### Optimization and Systems Theory Seminar

Friday, April 18, 2008, 11.00-12.00, Room 3721, Lindstedtsvägen 25

Fredrik Carlsson, KTH

E-mail: fcar@math.kth.se

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Utilizing Problem Structure in Optimization of Radiation Therapy

This talk summarizes my thesis, which concerns optimization approaches for
intensity-modulated radiation therapy. The first part of the talk gives an
introduction to radiation therapy with emphasis on mathematical structure and
treatment delivery aspects. The two optimization problems central to the thesis
are formulated; (i) the fluence map optimization problem and (ii) the
step-and-shoot optimization problem.
The second part of the talk is more focused on the results of the thesis.
So-called iterative regularization of the fluence map optimization problem is
first discussed. The idea is to find regular solutions by utilizing a sequential
quadratic programming method that is able to find near-optimal solutions with
non-jagged fluence profiles in few iterations. Then, a column generation
approach to the step-and-shoot optimization problem is presented. Some
properties of the approach are discussed and numerical results are provided.
Finally, the impact of extending the column generation approach by adjusting the
leaf positions of the generated multileaf collimator segments is discussed.

Calendar of seminars
*Last update: April 15, 2008 by
Marie Lundin.
*