Verification of leaf positions for multi-leaf collimator using multiple verification systems

Patent metadata

Field	Value
Publication number	US-10758748-B2
Application number	US-201815916068-A
Country	US
Kind code	B2
Filing date	Mar 8, 2018
Priority date	Jun 12, 2015
Publication date	Sep 1, 2020
Grant date	Sep 1, 2020

Abstract

A method includes determining a first estimate of leaf positions for a plurality of leaves of a multi-leaf collimator (MLC) in a reference coordinate space based on an image generated by an image-based aperture verification system, wherein the leaf positions for the plurality of leaves define an aperture for the MLC. The method further includes determining a second estimate of the leaf positions for the plurality of leaves in the reference coordinate space based on data from an additional source. The method further includes verifying the leaf positions for the plurality of leaves based on comparing the first estimate to the second estimate, wherein the leaf positions are verified if the first estimate deviates from the second estimate by less than a threshold value.

First claim

What is claimed is:

1. A method comprising:
determining a first estimate of leaf positions for a plurality of leaves of a multi-leaf collimator (MLC) in a reference coordinate space based on an image generated by an image-based aperture verification system, wherein the leaf positions for the plurality of leaves define an aperture for the MLC;
determining a second estimate of the leaf positions for the plurality of leaves in the reference coordinate space based on data from an additional source, wherein the additional source comprises an additional aperture verification system;
generating a pictorial representation of the second estimate;
displaying the image generated by the image-based aperture verification system; and
displaying an overlay of the pictorial representation over the image;
determining a first sequence of updates to the first estimate of the leaf positions based on a sequence of images generated by the image-based aperture verification system;
determining a second sequence of updates to the second estimate of the leaf positions based on a sequence of data from the additional aperture verification system;
synchronizing the first sequence of updates and the second sequence of updates in time;
generating a sequence of updated pictorial representations for the second sequence of updates; and
verifying, by a processing device, the leaf positions for the plurality of leaves based on comparing the first estimate to the second estimate, wherein the leaf positions are verified if the first estimate deviates from the second estimate by less than a threshold value.

2. The method of claim 1 , further comprising:
determining that the first estimate deviates from the second estimate by less than the threshold value for a first leaf of the plurality of leaves; and
providing a first visual indication overlaid on the image for the first leaf.

3. The method of claim 2 , further comprising:
determining that the first estimate deviates from the second estimate by at least the threshold value for a second leaf of the plurality of leaves; and
providing a second visual indication overlaid on the image for the second leaf.

4. The method of claim 1 , wherein:
the image-based aperture verification system comprises an image sensor offset from a beam axis of the MLC, wherein the image sensor is directed toward the plurality of leaves and generates an oblique-view image of the aperture, wherein determining the first estimate comprises transforming the oblique-view image into a top-view image having the reference coordinate space; and
the additional aperture verification system comprises a distinct displacement gauge for each leaf of the plurality of leaves, wherein the data from the additional aperture verification comprises a plurality of leaf displacement measurements, and wherein determining the second estimate comprises transforming the plurality of leaf displacement measurements into the reference coordinate space.

5. The method of claim 1 , wherein the second estimate comprises planned leaf positions of a treatment plan, the method further comprising:
displaying the image generated by the image-based aperture verification system;
mapping the planned leaf positions of the treatment plan to the reference coordinate space;
generating a pictorial representation of the planned leaf positions; and
displaying an overlay of the pictorial representation over the image.

6. The method of claim 1 , further comprising:
displaying the image generated by the image-based aperture verification system;
generating a pictorial representation of the first estimate of the leaf positions; and
displaying an overlay of the pictorial representation over the image.

7. The method of claim 1 , further comprising:
displaying the image generated by the image-based aperture verification system;
generating a digitally reconstructed radiograph (DRR) of a target, the DRR having the reference coordinate space and an orientation corresponding to the image; and
displaying an overlay of the DRR over the image.

8. The method of claim 1 , wherein leading edges of the plurality of leaves are not shown in the image, the method further comprising:
computing positions of the leading edges based on visible portions of the plurality of leaves in the image and known offsets between the leading edges and the visible portions.

9. The method of claim 1 , wherein the determining of the first estimate, the determining of the second estimate, and the verifying are performed before a radiation delivery apparatus delivers a radiation beam.

10. An apparatus comprising:
a memory; and
a processing device coupled to the memory, the processing device to:
determine a first estimate of leaf positions for a plurality of leaves of a multi-leaf collimator (MLC) in a reference coordinate space based on an image generated by an image-based aperture verification system, wherein the leaf positions for the plurality of leaves define an aperture for the MLC;
determine a second estimate of the leaf positions for the plurality of leaves in the reference coordinate space based on data from an additional source, wherein the additional source comprises an additional aperture verification system;
determine a first sequence of updates to the first estimate of the leaf positions based on a sequence of images generated by the image-based aperture verification system;
determine a second sequence of updates to the second estimate of the leaf positions based on a sequence of data from the additional aperture verification system;
synchronize the first sequence of updates and the second sequence of updates in time;
generate a sequence of updated pictorial representations for the second sequence of updates; and
verify the leaf positions for the plurality of leaves based on comparing the first estimate to the second estimate, wherein the leaf positions are verified if the first estimate deviates from the second estimate by less than a threshold value;

a display operatively coupled with the processing device, wherein the processing device is further to:
generate a pictorial representation of the second estimate;
output the image generated by the image-based aperture verification system on the display; and
output an overlay of the pictorial representation over the image on the display.

11. The apparatus of claim 10 , wherein the processing device is further to:
determine that the first estimate deviates from the second estimate by less than the threshold value for a first leaf of the plurality of leaves; and
provide a first visual indication overlaid on the image for the first leaf.

12. The apparatus of claim 10 , further comprising:
the image-based aperture verification system, comprising an image sensor offset from a beam axis of the MLC, wherein the image sensor is directed toward the plurality of leaves and is to generate an oblique-view image of the aperture; and
the additional aperture verification system, comprising a distinct displacement gauge for each leaf of the plurality of leaves, wherein the data from the additional aperture verification comprises a plurality of leaf displacement measurements;
wherein the processing device is further to:
map the first estimate to the reference coordinate space by transforming the oblique-view image into a top-view image having the reference coordinate space; and
map the second estimate to the reference coordinate space by transforming the plurality of leaf displacement measurements into the reference coordinate space.

13. The apparatus of claim 10 , wherein the second estimate comprises planned leaf positions of a treatment plan, a

Assignees

• Accuray Inc

Inventors

• Chappelow Jonathan Cecil
• Jordan Petr
• Maurer Calvin
• Singh Sarbjit
• Fitting Andrew W
• Myronenko Andriy
• Gao Jian

Classifications

• G21K1/046 Primary

  varying the contour of the field, e.g. multileaf collimators · CPC title

• A61N2005/1054

  using a portal imaging system · CPC title

• G06T7/0012

  Biomedical image inspection · CPC title

• A61N5/1048

  Monitoring, verifying, controlling systems and methods · CPC title

• A61N5/1049 Primary

  for verifying the position of the patient with respect to the radiation beam · CPC title