29, however, an additional, in particular temporally variable magnetic field can be superimposed on this magnetic field. As a result, the (energy-dependent) focus of particles 3 of a specific energy along the central axis 1 1 of the energy filter 23 can be shifted by "electrical measures." In particular, the energy-filtering properties of the energy filter 23 can be varied. In the illustrated embodiment of the energy filter 23, a diaphragm block 30 is provided. The diaphragm block 30 has a double truncated cone-like recess 31 in its interior. The recess 31 is shaped so that they each run parallel to particles 3 with the highest, still permissible (not weakened) energy or the lowest, still permissible (not weakened) energy. Accordingly, the surface of the recess 31 of the diaphragm block 30 is designed obliquelystraight-optimized. Again, the effect is - as already explained above - that either no attenuation takes place or a weakening over the entire length of the diaphragm block 30 takes place away.

As indicated by the shift arrow 21, the diaphragm block 30 can be moved parallel to the central axis 1 1 in the embodiment of the energy filter 23 shown here. Optionally, a variability of the recess 31 (in particular in terms of size and / / shape) to think.

The particles 3 leaving the diaphragm block 30 are fed to a scattering foil 19 (analogous to the energy filter 1 shown in FIG. 1), where they are easily processed and smeared with respect to their energy ranges. Subsequently, the particles 3 are "parallelized" in a downstream solenoid 20 to form a parallel beam 16.

FIG. 3 shows a typical energy spectrum of an output particle beam 16. Here, along the abscissa 32, the particle energy in the MeV and along the ordinate 33, the relative transmission is shown. As can be seen, the filter curve 34 has flattened lateral flanks 35 (in particular due to the permeability of the round hole 18 and the influence of the scattering foil 19) and a flat plateau 36. For some applications, the flat plateau 36 of the filter curve 34 is undesirable. Especially in the treatment of a tumor by a raster scan application using a pencil-thin particle beam, it is desirable that the filter curve has a Gaussian profile. Because a superimposition of different Gaussian profiles again results in a gaussiform profile, so that the calculation of the treatment planning - and thus the subsequent actual irradiation - can be made more accurate and easier. In order to make the filter curve 34 "gauss-like" shown in FIG. 3, it is possible, instead of a diaphragm block 30 with a substantially circular recess 31, to use a diaphragm block 37 which has a suitably formed passage cross-section 38 4. A possible embodiment for a diaphragm block 37 with a suitable recess 38 is shown in Fig. 4. Here, the diaphragm block 37 is shown in a schematic cross-section The cross-sectional plane is perpendicular to the central axis 1 1 of the energy filter Block 37 may be used instead of the shutter block 30 of the energy filter 23 shown in FIG.

As you can see, the recess 38 has a central hole 39 in the middle. At the outer edge of this central hole 39 - in the present case four - club-like extensions 40 of the recess 38 can be seen. Of course, it is possible that a different number of club-like extensions 40 is used. In the present case, the club-like extensions 40 are each formed identically; However, it is quite conceivable that the club-like extensions 40 are each formed differently. Due to the special shaping of the club-like extensions 40, it is possible that with respect to the energy no sharp section edge occurs, but different energies with different percentages can pass through the aperture block 37. The recess shown in Fig. 4 is designed so that ultimately an approximately gaussian configuration of the filter curve 41 (see FIG. 5) results.

In the shaping of the recess 38 (in particular the club-shaped extensions 40), care must be taken that the relative transmission of a particle group to the energy with associated radius R _{b is} T = F (R _B ) / (RB ² × π) where F _B = F (R _B ) is the area not occupied by absorber material within the recess 38.

In addition, the recess 38 is shaped such that again results in a schrägstrahloptimierte surface of the recess 38. For cross-sections that lie in front of or behind the cross-sectional plane shown in FIG. 4 in the direction of the central axis 11, the recess 38 is correspondingly larger or smaller.

Finally, FIG. 6 briefly shows a method 42 for the energy-dependent filtering of particle radiation 3 of charged particles. For this purpose, in a first method step 43, the electrically charged particles 3 produced, for example, by a high-energy laser 5 in conjunction with a target 7 are directed to a suitable focal point 14 by a suitable device (for example one or more solenoids 12, 27, 28, 29) focused. In a second method step 44, the particles 3 focused on the focal point 14 are separated from the other particles 3 (the other particles 3 preferably being attenuated). Thus, at the end 45 of the process 42 (of course, the process 42 can still be modified), a focused particle beam 16 is obtained with particles 3 of suitable energy. LIST OF REFERENCE NUMBERS

1 . Energy filter 23. Energy filter

2. Particle beam source 24. Particle beam source

3. Particles 30 25. Stopperblock

4. accelerator stage 26. recess

5. Laser 27th solenoid assembly

6. Laser beam 28. Superconducting solenoid

7. Target foil 29. Normal conducting solenoid

8. Impact area 35 30. Aperture block

9. accelerator area 31. recess

10. Divergent rays32. abscissa

bundle 33rd Ordinate

1 1. Center axis 34. Filter curve

12. Solenoid Coil 40 35. Flank

13th focal point (wrong Ener36th plateau

gie) 37. Aperture block

14th focal point (right Ener38 recess

gie) 39. central hole

15. Rod-shaped absorber 45 40. Extensions

16. Source particle beam 41. Filter curve

17. Aperture 42. Method of energy ab¬

18. Round-shaped filtering of

19. Scattering film radiation

20. Solenoid 50 43. Focus on Brenn¬

21. Shift arrow point

22. Size change arrow 44. Separation of particles

Claims

P a n t a n s p r e c h e

Energy filter device (1, 23) for radiation, in particular energy filter device (1, 23) for particle radiation (3), preferably energy filter device (1, 23) for radiation from charged particles (3), comprising at least one focusing device (12, 20, 27, 28 , 29), as well as at least one radiation separation device (15, 17, 25, 30, 37), characterized in that the at least one focusing device (12, 20, 27, 28, 29) as energy - dependent focusing device (12, 20, 27, 28 , 29) is formed.

