SYSTEMS, DEVICES, AND METHODS FOR QUALITY ASSURANCE OF RADIATION THERAPY

• US 20160271425A1
• Filed: 05/26/2016
• Published: 09/22/2016
• Est. Priority Date: 10/12/2012
• Status: Active Grant

• Current Assignee: Siemens Healthineers International AG
• Original Assignee: Varian Medical Systems International AG (Siemens AG)
• Inventors: TOIMELA, Lasse Heikki, NORD, Janne
• Granted Patent: US 10,112,059 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61N 2005/1054 using a portal imaging system
• CPC Class Codes: A61N 2005/1072 taking into account movement of the target
• CPC Class Codes: A61N 5/103 Treatment planning systems
• CPC Class Codes: A61N 5/1031 using a specific method of dose optimization
• CPC Class Codes: A61N 5/1064 for adjusting radiation treatment in response to monitoring
• CPC Class Codes: A61N 5/1071 for verifying the dose delivered by the treatment plan

Abstract

Systems, devices, and methods for quality assurance for verification of radiation dose delivery in arc-based radiation therapy devices using a 3D gamma evaluation method.

Claims

1-31. -31. (canceled)

32. A method for verifying radiation dose delivered to a subject, comprising:

generating 2D images of the subject by delivering radiation beams to the subject at predetermined radiation fields;

converting the 2D images into radiation dose distribution images;

comparing the radiation dose distribution images with corresponding predicted radiation dose distribution images using a three-dimensional (3D) gamma evaluation method, the comparing comprising calculating radiation dose differences, spatial differences, and angular differences between points in the generated radiation dose distribution images and corresponding points in the predicted radiation dose distribution images;

evaluating the calculated differences; and

determining acceptability of the radiation dose delivered to the subject based on a result of the evaluation.

33. The method of claim 32, wherein the evaluating includes determining minimums of a metric comprising the calculated differences as parameters.

34. The method of claim 32, further comprising storing the radiation dose distribution images in a data structure where positional information of the points in the dose distribution images are stored together with corresponding values of the points.

35. The method of claim 34, wherein the storing includes storing the radiation dose distribution images as a first data set mapped as a first 3D array including 3D positional information of the points in the radiation dose distribution images, wherein the 3D positional information includes spatial and angular locations of the delivered beams (X, Y, θ

).

36. The method of claim 35, further comprising storing the predicted radiation dose distribution images as a second data set mapped as a second 3D array including 3D positional information of the points in the predicted radiation dose distribution images, wherein the 3D positional information includes spatial and angular locations of the predicted beams (X, Y, θ

).

37. The method of claim 36, wherein the comparing includes comparing the points in the first and second data sets using the 3D gamma evaluation method.

38. The method of claim 37, wherein the comparing includes computing a 3D gamma error matrix.

39. A system for verifying radiation dose delivered to a subject, comprising:

a portal dose imaging device configured to generate portal dose images of radiation dose delivered to a subject from predetermined radiation fields; and

a processing device operably connected to the portal dose imaging device and configured to store the portal dose images in a first data array having spatial and angular locations of the delivered beams (X, Y, θ

) as dimensions, and to store corresponding predicted portal dose images in a second data array having spatial and angular locations of the predicted beams (X, Y, θ

) as dimensions;

wherein the processing device compares points in the first data array with corresponding points in the second data array using a gamma evaluation method, the gamma evaluation method including dose differences, spatial differences, and angular differences between corresponding points in the first and second data arrays as parameters, and

wherein the processing device determines errors in the delivered radiation dose based on the comparison.

40. The system of claim 39, wherein the first and second data arrays are 3D data arrays.

41. The system of claim 39, wherein the gamma evaluation method is a 3D gamma evaluation method.

42. The system of claim 39, wherein the processing device is further configured to generate a 3D gamma error matrix based on a gamma error function comprising gamma values, wherein the gamma values in the 3D matrix are minimum values of a distance metric indicating a measure of acceptability of the radiation dose.

43. The system of claim 42, wherein the processing device is further configured to calculate distance metric values using:

Γ

((x_m, y_m, θ

_m), (x_p, y_p, θ

_p))=√

{square root over (s_xy(Δ

x²+Δ

y²)+s_d(Δ

D)²+s_θ

Δ

θ

²)},

wherein Δ

D is the dosimetric difference between measured and predicted dose values, Δ

x=x_m−

x_p and Δ

x=y_m−

y_p are spatial differences between corresponding points in the first and second data arrays, and Δ

θ

=θ

_m−

θ

_p are angular differences between corresponding points in the first and second data arrays.

44. The system of claim 39, wherein portal imaging device is an electronic portal imaging device (EPID).

45. A method for verifying radiation dose delivered to a subject, comprising:

delivering radiation beams to the subject at a plurality of radiation fields;

measuring radiation transmitted or absorbed by the subject using an electronic portal dose imaging device and generating digital images based on the measured radiation;

converting the digital images into corresponding portal dose images;

storing the portal dose images as data points in a first data array, wherein each data point in the first data array represents a spatial and angular location of the portal imaging device at the time of delivery of the measured beam, and storing corresponding predicted portal dose images as data points in a second data array, wherein each data point in the second data array represents a spatial and angular location of the portal imaging device at the time of delivery of a predicted beam;

comparing data points in the first data array with corresponding data points in a second data array using a gamma evaluation method, the gamma evaluation method including dose differences, spatial differences, and angular differences between corresponding data points in the first and second data arrays as parameters; and

validating the delivered radiation dose based on a result of the comparison.

46. The method of claim 45, wherein the first and second data arrays are 3D data arrays.

47. The method of claim 45, wherein the gamma evaluation method is a 3D gamma evaluation method.

48. The method of claim 45, further comprising determining a source of the dose delivery error.

49. The method of claim 48, wherein the source comprises one or more of erroneous treatment parameter, variation in radiation beam delivery output, changes in subject setup, changes in subject shape, and subject organ motion.

50. The method of claim 49, further comprising automatically responding to a detection of an error in the radiation dose delivery.

51. The method of claim 50, further comprising responding in accordance with a type of source of error detected.