SYSTÈME D'IRRADIATION COMPORTANT UN SUPPORT DE CIBLERIES DANS UNE ENCEINTE DE RADIOPROTECTION ET UN DISPOSITIF DE DÉFLECTION DE FAISCEAU D'IRRADIATION

SYSTEM OF RADIATION WITH A CIBLERIES SUPPORT IN PREGNANT AND RADIATION BEAM DEFLECTION DEVICE FOR RADIATION This application relates to an irradiation system of a target, especially a radiation system including accelerator particles.

Particle accelerators are devices that are designed to produce beams characterized primarily by the nature of the particles (protons, electrons, etc.), the particle energy and the beam current. Depending on the application for which the accelerator is used (radioisotope production, X-ray or gamma radiation, neutron production, etc.) the beam can interact with different types of targets, e.g. mainly:

- Target the heart which held nuclear reactions, such as the targets used with cyclotrons for the production of radioisotopes for imaging by Positron Emission Tomography (PET or PET in English);

- The stopper targets that are intended to stop and characterize the beam when the accelerator setting phases.

However, the interaction between the beam and the target may result in different types of reactions and consequently to different types of radiation from the target.

Indeed, typically irradiated target in turn emits radiation having particular neutrons and high-energy photons, typically in the form of X or gamma rays. These neutrons and photons are called "primary" when produced by the nuclear reaction that occurs in the target and "secondary" when they come from reactions between neutrons and primary photons and the surrounding material.

A cyclotron is a particle accelerator often used in medical imaging for the production of radioactive isotopes with very short half-life, or even equal half-life less than two hours, such as the following: ¹⁸ F (18 F) : 109.7 minutes, ⁶⁸ Ga (gallium 68): 67.7 minutes, ¹¹ C (1-carbon 1) 20.4 minutes. Other types of particle accelerators are of course conceivable such as a linear accelerator (LINAC) or a synchrocyclotron.

For example, a cyclotron producing a proton beam (p) to 12

MeV and 20 μΑ (microamperes) interacting with a water having target enriched to 95% in ¹⁸ 0 (oxygen-18) Product ¹⁸ F (fluorine 18) accompanied by a neutron flux (n) and photons in a certain proportion, for example, typically 6 ^* 10 ¹¹ g / s (Gamma per second) and 4 ^× 10 ¹¹ n / s (neutrons per second). This reaction is denoted eg: ¹⁸ 0 + p → n + ^18F.

In another example, interaction between the same proton beam (p) but this time with a target comprising the ¹⁴ N (nitrogen 14) will produce ¹¹ C (1-carbon 1) and photons of high energy neutrons, but in different proportions from those of the previous reaction, for example typically 1 ^* 10 ¹² g / s and 2 ^× 10 ⁹ n / sec to 20 μΑ.

The dose rate accumulated near the target is large (several Sv (Sievert, with 1 Sv = 1 ^m2. S ^"2 = 1 ^{J.kg" 1)} per second in contact with a production target of ¹⁸ F and a beam 20 μΑ protons at 12 MeV (mega-electron volt)). These intense radiation is ionizing and therefore dangerous to humans and the environment. The intensity of this radiation is about one million times the radiation emitted by a cyclotron external ion source producing the beam described above, that is to say 20 μΑ protons at 12 MeV . In the case of a cyclotron internal ion source, the radiation emitted by the acceleration of ions in the cyclotron is greater, which reduces this ratio of the order of one million between the intensities of radiation of a cyclotron and a target, but the target remains the primary radiation source.

In the example cited above, the energy spectrum of the particles emitted by the accelerator has a maximum averaging around 2 MeV; so there are particles that may be issued at higher energies. The radiation from the target is likely to interact in turn with elements of the surrounding environment (air, equipment, walls, etc.) and activate these. Depending on the materials used for the Targetry, radioactive isotopes with short half-lives even longer (that is to say half-life of at least 100 days or years) can be created, which represents a disadvantage for this type of technology.

