WO2011026697A2

WO2011026697A2 - Mwpc detector comprising graphene for reducing penumbrae in particle therapy

Info

Publication number: WO2011026697A2
Application number: PCT/EP2010/061047
Authority: WO
Inventors: Matthias Saar
Original assignee: Siemens Aktiengesellschaft
Priority date: 2009-09-03
Filing date: 2010-07-29
Publication date: 2011-03-10
Also published as: DE102009040007A1; WO2011026697A3

Abstract

The invention relates to a detector for determining a position of charged particles of a particle beam having an outer envelope closing off a gas volume, said beam passing the detector and the gas being ionizable by the particles. The detector comprises: an anode (A) and two cathode planes (SE1, SE2) arranged on different sides of the anode (A), every cathode plane (SE1, SE2) having a plurality of parallel signal paths (Gr, Cu) for detecting gas ions and thus the presence and the position of a particle. The signal paths (Gr, Cu) of the two cathode planes (SE1, SE2) are twisted relative to each other about an angle. The detector finally contains at least one component of graphene.

Description

description

MWPC detector with graphene for reducing penumbra in particle therapy

The invention relates to a detector for determining a position of charged particles of a particle beam passing through the detector. Such a detector can be used in particular in the context of particle therapy.

Particle therapy is an established method for loading ^¬ treatment of tissue, in particular tumor diseases. Irradiation methods, as they are ^¬ sets in particle therapy find, even in non-therapeutic overall offer application. These include, for example, research work, such as product development, in the context of particle therapy, which are performed on non-living phantoms or bodies, radiation of materials, etc. This charged particles such as protons or carbon or other ions are accelerated to high energies, too formed a particle beam and guided over a high-energy beam transport system to one or more irradiation rooms. The object to be irradiated is usually POSITION YOUR accurately on a roboterba ^{¬-stabilizing} table bearing plate. After this positioning, the irradiation with the particle beam can take place. Accordingly, in the irradiation chamber, the object to be irradiated is irradiated in a target volume with the par ^¬ tikelstrahl. Charged particles such as protons or heavy ions provide the

Advantage that their energy loss at the end of their range in ^¬ within the object to be irradiated increases sharply. For this reason, a particle beam has a good depth dose distribution, which is described by the so-called Bragg curve. The depth of the sharp Bragg maximum can be precisely determined by the particle energy. This makes it possible to lie in front of and behind the target volume. to save weave; in this area almost no dose is depo ^¬ ned.

The object underlying the invention is to disclose a detector for determining the position of charged particles, which fin can ^¬ the particular within the framework of the particle therapy use.

This object is achieved by a detector having the features of claim 1. Advantageous embodiments and further ^¬ formations are the subject of dependent claims.

The detector according to the invention for determining a position of charged particles of a particle beam passing through the detector has an outer gas volume that terminates the gas

Shell on. Here, the gas is such that it is ionized by the Parti ^¬ angles. Furthermore, the detector comprises an anode and two cathode planes arranged on different sides of the anode. In this case, each cathode plane has a plurality of parallel signal paths for the detection of gas ions and thus the presence and the position of a particle. The signal paths of the two Katode levels are rotated by an angle to each other. Finally, the detector comprises one or more components of graphene.

As it passes through the detector, the particles whose position it is to ionize ionize the gas. Preferably, the particles are charged particles. Due to a successful ionization, the resulting positive ions fly to the two cathode planes. Here they are detected by signal paths. Since several signal paths are present, the determination of the position of a Parti ^¬ cle is thus possible. Because the ionization of the gas takes place at the particle position to be determined, and the resulting positive ions reach the nearest signal paths. Your impact on the signal paths thus indicates the particle position. Each Katodenebene contains multiple signal paths which run paral ^¬ lel to each other. The signal paths of a Katodenebene are rotated through an angle, preferably by 90 °, against Dieje ^¬ Nigen the other Katodenebene. As a result, the particle position can be specified in two mutually perpendicular directions.

In the detector according to the invention is at least one component of graphene; this is a material which has interesting properties. Insbeson ^¬ particular, the electrons within the graphene have a high speed so that the duration of electric signals is small. So using graphs for electrical Messun ^¬ gen, then the required measurement time is reduced. Furthermore, graphene is gas-tight in the form of an extremely thin layer or membrane.

