METHODS AND APPARATUS FOR THE PLANNING AND DELIVERY OF RADIATION TREATMENTS

• US 20110110492A1
• Filed: 01/07/2011
• Published: 05/12/2011
• Est. Priority Date: 07/25/2005
• Status: Active Grant

• Current Assignee: Siemens Healthineers International AG
• Original Assignee: Karl Otto
• Inventors: OTTO, Karl
• Granted Patent: US 8,696,538 B2
• Time in Patent Office: Days
• US Class Current: 378/65
• CPC Class Codes: A61B 2034/101 Computer-aided simulation of surgical operations
• CPC Class Codes: A61B 34/10 Computer-aided planning, simulation or modelling of surgical operations
• CPC Class Codes: A61B 5/0036 including treatment, e.g., using an implantable medical device, ablating, ventilating
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61N 2005/1032 Genetic optimization methods
• CPC Class Codes: A61N 2005/1034 Monte Carlo type methods; particle tracking
• CPC Class Codes: A61N 2005/1035 Simulated annealing
• 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 5/1036 Leaf sequencing algorithms
• CPC Class Codes: A61N 5/1037 taking into account the movement of the target, e.g. 4D-image based planning
• CPC Class Codes: A61N 5/1039 using functional images, e.g. PET or MRI
• CPC Class Codes: A61N 5/1042 with spatial modulation of the radiation beam within the treatment head
• CPC Class Codes: A61N 5/1045 using a multi-leaf collimator, e.g. for intensity modulated radiation therapy or IMRT
• CPC Class Codes: A61N 5/1047 with movement of the radiation head during application of radiation, e.g. for intensity modulated arc therapy or IMAT
• CPC Class Codes: A61N 5/1049 for verifying the position of the patient with respect to the radiation beam
• CPC Class Codes: A61N 5/107 in real time, i.e. during treatment
• CPC Class Codes: A61N 5/1077 Beam delivery systems
• CPC Class Codes: A61N 5/1082 having multiple beam rotation axes

Abstract

Methods and apparatus are provided for planning and delivering radiation treatments by modalities which involve moving a radiation source along a trajectory relative to a subject while delivering radiation to the subject. In some embodiments the radiation source is moved continuously along the trajectory while in some embodiments the radiation source is moved intermittently. Some embodiments involve the optimization of the radiation delivery plan to meet various optimization goals while meeting a number of constraints. For each of a number of control points along a trajectory, a radiation delivery plan may comprise: a set of motion axes parameters, a set of beam shape parameters and a beam intensity.

Claims

1. A method for planning delivery of radiation dose to a target region within a subject, the method comprising:

iteratively optimizing a simulated dose distribution relative to a set of one or more optimization goals comprising a desired dose distribution in the subject over an initial plurality of control points along a trajectory which involves relative movement between a radiation source and the subject;

upon reaching one or more initial termination conditions;

specifying an increased plurality of control points along the trajectory, the increased plurality of control points comprising a larger number of control points than the initial plurality of control points; and

iteratively optimizing a simulated dose distribution relative to the set of one or more optimization goals over the increased plurality of control points.

2. A method according to claim 1 wherein iteratively optimizing the simulated dose distribution relative to the set of one or more optimization goals over the initial plurality of control points comprises iteratively optimizing the simulated dose distribution subject to one or more initial optimization constraints.

3. A method according to claim 2 wherein iteratively optimizing the simulated dose distribution relative to the set of one or more optimization goals over the increased plurality of control points comprises iteratively optimizing the simulated dose distribution subject to one or more subsequent optimization constraints.

4. A method according to claim 3 wherein at least one of the subsequent optimization constraints is different than a corresponding at least one of the initial optimization constraints.

5. A method according to claim 1 comprising discontinuing the iterative optimization over the increased plurality of control points upon reaching one or more subsequent termination conditions.

6. A method according to claim 5 wherein:

upon reaching the one or more initial termination conditions, a difference between the simulated dose distribution and the set of one or more optimization goals is greater than an acceptable dose quality threshold; and

before discontinuing the iterative optimization over the increased plurality of control points, the difference between the simulated dose distribution and the set of one or more optimization goals is within the acceptable dose quality threshold.

7. A method according to claim 1 wherein iteratively optimizing the simulated dose distribution relative to the set of one or more optimization goals over the initial plurality of control points comprises achieving an initial dose simulation accuracy and wherein iteratively optimizing the simulated dose distribution relative to the set of one or more optimization goals over the increased plurality of control points comprises achieving an increased dose simulation accuracy, the increased dose simulation accuracy more accurately representing actual dose distribution in the subject than the initial dose simulation accuracy.

8. A method according to claim 1 wherein iteratively optimizing the simulated dose distribution relative to the set of one or more optimization goals over the increased plurality of control points comprises, for each iteration:

varying one or more radiation delivery parameters associated with one or more of the increased plurality of control points;

determining the simulated dose distribution based on the one or more varied radiation delivery parameters;

determining, on the basis of an optimization algorithm and the simulated dose distribution based on the one or more varied radiation delivery parameters, whether to accept or reject the one or more varied radiation delivery parameters; and

if a determination is made to accept the one or more varied radiation delivery parameters, updating the current radiation delivery parameters to include the one or more varied radiation delivery parameters.

