Device And Method For Particle Therapy Monitoring And Verification

• US 20110248188A1
• Filed: 05/06/2009
• Published: 10/13/2011
• Est. Priority Date: 05/06/2008
• Status: Active Grant

• Current Assignee: Ion Beam Applications s.a.
• Original Assignee: Ion Beam Applications s.a.
• Inventors: Marchand, Bruno, Brusasco, Caterina
• Granted Patent: US 8,716,663 B2
• Time in Patent Office: Days
• US Class Current: 250/492.1
• 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

Abstract

The present invention relates to a device and method for monitoring and verification of the quality of a radiation treatment beam in conformal radiation therapy, and in particular for IMPT (Intensity Modulated Particle Therapy) applications. The device comprises a 2D electronic detector measuring 2D responses to the delivered treatment beam. These 2D responses are compared with predicted 2D responses and differences in responses are signalled. Based on the measured 2D responses the effectively delivered 3D dose distribution in the target can be reconstructed.

Claims

1. A device for monitoring and verification of treatment beam delivery with a particle radiation apparatus, said treatment beam comprising one or more treatment sub beams corresponding each to a treatment beam layer, each of said treatment beam layers being characterized by a set of treatment beam layer parameters, said particle radiation apparatus being configurable for a given set of treatment beam layer parameters, said device comprising:

an acquirer configured to acquire treatment beam layer parameters for each said treatment beam layer;

an electronic 2D detector device configured to measure 2D responses of said treatment beam layer in a plane essentially perpendicular to the central axis of said treatment beam;

a 2D detector response predicting module configured to determine predicted 2D detector responses for each of said treatment beam layers to be delivered with said particle radiation apparatus configured with said given set of treatment beam layer parameters;

a memory to store the predicted 2D detector responses of each said treatment beam layer;

an acquirer configured to acquire in real time the 2D detector responses caused by said treatment beam layer delivered by said particle radiation apparatus being configured with said given set of treatment beam layer parameters;

a 2D detector response comparison module configured to perform a comparison between the measured 2D detector responses and the corresponding said predicted 2D detector responses; and

an error handling module configured to signal the difference between said measured 2D detector responses and said predicted 2D detector responses.

2. The device according to claim 1, wherein said 2D detector response predicting module further comprises:

a 2D detector fluence calculation device configured to calculate the particle fluence at the 2D detector position for said treatment beam layer parameters;

said particle fluence calculation device comprising a beam model, said beam model being based on a set of beam model parameters, said beam model parameters comprising characteristics of the particle radiation apparatus and said particles; and

a 2D detector response calculation device configured to calculate for a given said particle fluence at the 2D detector position the corresponding 2D detector responses, said 2D detector response calculation device comprising a detector model of said 2D detector device describing the geometry of the 2D detector and a detector response model describing the response of the 2D detector to particle irradiation.

3. The device according to claim 2 wherein said 2D detector fluence calculation device and/or said 2D detector response calculation device is based on a Monte Carlo algorithm calculating the particle fluence at the 2D detector position or calculating the 2D detector responses.

4. The device according to claim 1 further comprising a measurer configured to measure the energy of particles of a said treatment beam layer.

5. The device according to claim 4, wherein the measurer comprises a particle range detector, said particle range detector configured to measure the particle waterequivalent range, said particle waterequivalent range being a function of said particle energy.

6. The device according to claim 4, wherein the measurer further comprises an energy calculating device, said energy calculating device being based on examining distortions in the shape of the measured 2D detector responses when compared with the predicted 2D detector responses, said distortions being function of variations in said energy.

7. The device according to claim 1, wherein the device further comprises:

an importer configured to import a description of the target volume in an object, said description comprising the 3D shape, density distribution and position of the target volume and/or organs at risk within the object;

a treatment beam parameter reconstructing device configured to compute for each delivered treatment beam layer the delivered treatment beam layer parameters based on the measured 2D detector responses of each layer and a beam model, said beam model being characterized by a set of beam model parameters;

a particle fluence calculation device configured to calculate for each delivered treatment beam layer the delivered layer particle fluence through the object based on the delivered treatment beam layer parameters and said beam model;

a dose calculation device configured to compute the delivered 3D dose distribution within the object, said 3D dose distribution resulting from one or more delivered treatment beams, each said delivered treatment beam comprising one or more said delivered treatment beam layers, said computing the delivered 3D dose distribution being based on said delivered layer particle fluence of each layer of each treatment beam; and

a display configured to display the delivered 3D dose distribution in the object.

8. The device according to claim 7, wherein:

said treatment beam parameter reconstructing device further comprises an iterative algorithm configured to update the beam model parameters and/or said layer treatment beam parameters until the comparison between the measured 2D detector responses and the corresponding predicted 2D detector responses minimizes a scoring function and assign the new values of beam model and/or treatment beam layer parameters, obtained after minimizing the scoring function, as the delivered beam model parameters and/or delivered treatment beam layer parameters; and

said particle fluence calculation device configured to calculate for each delivered treatment beam layer the delivered layer particle fluence through the object is using the delivered treatment beam layer parameters and the delivered beam model parameters.