It is particularly advantageous if the at least one loading ^¬ stand part is from graphs of the limitation of the beam spread of the particle beam in the position determination of the particles. To determine the position, one or more suitable detectors must be used. However, each material causes a scattering of the particles and thus a Strahlauf ^¬ expansion. This is undesirable since this changes a previously defined beam shape. Accordingly, the detectors cause a beam expansion. It is desirable, therefore, to design the detectors in such a way that reliable detection is compatible with low beam expansion.

In a further development of the invention, the at least one component of graphene is part of the two cathode levels. This approach is based inter alia on the property of large electric ^¬ nengeschwindigkeit in the graph. For this purpose, each cathode plane preferably comprises, as signal paths, parallel graphene tracks and, at an angle, twisted metal tracks parallel thereto. Thus, both the graphene orbits and the metal orbits of each cathode plane become the positively charged ones Ions of the gas detected. The angle between the tracks of the different materials is preferably 90 °. The use of the two different webs in the Katoden levels, for example, by the Katode levels each include a film on one side of the Graphene tracks and on the other side of the metal tracks are attached. This verhin ^¬ changed a self-touching the different paths.

It is particularly advantageous if the graphene paths of each cathode plane are parallel to the metal tracks of the respective other cathode plane. This allows a redundant position ^¬ determination, because the parallelism between the signal paths of the two cathode levels give the two Katode levels each other corresponding results.

According to an embodiment of the invention, the detector further comprises an evaluation unit for determining the position of particles from signals of their signal paths supplied by a single cathode plane. Since there are two cathode levels, the evaluation unit can thus determine two individual positions. Furthermore, it is advantageous if the evaluation unit is designed for determining and / or checking the position of particles using, on the one hand, the position determined from signals of its signal paths supplied by a single cathode plane and, on the other hand, the signals supplied from the respective other cathode plane their signal paths certain position. This corresponds to a redundant position determination, which takes place using two individual positions. The reliability of the measurement is thereby increased.

In an embodiment of the invention the evaluation unit is ^¬ forms to determine the position of particles by determination of signal time differences between signals of the paths of a graph Katodenebene and the metal tracks of each other Katodenebene. There is thus a respective Gra ^¬ phenbahn which provides a signal, and a parallel thereto metal web of the other Katodenebene which likewise if a signal has been supplied, compared with each other. Since the electron velocities in the metal track and the graphene track differ from each other, there is a different transit time of the signals in the two signal paths. The transit time difference can be used to draw conclusions about the location of the impact of the positive ions on the signal paths and thus on the position of the Parti ^¬ cle. Thus, the consideration of the Sig ^¬ nalzeitunterschiede allows position determination, whereby a further redundancy of the position determination is provided.

An increase in the redundancy of the position determination within a single detector is advantageous because it can be omitted ^¬ through the use of other detectors. As a result, the unwanted beam expansion is effectively limited.

According to another development of the invention, which can be used additionally or alternatively to the use of graphene in the cathode levels, the at least one component forms as graphene film at least a part of the casing. The envelope enclosing the gas volume is thus either entirely or partially graphene. In doing so, the property of the gas impermeability of even the thinnest graphene films is exploited.

Advantageously, the detector is formed as MWPC-Dekektor ^¬ out. Such detectors are used in particular in particle irradiation systems, which is why the detector according to the invention is particularly suitable for use in a particle irradiation ^facility .

In the following the invention on the basis ^of an exemplary ^embodiment is explained in detail. Showing:

Figure 1: a first schematic overview of the

Construction of a particle therapy system, Figure 2 is a schematic illustration of an irradiation of a target volume by means of a raster scanning device ^¬,

Figure 3: a second schematic overview of the

Construction of a particle therapy system,

FIG. 4 shows the structure of a currently used MWPC

Detector,

FIG. 5: a first novel MWPC detector,

FIG. 6 shows a second novel MWPC detector. Figure 1 shows a schematic representation of a structure of a particle therapy system. This is used to irradiate a patient 14 arranged on a positioning device 12 with a jet 16 of particles, which is referred to below as the particle beam 16. In particular, a tumor-affected tissue of the patient 14 can thereby be connected to the patient

Particle beam 16 are irradiated. It is also possible to enforce the particle irradiation system for irradiating a non ^¬ living object 18, in particular a water phantom, a ^¬. The irradiation of the water phantom 18 is effected examples play for purposes of checking and verifying irradiation parameters before and / or 14, after completed irradiation of a patient may also be provided, other objects, and in particular experimental set-ups as in ^¬ play, cell cultures or bacteria cultures to research schungszwecken with the particle beam 16 to irradiate.

