Device For Ultra-High Dose Rate Radiation Treatment

Abstract

The present relates to device for ultra-high dose rate radiation treatment to a patient, comprising: —a radiation source for providing a radiation beam, and —a linear accelerator for accelerating said radiation beam until a predetermined energy, and —a beam delivery module for delivery the accelerated radiation beam. The device is arranged for generating an accelerated radiation beam having a predetermined energy between about 50 MeV and about 250 MeV, to deliver rate radiation dose of at least 10 Gy, during an overall time less than about 200 ms in order to generate a radiation field for treating a target volume of at least about 30 cm3, with said ultra-high dose rate radiation dose and/or a target volume located at least about 5 cm deep in the tissue of the patient with said ultra-high dose rate radiation dose.

Claims

1. A device for providing an ultra-high dose rate radiation treatment to a patient, the device comprising-: a radiation source arranged to provide a radiation beam; a linear accelerator arranged to accelerate said radiation beam until reaching a predetermined energy; and a beam delivery module arranged to deliver the accelerated radiation beam from said linear accelerator toward the patient to treat a target volume with a radiation dose, wherein: the device is arranged to generate the accelerated radiation beam having the predetermined energy between about 50 MeV and about 250 MeV, and to deliver an ultra-high dose rate radiation dose of at least about 10 Gy, during an overall time less than about 200 ms, so that the device is arranged for generating a radiation field for treating the target volume of at least about 30 cm.sup.3, with said ultra-high dose rate radiation dose, and/or treating a target volume located at least about 5 cm deep in the tissue of the patient with said ultra-high dose rate radiation dose.

2. The device according to claim 1, wherein the beam delivery module is arranged to separate the accelerated radiation beam into a plurality of accelerated beam lines with a radiation dose of about 7 Gy per beam delivered during said overall time.

3. The device according to claim 1, wherein the linear accelerator is arranged for generating a single accelerated beam comprising multiple trains of particle bunches, the beam delivery module is arranged to separate the single accelerated radiation beam into a plurality of accelerated beam lines separated by a determined angle, and subsequently focus each of said beam lines toward the patient to arrive simultaneously on the target volume, and each beam line corresponds to multiple trains of particle bunches.

4. The device according to claim 3 wherein each train has energy which differs by at least about 10%, and/or each beam line has an energy of at least about 50 MeV.

5. The device according to claim 2, wherein the beam delivery module includes energy-based separating means comprising at least one of a magnetic spectrometer, and radio frequency deflector based means.

6. The device according to claim 1, wherein the device is arranged to control the conformal irradiation of the beam arriving on the target volume.

7. The device according to claim 1, wherein said radiation dose comprises radiation pulses of the accelerated radiation beam, each radiation pulse comprising at least one particle bunch, and the device is arranged for delivering the ultra-high-dose rate radiation dose with at least about 2 Gy per radiation pulse, with a dose rate in the pulse of at least about 10.sup.6 Gy/sec.

8. The device according to claim 1, wherein the device is arranged for delivering the dose with a homogeneity of target volume coverage of at least about 85%.

9. The device according to claim 1, wherein the radiation source is an electron source.

10. The device according to claim 1, wherein the radiation source is arranged for delivering the radiation dose in a sequence of a train of particle bunches with a capability of up to ten trains of particle bunches of 250 nC each in said overall time.

11. The device according to claim 1, wherein said accelerated beam is a very high energy electron (VHEE) beam with a charge of at least about 1000 nC.

12. The device according to claim 1, wherein the radiation source comprises at least one of a radio-frequency laser-driven injector, and a thermionic injector.

13. The device according to claim 1, wherein the linear accelerator comprises radio frequency accelerating structures arranged to accelerate the radiation beam in the required overall time.

14. The device according to claim 1, wherein the linear accelerator is operating on a frequency including at least one of X-band, C-band and S-band.

15. The device according to claim 1, wherein the device is arranged to perform scanning of the target volume.

16. The device according to claim 1, wherein the device comprises at least two beam delivery modules, and each delivery module is arranged for treating one patient.

17. The device according to claim 1, wherein the device is arranged to generate the accelerated radiation beam having the predetermined energy between about 120 MeV and about 150 MeV, to deliver the ultra-high dose rate radiation dose up to about 25 Gy, during an overall time less than about 100 ms.

18. The device according to claim 1, wherein the device is arranged to generate the accelerated radiation to deliver the ultra-high dose rate radiation dose of up to about 35 Gy during an overall time less than about 50 ms.

19. The device according to claim 1, wherein the device is arranged to generate the accelerated radiation beam to deliver the ultra-high dose rate radiation dose during an overall time less than about 10 ms.

20. The device according to claim 1, wherein the device is arranged to generate the radiation field for treating the target volume between about 30 cm.sup.3 and about 1000 cm.sup.3 with said ultra-high dose rate radiation dose, and/or treat the target volume located between about 5 cm and about 25 cm deep in the tissue of the patient with said ultra-high dose rate radiation dose.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0098] 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

[0099] FIGS. 1 and 2 represent a device according to the present invention according to a first embodiment;

[0100] FIG. 3 illustrates a simulation of a FLASH-Therapy with the present invention in a patient with a large (10 cm diameter) lung cancer;

[0101] FIG. 4 shows the evolution of the cognitive sparing of murine brain after 10 Gy brain irradiation by a 6 MeV electron beam;

[0102] FIG. 5 shows dosimetry simulations for the penetration into human thorax of the irradiation by single electron beam in the range of energies 25 MeV to 140 MeV.

DETAILED DESCRIPTION OF THE INVENTION

[0103] 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.

[0104] FIGS. 1 and 2 represent a device 1 according to the present invention according to a first embodiment.

