DOSE ESTIMATION FOR THE IRRADIATION OF AN OBJECT

Abstract

In accordance with a method for dose estimation for the irradiation of an object, a model with a total number of spatial elements is provided on a memory element. For each spatial element, the model specifies a material composition of the object. A neighborhood material composition is determined for a neighborhood of spatial elements depending on the model by a computing unit. A radiation dose for the neighborhood with regard to an ionizing radiation is determined with aid of a simulation depending on the neighborhood material composition. A dose distribution for the object with regard to the ionizing radiation is determined based on the radiation dose for the neighborhood.

Claims

1. A computer-implemented method for dose estimation for irradiation of an object with an ionizing radiation, wherein a three-dimensional model with a total number of spatial elements is provided on a memory element, and the three-dimensional model specifies for each spatial element a material composition of the object, the method comprising: determining, by a computing unit, a neighborhood material composition for a coherent neighborhood of spatial elements of the total number of spatial elements, depending on the three-dimensional model; determining, by the computing unit, a radiation dose for the neighborhood with regard to the ionizing radiation with aid of a simulation depending on the neighborhood material composition; and determining, by the computing unit, a dose distribution for the object as regards the ionizing radiation based on the radiation dose for the neighborhood.

2. The computer-implemented method of claim 1, further comprising: determining, depending on the radiation dose, a fluence for the neighborhood with regard to the ionizing radiation; and determining the dose distribution for the object depending on the fluence.

3. The computer-implemented method of claim 2, further comprising: determining a neighborhood material composition in each case for a plurality of further coherent neighborhoods in each case of spatial elements of the total number of spatial elements, depending on the three-dimensional model; determining a further radiation dose with regard to the ionizing radiation with the aid of a simulation for each of the further neighborhoods depending on the neighborhood material composition of the respective further neighborhood; and determining the dose distribution for the object based on the further radiation doses for the further neighborhoods.

4. The computer-implemented method of claim 3, wherein a smoothing filter algorithm is executed by the computing unit depending on the radiation dose and the further radiation doses, in order to determine the dose distribution for the object.

5. The computer-implemented method of claim 4, wherein the smoothing filter algorithm comprises a guided filter algorithm, a Perona-Malik filter algorithm, a Savitzky-Golay filter algorithm, or a bilateral filter algorithm.

6. The computer-implemented method of claim 5, wherein an interpolation algorithm is executed by the computing unit depending on the radiation dose and the further radiation doses, and wherein the smoothing filter algorithm is executed based on a result of the interpolation algorithm.

7. The computer-implemented method of claim 4, wherein an interpolation algorithm is executed by the computing unit depending on the radiation dose and the further radiation doses, and wherein the smoothing filter algorithm is executed based on a result of the interpolation algorithm.

8. The computer-implemented method of claim 1, further comprising: determining a neighborhood material composition in each case for a plurality of further coherent neighborhoods in each case of spatial elements of the total number of spatial elements, depending on the three-dimensional model; determining a further radiation dose with regard to the ionizing radiation with the aid of a simulation for each of the further neighborhoods depending on the neighborhood material composition of the respective further neighborhood; and determining the dose distribution for the object based on the further radiation doses for the further neighborhoods.

9. The computer-implemented method of claim 8, wherein a smoothing filter algorithm is executed by the computing unit depending on the radiation dose and the further radiation doses, in order to determine the dose distribution for the object.

10. The computer-implemented method of claim 9, wherein the smoothing filter algorithm comprises a guided filter algorithm, a Perona-Malik filter algorithm, a Savitzky-Golay filter algorithm, or a bilateral filter algorithm.

11. The computer-implemented method of claim 9, wherein an interpolation algorithm is executed by the computing unit depending on the radiation dose and the further radiation doses, and wherein the smoothing filter algorithm is executed based on a result of the interpolation algorithm.

12. The computer-implemented method of claim 1, wherein the simulation for determining the radiation dose comprises a Monte-Carlo simulation or a finite difference simulation.