It is therefore important to protect people and the environment from ionizing radiation to reduce radiation risks and activation of components of the environment during the operation of the accelerator. In particular, it is appropriate to protect people and the environment from radiation from the target.

In order to protect people and the environment of these ionizing radiation, such systems are often installed in heavy bunkers, cumbersome and expensive. Indeed, the walls of a bunker are usually very thick: about 2 meters thick concrete.

But it is not always possible to build a bunker in existing facilities, such as in a hospital for example.

The development of some applications is therefore hampered by constraints associated with the installation possibilities of these irradiation systems.

To reduce this footprint, particle accelerators are sometimes equipped with a radiation enclosure called "local". This reduces the flow of radiation in the bunker but not to dispense with a bunker.

Examples for such radiation to mitigate at least the high-energy photons, primary and / or secondary from the target, it is for example advantageous to use materials known as "dense". Concrete and lead are often used as "dense" materials in particular for reasons of cost and ease of implementation. However, a goal of compactness and weight reduction, it can be interesting to use more dense materials, such as tungsten.

The attenuation of neutrons is possibly in two stages, namely, for example, at first, slow neutrons, and secondly, trap neutrons. Neutrons are slowed down for example by elastic collisions with matter. The hydrogen compounds (water, some polymers etc ..) are for example well suited to slow neutrons. After the slow neutrons, they are trapped by such a "trap neutron" or "neutron poison". Boron may for example be used to capture neutrons. One solution is for example to load a hydrogen-rich material, for example polyethylene, boron, up to a few percent, typically 1% to 8% (atomic). In the context of the present application, "rich" means that the hydrogen content is equal to or greater than about 30% or 40% by atomic concentration in the loaded material.

However, neutron capture in turn generates so-called high-energy photons "secondary" which in turn must be mitigated.

Thus, to mitigate these radiation, a radiation chamber for a target such as a production target of ¹⁸ F comprises for example a succession of hydrogen-rich material layers comprising a neutron poison and dense material layers.

In order to mitigate both neutrons and high-energy photons, primary and secondary, these functions may optionally be combined, for example by loading a resin with boron and a dense material such as lead or tungsten.

In addition, the fact that the targets are generally positioned adjacent to the acceleration region, or mounted directly at the outlet of the particle accelerator used, the enclosure radiation protection therefore encompasses both the target and the accelerator particles.

The result is that such radiation enclosure does not therefore prevent the radiation from the target of significantly activating the particle accelerator and the mass of the radiation remains high (typically 40 to 80 tons for producing cyclotrons protons from 10 to 18 MeV, which must be added 10 to 20 tons for the particle accelerator itself). These solutions therefore reduce the risks associated with non-persistent radiation but do not protect the accelerator activation by radiation from the target and, because of their mass, do not facilitate the implementation of accelerators or sometimes blocking for installation in existing buildings.

To avoid activation of the particle accelerator by the target, a possibility resides in the fact deporting the target away from the accelerator, thus making it possible to dispense with the particle accelerator include in the enclosure of radiation and so reduce the radiation closer to the target.

Activation of the accelerator is then much lower when the target is offset and radio-protected only when the target is mounted directly on the accelerator and the assembly is radio-protected.

This also significantly reduces the size and therefore the mass of the enclosure since radiation can then no longer contain the particle accelerator.

However, it is still possible that radiation back along the radiation beam emitted by the particle accelerator and activate within the accelerator. This is particularly troublesome for neutrons which "bounce" against metal surfaces of the accelerator by elastic shock. If the installation constraints induce avoid building thick walls, this neutron return is particularly troublesome because it alone generates a significant dose rate.

The use of a remote target makes it possible to greatly reduce the mass of the radiation, but radiation risks remain to the environment associated with such leakage neutron.

Moreover, for some applications it may be advantageous to use different targets with the same accelerator.