Particles used are charged particles, such as, for example, protons, pions, helium ions, carbon ions or ions of other elements. Typically, such particles are generated in a particle or ion source 20. ^{Instead of} the ion source 20 shown in FIG. 1, a plurality of ion sources 20 may also be present, so that a Radiation with different types of particles is possible, for example with carbon ions and protons.

The ion beam or particle beam generated by the ion source 20 is at a first in the pre-accelerator 22

Energy level accelerates. The pre-accelerator 22 is at ^¬ example, a linear accelerator. Subsequently, the particles are fed into a further accelerator 26, for example a circular accelerator, in particular a synchrotron or cyclotron. In the accelerator 26, the particle beam will be accelerated ^¬ to a required for irradiation energy. After the particle beam has exited the accelerator 26, a high-energy beam transport system 28 transports the particle beam into one or more irradiation rooms 30, 30 ', 30'', where, for example, the positioning device 12 - such as a patient bed - with the patient 14 or the phantom for irradiation planning verification is arranged. In the irradiation space 30 or 30 ', the irradiation of the body 14, 18 takes place from a fixed direction, wherein the body 14, 18 is arranged fixed in space. This Bestrahlungsräu ^¬ me 30, 30 'are called "fixed beam" -Spaces referred. In Be ^¬ action space 30 '' is arranged movably about an axis 32, preferably rotatably mounted gantry 34 vorgese ^¬ hen. By means of the gantry 34, the body 14, 18 to be irradiated can be irradiated from different directions. In this case, the particle beam 16 is rotated about the body 14, 18 to be irradiated by means of the gantry beam guide 36 arranged in the gantry 34. They are representative of the different positions of the Gantrystrahlführung 36 of the gantry 34 in Figure 1, a first position 38 and a second posi tion ^¬ 38 'is shown. Of course, intermediate ^¬ Posi tions for Gantrystrahlführung 36, which are not shown for reasons of clarity, on at least one

Semicircle above the body to be irradiated 14, 18 in ei ^¬ ner imaginary sphere around the body to be irradiated 14, 18 possible. Thus, the target volume to be irradiated can be increased by several Reren directions from perpendicular to the axis 32 are irradiated. This is advantageous for geometric reasons.

In the irradiation space 30, 30 ', the particle beam emerges from an end of a vacuum system of the high-energy beam ^guide 28 designated as a beam outlet 40, 40' and strikes the target volume to be irradiated in the body 14 or 18. The target volume here is usually in an isocenter 42, 42 'of the respective irradiation room 30, 30' are arranged.

The basic structure of a Parti ^¬ keltherapieanlage illustrated with reference to Figure 1 is an example of Partikeltherapieanla ^¬ gen, but can also vary. The embodiments described below are applicable both in connection with the illustrated with reference to Figure 1 and with other particle therapy systems.

FIG. 2 schematically shows an irradiation of a target volume 56 with the raster scanning technique. The raster scanning device has a first particle beam deflection device 46 and a second particle beam deflection device 48, which may in particular comprise magnets. The two particle beam deflection devices 46, 48 are able to divert the beam 16 horizontally or vertically. The arrows indicate the deflection direction of the particle beam 16 in the x-direction (horizontal) and in the y-direction (vertical). Thus, the grid ^¬ caneinrichtung capable of a two-dimensional matrix of dots with the positions (x _j, _j y) to scan or to depart. These points (x _j, y _j) particle energy weils used in combination with the JE as scans spots, scanning punk ^¬ te or sample points are designated. That is, a sampling point is determined by the orientation of the particle beam 16 in the x-direction and y-direction, and by the particle energy. For a combination of x and y values thus exist sev- eral sampling points when particles of different energies are sent from ^¬. The target volume 56 to be irradiated in the patient or object to be irradiated can be considered as isoenergetic

Slices or layers 58a, 58b, 58c, ... 58i together amount ^¬ is considered. In this case, the iso-energy layers 58a, 58b, 58c, ... 58i are each assigned to a specific position on the z-axis. The layers are referred to as isoenergetic, since particles of a certain initial energy mainly interact with the matter of the respective layer, ie the absorbed dose of the particles of this particular initial energy has a large effect only on the respective iso-energy layer according to the respective Bragg maximum.

In the example of Figure 2, the count of the layers on the raster scanning device side starts at 58a, while the layer furthest away from the raster scan device, the distal layer, has the designation 58i, where i denotes the number of layers. For adjusting the particle beam 16 to a respective layer 58a, 58b, 58c, ... 58i, the particle beam 16 each has a different initial energy, wherein the initial energy is that of the particles prior to interaction with the object 14 or 18. Here, the particle beam 16 with the lowest energy in the disc 58a and the particle beam 16 with the highest energy is deposited in the disc 58i.