13. A method for setting parameters for irradiation of an object, the method comprising: defining a predefined first parameter set for an ionizing radiation, determining, by a computing unit, a neighborhood material composition for a coherent neighborhood of spatial elements of a total number of spatial elements, based on the first parameter set; determining, by the computing unit, a radiation dose for the neighborhood with regard to the ionizing radiation with aid of a simulation depending on the neighborhood material composition; determining, by the computing unit, a dose distribution for the object as regards the ionizing radiation based on the radiation dose for the neighborhood; and determining, depending on the dose distribution determined based on the first parameter set, a second parameter set for the ionizing radiation.

14. The method of claim 13, further comprising: irradiating the object with the ionizing radiation in accordance with the second parameter set, in order to image the object.

15. An arrangement for dose estimation for irradiation of an object with an ionizing radiation, the arrangement comprising: a memory configured to store a three-dimensional model with a total number of spatial elements, wherein for each spatial element the three-dimensional model specifies a material composition of the object; and a computing unit configured to: determine a neighborhood material composition for a coherent neighborhood of spatial elements of the total number of spatial elements, depending on the three-dimensional model; determine a radiation dose for the neighborhood with regard to the ionizing radiation with aid of a simulation depending on the neighborhood material composition; and determine a dose distribution for the object with regard to the ionizing radiation based on the radiation dose for the neighborhood.

16. An irradiation apparatus for irradiation of an object, the irradiation apparatus comprising: a memory configured to store a three-dimensional model with a total number of spatial elements, wherein for each spatial element the three-dimensional model specifies a material composition of the object; a computing unit configured to: determine a neighborhood material composition for a coherent neighborhood of spatial elements of the total number of spatial elements, depending on the three-dimensional model; determine a radiation dose for the neighborhood with regard to ionizing radiation with aid of a simulation depending on the neighborhood material composition; and determine a dose distribution for the object with regard to the ionizing radiation based on the radiation dose for the neighborhood; and a control unit configured to define a parameter set for an ionizing radiation for irradiation of the object depending on the dose distribution for the object.

17. The irradiation apparatus of claim 16, further comprising: a radiation source, wherein the control unit is configured to control the radiation source to emit the ionizing radiation in accordance with the parameter set defined.

18. The irradiation apparatus of claim 17, wherein the radiation source is an x-ray radiation source.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The features and combinations of features described here in the description and also below in the description of the figures and/or features and combinations of features described in the figures alone are able to be used not only in the respective combination specified but also in other combinations, without departing from the framework of the disclosure. Embodiments and combinations of features are also to be seen as disclosed that do not have all features of an originally formulated independent claim and/or which go beyond combinations of features set out in the references of the claims or deviate from them.

[0064] FIG. 1 depicts a schematic block diagram of an example of a form of embodiment of an irradiation apparatus in accordance with the improved concept.

[0065] FIG. 2 depicts a flow diagram of an example of a form of embodiment of a computer-implemented method for dose estimation according to the improved concept.

DETAILED DESCRIPTION

[0066] Shown in FIG. 1 is a block diagram of an example of a form of embodiment of an irradiation apparatus 1 for irradiation of an object 5.

[0067] The irradiation apparatus 1 has an example of a form of embodiment of an arrangement 2 for dose estimation for the irradiation of the object 5 with ionizing radiation. The arrangement 2 for dose estimation includes a computing unit 3 and a memory element 4, which is coupled to the computing unit 3 or is included in the computing unit.

[0068] The irradiation apparatus 1 moreover has a control unit 6 and also a radiation source 7, for example, an x-ray radiation source. The irradiation apparatus 1 may also have a detector 8 for detecting ionizing radiation generated by the radiation source 7 and that has passed at least partly through the object 5. Purely by way of example and in a non-restrictive way, the irradiation apparatus 1 is shown in FIG. 1 as a C-arm device. Depending on the concrete form of embodiment of the irradiation apparatus 1 and depending on the type of radiation used, the irradiation apparatus 1 may also have a different structure.

[0069] The control unit 6 is coupled to the radiation source 7 in order to control the latter. The control unit 6 is also coupled to the computing unit 3. The detector 8 may be coupled to the computing unit 3 and/or the control unit 6.