One possible solution is to move the selected target face to the irradiating beam. But such a solution usually requires breaking an existing vacuum in the system, change the target, then redo the vacuum before you can use the system.

Furthermore, for the irradiation of the target is the most optimal, it is necessary that the target is positioned as possible in front of the beam. This has the effect of creating a direct line of flight for ionizing radiation (neutrons and high energy photons) from the target to the cyclotron. This has two consequences. The first is that a portion of the cyclotron is still able to be activated. The second is that the neutrons back line beam "bounce" by elastic impact on metal parts of the cyclotron, thereby creating a secondary source of radiation that must be shielded.

The US5608224 discloses such a device comprising a barrel for using different targets. If this solution is then used to change the target without breaking the vacuum, it is parallel to ensure that the target to be irradiated is the best positioned in the collimator of the radiation beam. Such a solution does not then allow to solve the problem of neutrons back into the particle accelerator.

The purpose of this application is to solve at least in part, the aforementioned drawbacks.

To this end, there is provided, in a first aspect, a radiation system of a target, comprising at least:

- a particle accelerator configured to at least transmit a radiation beam along an axis,

- a cibleries holder positioned outside the accelerator vis-vis the radiation beam, comprising at least one port configured to receive a Targetry configured to receive a target to be irradiated, and

- a radiation protection enclosure surrounding the cibleries carrier, the particle accelerator being positioned outside the enclosure, the system being characterized in that the Targetry support is fixed relative to the particle accelerator, and in that the port is offset from the axis of the radiation beam, and in that the system comprises a deflection device positioned within the confines of radiation and configured to deflect the radiation beam towards the port targetry wherein the target to be irradiated is introduced.

The solution proposed here thus consists in using a beam deflection device which allows to direct the beam toward a target inserted into a Targetry mounted on a fixed port and positioned outside of the solid angle of leakage of the irradiation beam or enabling address a cibleries among multiple pre-positioned on different ports. The deflection device is thus target selector office or changer by analogy targets.

Preferably, the target support comprises at least two ports, for example, five ports.

For example, at least one of the ports, if all the ports are offset with respect to the axis of the radiation beam emitted by the particle accelerator.

According to one embodiment, the ports are arranged in the same plane.

And for example, the plane in which the ports are disposed is a horizontal plane.

In another embodiment, the ports are arranged in a volume.

It then becomes possible to achieve different targets surrounded by a radiation protection while minimizing the drain lines. Thus, the dose rate near the corresponding Targetry and the particle accelerator and activating equipment around, that is to say elements of the environment, are small while having a radiation protection mass scaled down.

The enclosure of radiation attenuates the residual radiation and non-retentive generated by interaction between the target and the beam and the combination between the use of a beam deflection device and a near radiation chamber around cibleries can reduce or even eliminate direct leakage lines of target radiation towards the particle accelerator while permitting to reduce the mass of the radiation, possibly by a factor of 5 to 15, while maintaining radiation effective.

For example, the enclosure of radiation comprises an alternation of at least one layer comprising a dense material and at least one layer comprising a hydrogen-rich material comprising a neutron poison.

For example, the hydrogen-rich material is polyethylene (PE) loaded with boron as neutron poison to approximately 5% to 7% (atomic).

For example, the dense material is tungsten (W) and / or lead

(Pb).

And optionally, radiation protection enclosure further comprises an additional piece of radiation surrounding cibleries mounted on the Targetry support. The additional part is for example positioned in a wall of the enclosure radiation protection. Such a part is, for example fixed to the cibleries support.

Preferably, the radiation layer positioned closer to cibleries, the extra piece if any, is a dense material.

In other words, a radiation protection layer of the radiation protection chamber near an inner surface of the enclosure is a dense material layer.

In an exemplary embodiment, the enclosure comprises a radiation protection wall comprises an additional layer of hydrogen-rich material positioned between the additional piece of cibleries radiation protection and the layer of the innermost dense material.