The irradiation with a raster scan method thus uses a particle beam 16 which is dimensioned so that a single dose can be deposited in the target volume 56 only in a small, circumscribed area. Such a small district corresponds to a destination point, the coordinates of the destination points for the treatment planning being known. Accordingly, a particular destination can be irradiated by driving a ^¬ be voted sampling.

In order to irradiate the entire target volume 56, the different sampling points are successively driven. The Parti ^¬ kelstrahl 16 is thereby using the Partikelstrahlablenkein- deflected directions 46 and 48 and so steered over the target volume. For irradiation of different iso-energy layers, the energy of the particle beam 16 is adjusted to pas ^¬ send. Is shown in Figure 2, a target volume 56 in which three distal iso-energy layers 58 ± 58 ± -i, 58i_2 have been irradiated be ^¬ already, and which scans currently the Parti ^¬ kelstrahl 16 via the subsequent iso-energy layer 58i_3. FIG. 3 shows a further schematic representation of a

Particle irradiation system suitable for raster scan technology. There are two ion sources 20, the Vorbe ^¬ accelerator 22, the circular accelerator 26 and two particle beam deflection means to see 44 and 46th The deflection of the particles by the particle beam deflection devices 44 and 46 takes place in the x and y direction as shown in FIG. 2, while z denotes the direction along the beam. If the particles damage the tissue of the object to be examined, it is necessary to check whether the particle beam is aligned with the correct target volume. As already mentioned above, the alignment of the beam and on the other hand, the particle energy are to determine this volume affected by the radiation-Be ^¬ one hand relevant. ^¬ the corresponding join the Partikelstrahlablenkungs- devices 44 and 46 detectors DET for determining the beam orientation and ionization chambers to determine the particle energy on. The detectors DET measure the position and shape of the particle beam; In this case, the detectors DET are designed as MWPC detectors (Multi Wire Proportional Chamber). For reasons of redundancy, the detectors DET are designed in duplicate, as can also be seen in FIG.

Figure 4 shows the structure of currently used MWPC detectors. This is to detectors for ionizing Strah ^¬ lung or particles which also referred to as wire chambers become. They consist of a rectangular frame Ra, which is enclosed on both sides with a gas-tight film F. Polyimide is usually used here as the film material, eg Kapton®.

The MWPC detectors are traversed by gas (eg 80% Ar and 20% C0 ₂ ) with slight overpressure. The composition and the pressure of the gas are determined so that each particle causes ei ^¬ ne ionization, but without it comes to an independent gas discharge. Inside the frame are three levels SEI, A and SE2 of wires, in each level the wires being parallel to each other. The middle level A is connected to a high voltage source, eg with a positive voltage of 1600 V, and represents the anode. The other two levels SEI and SE2 are the signal levels; they serve to obtain the measurement signal. They are connected via electronic amplifiers to ground, so represent the cathodes. The signal levels SEI and SE2 each have a variety, eg 112, parallel wires at a small distance, eg 2mmm, each other, the wires of the signal level SEI to those of the signal level SE2 rotated by 90 °.

Where the particle beam passes through the detector, the gas is ionized. The ions and resulting in this case Elect ^¬ Ronen of the gas are accelerated by the high voltage. As a result, an avalanche reaction in the vicinity of the wires of the anode A is triggered by the electrons due to the large voltage of the anode. The nearest wires of the signal levels SEI and SE2 pick up the ions from the primary ionization and the avalanche reaction and supply them to the measuring amplifiers, so that they can be detected as a measurement signal. A processor located in the detector reads the measuring amplifiers in the time frame 50 - 250 \ is off. By determining those wires of the signal planes SEI and SE2 which supplied the signals, the x and y direction of the respective particle can be determined. Each solid state in the jet causes a dispersion of the particles and thus a widening of the beam, that is, a magnification ^¬ fication of the penumbra. This scattering is disadvantageous, as this causes a deviation from the desired target volume and thus healthy tissue is also irradiated. The ratio of scattering in solid to air is about 1000 to 1, ie the scattering of a 25 μm thick film corresponds to the scattering in 25 mm air. It is therefore desirable to have as little material as possible in the particle beam after the particle beam ^{deflection devices} 44 and 46. In order to reduce the solid constituents which the particle beam must pass for a reliable determination of its position, the use of graphene is proposed according to the invention.

