FR2840223A1 - Hadrontherapy installation for medical treatment comprises a cyclotron together with a high frequency linear accelerator cavity for acceleration of particles exiting from the cyclotron - Google Patents

Abstract

Hadrontherapy installation comprises a cyclotron (2) and at least a high frequency linear accelerator cavity (13) for acceleration of the particles issuing from the cyclotron. The installation also has an actuator (21) for acting on the particles before their acceleration in the cyclotron, a sensor (8) for particle beam intensity and a programmable control device for beam intensity.

Description

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  The present invention relates to hadrontherapy facilities.

  Hadrontherapy corresponds to the treatment of the human body by a beam of charged or uncharged particles such as for example protons, light ions such as Bs +

  or C6 + and in general all cux of charge / mass ratio equal to 1/2, and the neutrons.

  The intensity of the beam which is delivered over the region to be treated may be less than or equal to

2 pA for example.

  Light ions have the advantage of having a higher relative biological efficiency than protons, electrons or X-rays. However, the energy required to accelerate these ions in order to obtain a sufficient depth of treatment for

  reaching deep tumors is considerably higher than for protons.

  Many installations of hadrontherapy are described in the publication Accelerators for Hadrontherapy, Joint Universities Accelerator School 1998, Archamps,

  March 1998, whose author is Pierre Mandrillon.

  The publication EP 0 526 306 describes a linear accelerator usable for a

therapeutic application.

  US Pat. No. 5,585,642 describes an installation which includes a synchrotron and presents a configuration cited as a fishbone, that is to say that the service lines of the treatment rooms are grafted onto a common line. The unique extraction configuration requires the treatment rooms to be located along the beam path. In addition, the synchrotron delivers a short duration pulsed beam which is more difficult for a scanning operation of a region to be treated than a continuous beam in time, as emitted by a cyclotron. Complex devices are sometimes used to temporarily extend each pulse of the synchrotron, to the detriment of the cost of the installation. Devices including a cyclotron and wind energy degraders are also used. The use of energy degraders tends to adversely affect the geometry of the beam and the optical elements must be numerous and of relatively large air gap. In addition, wind analysis magnets required for

  fixed energy cyclotrons using degraders, to select the required energies.

  There is a need to increase the number of hadrontherapy facilities a

available to the sick.

  The invention meets this need in particular thanks to an installation

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  of hadrontherapy which can be characterized by the fact that it comprises a cyclotron and at least one linear accelerating cavity for accelerating particles coming from the cyclotron, in particular a plurality of HF cavities operating at a harmonic frequency of that of the cyclotron. Thanks to the invention, it is possible to deliver a continuous beam of particles with the required energy, possibly in several directions. It is thus possible to have, for example, an exit of H + protons in one direction and at least one exit of light ions in another direction, for example at least two. The treatment rooms then no longer have to be arranged according to the beam flow necessarily but can be arranged around the cyclotron, which can possibly simplify the 'implantation of the installation. The linear accelerating cavity or cavities are advantageously configured to allow the particles to be accelerated with an acceleration level chosen from among several. It is then possible to deliver a beam with the sound energy without using

  of energy degrader, thus without deteriorating the optical properties of the beam.

  The various optical elements of the power lines of the isocentric holiday (s) as well as that (s) can be relatively few thanks to the absence of energy degrader. The magnets can keep a modest size because the beam can leave the cyclotron with a relatively weak emittance and the air gap has

  not to be increased as is the case when energy degraders are used.

  The cyclotron is preferably superconductive.

  The installation may include a source of light ions having a charge number greater than one, in particular C6 + or Bs + ions or other light ions in the

load / mass ratio equal to 1/2.

  The installation can also comprise a source of H2 + ions and the cyclotron can comprise a peeler making it possible to transform in its passage the ions H2 + into protons H + The cyclotron can be for example configured to confer on the particles

  accelerated energy greater than or equal to 100 MeV per nucleon.

