METHOD FOR EFFICIENT DAILY CONSTANCY CHECK OR CALIBRATION OF PROTON THERAPY SYSTEM

• US 20130068938A1
• Filed: 09/21/2011
• Published: 03/21/2013
• Est. Priority Date: 09/21/2011
• Status: Active Grant

• Current Assignee: Varian Medical Systems Particle Therapy GmbH & Company KG (Siemens AG)
• Original Assignee: Juergen Heese
• Inventors: HEESE, Juergen
• Granted Patent: US 9,645,255 B2
• Time in Patent Office: Days
• US Class Current: 250/252.1
• CPC Class Codes: A61N 2005/1087 Ions; Protons
• CPC Class Codes: A61N 5/1075 for testing, calibrating, or quality assurance of the radiation treatment apparatus
• CPC Class Codes: G01T 1/169 Exploration, location of contaminated surface areas
• CPC Class Codes: G01T 1/185 with ionisation chamber arrangements
• CPC Class Codes: G01T 1/29 Measurement performed on radiation beams, e.g. position or section of the beam; Measurement of spatial distribution of radiation

Abstract

Systems and methods are provided for efficiently performing daily maintenance or quality assurance on proton therapy systems. Specifically, a system is provided which includes a solid-state phantom, a plurality of ionization chambers disposed within the solid-state phantom, and a measuring device coupled to the plurality of ionization chambers and operable to perform radiation measurements of proton beams received within the plurality of ionization chambers. Measurements of proton beams received in the ionization chambers may be used to derive the dose at the ionization chambers and be subsequently compared to pre-generated target data (e.g., data corresponding to proper treatment according to a radiation therapy treatment plan). If the data obtained through the maintenance procedure does not conform to the target data, the proton beam generator may be further calibrated.

Claims

1. A system comprising:

a solid-state phantom;

a plurality of ionization chambers disposed inside the solid-state phantom; and

a measuring device coupled to the plurality of ionization chambers and operable to perform radiation measurements in the plurality of ionization chambers,

wherein a proton beam generated by a radiation generating device is received in the plurality of ionization chambers and measured by the measuring device to generate a plurality of performance tests, the plurality of performance tests being used to perform constancy checks of the radiation generating device.

2. The system according to claim 1, wherein the proton beam generated by the radiation generating device generates a mono-energetic field of protons targeted at the solid-state phantom.

3. The system according to claim 1, wherein the measuring device comprises a multi-channel electrometer.

4. The system according to claim 1, wherein the plurality of performance tests comprises receiving the proton beam in the plurality of ionization chambers at a plurality of different angles.

5. The system according to claim 1, wherein the phantom is comprised of plastic.

6. The system according to claim 1, wherein the phantom is comprised of at least one of:

polymethyl methacrylate (PMMA) and polycarbonate.

7. The system according to claim 1, wherein the measuring device measures doses of radiation from the protons of the proton beam received in the plurality of ionization chambers.

8. The system according to claim 1, wherein an ionization chamber of the plurality of ionization chambers is positioned in the phantom at a depth corresponding to a distal falloff of a Bragg-peak curve plotted for the radiation measured by the measuring device.

9. The system according to claim 8, wherein the constancy checks of the radiation generating device comprise determining the range of the proton beam generated by the radiation generating device from the distal falloff of a Bragg-peak curve corresponding to the radiation measured by the measuring device.

10. A method comprising:

applying the proton beam to a first location according to a proton treatment plan;

receiving the proton beam applied to the first location in a first ionization chamber of an array of ionization chambers of a proton beam generating system;

redirecting, by using a magnetic field generated from a plurality of magnets, the proton beam to a second location corresponding to the proton treatment plan;

receiving the proton beam applied to the second location in a second ionization chamber of the array of ionization chambers;

measuring the proton beam received at the first and second ionization chambers to generate proton beam data; and

comparing the generated proton beam data to a pre-derived set of beam data.

11. The method according to claim 10, wherein comparing the generated proton beam data to a pre-derived set of beam data comprises comparing a deflection of the proton beam achieved by redirecting the proton beam with the magnetic field in the generated proton beam data and the pre-derived set of beam data.

12. The method according to claim 10, wherein the two dimensional array of ionization chambers comprise a raster of separated spots.

13. The method according to claim 12, wherein the raster of separate spots comprises a raster of equidistant spots.

14. The method according to claim 10, wherein the proton beam comprises a pencil beam.

15. The method according to claim 10, wherein the pre-derived set of beam data comprises at least one of:

DICOM Ion RT data; and

irradiation data to be applied by the treatment scanning system according to the proton treatment plan.

16. A method to calibrate a proton spot scanning beam delivery system, the method comprising:

receiving, in an ionization chamber disposed in a solid-state phantom, a proton beam emanating from a radiation treatment head;

generating a homogenous radiation field in the solid-state phantom from the proton beam;

measuring a homogenous radiation field in the ionization chamber to determine an absorbed dose from receiving the proton beam;

referencing a set of pre-defined proton beam data corresponding to a target performance of the proton spot scanning beam delivery system;

calculating a radiation dose corresponding to the homogenous radiation field by comparing the generated homogenous radiation field to the set of pre-defined proton beam data, the set of pre-defined proton beam data comprising a target radiation dose; and

calibrating the radiation treatment head to generate a proton beam with a radiation dose which more closely approximates the target radiation dose.

17. The method according to claim 16, wherein the homogenous radiation field is a two-dimensional radiation field.

18. The method according to claim 16, wherein the homogenous radiation field is a mono-energetic radiation field.

19. The method according to claim 16, wherein the homogenous radiation field comprises a plurality of pre-determined monitor units.

20. The method according to claim 16 wherein measuring the homogenous radiation field to determine an absorbed dose comprises measuring an absorbed dose per number of monitor units from receiving the proton beam.

21. The method according to claim 16, wherein the ionization chamber is a thimble ionization chamber.

22. The method according to claim 16, wherein the ionization chamber is disposed within the solid-state phantom at a shallow depth.

23. The method according to claim 16, wherein the ionization chamber is disposed within a liquid phantom at a shallow depth.

24. The method according to claim 16, wherein the proton beam comprises a pencil beam.

25. The method according to claim 16, wherein the set of pre-defined proton beam data comprises at least one data type from the group comprised of:

number of target spots, spot distance, and monitor units per spot.