Radiation therapy planning

1. A system for assisting in planning a radiation therapy treatment of a body region of a patient, wherein the treatment is provided on the basis of a treatment plan comprising irradiation parameters for controlling a delivery of radiation to the body region, the system being configured to:

receive a first dose distribution (d AI ) for the body region,

obtain a first objective function (F), which depends upon at least one parameter and upon a dose distribution in the body region,

determine a first value of the at least one parameter such that the first objective function (F) fulfills a predefined criterion when being evaluated for the first value of the at least one parameter and for a second dose distribution (d app P) derived from the first dose distribution (d AI ),

provide the first objective function (F) in connection with the first value of the at least one parameter to a user for modifying the first objective function (F) to generate a second objective function, and

determine the treatment plan using the second objective function.

2. The system as defined in claim 1 , configured to generate the first dose distribution (d AI ) is by means of an algorithm using artificial intelligence, particularly by means of a neural network.

3. The system as defined in claim 1 , configured to derive the second dose distribution (d app ) by approximating the first dose distribution (d AI ) as a function of beam elements to be applied in the treatment using a physical model describing the radiation absorbed in the body region of the patient depending upon the beam elements.

4. The system as defined in claim 3 , wherein the physical model is a linear model describing the radiation dose absorbed in the body region as a product of an influence matrix with a vector of beam elements.

5. The system as defined in claim 1 , configured to derive the second dose distribution (d app ) based on a template specifying possible beam elements for a treatment mode selected for the treatment.

6. The system as defined in claim 5 , wherein the template is selected from a plurality of templates on the basis of a modality of the treatment, the modality of the treatment being selected from a group at least comprising step-and-shoot intensity modulated radiation therapy, IMRT, and volumetric modulated arc therapy, VMAT.

7. The system as defined in claim 1 , configured to derive the second dose distribution (d app ) by minimizing a third objective function, which depends on a difference between the first and the second dose distribution (d AI ,d app ).

8. The system as defined in claim 7 , wherein elements of the first and second dose distribution (d AI ,d app ) are provided with different weights in the third objective function, the weights being selected based on the parts of the body region to which the elements of the first and second dose distribution (d AI ,d app ) belong.

9. The system as defined in claim 1 , wherein the first objective function (F) includes a sum of individual objective functions entering into the first objective function with an associated weight and wherein the at least one parameter is at least one of the weights.

10. The system as defined in claim 9 , wherein each of the individual objective functions represents a requirement of the radiation to be delivered to a part of the body region during the treatment.

11. The system as defined in claim 9 , wherein the second objective function is derived from the first objective function by a modification from group comprising a modification of at least one of the weights, an addition of an individual objective function to the objective function and a deletion of an individual objective function.

12. A method for assisting in planning a radiation therapy treatment of a body region of a patient, wherein the treatment is provided on the basis of a treatment plan comprising irradiation parameters for controlling a delivery of radiation to the body region, the method comprising:

receiving a first dose distribution (d AI ) for the body region,

obtaining a first objective function (F), which depends upon at least one parameter and on a dose distribution in the body region,

determining a first value of the at least one parameter such that the first objective function (F) fulfills a predefined criterion when being evaluated for the first value of the at least one parameter and for a second dose distribution (d app ) derived from the first dose distribution (d AI ),

providing the first objective function (F) in connection with the first value of the at least one parameter to a user for modifying the first objective function (F) to generate a second objective function, and

determining the treatment plan using the second objective function.

13. A computer program comprising program code for instructing a computer to perform a method as defined in claim 12 , when the program code is executed in the computer.