WO2012062302A1

WO2012062302A1 - Arrangement for producing high-energy proton beams and use of said arrangement

Info

Publication number: WO2012062302A1
Application number: PCT/DE2011/075220
Authority: WO
Inventors: Thomas HERRMANNSDÖRFER; Thomas E. Cowan; Roland Sauerbrey
Original assignee: Helmholtz-Zentrum Dresden - Rossendorf E. V.
Priority date: 2010-09-16
Filing date: 2011-09-14
Publication date: 2012-05-18
Also published as: DE102011052269B4; DE102011052269A1

Abstract

The invention relates to an arrangement for producing high-energy proton beams using pulsed high-field magnetic coils. Said arrangement can be used, among other things, in laser-driven proton beam therapy. An important advantage of irradiation with protons compared to irradiation with high-energy photons is that the tumor is effectively switched off due to the energy input of the protons and the healthy tissue surrounding the tumor can be protected more efficiently. A further advantage of the described arrangement due to the use of high pulsed magnetic fields is that proton beam apparatuses for medical applications, among other things, can be produced as "tabletop devices" having a compact size, in other words, with considerably reduced investment funds. First examinations show that dimensional savings in the length and the width by a factor of at least 3 can be achieved. The energy consumption needed to produce a magnetic pulse is only 10 to 100 kJ. At an electricity price of ~0.1 EUR/kWh, costs of 0.0003 to 0.003 EUR per pulse are incurred. A further advantage of the arrangement according to the invention is the simplified dosing of the radiation intensity and the more accurate focusing of the region to be irradiated. Thus, said devices can be operated more easily.

Description

Arrangement for generating high-energy proton beams

and their use

Technical area

The application describes an arrangement for generating high-energy proton beams. Laser-driven proton beam therapy uses these polyenergetic proton beams. The aim of proton laser radiation therapy is the targeted, metered and effective irradiation of tumor tissue.

State of the art

Chang-Ming Ma proposes in US 7,268,835 B2 and US 7,317,192 A,

to use superconducting magnets for beam guidance. At the same time, the energies of the proton beams and the beam guidance are investigated.

[0003] Proton beam therapy using classical

Proton accelerators lead to a combination of sensitive medical treatment methods in operation large

Research institutions. The establishment of the prior art accelerator systems in medical centers requires major structural measures and significant investment.

Brief description of the invention

A compact and precise proton beam guidance is especially for small

Tumor structures necessary. In the treatment of large tumor structures, the use of a polyenergetic proton beam seems to be required to achieve simultaneous elimination of the total tumor volume. In this case, the proton beam must be spatially differentiated, so that the protons are directed to the respective absorption position with optimal energy. These beam guidance and power control requirements are not possible with the required accuracy with the prior art arrangements and methods.

Technical task

The object of the invention is to specify an arrangement for generating

high-energy proton beams, especially in the laser-driven

Proton beam therapy can be applied, which eliminates the shortcomings of the prior art.

Technical solution

The object is achieved by an arrangement which uses pulsed high-field magnetic coils and is described in claim 1. advantageous

Embodiments are given in the subclaims. The inventive arrangement allows an effective compact and precise proton beam and simultaneously generates a spatially differentiated high-energy proton beam.

Advantageous effects

Significant advantage of the irradiation with protons over the

Irradiation by high-energy photons means that the tumor can be more effectively eliminated due to the energy input of the protons and the healthy tissue surrounding the tumor can be protected more efficiently.

Another advantage of the arrangement described by the use of high pulsed magnetic fields is that proton beam devices, among other things for medical applications spatially very compact

"Tabletop-device", d. H. under considerably reduced

Investment funds, can be produced.

The energy required to generate a magnetic pulse is only 10 to 100 kJ. With an electricity price of ~ 0, 1 EUR / kWh, costs per pulse amount to between 0.0003 and 0.003 EUR.

[001 1] Another advantage of the arrangement according to the invention is the simplified

Dose of the radiation intensity and the more precise focusing of the area to be irradiated. This makes these devices easier to use.

Short description of the drawing figures

The invention will be described with the aid of figures. Fig. 1 shows the basic structure. Fig. 2 shows the control of the energy of the proton beam by varying the magnetic flux density of the coils. Figs. 3 and 4 show possible embodiments of the coils and Fig. 5 shows a possible embodiment of an arrangement for generating high-energy proton beams and their use.