[0070] Stored in the memory element 4 is a discrete three-dimensional model, (e.g., a voxel model), which approximately describes the object 5 or a part of the object 5. The basis for the three-dimensional model may be an earlier recording of the same object, for example, or the basis may be a statistical model, which may have been reconciled with the object in size and form, or the basis may be a generic model.

[0071] The way in which an irradiation apparatus 1 functions, as is shown in FIG. 1, is explained in more detail below in relation to FIG. 2 with the aid of examples of forms of embodiment of methods according to the improved concept.

[0072] Shown in FIG. 2 is a flow diagram of an example of a form of embodiment of a computer-implemented method for dose estimation according to the improved concept.

[0073] In act S1, the model for the object 5 is provided on the memory element 4. The model approximates to the object 5 or a part of the object 5 through a total number 9 of spatial elements or voxels, wherein the memory element 4 stores a material composition of the object 5 for each spatial element of the total number 9 of spatial elements. In this case, the material composition is homogeneous within each spatial element.

[0074] In act S2, for a coherent neighborhood 10 of spatial elements based on the model, in particular based on the material compositions of the individual spatial elements, a neighborhood material composition, which is the same for all spatial elements of the neighborhood 10, is determined.

[0075] In other words, the neighborhood 10 is treated like an artificially enlarged spatial element 10′ with homogeneous effective material composition, namely the neighborhood material composition.

[0076] In act S3, a value for a radiation dose of the ionizing radiation is simulated for the neighborhood 10. The simulation may be undertaken based, for example, on a Monte-Carlo simulation or a finite element simulation.

[0077] Based on the simulated radiation dose for the neighborhood 10 and, if necessary, based on correspondingly simulated radiation doses for further neighborhoods of the total number 9 of spatial elements, a dose distribution for the object 5 or for the total number 9 of the spatial elements is determined.

[0078] In particular, as described in relation to acts S2 and S3, all spatial elements of the total number 9 of spatial elements may be assigned corresponding neighborhoods and corresponding radiation doses may be simulated.

[0079] In act S3, for example, for the neighborhood 10 and for all other neighborhoods, a fluence based on the radiation dose simulated in each case is determined. To this end, it may be assumed that an equilibrium of charged particles is present and the radiation dose for a neighborhood 10 is therefore directly proportional to the fluence.

[0080] In act S4, for example, for each of the neighborhoods 10, an interpolation, (e.g., a next neighbor interpolation), is carried out, in order formally to restore the original resolution. In particular, each of the spatial elements of a neighborhood 10 is allocated a corresponding fluence depending on the fluence determined for the entire neighborhood 10. In this case, for example, each spatial element within a neighborhood 10 may be assigned the same fluence.

[0081] In act S5, a smoothing filter algorithm is applied to all spatial elements or the fluences allocated by the interpolation. In this case, an edge-preserving smoothing filter algorithm is used, in particular, (e.g., a guided algorithm).

[0082] As a result of the smoothing filter algorithm, there is now a fluence distribution over all spatial elements of the total number 9 of spatial elements. From the aforementioned approximately directly proportional relationship between fluence and radiation dose, the dose distribution for all spatial elements of the total number 9 of spatial elements may therefore be determined directly from the fluence distribution.

[0083] The dose distribution established in this way may be compared with a target distribution or a maximum value for the dose and corresponding parameters for the ionizing radiation may be adapted, (e.g., automatically by the control unit 6 or the computing unit 3), in order to fulfill the target requirements.

[0084] Then the control unit 6 may control the radiation source 7, in order to direct the ionizing radiation accordingly onto the object 5, in order to irradiate the object.

[0085] As described, in particular, in relation to the figures, it is made possible through the improved concept to determine a reliable estimation of the radiation dose distribution during the irradiation of an object with ionizing radiation with reduced computational effort and reduced variances.

[0086] It is to be understood that the elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present disclosure. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims may, alternatively, be made to depend in the alternative from any preceding or following claim, whether independent or dependent, and that such new combinations are to be understood as forming a part of the present specification.

[0087] While the present disclosure has been described above by reference to various embodiments, it may be understood that many changes and modifications may be made to the described embodiments. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description.