Energy filter device (1, 23) according to claim 1, characterized by exactly one and / or by exactly two radiation separation devices (15, 17, 25, 30, 37).

Energy filter device (1, 23) according to claim 1 or 2, characterized by at least one variable radiation separation device (17, 30) and / or by at least one displaceably arranged radiation separation device (17, 30, 37).

Energy filter device (1, 23) according to one of the preceding claims, characterized in that at least one focusing device (12, 20, 27, 28, 29) at least temporarily and / or at least partially as a magnetic field generating device (12, 20, 27, 28, 29) is formed, and in particular at least one, preferably a plurality of magnetic dipole devices and / or at least one ne, preferably a plurality of magnetic quadrupole devices, particularly preferably a doublet and / or a triplet and / or a quadruplet and / or a multiplet on quadrupole devices and / or at least one, preferably a plurality of solenoid devices (12, 20, 27, 28, 29) and / or at least one, preferably a plurality of Helmholtz coil devices and / or at least one, preferably a plurality of superconducting magnetic field generating devices (28) and / or at least one, preferably a plurality of normal conducting magnetic field generating devices (12, 20, 29 ) having.

Energy filter device (1, 23) according to one of the preceding claims, in particular according to claim 4, characterized by a plurality of focusing devices (12, 20, 27, 28, 29) and / or a plurality of magnetic field generating devices (12, 20, 27, 28, 29), wherein the focusing devices (12, 20, 27, 28, 29) and / or the magnetic field generating devices (12, 20, 27, 28, 29) at least partially and / or at least partially focusing in different directions.

Energy filter device (1, 23) according to one of the preceding claims, characterized in that at least one focusing device (12, 20, 27, 28, 29) the energy dependence (13, 14) at least temporarily and / or at least partially and / or or at least partially expressed as a shift of the focal point (13, 14), in particular as a shift of the focal point (13, 14) in the longitudinal direction (11) expresses.

Energy filter device (1, 23) according to any one of the preceding claims, characterized in that at least one radiation separation onsvorrichtung (15, 17, 25, 30, 37) at least partially and / or at least partially as a piece-wise absorber device (15, 17, 25, 30, 37) is formed.

8. Energy filter device (1, 23) according to one of the preceding claims, in particular according to claim 7, characterized in that the at least one radiation separation device at least partially and / or at least partially as a diaphragm device (17, 25, 30, 37) and / or at least partially and / or at least partially formed as an axial absorber device (15), wherein the at least one diaphragm device (17, 25, 30, 37) and / or the at least one axial

Absorbing device (15) is at least partially and / or at least partially provided with schrägstrahoptimierten surfaces (26, 31, 38) and / or at least partially and / or at least partially a frusto-conical (26) and / or a double truncated cone-like surface (31).

9. Energy filter device (1, 23) according to one of the preceding claims, in particular according to claim 7 or 8, characterized in that at least one radiation separation device (15, 17, 25, 30, 37) as a direction-dependent radiation separation device (25, 30,

37), in particular as an angular direction-dependent radiation separation device (25, 30, 37) is formed.

10. Energy filter device (1, 23) according to one of the preceding claims, characterized by at least one upstream radiation separation device (25), which in particular a radiation separation (25) with respect to the solid angle range (10) in the energy filter device (1, 23). Incoming radiation (3) causes. 1 1. Energy filter device (1, 23) according to any one of the preceding claims, characterized by at least one Strahlungsstreuungseinrich- device (4, 19), in particular for outgoing radiation (3, 16), which is preferably formed as a scattering film device (19) and / or characterized by at least one downstream focusing device (20), in particular for the radiation from the energy filter device (1, 23) emerging radiation (3, 16).

12. Particle radiation source (2, 24), in particular particle radiation source (2, 24) for the provision of particle radiation (3) with certain energies, comprising at least one target device (7), in particular at least one laser target device (5, 7), and at least one Energy filter device (1, 23) according to one of claims 1 to 10.

13. A method for energy-dependent filtering of radiation (3), in particular particle radiation of preferably charged particles (3), in which the radiation (3) using at least one energy-dependent focusing device (12, 20, 27, 28, 29) is split and then by means of at least one radiation separation device (15, 17, 25, 30, 37) radiation (3) is separated with a desired energy.

14. Use of an energy-dependent focusing device (15, 17, 25, 30, 37) for the energy-dependent filtering of radiation (3), in particular particle radiation (3) of preferably charged particles, wherein the radiation (3) using the energy-dependent focusing device (12, 20, 27, 28, 29) is split and then by means of at least one radiation separation device (15, 17, 25, 30, 37) radiation (3) is separated with a desired energy.