System and method for estimating and manipulating estimated radiation dose

Patent metadata

Field	Value
Publication number	US-9289627-B2
Application number	US-201113806677-A
Country	US
Kind code	B2
Filing date	Jun 22, 2011
Priority date	Jun 22, 2010
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

Abstract

Methods are provided for permitting manipulation of an achievable dose distribution estimate deliverable by a radiation delivery apparatus for proposed treatment of a subject. One such method comprises: determining a dose modification voxel for which it is desired to modify the dose value and a corresponding magnitude of desired dose modification; for each of a plurality of beams: (i) characterizing the beam as a two-dimensional array of beamlets, wherein each beamlet is associated with a corresponding intensity value and a ray line representing the projection of the beamlet into space; and (ii) identifying one or more dose-change beamlets which have associated ray lines that intersect the dose modification voxel; modifying the intensity values of at least one of the dose-change beamlets; and updating the achievable dose distribution estimate to account for the modified intensity values of the at least one of the dose-change beamlets.

First claim

What is claimed is:

1. A method for permitting manipulation of an achievable dose distribution estimate deliverable by a radiation delivery apparatus for proposed treatment of a subject, the achievable dose distribution estimate defined over a three-dimensional range of voxels with a dose value for each voxel, the method comprising:
(a) determining a dose modification voxel for which it is desired to modify the dose value and determining a corresponding magnitude of desired dose modification;
(b) receiving the achievable dose distribution estimate, the dose modification voxel and the corresponding magnitude of desired dose modification as input to a processor;
(c) for each of a plurality of beams:
(i) characterizing, using the processor, each beam as a two-dimensional array of beamlets, wherein each beamlet is associated with a corresponding intensity value and a ray line representing a projection of the beamlet into space; and
(ii) identifying, using the processor, one or more dose-change beamlets which have associated ray lines that intersect the dose modification voxel;

(d) modifying, using the processor, the intensity values of the one or more identified dose-change beamlets based on the magnitude of desired dose modification, wherein modifying the intensity values of the one or more identified dose-change beamlets comprises, for each of the one or more identified dose-change beamlets, modifying the intensity value of each identified dose-change beamlet by a corresponding amount, the corresponding amount based on the magnitude of the desired dose modification;
(e) updating, using the processor, the achievable dose distribution estimate to account for the modified intensity values of the identified dose-change beamlets; and
(f) outputting, from the processor, the updated achievable dose distribution estimate.

2. A method according to claim 1 wherein determining the dose modification voxel comprises:
receiving, as input to the processor, a requested modification to a dose quality metric; and using the requested modification to the dose quality metric to determine, using the processor, the dose modification voxel.

3. A method according to claim 2 wherein using the requested modification to the dose quality metric to determine, using the processor, the dose modification voxel comprises solving an inverted dose quality metric function that expresses coordinates and magnitudes of dose in terms of values of the dose quality metric.

4. A method according to claim 2 wherein the dose quality metric comprises a DVH curve associated with a tissue structure in the subject and wherein using the requested modification to the dose quality metric to determine, using the processor, the dose modification voxel comprises identifying a voxel in the tissue structure of the subject to be the dose modification voxel.

5. A method according to claim 4 wherein identifying the voxel in the tissue structure of the subject to be the dose modification voxel comprises identifying all of the voxels in the tissue structure of the subject to be dose modification voxels and performing steps (b), (c) and (d) for each of the dose modification voxels.

6. A method according to claim 4 wherein identifying the voxel in the tissue structure of the subject to be the dose modification voxel comprises:
receiving image data for the subject, the image data comprising an image of the tissue structure; and
associating particular voxels with the tissue structure based on the image data.

7. A method according to claim 2 wherein the dose quality metric comprises a DVH curve and wherein using the requested modification to the dose quality metric to determine, using the processor, the dose modification voxel comprises:
identifying a location of the requested modification on the DVH curve to have a dose value D_selected; and
identifying a voxel in the achievable dose distribution estimate having a dose value in a range D_selected±Δ to be the dose modification voxel, where Δ is a range parameter.

8. A method according to claim 7 wherein using the requested modification to the dose quality metric to determine, using the processor, the dose modification voxel comprises: unsuccessfully attempting to identify the voxel in the achievable dose distribution estimate having the dose value in the range D_selected±Δ and, increasing the range parameter Δ and repeating the attempt to identify the voxel with the increased range parameter Δ.

9. A method according to claim 7 wherein identifying the voxel in the achievable dose distribution estimate having the dose value in the range D_selected±Δ to be the dose modification voxel comprises identifying a plurality of candidate dose modification voxels having dose values in the range D_selected±Δ.

10. A method according to claim 9 wherein the plurality of candidate dose modification voxels comprise a number of candidate dose modification voxels that is greater than a threshold number V max , and the method comprises decreasing the range parameter Δ and repeating the attempt to identify the voxel in the achievable dose distribution estimate having the dose value in the range D_selected±Δ to be the dose modification voxel with the decreased range parameter Δ.

11. A method according to claim 1 comprising determining, using the processor, one or more secondary dose modification voxels and corresponding magnitudes of desired dose modification for the one or more secondary dose modification voxels and treating secondary dose modification values as dose modification voxels when performing steps (b), (c) and (d).

12. A method according to claim 11 wherein determining, using the processor, the one or more secondary dose modification voxels comprises determining the one or more secondary dose modification voxels to be in a marginal region proximate to the dose modification voxel.

13. A method according to claim 11 wherein the corresponding magnitudes of desired dose modification for the one or more secondary dose modification voxels are less than the magnitude of the desired dose modification for the dose modification voxel.

14. A method according to claim 1 wherein determining the magnitude of the desired dose modification comprises determining the magnitude to be one or more of: a fraction f (0≦f≦1) of the dose value for the dose modification voxel; a fraction f (0≦f≦1) of a maximum dose restriction for a tissue structure at the location of the dose modification voxel; a fraction f (0≦f≦1) of a prescription dose amount for a target tissue structure at the location of the dose modification voxel; an amount proportional to movement of a computer pointing device; an amount input by an operator; an operator-configurable fixed amount; a fixed amount that is a parameter of a system on which the method is performed.

15. A method according to claim 1 wherein modifying, using the processor, the intensity values of the one or more of the dose-change beamlets comprises determining magnitudes of intensity value changes for the one or more dose-change beamlets according to a function that is dependent on the magnitude of desired dose modification and the number of the one or more dose-change beamlets, and wherein the function is proportional to the magnitude of desired dose modification and inversely proportional to the number of the one or more dose-change beamlets.

16. A method according claim 1 wherein modifying, using the processor, the intensity values of one or more of the dose-change beamlets comprises subjecting proposed intensity value modifications to one or more intensity restrictions.

17.

Assignees

• Otto Karl
• Varian Medical Systems Int Ag

Inventors

• Otto Karl

Classifications

• A61N5/10

  X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy (A61N5/01 takes precedence) · CPC title

• G01T1/29

  Measurement performed on radiation beams, e.g. position or section of the beam; Measurement of spatial distribution of radiation · CPC title

• A61N5/1031 Primary

  using a specific method of dose optimization · CPC title

• A61N5/00

  Radiation therapy (ultrasound therapy A61N7/00; devices or apparatus applicable to both therapy and diagnosis A61B6/00) · CPC title

• H05K999/00

  Electricity · mapped topic