US 10,518,110 B1Granted

Systems and methods for calibrating and controlling collimator leaves

AssigneeElekta Limited

InventorsMiguel Jimenez-Carvajal, Ralf Spriestersbach

Life of this patent

Estimating the term…

Loading patent…

Abstract

Systems and methods for calibrating and controlling leaves of a multi-leaf collimator are disclosed. According to an exemplary method, a controller may receive images of collimator leaves and may determine a minor offset between an imaging marker and the tip of the respective leaf. In addition, the controller may quantify a barrel distortion effect associated with a leaf-imaging camera. The controller may correct leaf position data using the minor offsets and barrel distortion quantification, and may use the corrected leaf positions to accurately place the leaves during radiotherapy. Advantageously, a desired beam shaping window may be formed with the leaves, ensuring that healthy tissue is minimally irradiated while also ensuring that the target tissue receives the correct radiation dose. Embodiments of the present disclosure provide collimator calibration techniques which may be faster than prior calibration techniques, allowing shortened calibration times and faster radiotherapy sessions.

Claims20

Dependent claims

A computer-implemented method for calibrating leaves of a multi-leaf collimator of a radiotherapy device, the leaves comprising imaging markers and configured to shape a radiation beam emitted by the radiotherapy device by blocking radiation, wherein the radiotherapy device includes an imaging device configured to image the leaves, the imaging device including a lens, wherein the method comprises:

receiving, from the imaging device, a plurality of images of the leaves, wherein the leaves are in a first position in at least a first image and in a second position in at least a second image;
generating, based at least in part on the first image and the second image, initial position estimates of the leaves in the first position and in the second position, wherein the initial position estimates of the leaves are generated with respect to a predetermined coordinate space associated with the multi-leaf collimator;
determining, based at least in part on the initial position estimates of the leaves in the first position and in the second position, offsets for the leaves, the offsets reflecting differences between imaging marker positions of the leaves and positions of tips of the leaves;
identifying first position coordinates, with respect to the predetermined coordinate space, for the leaves based upon the offsets of the leaves and the initial position estimates of the leaves;
calculating a distortion coefficient of the lens based upon the first position coordinates for the leaves and the offsets of the leaves, the distortion coefficient representing an optical distortion effect associated with the lens;
determining corrected position coordinates, with respect to the predetermined coordinate space, for the leaves based on the distortion coefficient and the first position coordinates for the leaves;
correcting the offsets for the leaves based on the corrected position coordinates for the leaves;
and
calibrating the multi-leaf collimator based on the corrected offsets, wherein at least one leaf of the multi-leaf collimator is controlled based on the calibration.

6 more elements

A computer-implemented method for use in a radiotherapy device that emits a radiation beam to treat a target tumour of a patient, wherein the radiotherapy device comprises a multi-leaf collimator having a plurality of leaves, the leaves comprising imaging markers and configured to shape the radiation beam emitted by the radiotherapy device by blocking radiation, wherein the radiotherapy device includes an imaging device configured to image the leaves, the imaging device including a lens, wherein the method comprises:

receiving a treatment plan for treating the target tumour with radiation, wherein the treatment plan includes a therapeutic radiation beam shape for irradiating the target tumour;
identifying radiotherapy position coordinates, with respect to a predetermined coordinate space associated with the multi-leaf collimator, for the leaves of the multi-leaf collimator, wherein the leaves form the therapeutic radiation beam shape by blocking radiation when they are positioned at the radiotherapy position coordinates;
receiving offsets for the leaves, the offsets reflecting differences between imaging marker positions of the leaves and positions of tips of the leaves;
receiving calibration coefficients based on leaf position data from multiple multi-leaf collimators;
generating a position error function based on the calibration coefficients, wherein the position error function indicates a leaf position error associated with an optical distortion effect of the lens;
and
controlling the leaves to move to the radiotherapy position coordinates based on the offsets and the position error function.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/051,990Filed 1 Aug 2018
Granted: 31 Dec 2019
Term ends: Not estimatedThe source records don’t support an estimate.

Classification13 codes

A61N 5/1075
Monitoring, verifying, controlling systems and methods: for testing, calibrating, or quality assurance of the radiation treatment apparatus
A61N 5/1045
With spatial modulation of the radiation beam within the treatment head: using a multi-leaf collimator, e.g. for intensity modulated radiation…
A61N 5/1048
X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy: monitoring, verifying, controlling systems and methods
G21K 1/046
Using variable diaphragms, shutters, choppers: varying the contour of the field, e.g. multileaf collimators