Image-guided radiation therapy

Abstract

The disclosed systems and methods for Image-Guided Radiation Therapy (IGRT), utilises an iterative approach which adjusts a treatment plan based on inter- or intra-fraction images to improve the accuracy of the radiation delivered during the overall treatment. The prescribed dose of radiotherapeutic radiation is mapped onto the patient's anatomy using an image acquired of the region, which is to be the target for radiotherapeutic radiation. Following beam-angle-optimisation, fluence optimisation and segmentation, the efficiency of delivery of each segment is determined using an objective function, and the segments ranked according to their efficiency. The plan proceeds with the choice of the most efficient segment (or segments) to be delivered first. When this radiation has been delivered, having been tracked to establish its distribution, this delivered distribution can be subtracted from the original prescribed dose and the process repeated so that the delivered radiation gradually converges on the original prescribed dose.

1 - 39 . (canceled) 
     
     
         40 . A controller for a radiotherapeutic apparatus, the controller configured to perform operations comprising:
 receiving an image depicting patient anatomical data of at least a target region of patient tissue;   mapping a prescribed dose of radiotherapeutic radiation onto the image as a desired dose distribution to be achieved in the target region;   determining at least one beam angle corresponding to a direction from which the radiotherapeutic radiation is to be delivered from a source to the target region, wherein the source produces a directable beam of therapeutic radiation;   creating a mask for each beam angle, the mask defining a beam outline substantially matching an outline of the target region as seen from each beam angle;   discretizing each beam within its beam outline into a first plurality of pencil beams;   performing a fluence optimization process for each beam angle using pencil beam data from the first plurality of pencil beams, the patient anatomical data, and target region data to generate a distribution profile for a sub-dose to be delivered at that beam angle, wherein sub-doses from each beam angle in combination substantially equal the prescribed dose;   segmenting the sub-dose distribution profile into segments, each segment comprising a second plurality of pencil beams of matching fluence;   determining a segment selection metric of the segments;   calculating the amount and distribution of radiation delivered during each segment relative to the patient anatomical data, wherein the radiation is delivered based on the determined segment selection metric of the segments;   receiving an updated image depicting patient anatomical data of at least the target region;   mapping the prescribed dose onto the updated image as an updated desired dose distribution;   subtracting the calculated amount and distribution of radiation from the updated desired dose distribution to create a new prescribed dose; and   adjusting the sub-doses remaining to be delivered according to the new prescribed dose.