DEVICE FOR PROVIDING A RADIATION TREATMENT

Abstract

The present relates to a device for providing a radiation treatment to a patient comprising:—an electron source for providing a beam of electrons, and—a linear accelerator for accelerating said beam until a predetermined energy, and—a beam delivery module for delivering the accelerated beam from said linear accelerator toward the patient to treat a target volume with a radiation dose, The device further comprises intensity modulation means configured to modulate the distribution of the radiation dose in the target volume according to a predetermined pattern. The pattern is determined to match the dimensions of a target volume of at least about 50 cm.sup.3, and/or a target volume located at least about 5 cm deep in the tissue of the patient with said radiation dose, The radiation dose distributed is up to about 20 Gy delivered during an overall treatment time less than about 50 ms.

Claims

1. Device (1) for providing a radiation treatment to a patient, the device (1) comprising: an electron source (2) for providing a beam of electrons, and a linear accelerator (3) for accelerating said beam until a predetermined energy, the accelerated beam being composed of a plurality of trains of electrons bunches, and a beam delivery module (4) for delivering the plurality of trains of electrons bunches from said linear accelerator (3) toward the patient to treat a target volume (5) with a radiation dose, characterized in that the device (1) further comprises intensity modulation means (9) configured to modulate the distribution of the radiation dose in the target volume (5) according to a predetermined modulation pattern matching the target volume (5), the intensity modulation means (8) are configured to adjust the position, the total charge and energy of each electrons bunch within a train and between trains of electrons bunches, and to separate the trains of electrons bunches depending on the charge and/or energy of each train, the modulation pattern comprising several subsections and each subsection comprising trains of electron bunches with a determined charge and energy to irradiate a corresponding portion of the target volume (5) so that the intensity modulation means (9) allow to set the radiation dose received by each portion of the target volume (5), the modulation pattern is determined to match the dimensions of a target volume (5) of at least about 50 cm.sup.3, and/or a target volume (5) located at least about 5 cm deep in the tissue of the patient with said radiation dose, the device (1) being further characterized in that the radiation dose distributed by said intensity modulation means (8) named entire radiation dose is at least about 20 Gy, the radiation dose being delivered during an overall treatment time less than about 50 ms.

2. Device (1) according to claim 1, wherein the intensity modulation means (8) are configured to further adjust arrival angle, projected size each electrons bunch within a train and between trains of electrons bunches.

3. Device according to any one of claims 1 to 2, wherein the entire radiation dose is of at least 30 Gy, preferably of at least 35 Gy, preferably of at least 40 Gy.

4. Device (1) according to any one of claims 1 to 3, wherein each portion receives a radiation dose up to the entire radiation dose.

5. Device (1) according to claims any one of claims 1 to 4, wherein each portion receives at least one train of electrons bunches.

6. Device (1) according to claims any one of claims 1 to 5, wherein the intensity modulation means (8) comprises charge variation means to set the charge of each train independently and direct each train to a predetermined subsection of the pattern to reach a corresponding portion of the target volume (8) which modulates the distribution of radiation dose in the target volume (8).

7. Device (1) according to claims any one of claims 1 to 6, wherein the intensity modulation means (8) comprises energy variation means to set the energy of each train independently and direct each train to a predetermined subsection of the pattern to reach a corresponding portion of the target volume (5) which modulates the distribution of radiation dose along the direction of the accelerated beam through the target volume (5).

8. Device (1) according to the preceding claim, wherein each train has an energy which differs from about 1% to about 5%.

9. Device (1) according to any one of claims 1 to 8, wherein the accelerated electron beam is separated into a plurality of beam lines (6,7) by separating means (8), each beam lines (6,7) being separated by a determined angle, and subsequently focusing each of said beam lines (6,7) toward the patient to arrive in an overall time of less than 50 ms on the target volume (5), each beam line (6,7) further comprising independent intensity modulation means (8).

10. Device (1) according to the preceding claim, wherein each beam line (6,7) has an energy with differs from about 10% to about 40%.

11. Device (1) according to any one of claims 1 to 10, wherein the intensity modulation means (8) comprise deflecting means (13) for deflecting each train of electrons bunches position transversely relative to the accelerated beam direction, said deflecting means (13) having a deflecting speed faster than the interspacing time between two subsequent trains.

