Planning system, method and apparatus for conformal radiation therapy

Abstract

A system and associated methods to determine an optimal radiation beam arrangement are provided. The system includes a computer planning apparatus which includes a treatment plan optimization computer having a memory and an input device in communication with the treatment plan optimization computer to provide user access to control functions of plan optimization software. An image gathering device is in communication with the treatment plan optimization computer through a communications network to provide an image slice of the tumor target volume and the non-target structure volume. The plan optimization software computationally obtains and then optimizes a proposed radiation beam arrangement iteratively based on constraints to form an optimized radiation beam arrangement. A conformal radiation therapy delivery device in communication with the treatment plan optimization computer through the communications network then applies the optimized radiation beam arrangement to the patient.

1 - 14 . (canceled) 
   
   
       15 . A computer readable medium comprising a computer program to determine an optimized radiation beam arrangement from an externally formed radiation treatment plan to apply radiation to a target tumor volume while minimizing radiation to a non-target structure volume in a patient, the computer program comprising a set of instructions that, when executed by a computer, causes the computer to perform the following operations:
 receiving a non-compatible first radiation treatment plan created by an external system having a first radiation beam configuration defining a first radiation dose distribution developed based upon an arbitrary or non-existent objective function; and   constructing an optimization objective function having extremum corresponding to the first radiation beam configuration of the first radiation treatment plan to form a second compatible radiation treatment plan having a second radiation dose distribution approximately the same as the first radiation dose distribution, the second radiation treatment plan available for manipulation.   
   
   
       16 . The computer readable medium of  claim 15 , wherein the instructions that, when executed by the computer, causes the computer to construct an optimization objective function, further cause the computer to perform the following operations:
 forming a plurality of target tumor volume sampled points and a plurality of non-target structure volume sampled points by randomly sampling the first radiation dose distribution of the first radiation treatment plan;   determining a first value of radiation dose at each of the plurality of target tumor volume sampled points and the plurality of non-target structure volume sampled points; and   forming the optimization objective function by adding a term to the objective function for each of the plurality of target tumor volume sampled points and each of the plurality of non-target structure volume sampled points, wherein each term provides an extremum to the objective function, and wherein the terms associated with the target tumor volume sampled points are selected so that the objective function penalizes radiation dose when a second value of the radiation dose at either target tumor volume sampled point of the second radiation treatment plan substantially differs from the respective first value of radiation dose.   
   
   
       17 . The plan optimization software of  claim 15 , wherein the optimization objective function includes a plurality of constraints, and wherein the instructions that, when executed by the computer, cause the computer to construct an optimization objective function, further causes the computer to perform the following operations:
 determining the first radiation dose distribution; and   forming the optimization objective function by iteratively adjusting at least one of the plurality of the constraints so that the extremum of the optimization objective function corresponds to a radiation dose distribution approximately the same as the first radiation dose distribution.   
   
   
       18 . The computer readable medium of  claim 15 , wherein the instructions that, when executed by the computer, cause the computer to construct an optimization objective function, further causes the computer to perform the following operations:
 forming a plurality of target tumor volume sampled points and a plurality of non-target structure volume sampled points by randomly sampling the first radiation dose distribution of the first radiation treatment plan;   determining a first value of radiation dose at each of the plurality of target tumor volume sampled points and the plurality of non-target structure volume sampled points defining a sampled radiation dose distribution;   responsive to the sampled radiation dose distribution, determining a dose-volume statistic for each target tumor volume and non-target structure volume; and   forming the optimization objective function by adding a term to the objective function for each of the target tumor volume dose-volume statistics and the non-target structure volume dose-volume statistics, wherein each term provides an extremum to the objective function, and wherein the terms associated with the target tumor volume dose-volume statistic are selected so that the objective function penalizes the dose-volume statistic for the target tumor volume when a second value of the radiation dose at either target tumor volume sampled point of the second radiation treatment plan substantially undesirably differs from the respective first value of radiation dose.   
   
   
       19 - 28 . (canceled) 
   
   
       29 . A method of forming an optimized radiation treatment plan from an externally formed treatment plan to apply radiation to a target tumor volume while minimizing radiation to non-target structure volumes in a patient, the method comprising the steps of:
 providing a computer and an image gathering device to obtain an at least two-dimensional image of the target tumor volume and the non-target structure volumes;   providing a graphical user interface to display the image and to display user interface options;   identifying the target tumor volume and significant non-target structure volumes in the image;   receiving a first radiation treatment plan created by an external system having a first radiation beam arrangement; and   responsive to the first radiation treatment plan, constructing an optimization objective function having an extremum corresponding to the first radiation beam configuration of the first radiation treatment plan.   
   