9. A method according to claim 8 wherein the one or more radiation delivery parameters comprise one or more configurations of a multi-leaf collimator.

10. A method according to claim 9 wherein the one or more configurations of the multi-leaf collimator comprise positions of one or more leaves of the multi-leaf collimator.

11. A method according to claim 10 wherein the trajectory involves relative movement between the radiation source and the subject in a source trajectory direction, wherein the one or more leaves of the multi-leaf collimator are moveable in a leaf-translation direction and wherein, during relative movement between the radiation source and the subject along the trajectory, the leaf-translation direction is oriented at a MLC orientation angle φ

with respect to the source trajectory direction, an absolute value of the MLC orientation angle φ

satisfying 0°

<

|φ

|<

90°

.

12. A method according to claim 11 wherein the absolute value of the MLC orientation angle φ

satisfies 30°

≦

|φ

≦

60°

.

13. A method according to claim 10 wherein the trajectory involves relative movement between the radiation source and the subject in a source trajectory direction, wherein the one or more leaves of the multi-leaf collimator are moveable in a leaf-translation direction and wherein, during relative movement between the radiation source and the subject along the trajectory, the leaf-translation direction is oriented at a MLC orientation angle φ

with respect to the source trajectory direction, the MLC orientation angle constant throughout the trajectory.

14. A method according to claim 8 wherein the one or more radiation delivery parameters comprise an intensity of the radiation source for a plurality of the increased plurality of control points.

15. A method according to claim 1 wherein iteratively optimizing the simulated dose distribution relative to the set of one or more optimization goals over the initial plurality of control points comprises modeling a dose contribution for at least one of the initial plurality of control points by:

dividing a cross-sectional area of a beam into a plurality of two-dimensional beamlets; and

simulating a dose distribution contribution from each of the plurality of two-dimensional beamlets.

16. A method according to claim 11 wherein iteratively optimizing the simulated dose distribution relative to the set of one or more optimization goals over the initial plurality of control points comprises mapping between the plurality of two dimensional beamlets and one or more of:

a position of the radiation source and orientation of a beam from the radiation source relative to the subject;

a beam shape involving a configuration of one or more leaves of a multi-leaf collimator; and

an intensity of the radiation source.

17. A method according to claim 1 wherein iteratively optimizing the simulated dose distribution relative to the set of one or more optimization goals over the initial plurality of control points comprises performing the iterative optimization using a set of optimization parameters, the set of optimization parameters representative of one or more of:

a beam shape of the radiation source; and

a beam intensity of the radiation source.

18. A method according to claim 1 wherein the trajectory comprises at least one pair of locations where a first beam directed from the radiation source toward the subject from a first one of the pair of locations and a second beam directed from the radiation source toward the subject from a second one of the pair of locations are substantially parallel but opposing one another.

19. A method according to claim 1 wherein the trajectory comprises a plurality of arcs, each arc involving relating movement between the radiation source and the subject within a corresponding plane.

20. A method according to claim 19 wherein between successive ones of the plurality of arcs, the trajectory comprises inter-arc relative movement between the radiation source and the subject, the inter-arc relative movement comprising movement such that the corresponding planes associated with each arc intersect one another.

21. A method according to claim 19 wherein between successive ones of the plurality of arcs, the trajectory comprises inter-arc relative movement between the radiation source and the subject, the inter-arc relative movement comprising movement such that the corresponding planes associated with each arc are parallel to one another.

22. A method according to claim 1 wherein the trajectory comprises a non-self overlapping trajectory which involves non-self overlapping relative movement between the radiation source and the subject.

23. A method according to claim 1 wherein a start of the trajectory and an end of the trajectory comprise the same relative position between the radiation source and the subject and the trajectory is otherwise non-self overlapping.

24. A method according to claim 1 comprising at least one of:

defining the set of one or more optimization goals; and

receiving the set of one or more optimization goals from an external source.

25. A method according to claim 17 wherein specifying an increased plurality of control points comprises assigning optimization parameters to the increased plurality of control points not present among the initial plurality of control points, wherein assigning optimization parameters comprises interpolating optimization parameters based on the optimization parameters associated with the initial plurality of control points.

26. A program product comprising computer readable instructions which, when executed by a processor, cause the processor to execute a method for planning delivery of radiation dose to a target region within a subject, the method comprising:

iteratively optimizing a simulated dose distribution relative to a set of one or more optimization goals comprising a desired dose distribution in the subject over an initial plurality of control points along a trajectory which involves relative movement between a radiation source and the subject;

upon reaching one or more initial termination conditions;

specifying an increased plurality of control points along the trajectory, the increased plurality of control points comprising a larger number of control points than the initial plurality of control points; and

iteratively optimizing a simulated dose distribution relative to the set of one or more optimization goals over the increased plurality of control points.