Only one atomic layer of thin films of graphite are called graphene. It is, so to speak, a carbon sheet. The carbon atoms are arranged in the layer in a two-dimensional honeycomb lattice, so there is a two-dimensional hexagonal carbon crystal before. It is possible to obtain layers which are only one carbon atom thick, for example by stripping individual atom layers of a graphite block; even thicker membranes with several graphene single layers can be produced. The electrons can only move in two dimensions in the graph. For this reason, they move much faster in graphene than in other materials, namely at about 0.3 times the speed of light. In normal conductors such as copper or gold, the electron velocity is about 0.1 times the speed of light, so only one third of electrical ^¬ nengeschwindigkeit in graph. Furthermore, despite the thinness of the layer, graphene is impermeable to gases.

FIG. 5 shows an MWPC detector in which graphs are used. Like the detector of FIG. 4, it has the anode A in the middle, and the signal levels SEI and SE2 on both sides. On each of the signal planes SEI and SE2, parallel gold-coated copper wires are Cu and perpendicular arranged graphene webs or wires Gr. This Sig ^¬ naldrähte here are respectively applied to a film, for example on a coated polyimide film. The signal plane SEI has the gold-plated copper wires Cu in the vertical direction on one side of the film, and the graphene webs Gr in the horizontal direction on the other side of the film. Conversely, the signal plane SE2 has on one side of the film the gold-plated copper wires Cu in the horizontal direction, and on the other side of the film the grain paths Gr in the vertical direction. The copper wires Cu of the two signal levels SEI and SE2 are therefore rotated by 90 ° to each other, as well as the graphene tracks Gr. Accordingly, the horizontal graphene tracks Gr and the horizontal copper tracks Cu, as well as the vertical graphene tracks Gr and the vertical copper tracks Cu, face each other in the detector, separated by the anode A in each case.

The graphene sheets Gr can be produced with the aid of light, for example with a camera flash. This is capable of converting powder from graphite oxide into conductive graphene. A light pulse ^¬ can provide enough heat available to reduce the oxide powder chemically and connect so that graphene is formed. Mixing the graphite oxide with plastic powder results in flexible conductive layers. If you use a shielding pattern mask, you can create targeted paths and even circuits.

If a charged particle ION causes an avalanche at the anode A, the ions resulting therefrom are accelerated to both the right and to the left signal levels SEI and SE2 and trigger signals on the signal wires Cu, Gr on both sides. About measuring amplifier these are fed to a processor and evaluated. On the first signal level SEI, a horizontal graphene track Gr - in the example of FIG. 5, the first graphene track Gr from below - and a vertical copper track Cu - in the example of FIG. 5 the second copper track Cu is addressed from the left; from this, the location, ie the x and y coordinates of the charged particle can be determined. men. On the second signal plane SE2 is a vertical Gra ^¬ phenbahn Gr - the second graph train Gr from left -and a horizontal copper trace Cu in the example of figure 5 - in the example of Figure 5, the first copper track Cu Angle - addressed; from this, too, the location, ie the x and y coordinates of the charged particle can be determined. These two pairs of coordinates must match when measured correctly. This ensures a redundancy of the location. Thus, the use of a second detector is not necessary.

A second redundancy is achieved by considering the transit time differences of the opposite graphene tracks Gr and copper track Cu. The signals SIG1 to SIG4 output by the measuring amplifiers are indicated below in FIG. 5, the curve of the time t being shown to the left. It can be seen that the signals arriving SIG1 and SIG4 the Gra ^¬ phenbahnen Gr earlier than the signals SIG2 and SIG3 the copper traces Cu. This is based on the above-explained higher electron ^velocity in the graph compared to normal conductors.

The skew is now in itself gegenüberlie ^¬ constricting horizontal conductors and in itself determined gegenüberliegen- the vertical ladders. This means that the

Time difference between the signal SIG4 of the vertical graphene track Gr of the second signal level SE2 and the signal SIG3 of the vertical copper conductor Cu of the first signal level SEI is determined. From the difference it can be determined at which vertical position the ions have reached the signal levels SEI and SE2; this corresponds to the determination of the respective horizontal wire. Furthermore, the time difference between the signal SIG2 of the horizontal copper conductor Cu of the second signal level SE2 and the signal SIG1 of the vertical graphene track Gr of the first signal level SEI is determined. From the difference, it can be determined at which horizontal position the ions the signal levels SEI and SE2 achieved; this corresponds to the determination of the respective vertical wire.

