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

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

3. The device according to claim 1, wherein the entire radiation dose is of at least 30 Gy, or at least 35 Gy, or at least 40 Gy.

4. The device according to claim 1, wherein each portion receives a radiation dose up to an entire radiation dose.

5. The device according to claim 1, wherein each portion receives at least one train of electrons bunches.

6. The device according to claim 1, wherein the intensity modulation means comprises a 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 which modulates the distribution of radiation dose in the target volume.

7. The device according to claim 1, wherein the intensity modulation means comprises an 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 which modulates the distribution of radiation dose along the direction of the accelerated beam through the target volume.

8. The device according to claim 7, wherein each train has an energy which differs from 1% to 5%.

9. The device according to claim 1, wherein the accelerated electron beam is separated into a plurality of beam lines by a separating means, each beam lines being separated by a determined angle, and subsequently focusing each of said beam lines toward the patient to arrive in an overall time of less than 50 ms on the target volume, each beam line further comprising an independent intensity modulation means.

10. The device according to claim 9, wherein each beam line has an energy that differs from 10% to 40%.

11. The device according to claim 1, wherein the intensity modulation means comprises a deflecting means for deflecting each train of electrons bunches position transversely relative to the accelerated beam direction, said deflecting means having a deflecting speed faster than the interspacing time between two subsequent trains.

12. The device according to claim 11, wherein the deflecting means comprises a magnet.

13. The device according to claim 11, wherein the deflecting means comprises a radio frequency deflector.

14. The device according to claim 1, wherein the energy variation means is set for implementing predetermined energy variations between each train of electrons bunches, said energy variation means being operated from the linear accelerator.

15. The device according to claim 14, wherein the energy variation means is operated by controlling an amplitude and the phase of the radiofrequency pulses of the linear accelerator.

16. The device according to claim 1, wherein the intensity modulation means comprises a combination of charge variation means, energy variation means, deflection means and multiple beam lines.

17. The device according to claim 1, wherein the accelerated electron beam has a predetermined energy between 30 MeV and 250 MeV, or between 50 MeV and 250 MeV, or between 50 MeV and 150 MeV.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) 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

(2) 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;

(3) 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

(4) 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.

(5) 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.

(6) 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.

(7) The radiation source 2 is a high current electron source, in particular a Radiofrequency laser-driven photo-injector.

(8) 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 radiofrequency 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.

(9) 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.

(10) 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: Size: 1000 mm850 mm800 mm Weight: 3000 kg Material: iron yoke, copper coils Bending angle: 122 degrees (for low momentum beam); 65.5 degrees (for high momentum beam) Central field: 1.0 T Effective length: 0.555 m (for low momentum beam); 0.665 m (for high momentum beam)

(11) 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.

(12) The dipole of high momentum 11 has the following parameters: Size: 700 mm735 mm450 mm Weight: 1500 kg Material: iron yoke, copper coils Bending angle: 54.5 degrees Central field: 0.95 T Effective length: 0.5 m Current: 22.4 A

(13) The dipole of low momentum 12 has the following parameters: Size: 700 mm735 mm450 mm Weight: 1500 kg Material: iron yoke, copper coils Bending angle: 92.3 degrees Central field: 1.09 T Effective length: 0.5 m Current: 27.2 A

(14) 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.

(15) The deflecting means 13 are scanning magnets, preferably fast ramping magnets or magnets capable of fast field-ramping' with the following parameters: Size: 290 mm205 mm205 mm Weight: 1500 kg Material: iron yoke, copper coils Duty cycle: 10% Integrated field: 0.034 Tm Maximal deflection angle: 100 mrad Effective length: 0.3 m Current: 5.6 kA;

(16) 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%.

(17) FIGS. 3 and 4 represent two examples of dose distribution that can be achieved with the present invention.

(18) 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 1015 cm2 (in cross section) within a total time of 32 ms using 5 trains of 0.3 s 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.

(19) 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 1015 cm2 (in cross section) within a total time of 32 ms using 5 trains of 0.3 s 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 levelsfrom left to right: 11 Gy, 8 Gy, 10 Gy, 9 Gy and 12 Gyusing 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).

(20) 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

(21) 1 Device according to a first embodiment 2 Electron source 3 Linear accelerator 4 Beam delivery module 5 Target volume of a patient 6 High first beam line 7 Low momentum beam line 8 Separating means 9 Intensity modulation means 10 Splitter dipole 11 Dipole of high momentum 12 Dipole of low momentum 13 Deflecting means