Description of the embodiments

Protons can be compared to high-energy photons by means of

Magnetic fields are deflected and selected. The principle is based on the

Lorentz force and corresponds to the mode of action of a mass spectrometer. to

However, proton beam therapy will produce high energy protons

Energy range of 10 to 200 MeV is required, which is under non-relativistic

Simplifying the following relationships

r = rripVp / e B = (2 U m _p / e) ^y 7 B with v _p = (2 e U / m _p

only slightly deflected in smaller fields. For example, protons of 10 MeV energy would be at magnetic flux densities

B = 1 T (usual order of magnitude for the conduction of electrons) one Deflection radius of r = 46 cm experienced. This would require beam guiding magnets of considerable or unrealistic size.

The high speeds of the protons (see Tab. 1) require strong

Magnetic fields to reduce beam radii and dimensions of the magnets to reasonable size. The amplitude of the magnetic field is chosen so that the

Focusing distances for collimation and deflection of the proton beam on cm-distances made.

The use of pulsed pulse field coils with magnetic flux densities in the amount of four to five times the size of the magnetic flux density

superconducting coils leads to a four to five times stronger

Web curvature and thus a more efficient energy selection.

Despite the magnitude of the magnetic flux densities, the operation of the pulsed

Magnetic coils energetically advantageous because the short pulse times require more moderate connection power and pulse energies in the range of 10 to 100 kJ. For example, pulse repetition rates of 1 s ^"1 can be achieved with conventional

Three-phase power connections (25 to 250 A, 10 to 100 kW) are handled.

Fig. 1 shows a basic arrangement according to the invention for generating high-energy proton beams, consisting of a coil 1 for

Collimation of the protons, coils (shown in Fig. 1 as Helmholtz coil pairs) for energy selection 2 and proton beam 3. In the upper part of Fig. 1, the replacement image of the pulse circuit 4 is shown, the charger from charger V, charging relay R, pulse discharge capacitor C, triggerbarem

High current switch T is composed, the coils 1, 2 and 3 separately or together, as shown in the picture, are pulsed. These coils can be operated with pulse generators, including several

Chargers can be connected in parallel to achieve very short charging times.

Before the coil for collimation are still the proton source and lenses for focusing.

The energy selection of the partial proton beam of highest energy E _x (with Ei> E ₂ > E ₃ > ...) takes place with a pulsed Helmholtz coil pair.

The proton beam of highest energy is selected and then the beam will be guided by known concepts on the area to be irradiated. It makes sense, the coil for proton beam 3 is performed pulsed. In this case, the radiation intensity incident on the area to be irradiated can be determined by the choice of the pulse time of the proton beam during the pulse of the magnetic field. It is useful to split off not only a fixed energy level of the

Proton beam highest energy, but a Teilprotonenstrahlbereichs highest energy with E-ι to E _x with x + 1, preferably x = 2 or 3. The total energy of the remaining proton beam area is very small compared to the energy of the original proton beam.

Initial studies show that a structure for proton beam guidance with a compact arrangement as a gantry (expansion in each direction about 3 m), which includes solenoids, sector magnets, quadrupoles and / or diaphragms is possible, in which by an optimal design energies from 160 to 250 MeV can be achieved. The advantage of the use of these arrangements according to the invention are the enormous space savings compared to previously known arrangements.

Pulse Generator

A possible advantageous arrangement for operating the magnetic coils is the use of a 30 to 100 kJ / 10 to 20 kV / 50 kA / 0.2 to 0.4 GW pulse current generator using one or more parallel-connected voltage-controlled capacitor medium voltage charging devices and operate a laser-triggered high-current thyristor, the used transient medium-voltage pulse discharge capacitors (10 to 20 kV, 50 μΡ each) and a laser-triggered high-current thyristor operate (60 kA). The charging power achieved at 400 V and 32 A is about 16 kW. As a triggerable high-current switch can Thyrostorschalter, Ignitrons,

Thyratrons, IGBTs and other variants can be used.

The coils shown here can be both individually, as well as in

Pulse train in series. An amount of energy of about 30 kJ is already sufficient for the operation of the solenoid coils shown, larger energies can also be used.

A 32 kJ / 16 kV / 250 kA / 2 GW high-power pulse generator with

voltage-controlled capacitor medium-voltage charger (16 kW, 400 V, 32 A), several medium-voltage transient-capable

Pulse discharge capacitors (16 kV, 50 μΡ each) and Ignitron high current switch can also be used.