  The installation may include at least one linear accelerating cavity, particularly a plurality of cavities capable of being selectively put into service. Each cavity can have a plurality of cells which can be switched

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selectively.

  Each cavity can be configured for the weak, for example.

  The installation may also include: - at least one actuator for acting on the particles delivered by the source before their acceleration by the cyclotron, - at least one sensor capable of delivering information representative of the intensity of the beam of particles accelerated by the cyclotron, and - a programmable intensity control device capable of acting on the actuator as a function of the information supplied by the sensor and of a programmed control law of the intensity of the beam of accelerated particles in the time, so that the intensity of the beam delivered by the cyclotron respects the programmed control law.

  The invention will be better understood on reading the detailed description

  which follows, of an example of non-limiting implementation, and on examining the drawing 1 5 annex, in which: - Figure 1 is a schematic overview of an example of installation according to [the invention, - Figure 2 is a block diagram representing an intensity control loop. The hadrontherapy installation 1 shown very diagrammatically in FIG. 1 comprises a superconducting cyclotron 2 receiving ions delivered by at least one ion source, for example a source 3 of H2 + ions or a source 4 of light ions such than

  for example Bs or C6 + or other ions whose charge / mass ratio is equal to 1/2.

  The ions accelerated by cyclotron 2 follow a generally shaped path

  spiral, conventionally.

  The accelerated H2 + ions are transformed, by passage through a peeler 8, electrically insulated so as to allow an intensity reading, into H + protons which leave the cyclotron 2 by an output 5 and wind guided by optical elements 6 to a

first patient P '.

  The light ions B5 + or C6 + or other ions whose charge / mass ratio is equal to 1/2 can be extracted by conventional deflection and the cyclotron 2 comprises at least one system for extracting these light ions which can be put into service when the

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  cyclotron is not used to deliver H + protons.

  The light ions can leave the cyclotron 2 by a first outlet 10 having a different orientation from the outlet 5 and wind post-accelerated by an accelerator device, comprising in the example illustrated a plurality of linear HF accelerating cavities 13 superconductive, then reach an isocentric head 12 (also called gantry)

  allowing to treat a second patient P2.

  The ions can be accelerated by only a portion of the cavities 13 of the accelerator device 11, depending on the energy level desired, for example by a single

cavity 13.

  The installation comprises for example another outlet 16 for light ions, and wind post-accelerated by an accelerator device comprising for example a single linear accelerating HF cavity 13, before being directed to another isocentric head 15

  to treat a third patient P3.

  The cavities 13 may each include a plurality of cells 14.

  Cavities 13 could be even more numerous, and the number of patients

treats higher than trots.

  In the example considered, the cavities 13 are similar to those described in the publication Conceptual Design of the SPL at High-Power Superconducting Linac at ClEl? N, pages 27 to 35, the content of which is incorporated here by reference, the cavities 13 being configured for the falbles and having a quality factor for example of the order of 109. The cavities 13 operate at a frequency of the order of 350 MHz, fivefold

  that of the cyclotron which is in the example considered close to 70 M Hz.

  The electrical power of the source which feeds the cavities 13 can be relatively low, for example a hundred watts and the person skilled in the art will understand that taking into account the high quality factor Q of the cavities, these can be easily switched. The installation 1 may include a programmable intensity control device 20, shown diagrammatically in FIG. 2, which receives information representative of the intensity measured by the peeler 8 and makes it possible to control with

  precision over time the intensity of the H + proton beam delivered by the cyclotron.

  The intensity control device 20 can be programmed with a law

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  of any intensity, being configured to control, continuously, an actuator 21 of the injection line, not shown, making it possible to supply the cyclotron 2 with the ions

delivered by source 3.

  The cells 14 and / or cavities 13 can be switched selectively.

  A greater or lesser number of cells 14 and / or cavities 13 can thus be put into service to more or less accelerate the particles coming from the cyclotron and deliver to the patients P2 or P3 a beam of particles accelerated with the required energy, avoiding

energy degraders.

