Melvin's digital garden

Computer Assisted Surgical Planning

CREATED: 200701010953 Author: Danny Chen ** Background

  • intensity modulated radiation therapy
  • delivered using linear accelerator with multi-leaf collimator *** Methods

structure contouring (image segmentation)

** determine position of tumor

beam angle selection

** select a set of angles to cover the whole tumor with sufficient radition without harming healthy tissue

dose calculation and intensity maps

leaf sequencing

** compute a set of apertures to deliver intensity map in minimum time


** Step and shoot IMRT delivery

  • NP hard in general
  • special cases ** 2D SLS ** basic 3D SLS

** 2D SLS

  • property of collimator, polygon monotone in y-axis
  • assume intensitive either 0 or 1 (can be obtained by slcing the 3D problem)
  • consider structures such as valley and peaks since they indicate different apertures, due to monotone property
  • similar to matching valley and peaks but do not allow crossing
  • solve as max flow on a planar graph

** 3D SLS

  • restrict height of plateau to be 1
  • if intensity less than 10 (usually), basic SLS ~ general SLS *** Method

create delivery options

** may have exponential number of options ** actually only need to compute canonical option! => intervals are not contained

form graph, vertices as set of options, edge weight base on matching between options

compute shortest path

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