Apparatus For Particle Therapy Verification

• US 20140061493A1
• Filed: 02/03/2012
• Published: 03/06/2014
• Est. Priority Date: 02/04/2011
• Status: Active Grant

• Current Assignee: Ion Beam Applications s.a., Universite libre de Bruxelles
• Original Assignee: Frederic Stichelbaut
• Inventors: Prieels, Damien, Stichelbaut, Frdric, Smeets, Julien, Dubus, Alain, Dehaes, Jean-Claude
• Granted Patent: US 9,186,525 B2
• Time in Patent Office: Days
• US Class Current: 250/393
• CPC Class Codes: A61N 2005/1052 using positron emission tomography [PET] single photon emission computer tomography [SPECT] imaging
• CPC Class Codes: A61N 2005/1087 Ions; Protons
• CPC Class Codes: A61N 5/1048 Monitoring, verifying, controlling systems and methods
• CPC Class Codes: A61N 5/1071 for verifying the dose delivered by the treatment plan
• CPC Class Codes: A61N 5/1075 for testing, calibrating, or quality assurance of the radiation treatment apparatus
• CPC Class Codes: F04C 2270/041 Controlled or regulated
• CPC Class Codes: G01T 1/2914 Measurement of spatial distribution of radiation

Abstract

The invention is related to an apparatus and method for charged hadron therapy verification by detecting and/or quantifying prompt gammas produced when irradiating a target (6) with a charged hadron beam. The apparatus comprises a collimator (1) provided with a slit-shaped portion (2) configured to be arranged perpendicularly to the beam line and facing the target, a detection means (3,4) suitable for detecting said prompt gammas and a calculation and representation means. In the apparatus and method of the invention, the slit is configured to allow the passage of prompt gammas emitted from a range of depths in said target (6), said depths being measured in the direction of the charged hadron beam. Furthermore, said detection means is configured to detect prompt gammas emitted from each location within said range, and said calculation and representation means is configured to derive from a detected prompt gamma a value representative of the dose at the location from where said prompt gamma is emitted, and to represent a dose-related distribution for a plurality of locations within said range.

Claims

1. An apparatus for charged hadron therapy verification by detecting and/or quantifying prompt gammas produced when irradiating a target with a charged hadron beam, the beam being directed along a beam line, said apparatus comprising:

a collimator formed of a first material and provided with a slit-shaped portion which is open or which comprises a material of a lower thickness and/or density than said first material, said slit-shaped portion being configured to be arranged perpendicularly to the beam line and facing the target,

a detection means suitable for detecting said prompt gammas and

a calculation and representation means,

the slit-shaped portion is configured to allow the passage of prompt gammas emitted at least from a zone of the target corresponding to a portion of the beam line within said target, said portion of the beam line being larger than the width of the slit-shaped portion,

said detection means is configured to detect prompt gammas passing through the slit-shaped portion, said prompt gammas being emitted from a plurality of locations within said zone of the target,

said calculation and representation means is configured to derive from a detected prompt gamma a value representative of the dose at the location from where said prompt gamma is emitted, and to represent a dose-related distribution for said plurality of locations, thereby allowing to estimate the beam range within said target,

said detection means and said calculation and representation means are configured to calculate and represent said value in a plurality of portions of said zone arranged along the beam line, to thereby obtain a one-dimensional view of the dose-related distribution within said zone,

the apparatus comprising means for approximating said one-dimensional view by a 3-line segment curve.

2. The apparatus according to claim 1, wherein said detection means comprises a scintillator arranged at a distance from said slit-shaped portion, and having a surface facing said slit-shaped portion, and at least one array of photon counting devices associated with said scintillator.

3. The apparatus according to claim 2, wherein said scintillator is formed of a plurality of segments arranged in a row of segments oriented perpendicularly to the slit-shaped portion.

4. The apparatus according to claim 2, wherein said scintillator is formed of a plurality of segments arranged in a row of segments oriented in the direction of the thickness of said scintillator.

5. The apparatus according to claim 2, wherein said array of photon counting devices is arranged parallel to the scintillator.

6. The apparatus according to claim 1, wherein said array of photon counting devices is arranged laterally with respect to the scintillator and perpendicularly with respect to the slit-shaped portion.

7. The apparatus according to claim 1, wherein said slit-shaped portion comprises a solid material with a lower thickness and/or density than said first material.

8. The apparatus according to claim 1, wherein said slit-shaped portion extends between the front and back plane of the collimator, said front plane being configured to face the target, and wherein the slit-shaped portion has two side walls, at least one of said two side walls diverging from a given narrower section of the slit-shaped portion to a broader section of the slit-shaped portion situated at the front of the collimator.

9. The apparatus according to claim 8, wherein the slit-shaped portion comprises a middle portion and two side portions, said side portions being located respectively between the middle portion and said front plane of the collimator, and between the middle portion and said back plane of the collimator, said side portions having diverging walls tapering outwards from the middle portion to the front, respectively the back plane of the collimator.