12. Device (1) according to the preceding claim, wherein the deflecting means (13) comprise magnet, for instance dipole magnets quadrupole magnet with time varying magnetic fields, or dipole coils, or fast ramping magnets or magnets capable of fast field-ramping.

13. Device (1) according to any one of claims 11 to 12, wherein the deflecting means (13) comprise a radio frequency deflector.

14. Device (1) according to any one of claims 1 to 13, wherein the energy variation means are set for implementing predetermined energy variations between each train of electrons bunches, said energy variation means being preferably operated from the linear accelerator (3).

15. Device (1) according to the preceding claim, wherein the energy variation means are operated by controlling the amplitude and the phase of the radiofrequency pulses of the linear accelerator (3).

16. Device (1) according to any one of claims 1 to 15, wherein the intensity modulation means (8) comprise a combination of charge variation means, energy variation means deflection means (13) and multiple beam lines (6,7).

17. Device (1) according to any one of claims 1 to 16, wherein the accelerated electron beam having a predetermined energy between about 30 MeV and about 250 MeV, preferably between about 50 MeV and about 250 MeV, more preferably between about 50 MeV and about 150 MeV.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0111] Further particular advantages and features of the invention will become more apparent from the following non-limitative description of at least one embodiment of the invention which will refer to the accompanying drawings, wherein [0112] FIGS. 1 and 2 represent a first embodiment of the device according to the present invention, FIG. 1 being a general overview and FIG. 2 a detailed view of the beam delivery module of the device;

[0113] FIGS. 3 and 4 illustrate two examples of the dose distribution with intensity modulation means in the device according to the first embodiment;

DETAILED DESCRIPTION OF THE INVENTION

[0114] The present detailed description is intended to illustrate the invention in a non-limitative manner since any feature of an embodiment may be combined with any other feature of a different embodiment in an advantageous manner.

[0115] FIGS. 1 and 2 represent a device 1 according to the present invention according to a first embodiment, FIG. 1 being a general overview and FIG. 2 a detailed view of the beam delivery module of the device.

[0116] The device 1 comprises an electron source 2, a linear accelerator 3 and a beam delivery module 4. The device 1 is arranged for delivering a radiation dose to a target volume 5 of a patient.

[0117] The radiation source 2 is a high current electron source, in particular a Radio-frequency laser-driven photo-injector.

[0118] The linear accelerator 3 is a high current X-Band linac. The linac has parameters of eight half meter long accelerating structures, operating with a beam-loaded gradient of 35 MV/m. The linac is powered by two 50 MW peak power X-band klystrons and radio-frequency pulse compressors. FIG. 2 is a detailed view of the beam delivery module 4. The role of the beam delivery module 4 is to guide the beam from the electron source 2 until the target volume 5 of the patient. The beam delivering module 4 comprises separating means 6 and intensity modulation means 7.

[0119] The accelerated beam is first split into two distinct beam lines 8,9 by separating means 6, i.e. a high momentum beam line 8 and a low momentum beam line 9.

[0120] In this example, the separating means 6 is a splitter dipole 10 (separator magnet) to separate the accelerated beam exiting the linear accelerator 3 into two distinct beam lines. The splitter dipole 10 has with the following parameters: [0121] Size: 1000 mm×850 mm×800 mm [0122] Weight: 3000 kg [0123] Material: iron yoke, copper coils [0124] Bending angle: 122 degrees (for low momentum beam); 65.5 degrees (for high momentum beam) [0125] Central field: 1.0 T [0126] Effective length: 0.555 m (for low momentum beam); 0.665 m (for high momentum beam)

[0127] Then, the separating means 6 further comprises one dipole 11,12 on each beam line 5,6, i.e. a dipole of high momentum 11 on the high momentum beam line 6 and a dipole of low momentum 12 on the low momentum beam line 9.