In an exemplary embodiment given by way of illustration, the extra piece of radiation is made of tungsten (W) and has a thickness between about 5 cm and about 15 cm, for example about 6 cm or 1 1 cm.

The wall of the radiation chamber then comprises, for example: - The additional thickness of material rich in hydrogen with a thickness of between about 5 cm and about 15 cm, and is loaded in PE 5% boron;

- The layer of the innermost dense material having a thickness between about 3 cm to about 8 cm, and is made of tungsten (W);

- a next layer of hydrogen-rich material with a thickness between about 25 cm and about 40 cm, and is loaded in PE 5% boron;

- a next layer of dense material having a thickness between about 2 cm to about 8 cm, and is made of lead (Pb); and

- A layer of material rich in outermost hydrogen with a thickness of between about 15 cm and about 30 cm, and is loaded in PE to 5% boron.

Such an enclosure then comprises four layers, and an optional additional layer, further a possible additional piece.

The thickness values ​​are of course given for information and to evoke an order of magnitude and can vary from a few centimeters, for example +/- 5 cm.

Such an enclosure is particularly compact.

An order of magnitude of the wall thickness is then between about 50 cm and about 100 cm, in particular between about 60 cm and about 75 cm.

In a particularly advantageous example, the enclosure of radiation comprises at least one spherical wall.

Such a wall has such an outer diameter no greater than about 3 m (meters) or 2 m.

According to another embodiment, the enclosure of radiation comprises at least one wall parallelepiped geometry, which reduces production costs. At least one of its dimensions in width, length or height is then possibly no greater than about 3 m (meters) or 2 m. Such a system therefore reduces the risk of radiation exposure and minimizes the constraints of masses and volumes for the installation of such a system, for example in hospitals.

It should be noted however that there was a strong prejudice of the Expert against the idea to use such a device.

Indeed, given the usual energy ranges of the radiation beam, the deflection device is also implementing significant energy.

This is particularly noteworthy that for a deviation to avoid at best a neutron back to the particle accelerator and limit the mass of the assembly, it is preferable that the deflection angle is as large as possible with respect to the original beam axis, for example at least 5 ° or 10 °, for example ompris between 5 ° and 175 ° or between 5 ° and 40 °, in particular about 19 ente e.g. ° and about 38 °. Therefore, it is preferable that the deflection device is positioned closer to the Targetry support, or at the input of Targetry support.

Thus, in other words, the deflection device is then advantageously configured to deflect the beam with respect to the axis along which it is emitted by the particle accelerator, an angle of at least 5 °, or even 10 °, for example between 5 ° and 175 °, paexemple between 5 ° and 40 ° and preferably between 19 ° and 38 °.

For this example it is configured to emit a magnetic field. For example, the magnetic field is 1 to 2 tesla (T). According to a particular example, the magnetic field is of the order of 1 Tesla .4.

According to an advantageous embodiment, the deflection device comprises at least one electromagnetic quadrupole positioned on a path of the radiation beam, that is to say typically on the beam emission axis by the particle accelerator . The electromagnetic quadrupole comprises for example an electromagnet or four electromagnets.

In preferred examples, the deflection device comprises a single electromagnetic quadrupole or two electromagnetic quadrupole. Instead of a quadrupole there is preferably a dipole.

Other deflection devices may also be used depending on the type and energy of the accelerated particles, such as an electrostatic deflector for lighter particles (type electrons) and / or lower energies.

The deflection device is also positioned within the radiation chamber. Note that the deflection device is also involved in radiation protection. For this example it is composed of a dense material such as copper and / or iron in particular, which makes it effective for reducing photons. As part of a quadrupole, it is for example an iron frame surrounded by a copper wire, e.g., a yoke iron and a copper winding.