[0105] The device 1 comprises a radiation source 2, a linear accelerator 2 and a beam delivery module 3. The device 1 is arranged for delivering a radiation dose to a target volume 5 of a patient (not shown in figures).

[0106] The radiation source 2 is a high current electron source, in particular a Radio-frequency laser-driven photo-injector. The photo injector produces the electron bunches and accelerates them to an energy where they are relativistic. It consists of a set of coupled resonant cavities which are powered by a klystron modulator system. A short laser pulse impinges on the back plane of the first cavity causing the emission of electrons, to form a bunch, by the photoelectric effect. The back plane of the photocathode is coated with Cs.sub.2Te for increased quantum efficiency and a laser with 262 nm wavelength is used. Microwave fields of approximately 110 MV/m accelerate the bunch. Successive laser pulses during an rf pulse form a train of bunches. Successive rf pulses give multiple trains.

[0107] In the embodiment represented in FIGS. 1 and 2, the photo injector operates at S-band, specifically 2.9985 GHz, has 1.5 cells and accelerates the beam up to 5 MeV. The photoinjector is powered by a klystron and requires approximately 30 MW of input power.

[0108] The photo injector produces bunches of a charge of 0.308 nC with a spacing of ⅓ ns between bunches, giving an average current during the pulse of approximately 1 A. There are 953 bunches per train. Each bunch is approximately 300 micrometers long.

[0109] The linear accelerator 3, or linac, is a high current X-Band linac. In the embodiment represented in FIGS. 1 and 2, 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. The linac accelerates the beam up to the treatment energy. In the present example, the linac consists of repeated rf units which consists of a klystron modulator, an rf pulse compressor, a waveguide network and multiple accelerating structures.

[0110] In the embodiment represented in FIGS. 1 and 2, the linac accelerates the beam from the 5 MeV coming out of the injector, to adjustable energies up to a maximum of 140 MeV. The linac operates in X-band, specifically 11.994 GHz. An rf unit consists of a modulator driving a 50 MW klystron, the pulse compressor and four accelerating structures. The pulse compressor gives a factor of 2.8 in power gain. Each accelerating structure is 0.5 long and operates in the 2π/3 phase advance travelling wave mode. Each rf unit gives the beam 70 MeV of energy gain. The accelerating gradient, with the nominal beam current of approximately 1 A, is up to 35 MV/m. Two rf units give a maximum energy of 140 MeV.

[0111] A combination of magnetic elements and rf focusing controls the properties of the beam. The accelerating structures are equipped with higher-order-mode damping to transport the high current beam without instabilities.

[0112] The beam delivery module consists of normal conducting magnets; one main dipole magnet to deflect and separate the different energy beams, dipole magnets to give the trajectories that enter the patient at the defined angles and quadrupole magnets to guide the beam, then control the irradiation spot size of the beam entering the patient.

[0113] The beam delivery system represented in the present example consists of a separator magnet and bending magnet (as separating means) to respectively separate the single accelerated beam in multiple beam lines and direct said multiple beam lines on the patient. The separator magnet is used to direct trains of discrete energies of the single beam into the multiple beam lines. The multiple beam lines are divergent after the separator magnet. Bending magnets near the middle of the individual lines direct the particle trajectories back to the target volume. The quadrupoles in each the beamlines also expand the beam from the mm size in the linac to the final treatment dimensions which can be larger than 15 cm.

[0114] In the embodiment represented in FIGS. 1 and 2, the separator magnet has a length of 55.5 cm and a half aperture of 15 mm. The bending magnets have a length of 80 cm and a half aperture of 25 mm.

[0115] The quadrupoles in the beamlines have lengths of 20 cm and half apertures of 18 to 35 mm.

[0116] FIG. 3 represents simulation of a FLASH-Therapy with the present invention in a patient with a large lung cancer. In the present case, a device according to the present invention was used to simulate a FLASH-RT treatment in a T4-NO lung cancer patient having a 10 cm large tumor size.

[0117] In this FIG. 3, due to the proximity of the tumor with critical organs such as brachial plexus and oesophagus, as shown in FIG. 2, this patient could only receive 46 Gy in 23 fractions in conventional RT, which gave a tumor biological equivalent dose (BED) of 46 Gy. The simulation of a FLASH treatment using a device according to the present invention allowed to deliver a single dose of 28 Gy safely. This corresponds to a highly curative BED of 115 Gy for the tumor. Advantageously, this simulation integrates a normal tissue sparing factor of 33% due to the FLASH conditions.

[0118] FIG. 4 shows the evolution of the cognitive sparing of murine brain after 10 Gy brain irradiation by a 6 MeV electron beam. The experimental data are adapted from P. Montay-Gruel et al, Radiother Oncol, 2017; 124:365-9. The curve is a logistic fit through the data. The figure shows how the effect on neuroprotection as evaluated by novel Object Recognition tests (vertical axis: Recognition ratio in percent) varies with overall time for delivering 10 Gy (horizontal axis in ms). It clearly highlights the necessity of delivering the irradiation in less than 200 ms, preferably less than 100 ms, more preferably less than 50 ms to beneficiate of the FLASH protection effect as proposed by the present invention.

[0119] FIG. 5 shows dosimetry simulations for the penetration into human thorax of the irradiation by single electron beam in the range of energies 25 MeV to 140 MeV. The thin lines corresponds to the dose variations (isodoses) for an irradiation of 20 Gy at the depth of maximum. The thick line represents an 8 cm diameter tumour volume at 11 cm depth. The FIG. 5 illustrates the need to achieve an energy of more than 50 MeV to avoid an underdosage of the deeper part of the tumour as it is described in the present invention.

[0120] 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

[0121] 1 Device according to a first embodiment [0122] 2 Radiation source [0123] 3 Linear accelerator [0124] 4 Beam delivery module