   
       30 . A method of forming an optimized radiation treatment plan for applying radiation to a target tumor volume while minimizing radiation to a non-target structure volume in a patient, the method comprising the steps of:
 providing a conformal radiation therapy delivery device adapted to implement the optimized radiation treatment plan, the delivery device characterized by having a radiation beam delivery intensity and a plurality of radiation beam field segments, each controlled by the optimized radiation treatment plan;   constructing an optimization objective function having a plurality of constraints to form the optimized radiation treatment plan; and   adding to the optimization objective function one or more of the following: a constraint proportional to the number of radiation beam field segments, and a constraint proportional to average radiation beam attenuation, thereby controlling efficiency of the optimized radiation treatment plan.   
   
   
       31 . The method of  claim 30 , wherein the constraint proportional to the number of radiation beam field segments increases in a value as temporal efficiency decreases below a selected threshold value. 
   
   
       32 . The method of  claim 30 , wherein the average radiation beam attenuation is taken over substantially all pencil-beams that interest the target tumor volume, and wherein the constraint proportional to average radiation beam attenuation controls a total amount of ineffective radiation to be delivered during radiation treatment which is attenuated by modulation of the radiation beam delivery intensity of the conformal radiation therapy delivery device. 
   
   
       33 .- 36 . (canceled) 
   
   
       37 . A method to facilitate interactive plan adjustments to a proposed radiation treatment plan through radiation treatment plan optimization and recalculation and display of dose-volume statistics, the method comprising the steps of:
 providing a first radiation dose distribution for a target tumor volume and an non-target structure volume according to a first radiation beam arrangement;   forming a plurality of plan optimization sampled points for the first radiation beam arrangement by randomly sampling the first radiation dose distribution, each plan optimization sampled point having a value of radiation dose;   forming separately from the plan optimization sampled points a plurality of plan evaluation sampled points for the first radiation beam arrangement by randomly sampling the first radiation dose distribution;   determining the value of radiation dose at each of the plurality of optimization plan sampled points;   determining a value of radiation dose at each of the plurality of plan evaluation sampled points;   providing an optimization objective function constrained by the value of the radiation dose at each of the plurality of plan optimization sampled points;   graphically displaying radiation dose for the target tumor volume and non-target structure in the form of a plurality of dose volume histogram plots defining dose-volume statistics according to the value of the plurality of plan evaluation sampled points;   applying the optimization objective function to form a second radiation beam arrangement;   recalculating the value of radiation dose at each of the plurality of plan evaluation sampled points for the second radiation beam arrangement; and   displaying the dose-volume statistics for the target tumor volume and the non-target structure volume according to the recalculated value for the plurality of plan evaluation sampled points.   
   
   
       38 . A method of forming an optimized radiation treatment plan having a fixed set of discrete radiation beam intensity values from a radiation treatment plan characterized by having arbitrary radiation beam intensity values for applying radiation to a target tumor volume while minimizing radiation to an non-target structure volume in a patient, the method comprising the steps of:
 providing a candidate radiation treatment plan and an optimization objective function to iteratively evaluate the candidate radiation treatment plan;   iteratively evaluating the candidate radiation treatment plan to form an optimized radiation beam arrangement satisfying a plurality of a preselected clinical goals and having arbitrary radiation beam intensity values, defining a precedent radiation treatment plan;   providing a record of at least two radiation treatment plan iterations evaluated during optimization of the candidate radiation treatment plan; and   responsive to the iterative evaluations, inferring the combination of discrete radiation beam intensities required to substantially match the clinical radiation delivery goals of the precedent radiation treatment plan from the at least two radiation treatment plans evaluated, to thereby form the optimized radiation treatment plan.   
   
   
       39 . A method to facilitate interactive plan adjustments to a proposed radiation treatment plan through recalculation and display of radiation dose minimum and radiation dose maximum for a target tumor volume and non-target structure volumes, the method comprising the steps of:
 providing a radiation dose distribution for the target tumor volume and at least one non-target structure volume according to a radiation beam arrangement;   forming a plurality of sampled points for the radiation beam arrangement by randomly sampling the first radiation dose distribution;   determining a value of radiation dose at each of the plurality of sampled points;   identifying, for each of the target tumor volume and the at least one non-target structure volume, a first set of the plurality of sampled points having the highest values and a second set of the plurality of sampled points having the lowest values;   applying a gradient assent algorithm to each first set to determine and to display the radiation dose maximum for the target tumor volume and the at least one non-target structure volume; and   applying a gradient descent algorithm to each second set to determine and to display the radiation dose minimum for the target tumor volume and the at least one non-target structure volume.