This raises an additional bias against the exploration of such a solution since such a deflection device then preferably being positioned within the protective enclosure, another difficulty could reside in the choice of the configuration the passage of the necessary power supplies for the operation of deflection device through the protective enclosure.

According to an advantageous embodiment, the passages of power, for example cables or pipes, are baffled.

Once these prejudices overcome, thanks to such positioning, the deflection device itself participates in radiation protection by reducing the high energy photons.

In addition, if the carrier nevertheless cibleries comprises a port positioned in the beam axis, the target of the Targetry mounted on this port is preferably a target including a source term is low neutrons, i.e. whose neutron flux is at least 100 times less than the flux of primary photons (e.g. within about 1 ^* 10 ¹⁰ n / s). This is for example a load target (that is to say a target that adjusts the cyclotron adapted to be irradiated but which does not produce radioactive products), for example graphite, for adjusting or optionally a carbon production target 1 1 because it radiates relatively few neutrons for a beam as described above, that is to say 20 μΑ protons at 12 MeV. Thus, it is preferable to mount the Targetry containing the target is least used and / or that the term having the lowest source (for example a target load) of the port in the beam axis.

Such a system has the further advantage of being a more responsive system changer mechanical targets. In other words, it is possible to move the beam from one target to another positioned in two cibleries mounted on two different ports faster than with a conventional mechanical system without breaking the vacuum, typically within one second.

According to an advantageous embodiment, the system comprises a beam irradiation position of the setting device and a focus adjustment device of the irradiation beam, and the position adjusting device and the focus adjustment device are positioned upstream of the deflection device.

In an exemplary embodiment, the deflection device differs from the device for adjusting the position.

In an exemplary embodiment, the adjusting device position and the focusing adjustment device are positioned outside the radiation chamber.

In another exemplary embodiment, the position adjusting device and the focus adjustment device are positioned at least partially within the enclosure of radiation, even at least in part within the wall of the radiation chamber.

In an exemplary embodiment, the adjusting device position and the focusing adjustment device are jointly realized for example by a pair of electromagnetic quadrupoles.

According to yet another advantageous embodiment, the system comprises a control module including a control module and a control unit, the control unit being configured to integrate information and measurements relating to the position and the focusing of the beam irradiation and to send instructions to the control unit, and the control unit being configured to actuate the adjusting device position and / or in focus adjustment device and / or the deflecting device in order to optimize interaction between the radiation beam and the target to be irradiated.

Another object which the invention is Targetry support, in conjunction with its radiation enclosure, but without the accelerator. Specifically, this other object is a set of Targetry having a given reference direction which is to be subjected to a radiation beam, comprising:

- a cibleries support, intended to be positioned vis-à-vis said direction, having at least one port configured to receive a Targetry configured to receive a target to be irradiated, and

- a radiation protection enclosure surrounding the cibleries holder being traversed by said direction,

the assembly being characterized in that the Targetry carrier is fixed with respect to said direction and in that the port is offset with respect to this direction, and in that the assembly includes a deflection device positioned within the radiation enclosure and configured to deflect a radiation beam received in said direction towards the port targetry wherein the target to be irradiated is introduced.

Such an assembly is particularly configured for a system as defined above having some or all of the features described above.

The direction may be materialized within the confines of radiation by a next channel wherein the radiation is reduced or not significant, for example a hollow channel.

Such a system is particularly compact as well.

With such a system, it is possible to dispense with installing a complete wall between the particle accelerator and cibleries.

Such a system can thus be installed in a building room, for example a hospital complex room or mark, and by avoiding to request further processing or significant architectural adaptation, that is to say in a room with walls in conventional building materials (such as concrete and / or struts, etc.).

For example, walls 40 cm concrete enough when he had the walls of 2 m for devices of the prior art.

Such a system, including the radiation protection enclosure is thus independent of the room in which it is then installed.

In other words, such a system is thus configured to be installed in a building part.