9. The device according to claim 7 further comprising:

an importer configured to import the planned 3D dose distribution in the object as calculated by an external treatment planning system;

a comparer configured to compare the planned 3D dose distribution with the delivered 3D dose distribution; and

a reporter configured to report a set of parameters resulting from said comparison.

10. The device according to claim 7 further comprising:

a memory configured to store the delivered 3D dose distribution delivered during a treatment fraction;

an accumulator configured to accumulate the delivered 3D dose distributions delivered during subsequent treatment fractions; and

a display configured to display the accumulated 3D dose distribution in the object.

11. The device according to claim 10 further comprising:

an acquirer configured to acquire an updated description or image of an object;

a memory configured to store the updated description or image of the object; and

a display configured to display the accumulated 3D dose distribution with the updated description or image of the object.

12. The device according to claim 1, further comprising an input module for importing a treatment plan from an external device, said treatment plan comprising a plurality of plan parameters, said plurality of plan parameters comprising said treatment beam layer parameters, said a description of the target volume in an object, said planned 3D dose distribution.

13. The device according to claim 1, wherein the device is configured to operate independently from the particle radiation apparatus, receiving only a treatment plan from an external device.

14. The device according to claim 1, further comprising a commissioning module to optimize said set of beam model parameters based on measured data with the particle radiation apparatus.

20. The device according to claim 1, wherein the device is configured to receive synchronization, signals from a particle radiation apparatus for synchronizing the 2D detector device with the treatment beam delivery

15. A method for verifying treatment beam delivery from a particle radiation apparatus prior to patient irradiation, said method comprising:

providing a particle radiation apparatus for delivery of a treatment beam, said treatment beam comprising one or more treatment sub beams, each of said treatment sub beams being defined as a treatment beam layer corresponding to an irradiation layer and comprising particles having essentially the same energy, each of said treatment beam layers being characterized by a set of treatment beam layer parameters, said particle radiation apparatus being configurable for a given set of treatment beam layer parameters, said device comprising;

providing an acquirer configured to acquire prescribed treatment beam layer parameters;

providing a 2D detector device configured to provide a measured 2D detector response of said treatment beam layer in a plane perpendicular to the central axis of said treatment beam;

for each beam layer,

determining a predicted 2D detector response for said prescribed treatment beam layer parameters;

delivering said treatment beam layer with said particle radiation apparatus being configured with said prescribed treatment beam layer parameters;

measuring the 2D detector responses caused by the treatment beam layer delivered by said particle radiation apparatus;

performing a comparison between the measured 2D detector response and the corresponding predicted 2D detector response; and

signalling difference between said measured 2D detector response and said predicted 2D detector response.

16. The method according to claim 15, wherein the method further comprises:

providing a measurer configured to determine the layer energy of a treatment beam layer;

for each beam layer;

determining the delivered layer energy of the particles;

performing a comparison between the delivered layer energy and the prescribed layer energy, the prescribed layer energy being part of the treatment beam layer parameters; and

signalling difference between said measured layer energy and said prescribed layer energy.

17. The method according to claim 15, wherein the method further comprises:

providing a description of a target volume in an object, said description comprising the 3D shape, density distribution and position of the target volume within the object;

computing for each delivered treatment beam layer the corresponding delivered treatment beam layer parameters based on the measured 2D detector responses of each beam layer and a beam model, said beam model being characterized by a set of beam model parameters;

computing for each delivered treatment beam layer the delivered layer particle fluence through the object based on the delivered treatment beam layer parameters and said the beam model;

computing the delivered 3D dose distribution within the object, said 3D dose distribution resulting from one or more delivered treatment beams, each delivered treatment beam comprising one or more delivered treatment beam layers, said computing the delivered 3D dose distribution is based on said delivered layer particle fluence of each layer of each treatment beam; and

displaying the delivered 3D dose distribution in the object.

18. A method according to claim 17, wherein the step of computing delivered treatment beam parameters comprises:

a. providing new values for said treatment beam layer parameters and/or said beam model parameters;

b. obtaining new predicted 2D detector responses based on new values for said treatment beam layer parameters and/or beam model parameters;

c. repeating steps a and b until the comparison between the measured 2D detector responses and the corresponding predicted 2D detector responses minimizes a scoring function; and

d. assigning the new values of treatment beam layer parameters and/or beam model parameters obtained after minimizing the scoring function as the delivered treatment beam layer parameters and/or delivered beam model parameters;

wherein the step of computing for each delivered treatment beam layer the delivered layer particle fluence through the object being based on the delivered treatment beam layer parameters and said delivered beam model parameters.

19. A method according to claim 17 wherein the method further comprises:

importing the planned 3D dose distribution in the object as calculated by an external treatment planning system;

comparing the planned 3D dose distribution with the delivered 3D dose; and

reporting a set of parameters resulting from said comparison.