Time-resolved pre-treatment portal dosimetry systems, devices, and methods

Patent metadata

Field	Value
Publication number	US-2016136459-A1
Application number	US-201615002205-A
Country	US
Kind code	A1
Filing date	Jan 20, 2016
Priority date	Nov 7, 2013
Publication date	May 19, 2016
Grant date	—

Abstract

Systems, devices, and methods for pre-treatment verification of radiation dose delivery in arc-based radiation therapy devices using a time-dependent gamma evaluation method.

First claim

1 - 36 . (canceled)

37 . A dosimetric evaluation method, comprising:
generating a sequence of portal dose images, the portal dose images in the sequence corresponding to measured radiation doses delivered according to a treatment plan, comparing the generated portal dose images with corresponding previously obtained portal dose images using a time-dependent gamma evaluation method; and evaluating radiation dose delivery based on the comparison.

38 . The method of claim 37 , wherein the previously obtained portal dose images comprise predicted dose images, dose accumulation images, or dose rate images.

39 . The method of claim 37 , wherein the measured radiation doses are delivered at time intervals of the radiation treatment plan, and the comparing includes comparing the portal dose images generated for respective time intervals with corresponding previously obtained portal dose images.

40 . The method of claim 39 , wherein the evaluating is in real-time, and wherein if for a time interval in the sequence, a discrepancy between the measured and the previously obtained portal dose image is determined, radiation delivery is rectified prior to the delivery of a radiation dose for the next time interval in the sequence.

41 . The method of claim 39 , wherein the time intervals comprise control points (CPs) of the radiation treatment plan.

42 . The method of claim 37 , wherein the comparing comprises comparing dose distributions.

43 . The method of claim 37 , wherein the evaluating comprises determining at least one of a dose delivery error and a dose rate.

44 . The method of claim 37 , wherein the generating of the sequence of portal dose images is with the patient in the radiation beam.

45 . The method of claim 37 , wherein the generating of the sequence of portal dose images is during in vivo portal dosimetry.

46 . The method of claim 37 , wherein the radiation dose delivery is by movement of the radiation beam around a patient, by movement of the patient, or by simultaneous movement of the radiation beam and the patient.

47 . A method for verifying quantities of interest of a delivered radiation beam, comprising:
acquiring portal dose images during radiation beam delivery; resampling the acquired portal dose images into respective time divisions, the time divisions comprising control points (CPs) of a radiation treatment plan, to obtain a sequence of measured portal dose images; comparing the measured portal dose images in the sequence with previously obtained portal dose images using a gamma evaluation method; and determining dose delivery errors based on the comparison.

48 . The method of claim 47 , wherein the determining includes determining radiation dose rate.

49 . The method of claim 47 , wherein the previously obtained portal dose images comprise predicted dose images, dose accumulation images, or dose rate images.

50 . The method of claim 47 , wherein the gamma evaluation method is a time-dependent gamma evaluation method.

51 . The method of claim 47 , wherein the verifying is with a patient in the radiation beam.

52 . The method of claim 47 , wherein the determining is in real-time, and wherein, if for a time interval in the sequence, a discrepancy between the measured and the previously obtained portal dose image is determined, radiation delivery is rectified prior to the delivery of a radiation dose for the next time interval in the sequence.

53 . A system for verifying a quantity of interest of a radiation beam, comprising:
a portal imaging device configured to measure incident radiation dose from predetermined radiation fields and to generate a series of portal dose images; and a processing device operably connected to the portal dose imaging device and configured to store the series of portal dose images in a first data array having spatial locations and time of delivery of the predetermined radiation fields as dimensions, the processing device being further configured to store a series of portal dose images in a second data array having spatial locations and time of delivery of radiation fields as dimensions, wherein the processing device is further configured to compare points in the first data array with corresponding points in the second data array using a 4D gamma evaluation method, the gamma evaluation method including dose differences, spatial differences, and time differences between corresponding points in the first and second data arrays as parameters, and wherein errors in the quantities of interest are determined based on the comparison.

54 . The system of claim 53 , wherein the quantities of interest is of a radiation beam in a radiation therapy device.

55 . The system of claim 53 , wherein the radiation therapy device is a dynamic radiation therapy device.

56 . The system of claim 53 , wherein the portal imaging device is an electronic portal imaging device (EPID).

57 . The system of claim 53 , wherein the quantities of interest comprise radiation dose, radiation dose rate, and collimator offset.

58 . A system including a radiation therapy device and a computer processing system which executes a sequence of programmed instructions embodied on a computer-readable storage medium to cause the computer processing system to:
initiate radiation beam delivery in the radiation therapy device according to a radiation treatment delivery plan; acquire portal dose images during the radiation beam delivery; resample the portal dose images into time divisions to obtain a sequence of measured portal dose images; compare the measured portal dose images in the sequence with corresponding one of predicted portal dose images, dose accumulation images, or dose rate images, using a time-dependent gamma evaluation function; and determine radiation dose delivery errors based on the comparison.

59 . The system of claim 58 , wherein the time-dependent gamma evaluation method includes a 4D evaluation method including time as the fourth dimension.

60 . The system of claim 58 , wherein the determining includes determining radiation dose rates.

61 . The system of claim 58 , wherein the determining is in real-time, and wherein if for a time interval in the sequence, a discrepancy between the measured and the predicted portal dose image, the dose accumulation image, or the dose rate image is determined, radiation delivery is rectified prior to the delivery of a radiation dose for the next time interval in the sequence.

62 . The system of claim 58 , wherein the radiation dose delivery is by movement of the radiation beam around a patient, by movement of the patient, or by simultaneous movement of the radiation beam and the patient.

63 . The system of claim 58 , further including storing the predicted portal dose images as a first data set including positional information and time information of the points in the predicted portal dose images as parameters, and storing the measured portal dose images as a second data set including positional information and time information of the points in the measured portal dose images as parameters, wherein the positional information includes spatial locations of the predicted and measured radiation fields, and the time information includes the times of the predicted and measured radiation fields, and wherein the comparing includes comparing the first and second data sets using

Assignees

• Varian Medical Systems Int Ag

Inventors

• Verhaegen Frans
• Podesta Mark
• Nijsten Sebastiaan M J J G
• Persoon Lucas C G G
• Baltes Christof
• Scheib Stefan G

Classifications

• A61N2005/1054

  using a portal imaging system · CPC title

• A61N5/1075

  for testing, calibrating, or quality assurance of the radiation treatment apparatus · CPC title

• A61N5/1071 Primary

  for verifying the dose delivered by the treatment plan · CPC title

• A61N5/1047

  with movement of the radiation head during application of radiation, e.g. for intensity modulated arc therapy or IMAT · CPC title

• A61N5/1031

  using a specific method of dose optimization · CPC title