[0128] The dipole of high momentum 11 has the following parameters: [0129] Size : 700 mm×735 mm×450 mm [0130] Weight: 1500 kg [0131] Material : iron yoke, copper coils [0132] Bending angle: 54.5 degrees [0133] Central field: 0.95 T [0134] Effective length: 0.5 m [0135] Current: 22.4 A

[0136] The dipole of low momentum 12 has the following parameters: [0137] Size : 700 mm×735 mm×450 mm [0138] Weight: 1500 kg [0139] Material: iron yoke, copper coils [0140] Bending angle: 92.3 degrees [0141] Central field: 1.09 T [0142] Effective length: 0.5 m [0143] Current: 27.2 A

[0144] The device 1 further comprises intensity modulation means 7. In the example illustrated in FIGS. 1-2, the intensity modulation means 7 comprise deflecting means 13 positioned on each beam lines 8,9 downstream respectively the dipole of high momentum 11 and the dipole of low momentum 12.

[0145] The deflecting means 13 are scanning magnets, preferably fast ramping magnets or magnets capable of fast field-ramping' with the following parameters: [0146] Size: 290 mm×205 mm×205 mm [0147] Weight: 1500 kg [0148] Material: iron yoke, copper coils [0149] Duty cycle: 10% [0150] Integrated field: 0.034 Tm [0151] Maximal deflection angle: 100 mrad [0152] Effective length: 0.3 m [0153] Current: 5.6 kA;

[0154] Optionally, the intensity modulation means 6 can further comprise energy modulation means (not represented in figures). For instance, the energy modulation means to further deflect the trajectory of each train of particles bunches by an angle from 1% to 5%.

[0155] FIGS. 3 and 4 represent two examples of dose distribution that can be achieved with the present invention.

[0156] FIG. 3 shows an example of a uniform (homogeneous) dose distribution profiles of a 100 MeV beam obtained with the described intensity modulation of the present invention. FIG. 3 shows a graph of a uniform (homogeneous) dose distribution at a depth of 10 cm in a target volume produced by a single beam line. In this example, the beam has an energy of 100 MeV and the intensity modulation pattern comprises five elliptical subsections of 10 cm by 3 cm cross-section each. An average dose of 10 Gy is produced in the portions of the target volume, each portion having an area of 10×15 cm2 (in cross section) within a total time of 32 ms using 5 trains of 0.3 μs duration repeated every 8 ms. The graph shows that when 10 Gy (no modulation) is delivered to each subsection, the superposition in the transverse direction of the five adjacent subsections adds up to a uniform total dose.

[0157] FIG. 4 shows an example of a non-uniform (heterogeneous) dose distribution profiles of a 100 MeV beam obtained with the described intensity modulation of the present invention. FIG. 4 shows a graph of a non-uniform (heterogeneous) dose distribution at a depth of 10 cm in a target volume produced by a single beam line. In this example, the beam has an energy of 100 MeV and the intensity modulation pattern comprises five elliptical subsections of 10 cm by 3 cm cross-section each. An average dose of 10 Gy is produced in the portions of the target get volume, each portion having an area of 10×15 cm2 (in cross section) within a total time of 32 ms using 5 trains of 0.3 μs duration repeated every 8 ms. In contrast to FIG. 3, the graph of FIG. 4 shows that if the dose of each subsection is set to different levels - from left to right: 11 Gy, 8 Gy, 10 Gy, 9 Gy and 12 Gy—using of the modulation means of the present invention, the superposition in the transverse direction of the five adjacent subsections adds up to an intensity modulated dose distribution with a range of +/−20%. To produce other modulation patterns, the subsection charges and spot shapes will be optimized to generate the prescribed dose distribution (−140 nC, 100 nC, 120 nC, 110 nC and 150 nC for this graph).

[0158] While the embodiments have been described in conjunction with a number of embodiments, it is evident that many alternatives, modifications and variations would be or are apparent to those of ordinary skill in the applicable arts. Accordingly, this disclosure is intended to embrace all such alternatives, modifications, equivalents and variations that are within the scope of this disclosure. This for example particularly the case regarding the different apparatuses which can be used.

REFERENCE NUMBERS

[0159] 1 Device according to a first embodiment [0160] 2 Electron source [0161] 3 Linear accelerator [0162] 4 Beam delivery module [0163] 5 Target volume of a patient [0164] 6 High first beam line [0165] 7 Low momentum beam line [0166] 8 Separating means [0167] 9 Intensity modulation means [0168] 10 Splitter dipole [0169] 11 Dipole of high momentum [0170] 12 Dipole of low momentum [0171] 13 Deflecting means