Portal dosimetry systems, devices, and methods

• US 9,987,504 B2
• Filed: 04/02/2015
• Issued: 06/05/2018
• Est. Priority Date: 04/02/2015
• Status: Active Grant

• Current Assignee: Siemens Healthineers International AG
• Original Assignee: Varian Medical Systems International AG (Siemens AG)
• Inventors: Nord, Janne, Toimela, Lasse Heikki
• Primary Examiner(s): Kiknadze, Irakli
• Application Number:
  US14/677,392
• Publication Number:
  US 20160287906A1
• Time in Patent Office: 1,160 Days
• Field of Search: 378 64, 378 65, 378 97
• CPC Class Codes: A61N 2005/1054 using a portal imaging system
• CPC Class Codes: A61N 5/103 Treatment planning systems
• CPC Class Codes: A61N 5/1071 for verifying the dose delivered by the treatment plan

Abstract

Systems, devices, and methods for dosimetric verification of radiation therapy treatments by selective evaluation of measurement points. Systems, methods, and computer program-products for providing dosimetric verification of radiation therapy treatments by evaluating measurement points using different evaluation criteria.

Claims

1. A method for evaluating radiation dose delivery to a target, comprising:

generating a radiation dose distribution image based on radiation delivered according to a treatment plan, the generated radiation dose distribution image including at least a first point and a second point;

comparing the generated radiation dose distribution image with a corresponding predicted radiation dose distribution image, the comparing including comparing points in the generated radiation dose distribution image with corresponding points in the predicted radiation dose distribution image;

evaluating the compared points using different evaluation criterias;

and

determining whether dose delivery is acceptable based on a result of the evaluation,

wherein the evaluating includes evaluating the first point using a first gamma criteria including dose and spatial differences and evaluating the second point using a second gamma criteria including dose and spatial differences, the second gamma criteria being different than the first gamma criteria, or evaluating the first point against a maximum absolute dose value and the second point against a minimum absolute dose value.

2. The method of claim 1, wherein the evaluating includes evaluating dose and spatial differences between the generated and predicted points.

3. The method of claim 1, wherein the radiation dose delivery is determined to be acceptable if a predetermined number of points in the generated radiation dose distribution image pass their respective gamma criteria.

4. The method of claim 3, wherein the predetermined number of points is at least 90% of the total amount of evaluated points in the generated radiation dose distribution image.

5. The method of claim 1, wherein the first point is associated with the target and the second point is associated with an organ at risk.

6. The method of claim 5, wherein the second gamma criteria is more stringent than the first gamma criteria.

7. The method of claim 1, wherein each point in the generated radiation dose distribution image is associated with a respective gamma criteria.

8. The method of claim 7, wherein each gamma criteria includes a first parameter and a second parameter.

9. The method of claim 8, wherein the first parameter is associated with an acceptable dose difference, and the second parameter is associated with an acceptable spatial difference.

10. The method of claim 9, wherein the first parameter includes a range of between 2% and 4% and the second parameter includes a range of between 2 mm and 4 mm.

11. The method of claim 7, wherein the gamma criteria used for a point is dependent on an anatomical structure that is projected onto the point.

12. The method of claim 11, wherein if an anatomical structure is projected onto a plurality of points in the generated radiation dose distribution image, the plurality of points are evaluated using a first gamma criteria.

13. The method of claim 11, wherein if two anatomical structures are projected onto a single point in the generated dose distribution image, the point is evaluated using a gamma criteria which is the more stringent one between a first gamma criteria associated with a first anatomical structure and a second gamma criteria associated with a second anatomical structure.

14. The method of claim 13, wherein the anatomical structure includes organs, the target, and normal tissues.

15. The method of claim 14, wherein the organs include organs located adjacent the target.

16. The method of claim 14, wherein the organ includes a critical organ.

17. The method of claim 16, wherein the critical organ includes at least a portion of one of the following:

spine, spinal cord, heart, brain, bladder, rectum, lung, heart, liver, stomach, kidney, pancreas, and eye.

18. The method of claim 1, wherein the portal dose images are obtained using an electronic portal dose imaging device (EPID).

19. The method of claim 18, wherein the electronic portal dose imaging device (EPID) is calibrated for measuring absolute dose.

