Adaptive radiation therapy planning

1. A system for adapting a radiotherapy treatment plan for treating a target structure within a target region of a patient body, the radiotherapy treatment plan comprising irradiation parameters for controlling a delivery of radiation to the target region, the system comprising:

a planning unit configured to adapt the radiotherapy treatment plan on a basis of a set of influence parameters quantifying an influence of the radiation on the target region per unit intensity emission in accordance with an anatomical configuration of the target region,

a storage for storing a plurality of sets of influence parameters, each set being associated with an image of the region of the patient body representing a particular anatomical configuration of the target region, and

an imaging unit configured to acquire an image of the region of the patient body,

wherein the planning unit is configured to select the set of influence parameters from the stored sets on the basis of a comparison between the captured image and at least one of the images associated with the sets of influence parameters.

2. The system as defined in claim 1 , wherein the radiotherapy treatment plan is delivered in a plurality of time intervals and wherein the planning unit is configured to determine updated irradiation parameters for controlling the delivery of the radiation to the target structure in a k-th time interval.

3. The system as define in claim 2 , wherein the planning unit is configured to determine only the irradiation parameters for the k-th time interval on the basis of the selected set of influence parameters.

4. The system as defined in claim 2 , wherein a relative orientation between a radiation beam and the target structure changes during the radiotherapy treatment, and wherein each time interval corresponds to a period with a constant relative orientation between the radiation beam and the target structure.

5. The system as defined in claim 2 , wherein the planning unit is configured to determine the irradiation parameters on the basis of a radiation dose distribution delivered to the target region prior to the k-th time interval.

6. The system as defined in claim 2 , further being configured to provide an estimate of a radiation dose distribution delivered to the target region in subsequent time intervals following the k-th time interval, wherein the planning unit is configured to determine the irradiation parameters for the k-th time interval on the basis of said estimate.

7. The system as defined in claim 6 , wherein the estimate is derived from an initial treatment plan determined prior to the radiotherapy treatment.

8. The system as defined in claim 6 , wherein the estimate of the radiation dose distribution is based on one predetermined anatomical configuration of the target region.

9. The system as defined in claim 6 , further being configured to provide plural estimates of the radiation dose distribution delivered to the target region in subsequent time intervals, each estimate being associated with the k-th time interval and one set of influence parameters, wherein the planning unit is configured to determine the radiotherapy treatment plan on the basis of the estimate associated with the selected set of influence parameters.

10. The system as define in claim 9 , wherein the estimates are based on predictions of the anatomical configuration of the target region in the subsequent time intervals, the predication being made using a model quantifying changes of the anatomical configuration of the body as a function of time.

11. The system as defined in claim 6 wherein the estimate or plural estimates are pre-stored in the storage.

12. The system of claim 6 , wherein the estimate is derived from an emitted fluence specified in an initial treatment plan for the subsequent time intervals.

13. The system as defined in claim 1 , wherein the planning unit is configured to select the set of influence parameters associated with an image that has the largest similarity with the captured image in accordance with a predefined similarity measure.

14. The system as defined in claim 1 , wherein each set of influence parameters comprises components of an influence matrix.

15. A method for adapting a radiotherapy treatment plan for treating a target structure within a target region of a patient body, the radiotherapy treatment plan comprising irradiation parameters for controlling a delivery of radiation to the target region, the method comprising:

storing a plurality of sets of influence parameters in a planning unit, the influence parameters quantifying an influence of the radiation on the target region per unit intensity emission in accordance with an anatomical configuration of the target region and each set of influence parameters being associated with an image of the target region representing a particular anatomical configuration of the target region,

obtaining an image of the target region acquired by an imaging unit,

the planning unit selecting the set of influence parameters from the stored sets on a basis of a comparison between the acquired image and at least one of the images associated with the sets of influence parameters, and

the planning unit adapting the radiotherapy treatment plan on the basis of the selected set of influence parameters.

16. A tangible, non-transitory computer readable medium having stored thereon software instructions that, when executed by a processor, cause the processor to perform a method for adapting a radiotherapy treatment plan for treating a target structure within a target region of a patient body, the radiotherapy treatment plan comprising irradiation parameters for controlling a delivery of radiation to the target region, the method comprising:

storing a plurality of sets of influence parameters in a planning unit, the influence parameters quantifying an influence of the radiation on the target region per unit intensity emission in accordance with an anatomical configuration of the target region and each set of influence parameters being associated with an image of the target region representing a particular anatomical configuration of the target region;

obtaining an image of the target region acquired by an imaging unit; and

selecting, by the planning unit, the set of influence parameters from the stored sets on a basis of a comparison between the acquired image and at least one of the images associated with the sets of influence parameters, the planning unit adapting the radiotherapy treatment plan on the basis of the selected set of influence parameters.

17. An apparatus for adapting a radiotherapy treatment plan for treating a target structure within a target region, the treatment plan comprising irradiation parameters for controlling a delivery of radiation to the target region, the apparatus comprising:

a controller comprising a processor; and a memory that stores instructions, which, when executed by the processor, cause the controller to:

store a plurality of sets of influence parameters in a planning unit, the influence parameters quantifying an influence of the radiation on the target region per unit intensity emission in accordance with an anatomical configuration of the target region, wherein each set of influence parameters are associated with an image of the target region representing a particular anatomical configuration of the target region;

obtain an image of the target region acquired by an imaging unit; and

select, by the planning unit, the set of influence parameters from the stored sets on a basis of a comparison between the acquired image and at least one of the images associated with the sets of influence parameters, the planning unit being adapted the treatment plan on the basis of the selected set of influence parameters.

18. The apparatus as defined in claim 17 , wherein the radiotherapy treatment plan is delivered in a plurality of time intervals, and the planning unit is configured to determine updated irradiation parameters for controlling the delivery of the radiation to the target structure in a k-th time interval.

19. The system as define in claim 18 , wherein the planning unit is configured to determine only the irradiation parameters for the k-th time interval on the basis of the selected set of influence parameters.

20. The system as defined in claim 18 , wherein a relative orientation between a radiation beam and the target structure changes during the radiotherapy treatment, and each time interval corresponds to a period with a constant relative orientation between the radiation beam and the target structure.