Method for Three Dimensional (3D) Lattice Radiotherapy

摘要

A method for high-dose Grid radiotherapy utilizing a three-dimensional (3D) dose lattice formation is described herein. The 3D dose lattice can be achieved by, but not limited to, three technical approaches: 1) non-coplanar focused beams; 2) multileaf collimator (MLC)-based intensity modulated radiation therapy (IMRT) or aperture-modulated arc; and 3) heavy charged particle beam. The configuration of a 3D dose lattice is comprised of the number, location, and dose of dose vertices. The optimal configuration of a 3D dose lattice can be achieved by manual calculations or by automating the calculations for a generic algorithm. The objective of the optimization algorithm is to satisfy three conditions via iteration until they reach their global minimum. With 3D dose lattice, high doses of radiation are concentrated at each lattice vertex within a tumor with drastically lower doses between vertices (peak-to-valley effect), leaving tissue outside of the tumor volume minimally exposed.

主权项

1. A method for delivering radiation to a tumor in a three-dimensional (3D) dose lattice formation using photon beams, comprising:
locating a tumor and determining its type, shape, and volume; determining if the tumor is clinically indicated for 3D lattice radiation treatment; generating a three-dimensional (3D) dose lattice formation plan by the following algorithm;
delineating and defining the tumor volume by a 3D boundary designated V;determining the desired maximum dose of the lattice Dmax;determining the desired minimum dose between dose vertices Dmin;determining the desired dose outside the tumor volume Dexm;setting a variable n as an estimated number of vertices based on the tumor shape and volume;designating each dose vertex as i such that the ith vertex is located at a position ri in the 3D lattice;representing the location of the dose vertices by a vector set RL(r1, r2, r3, r4, . . . rn)εV;defining a range σ from the center of a dose vertex, within which the maximum dose, Dmax, should fall;introducing m number of co-planar or non co-planar beam-lets each with its associated dose distribution, Dk(r), k=1 to m;deriving a composite dose distribution using the equationDk(r)=∑k=1mwkDk(r),where wk is the weighting factor for the kth beam-let, which forms a scalar set wL(w1, w2, . . . wm);
starting iteration to search the combination of beam-lets and wL(w1, w2, . . . wm), until:∑i[D(ri(σ))-Dmax]2≤δmax,and1)∑i,j[D(ri,j)min-Dmin]2≤δmin,and2)D(r∉V)≤Dexm,3) where, δmax is a predefined objective threshold for the fitness of Dmax; andδmin is a predefined objective threshold for the fitness of Dmin; and D(ri,j)min is a minimum dose along the vector ri,j=ri−rj, (i≠j); ending iteration; and using resulting beam-lets wL(w1, w2, . . . wm) to deliver the dose lattice with a radiation delivery system.