20. The method of claim 19, wherein the measured dose is an absolute dose.

21. The method of claim 19, wherein the absolute dose calibration includes an absolute (EPID) conversion model.

22. The method of claim 1, further comprising generating an alarm signal and/or stopping radiation dose delivery to the target when dose delivery is unacceptable.

23. A method for evaluating radiation dose delivery to a target, comprising:

generating a radiation dose distribution image based on radiation delivered according to a treatment plan;

projecting anatomical structures onto a measurement plane, the anatomical structures being associated with different gamma criterias;

associating points in the generated distribution image with gamma criterias based on the projections;

comparing points in the generated radiation dose distribution image with corresponding points in the predicted radiation dose distribution image;

evaluating the compared points using gamma criterias based on the associating; and

determining whether dose delivery is acceptable based on a result of the evaluation.

24. The method of claim 23, wherein the evaluating includes evaluating dose and spatial differences between the generated and predicted points.

25. The method of claim 23, wherein the evaluating includes evaluating using a gamma evaluation method.

26. The method of claim 23, wherein the radiation dose delivery is determined to be acceptable if a predetermined number of points in the generated radiation dose distribution image pass their respective gamma criterias.

27. A method for selectively evaluating radiation dose delivery to a target, comprising:

generating a radiation dose distribution image based on radiation delivered according to a treatment plan;

comparing the generated radiation dose distribution image with a corresponding predicted radiation dose distribution image;

the comparing including comparing selected points in the generated radiation dose distribution image with corresponding points in the predicted radiation dose distribution image;

evaluating the compared selected points; and

determining whether dose delivery is acceptable based on a result of the evaluation,

wherein the selected points include points selected based on patient surface information.

28. The method of claim 27, wherein the selected points exclude points that are irradiated with beams that do not intersect the surface of the patient.

29. The method of claim 27, wherein the selected points exclude points that are irradiated with beams that intersect the patient at a predetermined distance below the surface of the patient.

30. The method of claim 29, wherein the predetermined distance includes a distance that is less than about 1 cm.

31. The method of claim 27, wherein the evaluating includes evaluating using a gamma evaluation method.

32. The method of claim 27, wherein the comparing includes comparing dose and spatial discrepancies between the selected points in the generated portal dose image and the predicted portal dose image.

33. The method of claim 27, wherein the evaluation is in real-time.

34. The method of claim 27, wherein the portal dose images are obtained using an electronic portal dose imaging device (EPID).

35. The method of claim 34, wherein the electronic portal dose imaging device (EPID) is calibrated for measuring absolute dose.

36. The method of claim 35, wherein the measured dose is an absolute dose.

37. The method of claim 35, wherein the absolute dose calibration includes an absolute (EPID) conversion model.

38. The method of claim 27, wherein the evaluating includes evaluating using different gamma criterias for different selected points.

39. The method of claim 27, wherein the radiation dose delivery is determined to be acceptable if a predetermined number of selected points in the generated radiation dose distribution image pass a gamma criteria.

40. The method of claim 39, wherein the predetermined number of points is at least 90% of the total amount of evaluated selected points in the generated radiation dose distribution image.

41. A system for verifying radiation dose delivery in an arc-based radiation therapy device, comprising:

a portal imaging device configured to measure incident radiation dose from predetermined radiation fields and to generate portal dose images; and

a processing device operably connected to the portal dose imaging device and being configured to store the measured portal dose images in a first array having spatial and angular locations of the delivered beams as dimensions, the processing device being further configured to store a plurality of predicted portal dose images in a second array having spatial and angular locations of the predicted beams as dimensions;

the processing device being further configured to selectively compare points in the first array with corresponding points in the second array,

wherein the selectively comparing includes excluding points based on patient surface information from the comparison, and

wherein errors in the quantities of interest are determined based on the comparison.

42. The system of claim 41, wherein the excluded points include points that are irradiated by beams that do not intersect the patient surface.

43. The system of claim 41, wherein the excluded points include points that are irradiated by beams that intersect the patient surface at a distance of less than about 1 cm below the patient surface.

44. The system of claim 41, wherein the excluded points include points that are irradiated by beams at predetermined angles.

45. The system of claim 44, wherein the predetermined angles are angles at which the beams do not intersect the patient surface and/or intersect the patient surface at a distance within about 1 cm below the patient surface.