  This energy will be chosen for example according to the depth of the

tumor and the nature of the ions.

  Thanks to the absence of energy degraders, the air gap of the holiday magnets

  isocentric remains weak and the associated optics is largely simplified.

  In the illuske example, cyclotron 2 is capable of delivering a beam of

  particles accelerated with an energy of the order of 120 MeV per nucleon.

  Depending on the number of cells 14 and / or cavities 13 put into service, the energy conferred on the light ions can be chosen from a set of discrete values in a range for example between 120 and 300 MeV per nucleon, without it need it

  to use an energy degrader.

  Of course, the invention is not limited to the example which has just been given.

  We can in particular realize the cyclotron with more than two exits of light ions

  in order to feed, for example, a greater number of isocentric celebrations.

  We can also plan, for example, to post-accelerate the protons by

  placing after the exit 5 an accelerator device.

  Cavities other than those can be used as accelerating cavities

  described previously, in particular SPOKE type cavities.

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Claims (17)

  1. Hadrontherapy installation, characterized in that it comprises a cyclotron (2) and at least one linear accelerating HF cavity (13) to accelerate particles from the cyclotron. 2. Installation according to claim 1, characterized in that the linear accelerating HF cavity or cavities (13) are configured to allow acceleration of the   particles with an acceleration level chosen from among several.   3. Installation according to one of the preceding claims, characterized by   the cyclotron (2) is superconductive.   4. Installation according to any one of the preceding claims,   characterized by the fact that the cyclotron (2) is configured to be able to accelerate ions having a charge number greater than one, in particular ions whose charge /   mass is equal to 1/2, for example C6 + or Bs +.   5. Installation according to any one of the preceding claims,   characterized by the fact that the cyclotron has at least one outlet (10, 16) for   ions with a charge number greater than one and an output (5) for H + protons.   6. Installation according to any one of the preceding claims,   characterized by the fact that it comprises at least one isocentric head, in particular at   at least two isocentric parties (12, 15).   7. Installation according to any one of the preceding claims,   characterized by the fact that it comprises a source (3) of H2 + ions for supplying the cyclotron. 8. Installation according to the preceding claim, characterized in that the cyclotron (2) comprises a peeler (8) making it possible to transform the ions H2 + into protons TT + r   9. Installation according to any one of the preceding claims,   characterized by the fact that it comprises a source (4) of ions having a charge number greater than one, in particular ions having a charge / mass ratio equal to 1/2, by example C6 + or B5 +.   10. Installation according to any one of the preceding claims,   characterized by the fact that the cyclotron (2) is configured to confer on the particles 7 2840223   accelerated energy greater than or equal to 100 MeV per nucleon.   11. Installation according to any one of the preceding claims,   characterized by the fact that the linear accelerating HF cavity or cavities (13) are superconductive. 12. Installation according to claim 11, characterized in that it comprises a plurality of superconductive cavities (13) capable of being put selectively in service.   13. Installation according to any one of the preceding claims,   characterized by the fact that each cavity (13) comprises a plurality of cells (14)   can be switched selectively.   14. Installation according to any one of the preceding claims,   characterized by the fact that the frequency of the cyclotron (2) is around 70 MHz and that   of the cavity (s) (13) of the order of 350 MHz.   15. Installation according to any one of the preceding claims,   characterized by the fact that the cavity or cavities (13) are configured for low p.   16. Installation according to any one of the preceding claims,   characterized by the fact that it is devoid of energy degrader.   17. Installation according to any one of the preceding claims,   characterized by the fact that it comprises: - at least one actuator (21) for acting on the particles before their acceleration by the cyclotron (2), - at least one sensor (8) capable of delivering information representative of the intensity of the beam of particles accelerated by the cyclotron, and a programmable intensity control device (20) capable of acting on the actuator (21) according to the information supplied by the sensor (8) and a law of programmed control of the intensity of the beam of particles accelerated in time, so that the intensity of the beam delivered by the cyclotron respects the law of scheduled command.