Another way of defining the system is that as it is disposed in a room or an enclosure which surrounds the entire system, the cibleries are then disposed in an additional enclosure, the enclosure aforementioned radiation so the system is isolated from an external environment and cibleries isolated not only from the external environment but also vis-à-vis the particle accelerator, which in such a system, is less active as compared to the devices of prior art. The system thus has an autonomy.

The system can be installed in a single room, all system access is so easy. The system is also easily installable.

The invention, in one embodiment, will be well understood and its advantages appear better on reading the following detailed description, given as indicative and non-restrictive, with reference to the accompanying drawings in which:

FIG 1 schematically illustrates a radiation system of a target according to an exemplary embodiment of the present invention,

Figure 2, consisting of Figs 2a and 2b, illustrates schematically examples of geometric arrangements of the position of the ports.

Figure 3 shows an indicative change of the mass M (t, T) of a radiation chamber in accordance with its inner radius Ri (in millimeters, mm), and FIG 4 shows a block diagram of a control of an adjusting device in position and of a focusing adjustment device by a control module.

Identical elements shown in the aforementioned figures are identified by like reference numerals.

1 shows an irradiation system 1 comprising a particle accelerator 10, a cibleries holder 20 and a radiation chamber 30.

The particle accelerator 10 is for example a cyclotron. It is for example configured to emit a radiation Trunk group 1 1 having one of several megaelectronvolts proton beam (MeV).

The enclosure 30 surrounds here the radiation cibleries holder 20. The particle accelerator 10 is positioned outside the enclosure 30.

The enclosure of radiation 30 is for example in the form of a sphere, hollow, comprising a wall formed of a stack of successive layers.

For example, the wall of the radiation chamber 30 includes an alternation of a layer of a material called "dense" 31 and a layer of a hydrogen-rich material 32.

In practice, it is preferred that the enclosure of radiation comprises at least two layers, for example between two and ten layers, alternately forming a layer of dense material and a layer of hydrogen-rich material.

In order to limit the weight and size of the radiation, it is also interesting to position a layer of dense material 31 closer to cibleries 22 mounted on the support Targetry 20, as described later, to reduce first the primary rays.

It is then preferable to alternate hydrogen-rich layers of material 32, preferably having neutron poison, with dense layers of material 31 which attenuate the last primary rays and secondary rays originating from neutron capture. Illustratively, in the present exemplary embodiment of Figure 1, starting from the outermost layer, the wall comprises four layers alternating hydrogen-rich material 32 and dense material 31 so that the innermost layer, c ' is to say located closer to cibleries 22 is a dense layer of material 31.

Additionally here, to enhance radiation protection, cibleries 22 mounted on the ports 21 of Targetry 20 support are surrounded by an additional piece of radiation 33 which is preferably a dense material. The wall of the radiation chamber then comprises an additional layer 34 of hydrogen-rich material positioned between the additional piece of radiation 33 cibleries and the dense layer 31, the innermost material.

The hydrogen-rich material 32 is for example made of polyethylene (PE), optionally loaded with boron as neutron poison to approximately 5% to 7% (atomic). In the case of a cyclotron bombarding a production target of ¹⁸ F to 20 μΑ, numerical simulations showed an attenuation optimum if the PE is loaded into boron to approximately 7% (atomic).

The dense material 31, which mainly allows to reduce high primary and secondary energy photons, is advantageously of tungsten for example. Tungsten is very dense, it allows for a more compact, lightweight radiation protection enclosure. Tungsten however being a material difficult to be machined, it may be replaced by other materials, such as lead. The lead is less dense than tungsten, tungsten replace with lead, however, slightly increases the diameter of the radiation and therefore its mass enclosure.