Do the washing up

Coils with iron cores can not be used for this arrangement, because very strong magnetic fields are built up and the iron cores reach the saturation region. Known superconducting inductors can also not be used or are not well suited, because these for are designed for continuous operation and can not be used in pulse mode at pulse times in the micro and millisecond range.

Initial studies show that classic Helmholtz coil pairs (2 r _a ~ H) or cylindrical coils (2 r _a ~ H or 2 r _a ~ 3 ^* 2 ^"2 H) can be used for this arrangement.

A further advantageous embodiment of the coil form in one or more coils is the curved shape (similar to a banana), as shown in Fig. 4, because thus the beam guidance in the direction of the area to be irradiated can be made more efficient. At the same time, this shape allows easy separation of proton beams with simultaneous guidance of the

Proton beam as a combination of the coils 2 and 3 shown in Fig. 1. A further advantageous embodiment of the coils is the arrangement of individual coils as quadrupoles or multipoles, such. Example of the quadrupole shown in Fig. 3, with the targeted influence on individual protons of different energies can be taken.

use

The described arrangement for generating high-energy, pulsed

Proton beams can be used in laser-driven proton beam therapy.

The amplitude of the magnetic inductance B is selected in the range of greater than 2 T, preferably up to 60 T, more preferably in the range of 20 to 30 T. This achieves focusing distances for collimation and deflection of the proton beam in the cm range. Coils with this size of the magnetic field are in principle suitable for continuous operation, because in the pulse generation, the resulting mechanical stresses are still in the elastic range of material coefficients.

It can be stated that the pulsed generation of the magnetic field with pulse times in the range of 0.1 to 1.0 ms does not represent a disadvantage to the use of static magnets, since the laser-driven proton beam therapy also takes place in a pulsed manner and substantially shorter time scales are used ,

The beam guide also perform pulsed compared to the

Conventional continuous-current or superconductive magnetoresistive magnets have the advantage that helium cooling can be dispensed with. It turns out that air or nitrogen cooling or cooling with nitrogen-containing gases is sufficient. The selection of the energy E of the proton pulse takes place via the height of the magnetic flux density B of the magnetic field (FIG. 2). One variant uses magnetic pulses of the coils with a flux density which is greater than the required flux density (solid line). In this case, the meets

Proton pulse (Pi or P ₂ ) at the rise of the magnetic pulse at a certain time t on the coil. The time t correlates with the required one

Flux density B and the associated energy E.

The other variant uses magnetic pulses of different levels of magnetic inductance and the proton pulse P hits exactly the maximum of the magnetic pulse on the coil.

[0035]

Table 1 :

Fig. 5 shows a possible arrangement for generating high energy

Proton beams and their use in proton beam therapy. The arrangement shown in Fig. 5 comprises magnetic coils, sector magnets,

Quadrupole and diaphragms. The extent of the achieved

inventive arrangement is reduced by a factor of 3 in length or width over the prior art, because dimensions of about 3 meters are possible. ,

For the first example shown in Fig. 5 arrangement with interpretation of

Coil elements in the range from -200 T / m to 400 T / m can be reached at the end of the assembly proton energies in the treatment range from 160 to about 250 MeV.

Claims

claims

1 . Arrangement for generating high-energy proton beams consisting of

Proton source, lenses or objects for focusing the proton beam for collimation, energy selection and beam guidance, characterized in that pulsed high magnetic coils are used for energy selection and beam guidance and optionally for collimation.

2. Arrangement according to claim 1, characterized in that the pulsed coil for collimation is a cylindrical coil.

3. Arrangement according to claim 1, characterized in that at least one

Pulsed coil for energy selection is a Helmholtz coil pair, preferably designed as two cylindrical coils.

4. Arrangement according to claim 1, characterized in that at least one

Pulsed coil for energy selection is designed as a sector magnet in waveform to ensure an optional simultaneous beam guidance, the waveform is preferably carried out in banana shape.

5. Arrangement according to claim 4, characterized in that in the form of a curve

executed coil for energy selection is performed in pairs, similar to a Helmholtz coil pair.

6. Arrangement according to claim 1, characterized in that at least one

Pulsed coil for energy selection is designed as quadrupoles or multipoles.

7. Arrangement according to claim 1, characterized in that the pulsed coils for beam guidance as Helmholtz coil pairs and / or in curve form or as

Sector magnet are designed as a waveform preferably in the form of a banana, and / or formed as a quadrupole and / or multipole.

8. Use of the arrangement according to one of the preceding claims, characterized in that the pulsed coils used are pulsed individually or separately.

9. Use according to claim 8 in the laser-driven proton beam therapy.