Method for determining paths of particle beams through 3D tissue volumes

1. A method for determining a path of a particle beam through a 3D planning treatment volume (PTV), wherein the PTV includes a set of slices in a depth order, wherein each slice includes a set of locations, comprising the steps of:

defining X, Y, and Z direction for the particle beam, wherein movement along the X direction is faster than movement along the Y direction, and movement along the Y direction is faster than along the Z direction;

constructing independently tours, wherein the constructing of each tour further comprises:

grouping, for each slice, the set of locations into a set of lines along the X direction, wherein each line is a straight line and includes a starting location and an ending location;

connecting along the Y direction, for each slice, each line to one or two other lines, wherein the two lines are connected to either the starting location or the ending location of the each line, and the ending location is connected to the starting location to form each tour; and

connecting the tours through the slices in the Z direction to form the path of the particle beam, wherein the constructed and connected tours minimize a time for the particle beam to traverse the path to deliver a prescribed dose, and wherein the steps are performed in a processor.

2. The method of claim 1 , wherein the locations are spatially contiguous cubes of tissue.

3. The method of claim 1 , wherein the partitioning of the PTV is planar and in a depth order.

4. The method of claim 1 , wherein the lines are constructed independently of each other.

5. The method of claim 1 , further comprising:

partitioning each slice monotonically into regions, wherein each region is convex in a selected horizontal direction;

stacking, in each region, the locations in the set of lines into a sweep area including a starting location, a base area, and a return area;

traversing, in each region, the locations in the sweep area, then the base area, and then the return area in a generally clockwise direction beginning and ending at the starting location to construct a sub-path; and

merging the subpaths in each region to construct the tour.

6. The method of claim 5 , wherein the return area includes left-most location in the region and the traversing is from bottom to top, and the sweep area includes an odd number of rows and the traversing is in left to right in odd lines, and right to left in even lines, and the base includes the remaining locations between the sweep area and the return area.