In a preferred embodiment, the additional part of radiation 33 is tungsten (W) and has a thickness of about 6 cm. The wall of the enclosure radiation 30 then comprises:

- The extra thickness 34 of material rich in hydrogen has an inner radius (Ri) of about 24 cm and an outer radius (Re) of about 30 cm, a thickness of about 6 cm, and is loaded in PE boron than 5%;

- The layer of the innermost dense material 31 has an inner radius (Ri) of about 30 cm and an outer radius (Re) of about 35.5 cm, a thickness of about 5.5 cm, and is tungsten (W);

- The layer of hydrogen-rich material following 32 has an inner radius (Ri) of about 35.5 cm and an outer radius (Re) of about 64.5 cm, a thickness of about 29 cm, and is PE loaded with boron than 5%;

- The next layer of dense material 31 has an inner radius (Ri) of about 64.5 cm and an outer radius (Re) of about 68.5 cm, a thickness of about 4 cm, and is made of lead (Pb); and

- The layer of hydrogen-rich material 32 outermost has an inner radius (Ri) of about 68.5 cm and an outer radius (Re) of about 88.5 cm, a thickness of about 20 cm, and PE is loaded to 5% boron.

For example, if the cyclotron and cibleries media disclosed herein are used to one hundred and sixty minutes per day and 23 days per month, it is thus possible to produce a radiation enclosure of about 6.6 tons to a radius internal 240mm. Such enclosure of radiation 30 then reduces the dose rate outside walls 30 cm ordinary concrete within 80 μεν / ιηοίε, which is the limit set by the EURATOM guidelines for public areas.

The support cibleries 20 is positioned vis-à-vis the radiation Trunk group 1 1, the radiation chamber 30.

It comprises several ports 21 configured to receive one Targetry 22 containing the appropriate time a target to be irradiated, which are offset with respect to the irradiation beam January 1.

Here, in order to simplify the representation, the support cibleries 20 has two ports 21 with a Targetry 22 each, which are offset with respect to the irradiation Trunk group 1 1; and a port 21 'further positioned in the beam axis. As illustrated in Figure 1, this makes it possible, depending on the position of the 21 port concerned, more or less direct lessen creepage 12 produced when a target, inserted in the Targetry 21 mounted on the port concerned, is irradiated with the irradiation beam January 1.

When targets of different types are inserted into ports

21 or 21 ', it is preferable to position target generating the most intense neutron flow in ports 21 forming the angle with the highest irradiation beam January 1. A target generating less radiation and / or less used as a target load, may be inserted into the port 21 'which is in the beam axis when such a port exists.

For example, starting from the axis of the beam and by moving away, a possible configuration would be to position a load target in the port 21 'located in the axis of the Trunk group 1 1, and then a production target of ¹¹ C, then a production target of ¹⁸ F. These targets are then classified by generating ascending neutron flux at constant current.

Note that if a port 21 or 21 is vacant, that is to say that no target are inserted, it is best to put a tape, forming a tight cap, to better ensure sealing the system.

The number of ports 21 or the existence of a port 21 ', is based on the needs related to the application.

Through PET type applications, it is advantageous to have at least two cibleries, in order to use at least two different targets, such as between two and ten cibleries to eg use up to ten targets different. It is therefore useful to have as many ports as needed cibleries.

According to the existing space constraints in the context of the application considered, the ports are for example arranged in a plane as shown in Figures 1 and 2a, or in three dimensions, that is to say, by volume, as illustrated in Figure 2b.

For addressing a target positioned in any of cibleries ports 21 from the same radiation beam 1 1, the system 1 further comprises a deflection device of the radiation beam 40, configured to direct the beam irradiation January 1 to each of the ports 21 so that in operation for example, protons bombard a target positioned in one of targetry mounted on one of the ports 21 of the support 20 cibleries.

The deflection device 40 is also positioned in the radiation chamber 30. Note that the deflection device 40 is also involved in radiation protection. For this example it is composed of a dense material such as copper and / or iron in particular, which makes it effective for reducing photons. As part of a quadrupole, it is for example an iron frame surrounded by a copper wire.