10. The apparatus according to claim 9, wherein the middle portion is a throat section having zero length, and wherein the detection means comprises a rectangular face placed at a distance (A) from the central longitudinal axis of the throat section, said face being furthermore symmetrical with respect to the plane through said central longitudinal axis and perpendicular to the plane of the throat section, and wherein the field-of-view angle (γ

) is defined as the angle between said rectangular face of the detection means and a plane from the central longitudinal axis of the throat section to a side edge of the rectangular face, and wherein the angle (δ

) between the side walls of the side portion at the front of the collimator and the front plane of the collimator is between 80% and 100% of said field-of-view angle (γ

).

11. The apparatus according to claim 9, wherein the width of the middle portion of the slit-shaped portion is between 1 and 10 mm.

12. The apparatus according to claim 1, wherein the thickness of the collimator is between 30 mm and 50 mm.

13. The apparatus according to claim 1, wherein the scintillator material is LYSO or LSO.

14. The apparatus according to claim 1, wherein the collimator material is tungsten or a tungsten alloy.

15. The apparatus according to claim 1, wherein said scintillator and said array of photon counting devices are mounted inside a housing which is fixed with respect to the collimator.

16. The apparatus according to claim 1, wherein the apparatus is configured to be movable with respect to the target.

17. The apparatus according to claim 16, further comprising a holder onto which the apparatus is mounted and a robotic arm onto which the holder is mounted.

18. The apparatus according to claim 1, wherein the collimator has the form of a flat panel provided with a longitudinal slit shaped portion.

19. The apparatus according to claim 1, wherein the collimator is cylindrically shaped, and configured to be placed around the target, and wherein the slit-shaped portion extends along a circular circumference of the collimator.

26. The apparatus according to claim 1, wherein the means for approximating is configured to determine a shift of the 3-line segment curve with respect to a previously determined 3-line segment curve, or with respect to a simulated 3-line segment curve obtained from simulated data by which the apparatus is calibrated.

27. The method according to claim 20, wherein the previously obtained 3-line segment curve is a curve obtained by the apparatus according to claim 1.

28. The method according to claim 20, wherein the previously obtained 3-line segment curve is a curve obtained from simulation data by which the apparatus according to claim 1 is calibrated.

29. A method for determining changes in the beam range of a charged hadron beam irradiating a target, comprising the steps of:

applying the apparatus according to claim 1, for obtaining a 1-D dose-related distribution,

approximating the distribution by a 3-line segment curve,

determining the shift of the curve with respect to a previously obtained 3-line segment curve.

30. The method according to claim 29, wherein the previously obtained 3-line segment curve is a curve obtained by the apparatus.

31. The method according to claim 29, wherein the previously obtained 3-line segment curve is a curve obtained from simulation data by which the apparatus is calibrated.

20. A method for charged hadron therapy verification by detecting and/or quantifying prompt gammas produced when irradiating a target with a charged hadron beam, said beam being directed along a beam line, comprising the steps of:

arranging adjacent to a target a collimator with a longitudinal slit shaped portion, said slit-shaped portion being configured to be arranged perpendicularly to the beam line and facing the target, said slit-shaped portion being configured to allow the passage of prompt gammas emitted at least from a zone of the target corresponding to a portion of the beam line within said target, said portion of the beam line being larger than the width of the slit-shaped portion,

irradiating said target with a charged hadron beam directed along said beam line,

detecting prompt gammas emitted from a plurality of locations within said zone of the target, said prompt gammas passing through said slit-shaped portion,

deriving from said detected prompt gamma a 1-dimensional dose-related distribution for said plurality of locations,

approximating said distribution by a 3-line segment curve,

determining the shift of said curve with respect to a previously obtained 3-line segment curve.

22. The method according to claim 20, wherein a window of energy levels for prompt gammas is defined, and wherein only prompt gammas are detected within said energy window.

23. The method according to claim 22, wherein said energy window is between 3 MeV and 7 MeV, more preferably between 3 MeV and 6 MeV.

21. (canceled)

24. (canceled)

25. (canceled)

32. An apparatus for charged hadron therapy verification by detecting and/or quantifying prompt gammas produced when irradiating a target with a charged hadron beam, the beam being directed along a beam line, the apparatus comprising:

a collimator provided with a slit-shaped portion, the slit-shaped portion being configured to be arranged perpendicularly to the beam line and facing the target,

a detection means suitable for detecting the prompt gammas, and

a calculation and representation means,

wherein the slit-shaped portion is configured to allow the passage of prompt gammas emitted at least from a zone of the target corresponding to a portion of the beam line within the target,

wherein the detection means is configured to detect prompt gammas passing through the slit-shaped portion, the prompt gammas being emitted from a plurality of locations within the zone of the target,

wherein the calculation and representation means is configured to derive from a detected prompt gamma a value representative of the dose at the location from where the prompt gamma is emitted, and to represent a dose-related distribution for the plurality of locations, thereby allowing to estimate the beam range within the target,

wherein the detection means and the calculation and representation means are configured to calculate and represent the value in a plurality of portions of the zone arranged along the beam line, to thereby obtain a one-dimensional view of the dose-related distribution within the zone,

and wherein the apparatus is calibrated with simulated data so as to measure a shift in the beam range.