Since the signal speed is speed in graph 0.3 of the speed of light, scanning in the gigahertz should be Be ^¬ rich.

Thus, the x and y coordinates of the particle can also be determined on the basis of the transit time differences. It is using the detector of Figure 5 thus a triple Po ^¬ sitionsbestimmung possible. Due to this high reliability can be dispensed with the use of additional detectors. This has the advantage that the outer foils F of FIG. 4 only have to be traversed by the particle beam once, whereas when several detectors connected in series are used, these layers of material would have to be penetrated several times. Thus, the detector according to FIG. 5 contributes to the reduction of the penumbra. FIG. 6 shows a further MWPC detector in which graphs are used. Shown are the frame Ra, the two signal levels SEI and SE2, and arranged between them anode A. The two signal levels SEI and SE2 are preferably designed according to Figure 5; however, they can also be conventional. The films FGr terminating the detector on both sides consist of graphene. This is based on the fact that extremely thin gas-tight films can be produced from graphene. The graphene foils FGr are in this case only one atomic layer thick if possible; however, to increase the mechanical stability, it is also possible to use films consisting of several graphene layers.

Due to the use of graphene achieved reduction of the membrane thickness compared to conventional MWPC detectors, the particle beam is much less dilated. This also reduces penumbra. The invention has been described above by means of an embodiment. It is understood that numerous changes and modifications are possible without departing from the scope of the invention.

Claims

claims

First detector (DET) for determining a position of charged particles (ION) of the detector (DET) passing particle beam (16), with

an outer envelope closing gas volume (F, FGr), the gas being ionizable by the particles (ION),

an anode (A) and two cathode layers (SEI, SE2) arranged on different sides of the anode (A),

each Katodenebene (SEI, SE2) having a plurality of pa ^¬ rallelen signal traces (Gr, Cu) for the detection of gas ions and thus of the presence and position of a Par ^¬ tikels (ION)

where the signal paths (Gr, Cu) of the two Katoden levels

(SEI, SE2) are twisted at an angle to each other, and

at least one component of graphene.

2. Detector (DET) according to claim 1, wherein

the at least one constituent from the graph of limita ^¬ effect of the beam spread of the particle beam (16) is used (ION) when determining the position of the particles.

3. Detector (DET) according to claim 1 or 2, wherein

is at least a part of graphene part of the Katodenebenen at ^¬ (SEI, SE2).

4. Detector (DET) according to claim 3, wherein

each Katoden plane (SEI, SE2) as signal paths (Gr, Cu) parallel graphene tracks (Gr) and twisted at an angle to parallel metal tracks (Cu) comprises.

5. Detector (DET) according to claim 4, wherein

the Katoden levels (SEI, SE2) each comprise a film, on one side of the graphene sheets (Gr) and on the other side of the metal tracks (Cu) are mounted.

Detector (DET) according to one of claims 4 to 5, wherein the graphene sheets (Gr) of each Katode plane (SEI, SE2) are parallel to the metal tracks (Cu) of the other Kato denebene (SEI, SE2).

Detector (DET) according to one of Claims 3 to 6, having an evaluation unit for determining the position of particles (ION) from signals (SIG1, SIG2, SIG3, SIG4) supplied by a single cathode plane (SEI, SE2) of their signal paths (Gr, Cu).

A detector (DET) according to claim 7, wherein

the evaluation unit is designed to determine and / or check the position of particles (ION) using

on the one hand, the signals (SIG1, SIG2, SIG3, SIG4) of their signal paths (Gr, Cu) determined from a single cathode plane (SEI, SE2),

on the other hand, the signals (SIG1, SIG2, SIG3, SIG4) of their respective signal paths (Gr, Cu) from the respective other cathode plane (SEI, SE2).

Detector (DET) according to claim 7 or 8, wherein

the evaluation unit is designed to determine the position of particles (ION) by determining signal time differences between signals (SIG1, SIG4) of the graphene tracks (Gr) of a cathode plane (SEI, SE2) and signals (SIG2, SIG3) of the metal tracks (Cu) each other Katode level (SEI, SE2).

Detector (DET) according to one of claims 1 to 9, wherein the at least one component forms a graphene sheet (FGr) to at least a part of the shell (F, FGr).

The detector (DET) of any one of claims 1 to 10, which is a MWPC decker.

12. Particle irradiation system with a detector (DET) according to one of claims 1 to 11.

13. Use of a detector (DET) according to one of claims 1 to 11 for determining the position of particles (ION) of a detector (DET) passing particle beam (16) in a particle irradiation system.