The deflection device 40 comprises for example a deflector comprising, for example by a quadrupole formed of electromagnets, or preferably a dipole. Such a baffle is then positioned on a path of radiation beam 1 1 and is traversed by the latter, as shown schematically in Figure 1. Other deflection devices 40 may also be used depending on the type and energy of the accelerated particles, such as an electrostatic deflector for lighter particles (type electrons) and / or lower energies.

In the case of a three-dimensional arrangement as in Figure 2b, beam 1 1 must then be deflected in two dimensions (so that a deviation according to only one dimension is required in connection with the arrangement of Figure 2a) this may imply that the deflection device 40 will be larger, resulting in an increase of the internal volume of the radiation protection enclosure 30, and therefore an internal radius R of the enclosure 30 largest radiation, which then increases the mass M of the enclosure of radiation 30, as illustrated in Figure 3, which may create additional complexity.

The distance between a Targetry a 21 and the ground of the place where the port is installed the system 1, however, limit the maximum possible size of the radiation enclosure 30. Also, it is advantageous to have 21 ports on a plane horizontal rather than vertical. This allows further to limit the dose rate at the floor level and thus easier to install the system 1 on the floor of a building for example.

In the present embodiment, for compactness reasons, the distance between the particle accelerator 10 of the carrier 20 is for example cibleries very slightly greater than the distance established between a port 21 and the ground.

In order to ensure proper focusing and correct position of the radiation beam 1 1 at the deflection device 40 and an entrance window of each port 21, the system 1 here comprises an adjusting device in the position of beam irradiation 51 and an adjusting device by focusing the radiation beam 52.

The deflection device 40 differs from the setting device in position, in particular in that the deflection device 40 allows to deflect the radiation beam at angles of at least 5 °, while a device for adjusting its position allows to adjust a position of the point of impact or focal point of the beam, that is to say of only a few tenths of degrees, typically less than 0.5 °.

In the present embodiment, the position adjusting device and the focus adjustment device are mounted upstream of the deflection device 40, it being understood that "upstream" is in here refers to a transmission direction of the beam irradiation, from the accelerator to the cibleries support. They are also here positioned both outside the walls of radiation 30; However, they could also be positioned at least partially within the radiation chamber or at least partially within the wall.

The adjusting device 51 and the focusing position adjustment device 52 are for example carried out jointly by a pair of electromagnetic quadrupoles. However, if the beam diverges sufficiently low, that is to say, typically of the order of less than 0.5 °, it is not necessary to use a device for adjusting the focusing and / or position. To facilitate reliable and the use of such a device, the deflection device 40 is changeable and controllable distance example to address a selected target among multiple targets can be introduced in each of cibleries 22. In parallel, the device setting in position 51 and the focusing adjustment device 52 of the radiation beam may also be slaved to optimize the irradiation of the considered target.

For this purpose the system 1 comprises, for example, as is the case here, a servo module 60 for example comprising a control module 61 and a control unit 62.

It is then possible to drive the position adjustment device 51 and the focusing adjustment device 52 to perform positioning in three dimensions of the focal point of radiation beam 1 1 relative to a port entrance window 21 considered or port 21 '.

A geometric measurement unit 63, for example of Beam Position Indicator (BPI), is for example possibly used to send information to control module 61 regarding the position and dimensions of the Trunk group 1 1 at the window entry port 21 or 21 ', containing the target to be irradiated.

A current measuring module 64 is for example also used to measure the current generated by beam 1 1 of the target and provide current measurements to the control module 61.

These measures enable information and adjust the settings of the adjusting devices at position 51 and 52 and the focusing deflection device 40 so that the interaction between beam 1 1 and the target is optimal.

For this, the control module 61 integrates information and measurements provided by the module 63 and measuring module 64 and sends instructions to the control unit 62 which operates the adjusting device at position 51 and / or the device setting focus 52 and / or the deflection device 40.